Yangzhou Jiangsu Oilfield Ruida Petroleum Engineering Technology Development Co.,Ltd, China

1. A patented method of designing a sucker-rod pumping system with least energy consumption, Patent & Software IntroductionInventor: Zheng Haijin Yangzhou Jiangsu Oilfield Ruida Petroleum Engineering Technology Development Co.,Ltd, China 2008.4

2. Yangzhou Jiangsu Oilfield Ruida Petroleum Engineering Technology DevelopmentCo.,Ltd, China Address: No.1, Wenhui West Road, Yangzhou, Jiangsu Province, P.R.China Tel: (Technical Department) 0086-514-87761146 (Marketing Department) 0086-514-87761249 Fax: 0086-514-87761146 Email:yzruida@sina.com Http://www.yzruida.com

3. Contents • Overview • The theory of calculating the input power of a sucker-rod pumping system • Patented design method and its software for a rod pumping system with least energy consumption • Applying effects in oilfields’ Practice • Achievements and Market potential

4. I. Overview Owing to its unit’s simpleness, conveniencein operationand lower entire cost, sucker-rod pumping system is adopted in 80% oil wells all over the world. In these pumping wells, the system efficiency has been remaining low all the while, which results in a higher energy cost in oil production .

5. According to a statistical report of former CNPC in 1997, CNPC had 72047 rod-pumping oil wells ,the average system efficiency of these wells was only 26.7%, which meant that 73.3% of total energy consumption was wasted in the lifting process and resulted in serious mechanical wear. How to improve the system efficiency of pumping well had been focused on all along. Many researches had been done on mechanical innovation ,and had made some progress in this aspect.

6. Problem • By careful research, we found that, besides mechanical factor, an important reason caused low efficiency was that designed system parameters were unreasonable (it was technically executable but economically unreasonable). The key reason for this problem was lack of a theory of calculating input power of sucker-rod pumping system ,and lack of a more economical design method.

7. After several years’ research both on theory and experiments, we had founded a theory for calculating the input power of a sucker-rod pumping system ,and had set up formulas to calculate it. We also invented a method to design a rod pumping system of least input power or lowest annual cost for a target production. • It has been testified by practice that, compared with conventional designing methods, this expertise has more prominent virtue in improving efficiency of pumping system and reducing energy consumption. And also, it can remarkably reduce operating cost by prolonging the well’s TBO .

8. First stage：For the same target production ,a rod pumping system was designed on the principle of least investment . Second stage: For the same target production ,a rod pumping system was designed on the principle of lightest load. Third stage: For the same target production ,a rod pumping system is designed on the principle of least power consumption (or least input power). Design methods go through Three stage:

9. Contents • Overview • The theory of calculating the input power of a sucker-rod pumping system • Patented design method and its software for a rod pumping system with least energy consumption • Applying effects in oilfields’ Practice • Achievements and Market potential

10. 2. The theory of calculating the input power of a sucker-rod pumping system • Newly classify the components of the input power of a sucker-rod pumping system • Find out the influencing factors for each part of the input power • Bring forward functional relations of each part of the input power

11. 2.1Components of the input power Through analyzing energy consumption in lifting process, we, for the first time, bring forward that the input power of a sucker-rod pumping system should be classified into five major parts as follows: surface mechanical loss power:Psu down-hole viscous friction loss power:Pv Input power:Pin down-hole sliding friction loss power:Psl solution gas expanding power:Pex Useful power:Pu

12. 2.2 Surface mechanical loss power Definition: Surface mechanical loss power is the loss power of the pumping unit and the motor in lifting process.

13. surface mechanical loss power: influencing factors : ①motor power without load: Pd ②loads: Fup,average load of polished rod in up stroke;Fdown:average load of polished rod in down stroke; ③stroke length :s ④pumping speed :n ⑤influence coefficient of transmission power:k1 ⑥ influence coefficient of polished rod power:k2 the functional relation:

14. Cutting point

15. 2.3 Down-hole viscous friction loss power Definition: Down-hole viscous friction loss poweris the loss power caused by the friction occurred between liquid and the tubing , and between liquid and rod string in lifting process.

16. Down-hole viscous friction loss power: influencing factors:：①stroke , ② pumping speed , ③ tubing diameter , ④ rod diameter , ⑤ pump setting depth , ⑥ crude oil viscosity the functional relation:  ui：the average liquid viscosity in the i-th tubing segment li：length of the i-th tubing segment m: ratio of rod diameter to tubing diameter

17. 2.4 Down-hole sliding friction loss power Definition: Down-hole sliding friction loss poweris the loss power caused by the friction occurred ,because of well deviation, between the tubing and the rod string and between the plunger and the pump cylinder in lifting process 定义：因井斜造成的抽油杆与油管之间发生的磨擦以及泵柱塞与泵筒间发生的磨擦而损失的功率称作滑动损失功率。

18. Down-hole sliding friction loss power: influencing factors: ①pumping speed and stroke ②average rod weight of unit length ③horizontal length of inclination section ④sliding friction coefficient between rod and tubing the functional relation: fk：sliding friction coefficient between rod and tubing qrod：average rod weight of unit length Llevel：horizontal length of inclination section

19. 2.5 Solution gas expanding power Definition: In lifting process,solution gas is continuously separated from crude oil because of pressure drop in tubing. On the one hand ,this causes drop of liquid’s energy (viz. drop of intrinsic energy), on the other hand, the dropping portion of intrinsic energy is tranformed into volume expanding power which acts on the lifting system. This kind of power is called Solution gas expanding power.

20. Solution gas expanding power: influencing factors: ①daily oil production ,②saturation pressure , ③wellhead pressure ,④pump intake pressure , ⑤solution coefficient the functional relation:

21. 2.6 Influencing factors of wellhead temperature and its functional relation From the bottom of the well to wellhead, the temperature corresponding to different depth is fallen in pace with the decrease of depth. Meanwhile, oil viscosity varies with the change of temperature. The wellhead temperature needs to be determined if we want to know how much the change of temperature affects down-hole viscous friction loss power.

22. Wellhead temperature: influencing factors: ①reservoir temperature. ②surface temperature. ③liquid production.④water cut . ⑤ fluid level. ⑥solution gas expanding power the functional relation:

23. 2.7 Influencing factors of iLi and its functional relation iLi isthe accumulated total of multiplication of the length of each tubing section by the liquid viscosity in the corresponding tubing section. In order to calculate down-hole viscous friction loss power ,the value of iLi must be determined.

24. iLi influencing factors: ①reservoir temperature . ②surface temperature. ③ wax precipitation point . ④liquid production. ⑤water cut. ⑥50℃ degasified crude oil viscosity the functional relation:

25. 2.8 Useful power Influencing factors: Daily liquid production; Liquid density; Liquid lifting height; Definition: Useful power is the power needed to pump liquid production from the working fluid level to surface in lifting process.

26. 2.9 Calculating formulas of input power and system efficiency with each part of input power Pin = Pu+Psu+Psl+Pv-Pex η = Pu/ Pin = Pu/（Pu+Pv+Psu+Psl-Pex）

27. 2.10 Practical verification of the theory In order to verify the validity of the theory and its adaptability to different reservoirs, we tested the actual system input power of 428 wells of 28 reservoirs in Jiangsu oilfield, and calculated the theoretical input powers by the above formulas. Results showed that theoretical input powers matched well with the tested input powers.

28. Results of the verification • Wells tested ：428 • Total input power measured ：3362 Kw • Total input power calculated ：3327Kw • Average efficiency measured ：26.0% • Average efficiency calculated ： 26.3% • Relative error of input power：1.1%

29. Through analyzing the sensitivity of 14 variables to the input power (The 14 variables are detailed as follows: production rate, water cut, working fluid level, middle depth of oil layer, crude oil density, gas-oil ratio (GOR), saturation pressure, solution coefficient, reservoir temperature, wax precipitation point, surface temperature, 50 ℃degasified oil viscosity, oil viscosity in the oil layer, horizontal displacement of the well deviation) , it was found that the theory of calculating the input power is universally applicable to 428 wells with various production parameters in 28 reservoirs of different geophysical parameters.

30. Measured input power Calculated input power Useful power Measured efficiency Calculated efficiency relative error 133.9 138.3 39.1 29.2% 28.2% -3.2 % Measured input powers and calculated input powers in Chen 2 block

31. Measured input power Calculated input power Useful power Measured efficiency Calculated efficiency relative error 121.0 118.6 42.2 34.8% 35.5% 2.0% Measured input powers and calculated input powers in Fumin block

32. Measured input power Calculated input power Useful power Measured efficiency Calculated efficiency relative error 96.7 90.2 26.9 27.8% 29.8% 7.2% Measured input powers and calculated input powers in Hua, Lian,Ji blocks

33. Measured input power Calculated input power Useful power Measured efficiency Calculated efficiency relative error 151.5 151.2 43.2 28.5 28.6% 0.2% Measured input powers and calculated input powers in Shanian block

34. Verification by wells of Daqing Oilfield

35. Further verification had been made by applications of the new design method to about 10000 pumping wells in oilfields of China. It showed that the theory of calculating input power is universally applicable to all wells with various production parameters in different reservoirs of different geophysical parameters.

36. 2.11 Relationship between Influencing factors and losses power • rod speed (stroke × Pumping speed) • Load • No-load loss • Crude oil viscosity • Ratio of rod to tubing

37. Main ways to improve the efficiency • Slow the rod speed, namely increase plunger diameter or improve the pump’s efficiency • Reduce the load, namely reduce the weights of rods and liquid • Reduce the prime mover’s power under no load • Decrease the viscosity of oil • Increase the ratio of tubing radius to rod radius • Select favorable types of beam pumping unit and match the prime mover rationally • Reduce the weight of unit rod in deviated interval of well

38. Under same pumping depth, larger plunger diameter generally results in larger diameter of rod string, heavier fluid load and heavier rod weight. The total power loss is a decreasing function of plunger diameter, meanwhile is an increasing function of rod diameter, liquid load and rod weight. Under given working fluid level and given plunger diameter, to improve pump efficiency, it can be only realized by deepening pumping depth (or increase the submergence depth), which will undoubtedly increase load of rod string and lifted liquid, horizontal displacement of rods in deviated well. The total power loss is a decreasing function of pump efficiency , also an increasing function of rod diameter, load , pumping depth and horizontal displacement. Contradictions among various ways to improve the efficiency

39. Under different plunger diameter , different rod strings have distinct influence on pumping efficiency . Under same plunger diameter and same pumping depth, different steel grades of rod correspond to different rod string and different economic benefits

40. Contents • Overview • The theory of calculating the input power of a sucker-rod pumping system • Patented design method and its software for a rod pumping system with least energy consumption • Applying effects in oilfields’ Practice • Achievements and Market potential

41. 3、 Patented design method and its software for a rod pumping system with least energy consumption To overcome the contradictions mentioned above, we invented a method of designing pumping system parameters on principle of the lowest input power or the lowest annual cost. This design method has been granted patent. US patent No: US 6,640,896 B1 CN patent No: ZL 99 1 09780.7

42. 3.1 Design preconditions (known parameters) 9. reservoir temperature ; 10. wax precipitation point ; 11. surface temperature ; 12. 50 Celsius degasified oil viscosity; 13. oil viscosity in place ; 14. Relative parameters of well deviation 15.economical parameters 1.production rate ; 2.water cut ; 3.working fluid level 4.middle depth of oil layer ; 5. oil density ; 6.gas-oil ratio (GOR) ; 7.saturation pressure; 8.solution coefficient ;

43. 3.2 Designing outcome (parameters to be designed) • type of beam unit • type of motor • tubing diameter • pumping depth • plunger diameter • steel grade of rod-string • rod string • stroke • pumping speed

44. 3.3. Designing procedure (soluting procedure) In order to producing same target production , (1) Set the selective range of different tubing diameters, differentplunger diameters, different steel grades of rod string, differentrod strings, differentstrokes, differentpumping speeds, differentpump depths and different types of pumping unit.

45. (2)Find out all the systems or combinations of tubing diameter, steel grade of rod-string, plunger diameter, pump depth, rod-string, stroke and pumping speed , which can produce the target production. (3) Calculate respectively the input power and efficiency of each system or combination by the calculation formulas of system input power.

46. (4)From all the systems or combinations, choose the one of least input power as the result to be designed, which includes tubing diameter, steel grade of rod, plunger diameter, pump depth, rod-string, stroke, pumping speed, type of pumping unit and type of motor .

47. 3.4 Difference between the patented design method and the conventional design method ①Different design principles: Same Objective：Production Conventional method：Load , torque and pump efficiency serve as constraint conditions New method： Load, torque and input power serve as constraint conditions

48. ②Difference in parameters required for design Conventional method: Parameters needed : Result includes: 1. Liquid production 1. type of pumping unit 2. water cut 2. motor type 3. fluid level 3. tubing diameter 4. gas-oil ratio (GOR) 4. pump depth 5. crude oil viscosity 5. plunger diameter 6. middle depth of payzone 6. steel grade 7. Rod-string 8. stroke 9. pumping speed

49. The patented design method: • This patented designmethod needs 15 parameters as follows, while other conventional methods merely needs 6 ones(1-6 listed). • Parameters needed : Result includes:

50. ③Differences in system input power , efficiency and economic virtue between the patented design method and conventional design method Well name: Wei 2-6 Note: Annual cost includes energy cost and annual depreciation cost of tubing and rod string