Continuing from the previous article, click to jump to questions 1-50! This "100 Q&A on Oil Production Basics (Part 2)" continues in a Q&A format, covering questions 51-100. These questions primarily cover oil well performance analysis, oil well operation monitoring, water injection and flooding operations, pumping unit and electric pump well maintenance, and the basic concepts and operation of Christmas trees and oil and gas transmission systems.
51. What is the comprehensive water cut?
Answer: The comprehensive water cut refers to the mass percentage of the oilfield's monthly water production to its monthly liquid production, expressed in %.
52. What is the water cut rise rate?
Answer: The water cut rise rate refers to the percentage increase in water cut per 1% of geological reserves recovered.
53. What is the water cut rise rate?
Answer: The water cut rise rate refers to the water cut rise rate over a period of time (including monthly and annual averages).
54. What data is essential for daily oil well analysis?
Answer: Daily analysis of oil wells should include two categories of data: static data and dynamic data. Static data include: (1) perforation layer, perforation thickness, effective permeability, formation coefficient. (2) Connection relationship with adjacent wells, reserves, sedimentary environment, flooding conditions, etc.
Dynamic data include: (1) liquid production, oil production, gas production, reservoir pressure, and comprehensive water content. (2) Reservoir physical properties and water quality analysis. (3) Work system analysis.
55. What is oil production rate?
Answer: Oil production rate refers to the percentage of annual oil production to the geological reserves used, in "%".
56. What is recovery rate?
Answer: Recovery rate refers to the percentage of cumulative oil production to the geological reserves used, in "%".
57. What is the main oil reservoir in Daqing Oilfield?
Answer: The main oil reservoirs in Daqing Oilfield are Sartu, Putaohua and Gaotaizi.
58. What is the production decline rate?
Answer: The production decline rate refers to the rate of change in production per unit time.
59. What is the crude oil metered delivery difference?
Answer: The crude oil metered delivery difference is the difference between the wellhead oil production and the verified import and export production at the transfer station (combined station), expressed as a percentage of the wellhead production.
60. What is the oil production index?
Answer: The oil production index is the increase in daily oil production for every 1 MPa increase in the production differential pressure.
61. What is the liquid production index?
Answer: The liquid production index is the increase in daily liquid production for every 1 MPa increase in the production differential pressure.
62. What is reservoir pressure?
Answer: Reservoir pressure refers to the pressure in the middle of the reservoir measured after the well is shut in and the pressure has returned to a stable state. The unit is megapascals (MPa).
63. What is flowing pressure?
Answer: Flowing pressure refers to the pressure in the middle of the oil layer measured during normal production of the oil well, measured in megapascals (MPa).
64. What is a dynamometer diagram?
A: It is a graph measured by specialized instruments that reflects the operating conditions of a deep-well pump. It is drawn on a coordinate graph. The area enclosed by closed lines represents the work performed by the pump during one reciprocating motion. The resulting graph is called a dynamometer diagram.
65. What is a static liquid level?
A: After the well is shut in, the liquid level in the annular space of the casing rises to a certain height and then stabilizes. The depth of the liquid level at this point is called the static liquid level.
66. What is a dynamic liquid level?
A: The dynamic liquid level refers to the liquid level in the annular space of the casing during normal production of the well.
67. How does the downhole operation process work? Answer: The workflow for downhole operations is as follows:
Preparation - Well Connection - Well Control - Wellhead Movement - Wellhead BOP Installation - Tubing Movement - Treatment - Measures - Completion Tubing - Blowout Replacement - Trial Production - Acceptance - Well Handover.
68. Why is downhole operation supervision necessary?
Answer: Downhole operation supervision facilitates the effective implementation of the operation plan, helps control operational costs, improves operational quality, and enhances economic benefits.
69. What is a polymer?
Answer: A polymer is a substance produced by the polymerization (polyaddition) reaction of a single monomer.
70. What is the working principle of a pumping unit?
Answer: Power is supplied by an electric motor, which converts the motor's high-speed rotation into low-speed motion via a reduction gear. The crank-connecting rod-walking beam mechanism converts the rotational motion into reciprocating motion, driving the deep-well pump.
71. What are the main components of a pumping unit?
A: The pumping unit primarily consists of a chassis, reduction gearbox, crankshaft, counterweight, connecting rod, crossbar, bracket, donkey head, suspension, brake, motor, and circuit control unit.
72. What is the function of the reduction gearbox in the pumping unit?
A: It converts the high-speed rotation of the motor into the low-speed rotation of the crankshaft (output shaft) through a three-axis, two-stage gear reduction system, while also supporting the crank counterweight.
73. What is a "four-point line"?
A: Draw a line from the reduction gearbox pulley and the edge of the motor pulley through the centers of the two shafts. These four points on a straight line are called a four-point line.
74. How many oil formations are there in the Daqing Oilfield?
A: There are 13 oil formations. The Sartu oil formation is divided into three oil formations: Sa I, Sa II, and Sa III; the Putaohua oil formation is divided into two oil formations: Pu I and Pu II; and the Gaotaizi oil formation is divided into four oil formations: Gao I, Gao II, Gao III, and Gao IV.
75. What type of sediment does the Daqing Oilfield belong to?
A: It belongs to the fluvial-deltaic deposits of a large continental lake basin.
76. How many levels can the oil layer characteristics of Daqing Oilfield be divided into?
A: It is divided into three levels: (1) oil layer group (2) sandstone group (3) small layer.
77. What is the anti-surge distance?
A: In order to prevent the pump piston from colliding with the fixed valve cover when descending, the sucker rod column is appropriately lifted up a distance. This distance is called the anti-surge distance.
78. What is the reason for the crank pin bearing seat to grind the crank? How to deal with it?
A: The crank pin bushing is not placed in the right position, causing the crank pin to be too tight in the crank hole, resulting in too small a gap. In this case, remove the crank pin and move the bushing outward to the appropriate position to eliminate it.
79. What is the reason for the suspension wire to deviate to the donkey head? How to deal with it?
A: The reasons include the donkey head is not made correctly, the walking beam is tilted or twisted, and the base is not installed correctly. Solutions include placing pads under the donkey head pin seat, placing pads on one side of the support platform, adjusting the base level, and aligning the walking beam.
80. What is the pump efficiency of a deep well pump?
A: The ratio of the actual fluid production of the pumping unit to the theoretical displacement of the pump is called pump efficiency.
81. What is a water injection well?
A: A well used to inject water into an oil formation is called a water injection well.
82. What is trial injection?
A: The testing and construction process of injecting water into a new well or switching an oil well to another is called trial injection.
83. What is switching injection?
A: Switching injection begins when the wellbore is clean and the water quality meets standards through drainage and well washing.
84. What is regular injection?
A: Regular injection is the injection of water into the well through the oil pipe.
85. What do the "three structural adjustments" in oil field development refer to?
A: Adjustment of the water injection structure, adjustment of the fluid production structure, and adjustment of the storage and production structure.
86. What is injection pressure differential?
A: When injecting water into an injection well, the difference between the bottomhole pressure and the formation pressure is called the injection pressure differential.
87. What is general water injection?
Answer: Injecting water at the same pressure without stratifying the sections in the injection well is called general water injection.
88. What is stratified water injection?
A: Injecting water at different pressures using a stratified water distribution string composed primarily of packers and water distributors to treat different oil formations differently is called stratified water injection.
89. What is well flushing with a water injection well?
A: Well flushing is a method of flushing out corrosion, impurities, and other sediments from the bottomhole and wellbore of an injection well to clean the bottomhole and wellbore.
90. What is water injection?
A: Water injection is the process of injecting water into an oil formation through an injection well to replenish and maintain oil formation pressure.
91. What is water injection intensity?
A: The daily water injection rate per unit effective thickness is called the water injection intensity.
92. What is the water absorption index?
A: The daily water injection rate of an injection well under a unit injection pressure differential is called the water absorption index.
93. What happens at the wellhead if the flowline is blocked?
A: The most obvious symptom is increased back pressure, increased upstream load on the pumping unit, and increased upstream current on the motor.
94. How can you tell if a well is waxing?
A: As production gradually decreases, the upstream load on the pumping unit increases, while the downstream load decreases. This increases the upstream current on the motor and also the downstream current. Lowering the rod becomes difficult, and in severe cases, the rod will not lower at all. When the backpressure gate is closed and the sampling cock is opened, small wax lumps may be found. The trapped area on the indicator diagram is larger than normal.
95. What are the complete and accurate data for an injection well?
A: Eight items: daily water injection rate, oil pressure, casing pressure, pump pressure, static pressure, testing, well cleaning, and water quality testing.
96. What are the complete data of pumping wells?
A: Oil pressure, casing pressure, current, production, crude oil water content test, indicator diagram, dynamic liquid level (flow pressure), static liquid level (static pressure).
97. What are the complete data of electric pump wells?
A: Oil pressure, casing pressure, current, production, crude oil water content test, flow pressure, dynamic liquid level, static liquid level.
98. Under what conditions should water injection wells be flushed?
A: (1) New wells must be flushed before injection (before trial injection). (2) Operation wells must be flushed as required during construction. Wells with non-flushing packers must be flushed before the packers are released. (3) Water injection wells that have been shut in for more than 15 days must be flushed before reopening. (4) Under the same pressure, when the daily water injection volume is compared with the test water volume and a significant downward trend is observed, if the pressure gauge and water meter are checked and there are no problems, the wells with flushable well cappers should be flushed in time; the wells with non-flushable well cappers should be discharged with overflow water. (5) If unqualified water is found to be injected, the well should be flushed in time.
99. What is an artificial well bottom?
A: The top surface of the cement left at the bottom of the casing after the well cementing is completed is called an artificial well bottom.
100. What are the three parts of a Christmas tree?
A: It consists of a casing head, a tubing head, and a Christmas tree body.
Dongsheng has accumulated rich experience in oil production equipment, water injection development, oilfield management, and optimization technology, and will continue to update the "100 Questions and Answers on Basic Oil Production Knowledge" to share the latest industry practices and technological achievements. Stay tuned!