Control effect of fluid entry pressure on hydrocarbon accumulation

Abstract

The micromigration of oil-drive-water and gas-drive-water in oil and gas fields was studied, by using core slices and micro-experimental technology, and the migration processes and characteristics of oil and gas in pores and throats were observed, as well as entry pressures of oil/gas migration. Research shows that entry pressures of both oil-drive-water and gas-drive-water increase obviously as porosity decreases, and the statistical regularity observes the power function variation. However, there is a complex changing relationship between porosity and different entry pressure values of the two replacement processes, forming three curve sections, each representing a different accumulation significance. When the porosity is over 10%–12%, the difference between oil-drive-water and gas-drive-water entry pressures is small. Both oil and gas can migrate and accumulate in this kind of reservoir. The probabilities of oil and gas reservoir formation are nearly equal, forming conventional oil/gas pools. When porosity is between 5% and 10%–12%, the difference between the two is obvious, which indicates that this kind of reservoir can seal oil, but can also be a reservoir for gas, easily forming unconventional hydrocarbon pools (deep-basin gas pools). When porosity is less than 5%, the difference is indistinct and the entry capillary pressures show the same sealing function for oil and gas. In this condition, both oil and gas pools are difficult to form. Experimental results give a rational explanation for the difference of accumulation probability between deep-basin gas and deep-basin oil, and also for the mechanism of tight sand acting as cap rock.

Keywords

oil/gas-drive-water / entry pressure / micro-experiment / secondary migration / hydrocarbon accumulation

References

[1] JinZ.-j., ZhangF.-qiang.. Status and major advancements in study of hydrocarbon migration [J]. Oil and Gas Geology, 2005, 26(3): 263-270

[2] JinZ.-j., ZhangY.-w., WangJie.Hydrocarbon accumulation mechanism and oil/gas distribution [M], 2003, Beijing, Petroleum Industry Press: 130-185

[3] EmmonsW. H.. Experiments on accumulation of oil in sands [J]. AAPG Bulletin, 1921, 5(1): 103-104

[4] RoofJ. G.. Snap-off of oil droplets in water-wet pores [J]. Soc Petroleum Eng, 1970, 10: 85-95

[5] ZhangJ.-c., JinZ.-jun.Accumulation and distribution of deep basin gas [M], 2005, Beijing, Petroleum Industry Press: 22-127

[6] MattaxC. C., KyteJ. R.. Imbibition oil recovery from fractured, water-drive reservoir [J]. SPE Journal, 1962, 2(6): 177-184

[7] WeidnerD. E., SchwartzL. W.. An experimental and numerical investigation of buoyancy-driven two-phase displacement [J]. Physics Fluids A, 1991, 3(9): 2076-2080

[8] MeakinP., WagnerG., VedvikA., AmundsenH., FederJ.. Invasion percolation and secondary migration: Experiments and simulations [J]. Marine and Petroleum Geology, 2000, 17(7): 777-795

[9] KangY.-s., ZhuJ.-c., ChenL.-ming.. Results of physical experiment on petroleum migration in water saturated fractured media and their geological significance [J]. Earth Science—Journal of China University of Geosciences, 2002, 27(6): 736-740

[10] KangY.-s., GuoQ.-j., ZhuJ.-c., ChenL.-m., ZengL.-bo.. Light etched physical simulation experiment on oil migration in fractured media [J]. Acta Petrolei Sinica, 2003, 24(4): 44-47

[11] KongL.-r., QuZ.-hao.. Two-phase-drive experiment in sandstone model [J]. Petroleum Exploration and Development, 1991, 18(4): 79-85

[12] JiaH.-y., QuZ.-h., KongL.-rong.. Formation scaling mechanisms for low permeability oil fields—An experimental study in sandstone pore micro-models [J]. Petroleum Exploration and Development, 1997, 24(5): 104-107

[13] ZhuY.-s., KongL.-r., QuZ.-h., SunW., LiuB.-jun.. Using the natural sandstone micromodel to study viscous instability fingering [J]. Journal of Northwest University: Science and Technology, 1998, 28(2): 166-168

[14] ZhuY.-s., QuZ.-h., KongL.-r., ChenR., LiJ.-feng.. Determination of oil reservoir wettability in two phase displacement experiment of sandrock model [J]. Oil and Gas Geology, 1999, 20(3): 220-223

[15] TangX., JinZ.-j., YangM.-h., MingH.-hui.. Experimental study on water-oil migration and accumulation in 2-D micro-model of carbonate fractures media [J]. Geological Review, 2006, 52(4): 570-576

[16] DembickiH., AndersonM. J.. Secondary migration of oil: Experiments supporting efficient movement of separate, buoyant oil phase along limited conduits [J]. AAPG Bulletin, 1989, 73(8): 1018-1021

[17] CatalanL., FuX. W., ChatzisI., FrancisA. L. D.. An experimental study of secondary oil migration [J]. AAPG Bulletin, 1992, 76(5): 638-650

[18] ZhangF.-q., LuoX.-r., MiaoS., WangW.-m., ZhouB., HuangY.-zhang.. The patterns and its effect factors of secondary hydrocarbon migration [J]. Experimental Petroleum Geology, 2003, 25(1): 69-75

[19] ShiJ.-a., SunX.-j., WangJ.-p., WangQ., WangLei.. Physical simulating experiment of natural gas migration and its characteristics of composition differentiation and carbon isotope fractionation [J]. Petroleum Geology and Experiment, 2005, 27(3): 293-298

[20] ChateneverA., CalhounJ. C.. Visual examinations of fluid behavior in porous media (Part 1) [J]. AIME Petroleum Transactions, 1952, 195: 149-156

[21] ChatzisI., DullienF. A. L.. Dynamic immiscible displacement mechanisms in pore doublets: Theory versus experiment [J]. Journal of Colloids and Interface Science, 1983, 91(1): 199-222

[22] KimberK. D., AliS. M. F.. Scaled physical modeling of steam-injection experiments[J]. Society of Petroleum Engineers Reservoir Engineering, 1991, 18(8): 467-469

[23] ThomasM. M., JamieA. C.. Scaled physical model of secondary oil migration [J]. AAPG Bulletin, 1995, 79(1): 19-29

[24] IllingV. C.. The migration of oil and natural gas [J]. J Inst Petrol, 1933, 19(4): 229-260

[25] ZengJ.-hui.. Experimental simulation of impacts of vertical heterogeneity on oil migration and accumulation in fining upwards sands [J]. Petroleum Exploration and Development, 2000, 27(4): 102-105

[26] XinR.-c., JiangZ.-x., LiS.-tian.. Physical modeling of secondary oil migration and accumulation in deltaic sandstone reservoir and its result analysis [J]. Earth Science—Journal of China University of Geosciences, 2002, 27(6): 780-782

[27] JiangZ.-x., ChenD.-x., MiaoS., ZengJ.-h., QiuN.-sheng.. Model test and mechanism interpretaion of the petroleum accumulation of lenticular sandstone in Jiyang depression [J]. Oil and Gas Geology, 2003, 24(3): 223-227

[28] ZengJ.-h., JinZ.-j., WangW.-hua.. Status and advances of the studies on the experimental simulation of secondary hydrocarbon migration and accumulation [J]. Journal of the University of Petroleum, China, 1997, 21(5): 94-97

[29] ZHANG Yi-gang, CHEN Yan-hua, LU Jia-yan. Research of hydrocarbon migration and its accumulation [M]. Nanjing: Hohai University Press, 1997: 1–40. (in Chinese)

[30] ZENG Jian-hui, JIN Zhi-jun. An experiment of hydrocarbon secondary migration and accumulation [M]. Beijing: Petroleum Industry Press, 2000: 1–20. (in Chinese)

[31] LI Ming-cheng. Migration of oil and gas [M]. Beijing: Petroleum Industry Press, 2004: 1–200. (in Chinese)

[32] QU Zhi-hao, WAN Fa-bao, KONG Ling-rong, SUN Wei. Micro pore model and its production technology of real reservoir rock: CN11048 [P]. 1995-04-05.

[33] SchowalterT. T.. Mechanics of secondary hydrocarbon migration and entrapment [J]. AAPG Bulletin, 1979, 63(5): 723-760

[34] McauliffeC. D.. Oil and gas migration-chemical and physical constraints [J]. AAPG Bulletin, 1979, 63(5): 761-781

[35] MastersJ. A.. Deep basin gas trap, western Canada [J]. AAPG Bulletin, 1979, 63(2): 152-181

[36] SpencerC. W.. Geologic aspects of tight gas reservoirs in the Rocky Mountain region [J]. Journal of Petroleum Geology, 1985, 37(7): 1308-1314

[37] LawB. E.. Basin-centered gas systems [J]. AAPG Bulletin, 2002, 86(11): 1891-1919

[38] ZhangJ.-chuan.. Source-contacting gas: Derived from deep basin gas or basin-centered gas [J]. Natural Gas Industry, 2006, 26(2): 46-48

[39] SpencerC. W.. Review of characteristics of low-permeability gas reservoirs in western United States [J]. AAPG Bulletin, 1989, 73(5): 613-629

[40] YuanZ.-w., ZhuJ.-w., WangS.-lang.. Natural gas reservoir characteristics and classification of Shahejie Formation, East Depression [J]. Atural Gas Industry, 1990, 10(3): 6-11

[41] DAI Qi-de, JI You-liang. Oil and gas reservoir geology [M]. Dongying: Petroleum University Press, 1996: 1–100. (in Chinese)

[42] JinZ.-j., ZhangJ.-chuan.. Exploration strategy for deep basin gas reservoirs [J]. Petroleum Exploration and Development, 1999, 26(1): 4-5

[43] ZhangJ.-c., JinZ.-j., ZhangY.-wei.. Definition of deep basin gas accumulation and its geological characteristics [J]. Journal of the University of Petroleum, China, 2001, 25(6): 25-28

[44] YuH.-z., ZhangL.-x., HanS.-h., ZhuG.-h., SiC.-song.. The formation of the dense sandstone cap in the well Yingnan 2, Tarim Basin [J]. Petroleum Exploration and Development, 2004, 31(5): 133-135