Experiment of complex flow in full size horizontal wells with perforated completion

PETROLEUM EXPLORATION AND DEVELOPMENT Volume 40, Issue 2, April 2013 Online English edition of the Chinese language journal Cite this article as: PETROL. EXPLOR. DEVELOP., 2013, 40(2): 236–241.

RESEARCH PAPER

Experiment of complex flow in full size horizontal wells with perforated completion WEI Jianguang1,*, WANG Xiaoqiu2, CHEN Haibo3, ZHANG Quan2 1. School of Petroleum Engineering, Northeast Petroleum University, Daqing 163318, China; 2. School of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102249, China; 3. Department of Engineering and Technology of No.3 Oil Production Company of Daging, Daqing 163113, China

Abstract: A full size perforated casing of 139.7 mm in external diameter was adopted to simulate the horizontal wellbore. The influences of perforation parameters and injection rate on the pressure drop in horizontal wells were investigated by experiments. The results show that: (1) With the increase of perforation density, perforation diameter and perforation phase, both the frictional pressure drop and the total pressure drop increase and the mixture pressure drop decreases. (2) When the mainstream Reynolds number at the perforated casing exit remains constant, with the increase of injection rate, the total pressure drop and mixing pressure drop increase. When the injection rate is less than the critical injection rate (0.05%-0.10% under the study conditions), the mixing pressure drop is less than 0. When the injection rate is greater than the critical injection rate, the mixing pressure drop is greater than 0. The acceleration pressure drop can be neglected when the injection rate is less than 0.10%, otherwise the acceleration pressure drop rises significantly with the increase of injection rate. (3) With the increase of injection rate, the proportion of frictional pressure drop to total pressure drop decreases while that of acceleration pressure drop to total pressure drop increases. When the injection rate is less than 1.00%, the proportion of mixing pressure drop to total pressure drop tends to rise with the increase of injection rate. When the injection rate is greater than 1.00%, the proportion of mixing pressure drop to total pressure drop almost remains unchanged. Key words: horizontal well; perforated completion; wellbore complex flow; pressure drop rule

Introduction Compared with ordinary pipe flow, variable mass flow in perforated completion horizontal wells is very complicated, which is shown in the following two aspects: (1) The perforations in the casing make the surface roughness increase, which in turn lead to the rise of wall frictional pressure drop. (2) The mix of the inflow from the wall and the mainstream changes the speed profile of boundary layer near the wellbore and mainstream, which leads to the change of pressure drop in the wellbore. The pressure drop of complex flow in horizontal wellbores is the basis for performance prediction, trajectory design, optimization of well completion parameters and the selection of inflow control methods of horizontal wells[1−4]. Therefore, many scholars from home and abroad have conducted some in-depth experimental researches [5−18] on the pressure drop of single phase flow, but these researches have three deficiencies: (1) All these experiments adopt small-size experimental well section to simulate the horizontal wellbore according to analogue principle, which can not achieve the combination of geometric similarity, kinematic similitude and

dynamic similarity and have some disparity with the actual production; (2) Most scholars used Plexiglas pipes to simulate the horizontal wellbore and water as experimental fluid, which can not reflect the actual production conditions; (3) They did not provide the effect of perforation density, perforation diameter and perforation phase on various pressure drop in detail systematically. In this paper, a full size perforated horizontal pipe of 139.7 mm in external diameter is adopted to simulate the actual production. The influences of the perforation parameters (perforation density, perforation diameter, and perforation phase) and flux ratio on the pressure drop in horizontal wellbores are investigated by experimental simulation, which provides scientific basis for the establishment of the pressure drop model of perforated horizontal wellbore.

1

Experiment

The experiment system designed to simulate complex flow in perforated horizontal wellbores (Fig.1) is composed of three parts: Simulation unit, fluid supply and control unit, data collection and analysis unit.

Received date: 09 Jun. 2012; Revised date: 25 Nov. 2012. * Corresponding author. E-mail: [email protected] Foundation item: Supported by the National Science and Technology Major Project of China (2011ZX05009-005). Copyright © 2013, Research Institute of Petroleum Exploration and Development, PetroChina. Published by Elsevier BV. All rights reserved.

WEI Jianguang et al. / Petroleum Exploration and Development, 2013, 40(2): 236–241

Fig. 1 bores

Experiment system for complex flow in horizontal well-

The experimental well section (Fig.2) in the simulating part adopts a casing (124.0 mm in inner diameter, 139.7 mm in external diameter) and an outer casing pipe (149.1 mm in inner diameter, 190.5 mm in external diameter). The casing annulus is wrapped with tight gauze. This unit is 6.5 m long and the distance between two pressure monitoring points is 6 m. To improve the accuracy of the pressure difference transmitter, the pressure monitoring points are connected with difference pressure transmitter by soft transparent plastic pipes. The accuracy of the pressure difference transmitter is at the order of 1 Pa. At each end of this unit there is a liquid inlet to ensure the inflow profile uniform (one is on the upside; the other is on the down side). White oil with viscosity of 10 mPa⋅s instead of crude oil is used in the experiment. Before each experiment, the indoor temperature and viscosity of the white oil are measured to make sure the temperature and viscosity remain the same. Three kinds of perforation phase in the simulating unit are considered: 45° perforation in helix distribution (Fig.3), 90° perforation in helix distribution (Fig.4) and 180° perforation in helix distribution (Fig.5). Three kinds of perforation density are respectively 8 shots per meter, 16 shots per meter and 24 shots per meter. The perforation diameters are respectively 10mm, 20mm and 30 mm. The Reynolds number of mainstream is designed between 1 000 and 20 000, which corresponds to the flow range of 90 to 1 850 m3/d. The flux ratio is designed from 0.01% to 10.00%. The frictional pressure drop and the total pressure drop of perforated casing can be measured in the designed experi-

Fig. 3

45° screw perforating phasing

Fig. 4

90° screw perforating phasing

Fig. 5

180° screw perforating phasing

mental system. Pressure difference between the two monitoring points in the simulation unit is referred to as frictional pressure drop without inflow from the wall. The pressure difference between two monitoring points in the simulation unit is referred to as the total pressure drop with inflow from the wall. After the frictional pressure drop and total pressure having been measured, the acceleration pressure drop can be calculated according to momentum conservation law. The mixing pressure drop can be calculated by subtracting the frictional pressure drop and the acceleration pressure drop from total pressure drop.

2

Experimental results analysis

2.1 Effect of perforation parameter on frictional pressure drop Fig. 2

Simulation unit diagram

The relationship between the wall frictional pressure drop gradient of perforated casing and mainstream Reynolds num− 237 −

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ber is shown respectively from Fig.6 to Fig.8 without inflow from the wall, at different perforation density (perforation diameter of 20 mm, the perforation phase of 90°), different perforation diameter (perforation density of 16 shots per meter, the perforation phase of 90°) and different perforation phase (perforation density of 16 shots per meter, the perforation diameter of 20 mm). As shown from Fig.6 to Fig.8, the perforation density, as well as the perforation diameter and perforation phase, has significant impact on the wall frictional pressure drop of the perforated casing. With the increase of perforation density, perforation diameter and perforation phase, the wall frictional

Fig. 6 Frictional pressure drop gradient versus Re at different perforation densities without inflow

Fig. 7 Frictional pressure drop gradient versus Re at different perforation diameters without inflow

Fig. 8 Frictional pressure drop gradient versus Re at different perforation phases without inflow

pressure drop of the perforated casing increases. In addition, the frictional pressure drop of perforated casing is greater than that of ordinary casing under the condition of no inflow from the wall, indicating the perforations in the casing increase the surface roughness, which results in the increase of wall frictional pressure drop. 2.2 Effect of perforation parameters on total pressure drop when the mainstream Reynolds number at the perforated casing exit is 5 000, the relationship between the total pressure drop gradient of perforated casing and the flux ratio is shown respectively from Fig.9 to Fig.11 at different perforation densities (perforation diameter of 20 mm, perforation phase of 90°), different perforation diameter (perforation density 16 holes per meter, perforation phase 90°) and different perforation phase (the perforation density 16 holes per meter, the perforation diameter 20 mm). As shown from Fig.9 to Fig.11, with the increase of perforation density, perforation diameter and perforation phase, the total pressure drop of the perforated casing increases. In addition, when the mainstream Reynolds number at the perforated casing exit remains the same, the total pressure drop of the perforated casing increases with the increase of flux ratio.

Fig. 9 Total pressure drop gradient versus flux ratio at different perforation densities with inflow

Fig. 10 Total pressure drop gradient versus flux ratio at different perforation diameters with inflow

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Fig. 11 Total pressure drop gradient versus flux ratio at different perforation phases with inflow

2.3 Effect of perforation parameters on mixing pressure drop When the mainstream Reynolds number at the perforated casing exit is 5 000, the relationship between the mixing pressure drop gradient of perforated casing and the flux ratio is shown respectively from Fig.12 to Fig.14 at different perforation densities (perforation diameter of 20 mm, perforation phase of 90°), different perforation diameter (perforation density of 16 holes per meter, perforation phase of 90°) and different perforation phase (the perforation density 16 holes per

Fig. 14 Mixing pressure drop gradient versus flux ratio at different perforation phases with inflow

meter, the perforation diameter 20 mm). As shown from Fig.12 to Fig.14, with the increase of perforation density, perforation diameter and perforation phase, the mixing pressure drop of the perforated casing decreases. In addition, when the mainstream Reynolds number at the perforated casing exit remains the same, the mixing pressure drop of perforated casing increases with the increase of flux ratio. The result shows that there is a critical flux ratio. When the flux ratio is less than the critical value, the mixing pressure drop of the perforated casing is less than 0, which indicates that inflow from the wall reduces the total pressure drop of the perforated casing. When the flux ratio is greater than the critical value, the mixing pressure drop of the perforated casing is greater than 0, which indicates that inflow from the wall increases the total pressure drop of the perforated casing. The critical flux ratio mainly depends on perforation density and perforation diameter. The critical flux ratio goes up with the increase of perforation density and perforation diameter. 2.4

Fig. 12 Mixing pressure drop gradient versus flux ratio at different perforation densities with inflow

Fig. 13 Mixing pressure drop gradient versus flux ratio at different perforation diameters with inflow

Effect of flux ratio on various pressure drops

When the mainstream Reynolds number at the perforated casing exit is respectively 5 000 and 15 000, the relationship between the total pressure drop gradient, frictional pressure drop gradient, mixing pressure drop gradient, acceleration pressure drop gradient of perforated casing and the flux ratio are shown respectively in Fig.15 and Fig.16. We can see that the acceleration pressure drop can be neglected when the flux ratio is less than 0.10% under the above mainstream Reynolds number values. When the flux ratio is greater than 0.10%, the acceleration pressure drop rises obviously with the increase of flux ratio. In addition, the acceleration pressure is affected by the mainstream Reynolds number at the perforated casing exit. The acceleration pressure drop is close to frictional pressure drop when the mainstream Reynolds number is 5 000 and the flux ratio is 10.00%, while the acceleration pressure drop is greater than the frictional pressure drop when the mainstream Reynolds number is 15 000 and the flux ratio is 10.00%. When the mainstream Reynolds number at the perforated casing exit is respectively 5 000 and15 000, the relationship

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Fig. 15 Pressure drop gradient versus flux ratio with Re of mainstream at 5 000

Fig. 16 Pressure drop gradient versus flux ratio with Re of mainstream at 15 000

between the proportion of frictional pressure drop, mixing pressure drop, acceleration pressure drop to the total pressure drop and the flux ratio are shown in Fig.17. We can see: (1) The proportion of frictional pressure drop to the total pressure drop decreases with the increase of flux ratio, while the proportion of acceleration pressure drop increases with the

Fig. 17 Proportion of various pressure drop to the total pressure drop

increase of flux ratio; (2) When the flux ratio is less than 1.00%, the proportion of mixing pressure drop to total pressure drop increases with the increase of flux ratio. When the flux ratio is greater than 1.00%, the proportion of mixing pressure drop to total pressure drop almost remains the same (15% or so); (3) When the flux ratio is less than 0.10%, the proportion of frictional pressure drop to total pressure drop is around 97% at the mainstream Reynolds number of 5 000 and 15 000 respectively. The mixing pressure drop and acceleration pressure drop can be neglected; (4) When the flux ratio is less than 1.00%, the proportion of frictional pressure drop, mixing pressure drop and acceleration pressure drop is not affected by the mainstream Reynolds number.

3

Conclusions

An experiment system is designed to simulate complex flow in perforated horizontal wellbores. A full size perforated horizontal pipe with external diameter of 139.7 mm and white oil of 10 mPa⋅s in viscosity are used in the experiment to simulate the actual production. The effects of perforation parameters on frictional pressure drop, mixing pressure drop and total pressure drop are investigated in this paper. The results show that with the increase of perforation density, perforation diameter and perforation phase, the frictional pressure drop and total pressure drop of perforated casing increase while the mixing pressure drop decreases. The effects of flux ratio on various pressure drops are investigated. The results show that (1) When the mainstream Reynolds number at the perforated casing exit remains the same, with the increase of flux ratio, the total pressure drop and mixing pressure drop increase. When the flux ratio is less than the critical flux ratio (0.05% to 0.10%, under the experiment conditions), the mixing pressure drop is less than 0, which indicates the inflow from the wall reduces the total pressure drop. When the flux ratio is greater than the critical flux ratio, the mixing pressure drop is greater than 0, which indicates that the inflow from the wall increases the total pressure drop. When the flux ratio is less than 0.10%, the acceleration pressure drop can be neglected. When the flux ratio is greater than 0.10%, the acceleration pressure drop increases significantly with the increase of flux ratio; (2) With the increase of flux ratio, the proportion of frictional pressure drop to total pressure drop decreases while the acceleration pressure drop to total pressure drop increases. When the injection ratio is less than 1.00%, the proportion of the mixing pressure drop to total pressure drop increases with the increase of flux ratio. When the flux ratio is greater than 1.00%, the proportion of mixing pressure drop to total pressure drop almost remains the same. When the flux ratio from the wall is less than 0.10%, the proportion of frictional pressure drop to total pressure drop is around 97%, which indicates the mixing pressure drop and acceleration pressure drop can be neglected. When the flux ratio from the wall is less than 1.00%, the proportions of

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frictional pressure drop, mixing pressure drop and acceleration pressure drop to the total pressure drop are hardly affected by the mainstream Reynolds number.

[10] Yuan H, Sarica C, Brill J P. Effect of perforation density on

References

[11] Yuan H. Investigation of single phase liquid flow behavior in

wells. SPE Production & Facilities, 1995, 10(4): 249–256. single phase liquid flow behavior in horizontal wells. SPE 37109, 1996. horizontal wells. Tulsa: The University of Tulsa, 1997.

[1]

Zeng Xiaojing, Tong Dengke. An improvement of the design

[12] Yuan H, Sarica C, Brill J P. Effect of completion geometry and

method of optimal horizontal wellbore length. Petroleum Ex-

phasing on single-phase liquid flow behavior in horizontal

ploration and Development, 2011, 38(2): 216–220. [2]

Asheim H, Kolnes J, Oudeman P. A flow resistance correlation for completed wellbore. Journal of Petroleum Science and Engineering, 1992, 8(2): 97–104.

[3]

Zhou Shengtian, Zhang Qi, Li Mingzhong, et al. Experimental study on variable mass fluid flow in horizontal wells. Journal of the University of Petroleum, China: Natural Science Edition, 1998, 22(5): 53–55.

[4]

Zhang Shiming, Zhou Yingjie, Song Yong, et al. Design optimization for the horizontal well pattern with herringbone-like laterals. Petroleum Exploration and Development, 2011, 38(5): 606–612.

[5]

Su Z, Gudmundsson J S. Friction factor of perforation rough-

[7]

Su Z, Gudmundsson J S. Pressure drop in perforated pipes:

of single-phase and two-phase fluid flow in horizontal wells. SPE 46221, 1998. [15] Pang Wei, Chen Dechun, Zhang Zhongping, et al. Segmentally variable density perforation optimization model for horizontal wells in heterogeneous reservoirs. Petroleum Exploration and Development, 2012, 39(2): 214–221. [16] Zhou Shengtian, Zhang Qi, Li Mingzhong, et al. The advances on the variable mass flow in horizontal wells. Advances in [17] Wang Zhiming, Zhang Songjie, Xue Liang, et al. Pressure drop of variable mass flow in perforation completion of hori-

Ihara M, Brill J P, Shoham O. Experimental and theoretical

zontal wellbore. Oil Drilling & Production Technology, 2007, 29(3): 4–7. [18] Wang Zhiming, Xiao Jingnan, Wang Xiaoqiu, et al. Experi-

24766, 1992.

[9]

[14] Ouyang L B, Petalas N, Arbabi S, et al. An experimental study

experiments and analysis. SPE 28800, 1994. investigation of two-phase flow in horizontal wells. SPE [8]

zontal wells. Stanford: Stanford University, 1998.

Mechanics, 2002, 32(1): 119–127.

ness in pipes. SPE 26521, 1993. [6]

wells. SPE 48937, 1998. [13] Ouyang L B. Single phase and multiphase fluid flow in hori-

Ihara M, Shimizu N. Effect of accelerational pressure drop in

mental study for pressure drop of variable mass flow in hori-

a horizontal wellbore. SPE 26519, 1993.

zontal well. Journal of Experiments in Fluid Mechanics, 2011,

Ihara M, Yanai K, Takao S. Two-phase flow in horizontal

25(5): 26–29.

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