Technology of drilling oil and gas wells. Features of water well drilling technology
ÓÄÊ 622.24:622.143(075.8) ÁÁÊ 33.131
Ð å ö å í ç å í ò û:
Department of Oil and Gas Production, Kuban State Technological University; Dr. Tech. science prof. A.T. Koshelev; ä-ð òåõí. íàók ïrô. G.T. Vartumyan
Bulatov A.I., Proselkov Yu.M., Shamanov S.A.
B 90 Technique and technology of drilling oil and gas wells: Textbook. for universities. − M.: Nedra-Business Center LLC, 2003. − 1007 p.: ill.
ISBN 5-8365-0130-0
The issues of modern technology for drilling oil and gas wells, including directional and horizontal ones, are covered. Drill bits and drill heads, drill pipes, turbo drills, screw drills and electric drills, their operating conditions and drilling modes are described. The characteristics and composition of modern complete drilling rigs, the functional purpose and design of the component equipment are given. Particular attention is paid to special equipment for offshore well drilling. The background information necessary for engineering calculations is presented. Some methods of technological and technical calculations are considered.
For students of oil and gas universities and faculties.
Preface........................................................ ........................................................ .................................... |
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PART 1. TECHNOLOGY FOR DRILLING OIL AND GAS WELLS................................... |
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Chapter 1. Fundamentals of oil and gas field geology.................................................... ........................ |
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1.1. Composition of the earth's crust................................................... ........................................................ ............... |
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1.2. Geochronology of rocks.................................................................... ........................................................ ... |
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1.3. Sedimentary rocks and forms of their occurrence.................................................... ................... |
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1.4. Formation of oil and gas deposits.................................................... ........................................... |
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1.5. Physico-chemical properties of oil and gas.................................................... ................................ |
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1.6. Search and exploration of oil and gas fields.................................................... .................... |
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1.7. Drawing up a geological section of the well.................................................... .................... |
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1.8. Composition and mineralization of groundwater.................................................... ................................... |
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1.9. Well research......................................................... ........................................................ ...... |
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Chapter 2. General concepts about well construction.................................................... ........................ |
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2.1. Basic concepts and definitions......................................................... ........................................... |
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2.2. Geological substantiation of the location and design of the well as |
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engineering structure........................................................ ........................................................ .............. |
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2.3. Installation of equipment for well construction................................................................. ................ |
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2.4. Drilling the wellbore................................................................... ........................................................ ..... |
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2.5. Drill bits........................................................ ........................................................ ........................... |
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2.6. Drill string................................................... ........................................................ .................... |
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2.7. Bit drive................................................... ........................................................ ............................ |
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2.8. Peculiarities of drilling wells in offshore areas.................................................... ........................ |
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2.9. Well casing and formation isolation................................................................. ............................... |
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Chapter 3. Mechanical properties of rocks.................................................... ............................... |
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3.1. General provisions................................................... ........................................................ .................... |
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3.2. Mechanical and abrasive properties of rocks.................................................... ............. |
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3.3. The influence of confining pressure, temperature and water saturation on some |
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properties of rocks........................................................ ........................................................ .................... |
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Chapter 4. Drill bits.................................................... ........................................................ .................... |
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4.1. Roller bits................................................................ ........................................................ ............. |
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4.2. Kinematics and dynamics of roller bits.................................................... ............................ |
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4.3. Diamond bits................................................... ........................................................ ........................ |
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4.4. Blade bits................................................... ........................................................ ...................... |
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Chapter 5. Operation of the drill string.................................................... ................................................... |
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5.1. Physical model of the drill string................................................................. ........................................ |
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5.2. Stability of the drill string...................................................... ............................................ |
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5.3. Stresses and loads in drill string pipes.................................................... ............ |
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Chapter 6. Flushing wells.................................................... ........................................................ ............. |
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6.1. Terms and Definitions............................................... ........................................................ ............ |
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6.2. Functions of the well cleaning process.................................................... .................................... |
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6.3. Requirements for drilling fluids.................................................................... ........................................... |
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6.4. Drilling fluids................................................................... ........................................... |
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6.5. Preparation and cleaning of drilling fluids.................................................... ........................ |
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6.6. Technology of chemical treatment of drilling fluid.................................................... ......... |
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6.7. Hydraulic calculation of well flushing with incompressible fluid.................................... |
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6.8. Methods for disposal of spent drilling fluids and drill cuttings.................................... |
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6.9. Methods for neutralizing spent drilling fluids and cuttings.................................... |
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Chapter 7. Complications during drilling, their prevention and control.................................... |
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7.1. Classification of complications........................................................ ........................................................ ... |
7.2. Destruction of the well walls................................................................... ........................................................ . |
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7.3. Absorption of liquids in wells.................................................... ........................................ |
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7.4. Gas, oil and water shows................................................... ........................................................ ...... |
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7.5. Sticking, tightening and landing of pipe strings.................................................... ............................ |
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Chapter 8. Drilling modes.................................................... ........................................................ ............. |
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8.1. Introductory concepts........................................................ ........................................................ ....................... |
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8.2. Influence of various factors on the drilling process................................................... ............. |
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8.3. The influence of differential and oppressive pressure on the destruction of rocks |
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breeds........................................................ ........................................................ ........................................................ |
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8.4. Rational drilling of bits................................................................. ........................................................ |
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8.5. Design of drilling modes................................................................... ........................................... |
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8.6. Cleaning a well being drilled from sludge.................................................... ........................................ |
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Chapter 9. Drilling directional and horizontal wells.................................... |
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9.1. Goals and objectives of directional drilling .................................................................... ...................... |
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9.2. Basics of directional well design................................................................... ............... |
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9.3. Factors determining the well bottom trajectory.................................................................. .......... |
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9.4. Downhole assemblies for drilling directional wells.................................................... . |
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9.5. Methods and devices for monitoring well trajectories.................................................... ............. |
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9.6. Features of drilling and navigation of horizontal wells.................................................... |
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Chapter 10. Opening and drilling of productive formations.................................................... ......... |
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10.1. Drilling out the productive formation................................................................... ...................................... |
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10.2. Technological factors ensuring drilling and opening of productive |
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formation........................................................ ........................................................ ................................................... |
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10.3. Change in permeability of the near-wellbore formation zone. Drilling fluids for |
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well completion................................................................ ........................................................ .................... |
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10.4. Sampling of formations and testing of wells during drilling.................................... |
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Chapter 11. Well designs. Filters........................................................ ................................... |
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11.1. Fundamentals of well design.................................................................... ............... |
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11.2. Well bottom structures................................................................... ........................................................ |
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Chapter 12. Well casing and formation isolation.................................................... .................... |
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12.1. Wellbore preparation................................................................... ........................................................ |
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12.2. Technology of fastening wells with casing columns.................................................... ....... |
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12.3. Grouting cements and mortars.................................................... ......................................... |
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12.4. Calculation of well cementing................................................................... ............................................ |
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Chapter 13. Secondary opening of productive formations, triggering the influx of oil (gas) and |
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well development................................................................ ........................................................ ............................ |
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13.1. Bullet perforation................................................... ........................................................ .............. |
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13.2. Cumulative perforation................................................... ........................................................ .... |
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13.3. Perforation due to depression on the formation.................................................... ....................................... |
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13.4. Perforation during repression of the formation.................................................... ...................................... |
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13.5. Special solutions for well perforation................................................................. ................ |
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13.6. Buffer separators................................................... ........................................................ .......... |
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13.7. Technology for filling a well with a special liquid.................................................... |
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13.8. Inducing inflow by replacing fluid in the production casing................................. |
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13.9. Calling inflow using an air cushion.................................................... .................... |
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13.10. Calling inflow using release valves.................................................... ........ |
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13.11. Calling inflow using jet devices.................................................... ............... |
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13.12. Interval reduction of fluid level in the well.................................................... .. |
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13.13. Reducing the fluid level in a well by pistoning (swabbing) ................. |
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13.14. Inducing inflow from the reservoir using the aeration method.................................................... ........................... |
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13.15. Decrease in fluid level in a well under conditions of abnormally low formation |
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th pressure................................................ ........................................................ ........................................ |
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13.16. Inducing inflow from the formation using two-phase foams.................................................... .. |
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13.17. Technology for inducing inflow from the formation using foams using ejectors............ |
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13.18. Inducing formation inflow using test tool kits..... |
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13.19. Application of gaseous agents for well development. Well development |
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nitrogen........................................................ ........................................................ ................................................... |
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PART 2. TECHNIQUES FOR DRILLING OIL AND GAS WELLS................................................... |
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Chapter 14. Drilling rigs.................................................... ........................................................ .......... |
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14.1. Requirements for drilling rigs.................................................................... ............. |
14.2. Classification and characteristics of installations.................................................. ....................... |
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14.3. Complete drilling rigs for production and deep exploration |
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th drilling........................................ ........................................................ ........................................... |
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14.4. Selecting the type and main parameters of the drilling rig.................................................... ...... |
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14.5. Selecting the diagram and layout of the drilling rig equipment.................................................. |
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14.6. Requirements for the kinematic diagram of the drilling rig.................................................... .... |
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14.7. Drilling rigs manufactured by OJSC "Uralmashzavod"................................................... ...... |
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14.8. Drilling rigs manufactured by JSC Volgograd Drilling Equipment Plant...... |
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Chapter 15. Lifting and hoisting complex.................................................... ............................................ |
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15.1. The process of raising and lowering columns. Functions of the complex................................................... . |
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15.2. Kinematic diagram of the complex for open-air training.................................................... ........................... |
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15.3. Traveling system........................................................ ........................................................ ....................... |
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15.4. Selection of steel ropes for hoisting systems.................................................... ........................... |
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15.5. Crown blocks and traveling blocks.................................................... ........................................................ .... |
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15.6. Drilling hooks and hook blocks.................................................... ................................................... |
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15.7. Traveling mechanisms of drilling rigs of OJSC "Uralmashzavod" .................................................... |
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15.8. Traveling mechanisms of VZBT drilling rigs.................................................... ....................... |
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15.9. Drilling rigs................................................... ........................................................ ....................... |
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15.10. Drilling drawworks................................................... ........................................................ .................... |
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15.11. Drilling drawworks brake systems.................................................................... ........................................ |
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15.12. Volume of hoisting operations................................................................... ...................................... |
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15.13. Kinematics of the lifting mechanism................................................... .................................... |
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15.14. Dynamics of the lifting mechanism................................................... ......................................... |
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Chapter 16. Well flushing system equipment.................................................... ................... |
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16.1. Mud pumps......................................................... ........................................................ ....................... |
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16.2. Manifold........................................................ ........................................................ ............................... |
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16.3. Swivel................................................. ........................................................ .................................... |
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Chapter 17. Surface circulation system.................................................... ...................... |
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17.1. Parameters and completeness of circulation systems.................................................... ........ |
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17.2. Circulation system blocks................................................................... ............................................... |
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17.3. Mixers........................................................ ........................................................ .................... |
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17.4. Equipment for cleaning drilling mud from cuttings.................................................... ...... |
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17.5. Degassers for drilling fluids.................................................................... ......................................... |
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17.6. Installation for processing drilling fluid based on a centrifuge.................................... |
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17.7. Suction lines for mud pumps................................................................. ............................ |
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Chapter 18. Rock cutting tools: drill bits, drill heads, |
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expanders, calibrators................................................... ........................................................ ............ |
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18.1. Roller bits................................................................ ........................................................ ............... |
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18.2. Blade bits................................................... ........................................................ .................... |
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18.3. Milling bits................................................... ........................................................ ................... |
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18.4. ISM bits................................................... ........................................................ ............................ |
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18.5. Diamond bits................................................... ........................................................ ...................... |
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18.6. Roller drill bits................................................................... ........................................... |
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18.7. Blade and milling carbide drill heads.................................................. |
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18.8. Diamond drill heads and ISM drill heads.................................................... .... |
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18.9. Core pick-up tool................................................... ........................................................ . |
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18.10. Extenders........................................................ ........................................................ ........................... |
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18.11. Calibrators-centralizers................................................................... ........................................................ ..... |
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Chapter 19. Drill pipes. Calculation of drill strings................................................................... ............ |
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19.1. Leading drill pipes................................................................... ........................................................ ..... |
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19.2. Drill pipes with upset ends and couplings for them.................................................... .. |
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19.3. Locks for drill pipes with upset ends.................................................... ............ |
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19.4. Drill pipes with welded joints.................................................... ........................... |
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19.5. Light alloy drill pipes................................................................... ........................................... |
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19.6. Drill collars................................................................... ........................................... |
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19.7. Subs for drill strings................................................................... ....................................... |
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19.8. General principles and methods for calculating the arrangement of drill pipes in a string.......... |
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Chapter 20. Bit drive: drilling rotors, downhole motors.................................................... .... |
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20.1. Drilling rotors................................................... ........................................................ ...................... |
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20.2. Turbodrills........................................................ ........................................................ ............................... |
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20.3. Screw motors................................................................... ................................................... |
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20.4. Turboprop downhole motors.................................................................... ....................................... |
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20.5. Electric drills........................................................ ........................................................ ........................... |
Chapter 21. Wellhead equipment of wells being drilled.................................................... ............... |
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21.1. Column heads................................................... ........................................................ ................... |
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21.2 Anti-blowout equipment.................................................... ........................................... |
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Chapter 22. Casing pipes. Calculation of casing columns................................................... ............. |
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22.1. Casing pipes and couplings for them................................................... ................................................... |
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22.2. Calculation of casing columns................................................... ........................................................ ......... |
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Chapter 23. Power drive of the drilling complex.................................................... ............................... |
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23.1. Types of drives, their characteristics................................................................. ......................................... |
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23.2. Selection of power drive motors................................................................. ...................................... |
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23.3. Means of artificial adaptability for drives.................................................... |
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23.4. Couplings........................................................ ........................................................ ...................................... |
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23.5. Drilling rig chain drives.................................................................... .................................... |
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23.6. Power units and engines of modern drilling rigs.................................... |
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23.7. Layout of power drives and transmissions.................................................... .................... |
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Chapter 24. Equipment for mechanization and automation of technological processes |
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processes........................................................ ........................................................ ........................................... |
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24.1. Automation of bit feed................................................................... ........................................................ |
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24.2. Automation of descent and ascent (ASP)................................................... ....................................... |
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24.3. Automatic stationary drill wrench................................................................. ...................... |
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24.4. Pneumatic wedge grip................................................................... ........................................... |
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24.5. Auxiliary winch................................................... ........................................................ ....... |
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Chapter 25. Equipment for drilling oil and gas wells at sea.................................... |
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25.1. Features of the development of offshore oil and gas fields.................................... |
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25.2. The main types of technical means for the development of offshore oil and gas fields |
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deposits........................................................ ........................................................ ................................ |
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25.3. Floating drilling equipment (FDR) .................................................... ............................................ |
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25.4. Self-elevating floating drilling rigs (jack-up rigs) .................................................... .......... |
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25.5. Semi-submersible floating drilling rigs (SSDR) .................................................... .......... |
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25.6. Drilling ships (DS) .................................................... ........................................................ ...................... |
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25.7. Drilling derricks for PBS.................................................... ........................................................ ......... |
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25.8. Subsea wellhead equipment................................................................... ......................................... |
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25.9. Systems for holding floating drilling equipment at the drilling point.................................... |
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25.10. Offshore Fixed Platforms (MSP)............................................................ ........................... |
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25.11. Environmental protection during offshore drilling.................................................... ............... |
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Bibliography................................................ ........................................................ ........................... |
PREFACE
“Technique and technology for drilling oil and gas wells” is one of the special disciplines that determine the profile of an engineer for machinery and equipment in oil and gas fields. The purpose of teaching the discipline is to give students knowledge of the technology of drilling oil and gas wells and to introduce them to the equipment that ensures the implementation of all technological processes and operations under drilling conditions. This knowledge is necessary for a mechanical engineer when designing, installing and operating drilling rigs, individual equipment for them, devices, components and fixtures, and performing repair work.
The development of the oil and gas industry involves the widespread use of drilling operations to search, explore and develop oil and gas fields. Drilling of oil and gas wells, as a branch of the oil and gas industry, must be constantly improved, especially in connection with the increasing volume of work on deep and ultra-deep drilling, including in offshore areas, as well as the growing needs for drilling directional and horizontal wells.
The program of the discipline “Engineering and technology of drilling oil and gas wells” provides for the study of all components of the well construction cycle, starting with the concept of wells, their classification, designs, the technical means and technological operations used for destroying rocks and drilling a shaft, and ending with the processes of opening and testing productive horizons, securing wells with casing strings and separating layers with cementing materials, development and testing of wells. In addition, due attention is paid to drilling rigs and their associated equipment. Particular attention is paid to special drilling rigs designed for drilling wells in offshore areas.
There are no textbooks that fully satisfy the requirements of the discipline program. There is educational literature for certain sections of the program, but, unfortunately, many of its materials are outdated, since they have not been updated for at least the last 15 years.
The presented book is intended to fill these gaps in the educational literature and present educational material on drilling oil and gas wells in its modern understanding. It consists of two parts: the first part is devoted to the technology of drilling oil and gas wells, the second - to the technology for constructing these wells, drilling tools and underground equipment. A separate chapter is devoted to special equipment for offshore drilling, which is successfully developing as one of the branches of the oil and gas industry and for which specialization in the training of a mechanical engineer is possible. This location
The presentation of the educational material is logical, since technology determines the requirements for drilling equipment and tools for constructing wells.
A mechanical engineer must be able to perform calculations necessary both in the design and operation of drilling equipment. Therefore, the textbook is sufficiently rich in the simplest calculation methods and reference and information material.
At the end of the book there is a list of the main literature used by the authors. This literature is also recommended for a more in-depth study of the technology and technique of drilling oil and gas wells.
The textbook covers all processes and operations performed when drilling wells, including in difficult geological conditions; contains reference information necessary for technological calculations; it describes drilling rigs, their constituent drilling equipment, rock-cutting tools, drilling and casing pipes; The technical characteristics of equipment and tools necessary for their selection for specific conditions of well construction are given. In this regard, the textbook is universal and therefore can be successfully used in the educational process when training specialists in other specialties in the oil and gas field, the curriculum of which includes the study of the discipline “Drilling of oil and gas wells.”
To successfully study the material of the discipline, students need knowledge in mathematics, physics, chemistry, fluid mechanics, thermodynamics, theoretical and applied mechanics, strength of materials and materials science, as well as the basics of oil and gas engineering.
1 TECHNOLOGY FOR OIL AND GAS DRILLING
PART OF WELLS
1 BASICS OF OIL AND GAS FIELD CHAPTER OF GEOLOGY
Geological information is the basis for solving almost all issues of designing well construction and managing drilling processes. The characteristics of the rocks and formation fluids penetrated by the well largely determine the choice of bits, drilling fluid, methods of opening productive horizons, securing the walls of the well and isolating layers. For offshore drilling, information about hydrometeorological conditions, as well as characteristics of sea depths, sea waves, tides, sea currents, wind, and ice conditions are of great importance.
1.1. COMPOSITION OF THE EARTH'S CRUST
Geology is the science of the composition, structure and history of the Earth. It is assumed that the Earth consists of several distinguishable
shells: lithosphere 50−70 km thick; mantle to a depth of 2900 km; cores in the depth range 2900−6380 km. Above the lithosphere there is a water shell - the hydrosphere, and above - a gas shell - the atmosphere. The lithosphere is composed of rocks, the basis of which is various minerals - natural substances, approximately homogeneous in chemical composition and physical properties, resulting from physical and chemical processes.
Classification of rocks by origin:
A. Igneous (igneous) - crystalline rocks formed as a result of the solidification of molten matter (magma).
B. Sedimentary - rocks composed of tiny pieces of various minerals, often cemented together, containing the remains of animal and plant organisms. According to the method of accumulation in
The earth's crust is divided into mechanical sediments, rocks of chemical and mixed origin.
Mechanical sediments are the result of denudation processes of solar-wind-water destruction and the transfer of sediments of igneous rocks (boulders, pebbles, gravel). Chemical rocks (and some classified as sedimentary rocks) were formed through chemical reactions and the accumulation of complex salts (rock salt, anhydride, gypsum) on the earth's surface. Rocks of mixed origin include clastic material, substances of organic and chemical origin (limestone, chalk, clay, sand, sandstone).
B. Metamorphic rocks are secondary melted sedimentary and igneous rocks as a result of their immersion in the molten part of the Earth (quartzites, marbles, schists, gneisses).
1.2. GEOCHRONOLOGY OF ROCKS
To determine the historical and geological patterns of rock accumulation and the formation of the Earth as a planet, a stratigraphic scale is used, on the basis of which a geochronological table is compiled, reflecting the location in a certain sequence of conventional time periods of the formation of the earth’s crust (Table 1.1).
Ò à á è ö à 1.1
Geochronological table
Cenozoic |
chertvertichny (an- |
Holocene |
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tropogenic) |
Pleistocene |
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Neogene |
Pliocene |
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Miocene |
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Paleogene |
Oligocene |
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Eocene |
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Paleocene |
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Mesozoic |
Late Cretaceous |
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Early Cretaceous |
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Late Jurassic |
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Middle Jurassic |
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Early Jurassic |
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Triassic |
Late Triassic |
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Middle Triassic |
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Early Triassic |
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Paleozoic |
Permian |
Late Permian |
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Early Permian |
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Coal |
Late Carboniferous |
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Middle Carboniferous |
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Early Carboniferous |
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Devonian |
Late Devonian |
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Middle Devonian |
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Early Devonian |
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Silurian |
Late Silurian |
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Early Silurian |
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Ordovician |
Late Ordovician |
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Middle Ordovician |
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Early Ordovician |
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Proterozoic |
Late Proterozoic- |
Vendian |
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Late Riphean |
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Middle Riphean |
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Early Riphean |
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Middle Proterozoic- |
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Early Proterozoic |
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Archean |
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1.3. SEDIMENTARY ROCKS AND THEIR OCCUPATION FORMS
The main feature of sedimentary rocks is their layering, i.e. accumulation in the form of more or less homogeneous layers (layers). The surface limiting the layer from above is called the roof, and the surface limiting the layer from below is called the bottom.
The roof of the underlying layer is at the same time the base of the overlying one, and the base of the overlying one is the roof of the underlying one. The initially formed layers lay almost horizontally, but as a result of subsequent deformation of the earth’s crust, the shape of the occurrence often changed to a significantly inclined or even vertical one.
The formation is characterized by the thickness and angle of incidence at a given point in a specific direction (Fig. 1.1). Distinguish between true (shortest dis-
Rice. 1.1. Inclined fold-shaped strata:
АА – horizontal power; ÀÄ – vertical power; ÀÑ – true power
Rice. 1.2. Monocline
Mining is the extraction of natural resources from the depths of the earth. The development of solid minerals is carried out by quarry or mine method. Wells are drilled to extract liquid and gaseous natural resources. Modern well drilling technologies make it possible to develop oil and gas fields at depths of over 12,000 meters.
The importance of hydrocarbon production in the modern world is difficult to overestimate. Fuel (see) and oils are made from oil, and rubbers are synthesized. The petrochemical industry produces household plastics, dyes and detergents. For oil and gas exporting countries, fees on the sale of hydrocarbons abroad is a significant and often the main method of replenishing the budget.
Field exploration, installation of drilling rigs
At the proposed location of mineral deposits, a geological survey is carried out and a location for a research well is determined. Within a radius of 50 meters from the exploration well, the site is leveled and a drilling rig is installed. The diameter of the research well is 70-150 mm. During the drilling process, samples of drill cuttings are taken from different depths for subsequent geological survey. Modern complexes for geological research make it possible to accurately answer the question of whether it is worth starting the extraction of energy resources through this well on an industrial scale.
When a geological study of drill cuttings shows the prospects for industrial development, construction of a drilling site begins. The previously cleared area is concreted and fenced, and a grader road is laid (a road without a hard surface). On the created one, they build a tower, install a winch, mud pumps, install a generator and everything necessary. The assembled equipment is tested, gradually brought to planned capacity, and put into operation.
The most commonly used technology mechanical well drilling, which is carried out in a rotational, impact or combined way. The drill is attached to a square drill string and lowered into the well using a traveling system. A rotor located above the wellhead transmits rotational motion to the drill.
As the well is drilled, the drill string is expanded. Simultaneously with the process of drilling a production well, work on flushing the well is carried out using special pumps. To flush the well from particles of destroyed rock, a flushing liquid is used, which can be process water, an aqueous suspension, clay solutions or hydrocarbon-based solutions. After pumping the drilling fluid into special containers, it is cleaned and used again. In addition to cleaning the bottom of the drill cuttings, flushing fluids provide drill cooling, reduce friction of the drill string against the borehole walls and prevent collapse.
At the final stage of drilling, the production well is cemented.
There are two cementing methods:
- Direct method– the solution is pumped into the drill string and forced into the annulus.
- Reverse method– the solution is pumped into the annulus from the surface.
A number of specialized machines and mechanisms are used for drilling wells. On the way to the design depth, there are often sections of rock with increased hardness. To pass them, you have to put additional load on the drill string, so quite serious requirements are placed on production equipment.
Drilling rig equipment is not cheap and is designed for long-term use. If production stops due to a breakdown of any mechanism, you will have to wait for a replacement, which will seriously reduce the profitability of the enterprise. Equipment and mechanisms for hydrocarbon production must be made of high-quality and wear-resistant materials.
The drilling platform equipment can be divided into three parts:
- Drilling part– drill and drill string.
- Power part– rotor and traveling system, providing rotation of the drill string and tripping manipulations.
- Auxiliary part– generators, pumps, tanks.
The uninterrupted operation of the drilling rig depends on the correct operation of the equipment and maintenance of the mechanisms within the time limits prescribed by the manufacturer. It is equally important to change consumable parts in a timely manner, even if in appearance everything is fine with them. Without compliance with operating rules, it is impossible to guarantee the safety of drilling platform personnel, prevention of environmental pollution and uninterrupted oil or gas production.
Methods for drilling production wells
Methods of drilling wells are divided depending on the method of influencing the rock.
Mechanical:
- Shock.
- Rotational.
- Combined.
Non-mechanical:
- Hydraulic fracturing.
- High temperature exposure.
- Detonation.
It is worth noting that the main drilling method is rotary and rotary-impact; other methods are rarely used in practice.
Drilling is the impact of special equipment on soil layers, as a result of which a well is formed in the ground through which valuable resources will be extracted. The process of drilling oil wells is carried out in different directions of work, which depend on the location of the soil or rock formation: it can be horizontal, vertical or inclined.
As a result of the work, a cylindrical void in the form of a straight trunk, or well, is formed in the ground. Its diameter may vary depending on the purpose, but it is always less than the length parameter. The beginning of the well is located on the soil surface. The walls are called the trunk, and the bottom of the well is called the bottom.
Key milestones
If medium and light equipment can be used for water wells, then only heavy equipment can be used for drilling an oil well. The drilling process can only be carried out using special equipment.
The process itself is divided into the following stages:
- Delivery of equipment to the site where the work will be carried out.
- The actual drilling of the mine. The process includes several works, one of which is deepening the shaft, which occurs through regular washing and further destruction of the rock.
- To prevent the wellbore from being destroyed and clogging it, the rock layers are strengthened. For this purpose, a special column of interconnected pipes is laid into the space. The space between the pipe and the rock is fixed with cement mortar: this work is called plugging.
- The last job is mastery. The last layer of rock is opened there, a bottom-hole zone is formed, and the mine is perforated and fluid is drained.
Site preparation
To organize the process of drilling an oil well, it will also be necessary to carry out a preparatory stage. If development is carried out in a forest area, it is required, in addition to completing basic documentation, to obtain consent for the work from the forestry enterprise. Preparation of the site itself includes the following steps:
- Cutting down trees on the site.
- Dividing the zone into separate parts of the land.
- Drawing up a work plan.
- Creation of a settlement to house the workforce.
- Preparing the foundation for a drilling station.
- Carrying out markings at the work site.
- Creation of foundations for the installation of tanks in a warehouse with flammable materials.
- Arrangement of warehouses, delivery and debugging of equipment.
After this, it is necessary to begin preparing the equipment directly for drilling oil wells. This stage includes the following processes:
- Installation and testing of equipment.
- Wiring lines for power supply.
- Installation of bases and auxiliary elements for the tower.
- Installing the tower and raising it to the desired height.
- Debugging of all equipment.
When the equipment for drilling oil wells is ready for operation, it is necessary to obtain a conclusion from a special commission that the equipment is in good condition and ready for work, and the personnel have sufficient knowledge of safety rules for this kind of production. When checking, it is clarified whether the lighting devices have the correct design (they must have an explosion-resistant casing), and whether lighting with a voltage of 12V is installed along the depth of the shaft. Remarks regarding performance and safety must be taken into account in advance.
Before starting work on drilling a well, it is necessary to install a pit, bring in pipes to strengthen the drill shaft, a bit, small special equipment for auxiliary work, casing pipes, instruments for measurements during drilling, provide water supply and resolve other issues.
The drilling site contains accommodation facilities for workers, technical premises, a laboratory building for analyzing soil samples and the results obtained, warehouses for equipment and small working tools, as well as medical care and safety equipment.
Features of drilling an oil well
After installation, the processes of re-equipping the traveling system begin: during this work, equipment is installed, and small mechanical means are tested. Installing the mast opens the process of drilling into the soil; the direction should not diverge from the axial center of the tower.
After the alignment is completed, a well is created according to the direction: this process means installing a pipe to strengthen the trunk and filling the initial part with cement. After setting the direction, the alignment between the tower itself and the rotor axes is adjusted again.
Drilling for a hole is carried out in the center of the trunk, and during the work, casing is done using pipes. When drilling a pit, a turbo drill is used; to adjust the rotation speed, it is necessary to hold it with a rope, which is fixed on the tower itself, and physically held by the other part.
A couple of days before the launch of the drilling rig, when the preparatory stage has passed, a conference is held with the participation of members of the administration: technologists, geologists, engineers, drillers. Issues discussed at the conference include the following:
- Layout of strata in an oil field: a layer of clay, a layer of sandstone with water carriers, a layer of oil deposits.
- Design features of the well.
- Rock composition at the research and development site.
- Taking into account possible difficulties and complicating factors that may arise when drilling an oil well in a particular case.
- Review and analysis of the standard map.
- Consideration of issues related to trouble-free wiring.
Documents and equipment: basic requirements
The process of drilling an oil well can begin only after a number of documents have been completed. These include the following:
- Permission to start operating the drilling site.
- Map of standards.
- Journal on drilling fluids.
- Journal on ensuring labor safety at work.
- Accounting for the functioning of diesel engines.
- Shift log.
To the main mechanical equipment and consumables that are used in the process of drilling a well, The following types include:
- Equipment for cementing, the cement mortar itself.
- Safety equipment.
- Logging mechanisms.
- Process water.
- Reagents for various purposes.
- Water for drinking.
- Pipes for casing and actual drilling.
- Helicopter site.
Well types
In the process of drilling an oil well, a shaft is formed in the rock, which is checked for the presence of oil or gas by perforating the shaft, which stimulates the influx of the desired substance from the productive area. After this, the drilling equipment is dismantled, the well is sealed indicating the start and end dates of drilling, and then the garbage is removed and the metal parts are disposed of. At the beginning of the process, the trunk diameter is up to 90 cm, and by the end it rarely reaches 16.5 cm. During the work, the construction of a well is done in several stages:
- Deepening the bottom of a well, for which drilling equipment is used: it crushes the rock.
- Removing debris from the mine.
- Secure the trunk using pipes and cement.
- Work during which the resulting fault is examined and productive locations of oil are identified.
- Descent of depth and its cementing.
Wells can vary in depth and are divided into the following types:
- Small (up to 1500 meters).
- Medium (up to 4500 meters).
- Deep (up to 6000 meters).
- Ultra-deep (more than 6000 meters).
Drilling a well involves crushing a solid rock formation with a chisel. The resulting parts are removed by washing with a special solution; The depth of the mine becomes greater when the entire face area is destroyed.
Problems during oil drilling
While drilling wells, you may encounter a number of technical problems that will slow down or make work almost impossible. These include the following phenomena:
- Destruction of the trunk, collapses.
- Discharge of liquid into the soil for flushing (removing parts of rock).
- Emergency conditions of equipment or mine.
- Errors in drilling the barrel.
Most often, wall collapses occur due to the fact that the rock has an unstable structure. A sign of a collapse is increased pressure, greater viscosity of the fluid used for flushing, as well as an increased number of pieces of rock that come to the surface.
Liquid absorption most often occurs when the underlying formation completely absorbs the solution. Its porous system or high degree of absorbency contributes to this phenomenon.
During the process of drilling a well, the projectile, which moves clockwise, reaches the bottom and rises back. The drilling of the well reaches the bedrock formations, into which cutting up to 1.5 meters occurs. To prevent the well from being washed out, a pipe is immersed at the beginning, which also serves as a means of carrying the flushing solution directly into the trench.
The drill bit, as well as the spindle, can rotate at different speeds and frequencies; this indicator depends on what types of rocks need to be punched and what diameter of the crown will be formed. The speed is controlled by a regulator, which regulates the level of load on the bit used for drilling. During the work, the necessary pressure is created, which is exerted on the walls of the face and the cutters of the projectile itself.
Well drilling design
Before starting the process of creating an oil well, a project is drawn up in the form of a drawing, which outlines the following aspects:
- Properties of the discovered rocks (resistance to destruction, hardness, degree of water content).
- The depth of the well, its angle of inclination.
- The diameter of the shaft at the end: this is important to determine the extent to which it is affected by the hardness of the rock.
- Well drilling method.
Designing an oil well must begin with determining the depth, the final diameter of the shaft itself, as well as the level of drilling and design features. Geological analysis allows us to resolve these issues, regardless of the type of well.
Drilling methods
The process of creating a well for oil production can be carried out in several ways:
- Shock-rope method.
- Work using rotary mechanisms.
- Drilling a well using a downhole motor.
- Turbine type drilling.
- Drilling a well using a screw motor.
- Drilling a well using an electric drill.
The first method is one of the most well-known and proven methods, and in this case the shaft is pierced with chisel blows, which are carried out at certain intervals. The blows are made through the influence of the weight of the chisel and the weighted rod. The lifting of the equipment occurs due to the balancer of the drilling equipment.
Working with rotary equipment is based on the rotation of the mechanism using a rotor, which is placed at the wellhead through drilling pipes that perform the function of a shaft. Drilling small wells is done through the participation of a spindle motor in the process. The rotary drive is connected to a cardan and a winch: this device allows you to control the speed at which the shafts rotate.
Drilling with a turbine is carried out by transmitting rotating torque to the column from a motor. The same method allows you to transfer hydraulic energy. With this method, only one energy supply channel operates at the level before the face.
A turbo drill is a special mechanism that converts hydraulic energy in solution pressure into mechanical energy, which ensures rotation.
The process of drilling an oil well consists of lowering and lifting the column into the shaft, as well as holding it suspended. A column is a prefabricated structure made of pipes that are connected to each other using special locks. The main task is to transfer different types of energy to the bit. In this way, movement is carried out, leading to the deepening and development of the well.
Based on the method of impact on rocks, a distinction is made between mechanical and non-mechanical drilling. During mechanical drilling, the drilling tool directly affects the rock, destroying it, and during non-mechanical drilling, destruction occurs without direct contact with the rock from the source of impact on it. Non-mechanical methods (hydraulic, thermal, electrophysical) are under development and are not currently used for drilling oil and gas wells.
Mechanical drilling methods are divided into impact and rotary.
In percussion drilling, rocks are destroyed by a bit suspended on a rope. The drilling tool also includes a hammer rod and a rope lock. It is suspended on a rope, which is thrown over a block mounted on a mast (not shown).
Currently, shock drilling is not used in our country when drilling oil and gas wells.
Oil and gas wells are constructed using the rotary drilling method. With this method, rocks are not crushed by impacts, but are destroyed by a rotating bit, which is subject to an axial load. Torque is transmitted to the bit or from the surface from the rotator (rotor) through the drill pipe string (rotary drilling) or from a downhole motor (turbo drill, electric drill, screw motor) installed directly above the bit.
A turbodrill is a hydraulic turbine driven into rotation by means of flushing fluid injected into the well. An electric drill is an electric motor protected from liquid penetration, power to which is supplied via a cable from the surface. A screw motor is a type of downhole hydraulic machine in which a screw mechanism is used to convert the energy of the flushing fluid flow into mechanical energy of rotational motion.
Based on the nature of rock destruction at the bottom, a distinction is made between continuous and core drilling. During continuous drilling, rock destruction occurs over the entire face area. Core drilling involves the destruction of rocks only along the ring in order to extract a core - a cylindrical sample of rocks along the entire or part of the length of the well. Using core selection, the properties, composition and structure of rocks, as well as the composition and properties of the fluid saturating the rock, are studied.
A well is a mine working with a circular cross-section, drilled from the surface of the earth or from an underground working without human access to the face at any angle to the horizon, the diameter of which is much less than its depth. Wells are drilled using special drilling equipment
There are vertical, horizontal, and inclined wells. The beginning of the well is called its mouth, the bottom is called the bottom, and the inner side surface is called the walls. Well diameters range from 25 mm to 3 m. Wells can have sidetracks (SB), including horizontal ones (BGS)
Drill wells are distinguished by purpose: mapping, reference, structural, prospecting, exploration, production, geotechnological and engineering (mining, ventilation, drainage, barrage, blasting, etc.).
Gas well is a well that is drilled into a gas-bearing horizon and is used to extract gas and gas condensate.
An oil well is a well that is drilled into an oil-bearing horizon, or most often an oil-and-gas bearing horizon, and is used only to extract oil. The well cannot be used for gas production - this is due to the design of the well itself, and most importantly - the specifics of preparing oil for transportation; gas is cleaned and dried before transportation in accordance with SNiP, TU and other regulatory documents.
The decision to build your own water intake facility on the site is justified by several reasons, including:
- lack of centralized water supply;
- the desire to have a source of water with increased quality without treatment with chlorinating compounds;
- there is a great need for water for watering the garden - at current prices for life-giving moisture from the water supply network, running a household plot becomes an expensive pleasure, sometimes simply unprofitable.
Regardless of whether the work will be carried out by a third party or independently, the technology for drilling water wells should be as familiar as possible. This will help to avoid deception by performers and unnecessary costs for the implementation of the plan.
The choice of method depends on several factors:
- Availability of water on site. To a first approximation, this can be determined by observations of the environment; there are a number of signs indicating its presence or absence. You can also make several experiments with different objects to get an answer to this question.
- Characteristics of soil composition typical for a given area, which determines the choice of drilling method. Such data can be obtained from a local hydrogeological organization, where you also need to clarify your own forecast estimates for the presence of water in the area.
- Depth of upper-water (sand) layers and assessment of the depth of artesian (limestone) aquifers.
If such data is available, we can conclude that it is preferable to use one or another drilling technology.
Varieties of methods for passing well bores
Rotary drilling
Fig.3. Rotary well drilling toolTypically used in oil exploration drilling. Recently, with an increase in the need for wells, it is also used in the construction of water intakes.
A feature of the method is its high energy consumption and its applicability on heavy or especially heavy soils with the inclusion of rock formations, as well as on solid limestone.
When rotating, the rotor destroys the rock, which is carried to the surface by the washing solution. It also contains cement. As a result, part of the site will be hopelessly damaged. In addition, upon completion of work, such a well requires long-term flushing with clean water to remove cement, which is part of the solution, from the pores of the rock.
For a small suburban area, such technology seems undesirable.
Hydraulic drilling
This is the easiest technology for drilling water wells. During the work, the soil inside the casing is washed away, which lowers under its own weight. Only at the beginning of the process, when the casing is still light, do you have to resort to turning it with a special wrench.
Fig.4. Drilling with soil erosion under pressure To implement this method you will need:
- two pumps, one of them capable of supplying liquid under a pressure of at least 6 atm, the second - for pumping waste water back into the tank, corresponding to the performance;
- tank; capacity depends on the planned size and depth of the well and is calculated from the ratio:
V = Robs 2 (cm) x 3.14x H(cm), Where
V – tank volume,
R – internal radius of the casing,
3.14 – PI number.
So, for a well with a diameter of 273 mm (the maximum possible diameter of the wellbore using this drilling method), the internal diameter of the casing will be 260 mm (radius 13 cm), the estimated well depth is 15 meters (15,000 cm), the required tank volume will be:
13 2 x 3.14 x 1500 = 756000 (cm 3) = 756 (liters).
Considering that it is impossible to work if there is no water in the tank, we assume the required tank capacity is 2 cubic meters. This expense will not become a burden, since proper use of the site involves the use of an intermediate heating tank in the garden watering system.
- hydraulic monitor - a hose with a metal pipe at the end. The outlet hole of which should be about 20 mm.
The process runs as follows:
- Drilling is carried out with a garden drill, the diameter of which is 30 - 40 mm larger than the diameter of the casing pipe. The depth of the preliminary hole is about 1.5 meters.
- Installing the first section of casing into the drilled hole.
- The hydraulic monitor is inserted into the casing hole and water is supplied under pressure. In this case, the casing pipe must be rotated around its axis, promoting its subsidence as the soil is washed away.
- As the shaft deepens, flushing is periodically paused to install the next section of casing.
- Water is pumped out as it accumulates, discharging the liquid back into the tank.
The disadvantage of this method is its applicability only on sandy and sandy loam soils, and there is also a limitation on the depth of the well. As a rule, they are no deeper than 12 - 15 meters, in rare cases they reach 20.
Impact method
The technology of drilling water wells using the impact method is one of the most ancient methods, used back in ancient China. It consists of the following:
- A pit with a depth of about 1.5 meters and dimensions of 1.5 - 1.5 meters is opened.
- Drilling is being carried out to install the first section of casing pipe up to 2 meters deep.
- A drilling derrick is installed - a tripod with a height of at least 3 meters. The height of the drilling rig depends on the length of the casing sections; their maximum size is 6 meters.
Rice. 5. Homemade percussion drilling rig The impact part, suspended on a cable from a winch, is inserted into the hole in the casing and released into free fall. When it hits the ground, it actively destroys it and it, in crushed form, gets inside the impact part (made from a pipe). The end of the striker has teeth cut and set apart like on a saw.
There is a valve installed inside the striker that allows loose soil to enter, but prevents it from spilling out during the next ascent. When passing through wet clay layers, a hammer is used without additional devices (a glass); the wet clay holds well in it due to adhesion to the walls. After traveling a distance of about a meter, the firing pin must be removed from the barrel and its cavity cleaned.
In the arsenal of professional drillers, the number of modifications of impactors reaches 10 types or more. Various designs are used to pass through soils with different properties. Thus, a wide selection of tools allows you to pass through almost any soil, except for rocks. The quality of the wells remains the highest. Therefore, although not productive, impact punching technology remains the most popular.
Auger drilling
This technology for drilling a well under water is becoming increasingly popular due to its high productivity and ease of implementation.
In essence, this is drilling with a rotating tool, in which the cutting part destroys the soil in the direction of movement, and the spiral auger carries it out. About 40–50% of the soil is brought to the surface, the rest is used to compact the walls. Thus, it is possible to drill without simultaneously casing the walls. The casing is lowered into the hole after drilling is completed.
Fig.6. Auger drill This method has certain disadvantages that do not allow it to be used on sandy and other loose soils, as well as a limitation on the depth of the tables to 50 meters. Further deepening is carried out with periodic removal of the working tool for cleaning.
Drilling is done using a wide variety of equipment, and often done manually for wells to high water. Thus, the industry has mastered and produced various miniature drilling rigs, with the help of which boreholes are drilled to a depth of up to 50 meters in light and medium-heavy soils, excluding sandy ones.
Such equipment is actively used for arranging water intakes in suburban areas; often there is no need to purchase it, but can be rented.
At the same time, powerful artesian wells with high flow rates are produced using equally powerful drilling rigs.
Fig.7. Drilling rig for industrial drilling Perforation drilling
It is made by driving the “spear” with a headstock or a barbell. It is used, as a rule, to equip Abyssinian wells with a hand pump for pumping out water. The limited diameter of the well allows the work to be completed independently and in a short period of time.
In addition to the described methods, which are the most popular in practice, many techniques are used that combine the features of various methods.