Physical Properties and Seepage Characteristics of Unconsolidated Sandstone under Re-Compaction
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摘要: 疏松砂岩油藏在开发过程中由于地层压力下降会对储层产生损害,影响油井产能,需要对储层再压实作用下的物性及油水两相的渗流特性进行研究。首先采用储层压力条件下的连续测试方法,以恒定的驱动流速、变化内压的方式测试了储层岩心在再压实作用下的物性,从宏观角度分析了疏松砂岩再压实作用下的物性变化规律;再通过压实作用下的压汞试验,从微观角度阐述了疏松砂岩的孔隙结构演化特征;最后通过压实作用下储层岩心的油水流动试验,分析了压实作用下油水两相的渗流特性。疏松砂岩的渗透率随着再压实作用增强持续降低,降幅达53%左右,在孔隙度约降低7%时,岩石中相当大部分孔隙在压实作用下蜕变成喉道,孔喉体积比由1.50增至1.96,峰值对应孔径降至压实前的50%,造成渗透率下降幅度远超过孔隙度下降幅度;随着再压实作用增强,油、水两相的渗透率约降低50%,残余油饱和度由17.8%增至19.2%,束缚水饱和度由18.5%增至21.2%。研究结果表明,随着再压实作用增强,疏松砂岩的孔隙和喉道均被压缩,导致储层物性变差,而孔隙度的降幅相对较小,渗透率呈幂函数下降,降幅明显且在地层压力恢复过程中无法恢复;束缚水饱和度和残余油饱和度随有效应力增加呈指数上升,油相渗透率随有效应力增大呈线性下降,这就是在注水不及时或注水不足的区域油井产能大幅度降低的主要原因。Abstract: The formation pressure of unconsolidated sandstone reservoir drops in the development process which damages the reservoir and affect oil well productivity. It is necessary to study the physical properties and seepage characteristics of unconsolidated sandstone under re-compaction. First, a continuous testing method was adopted to measure the physical property of pay zone core under re-compaction in the way of constant driven flow rate and variable inner pressure, the variation laws of physical properties of unconsolidated sandstone under compaction were discussed at the macroscopic level. Then the evolution characteristics of the pore structure were further elaborated under compaction from microscopic point of view through mercury penetration experiment. Finally, the seepage feature under compaction was studied by the fluid variation experiment. The permeability of unconsolidated sandstone was reduced continuously with the enhancement of re-compaction, which represented a decline of 53%. When the porosity was reduced 7% or so, a majority of the pore was transformed into pore throats under compaction, the pore-throat volume ratio increased from 1.5 to 1.96, and the pore radius corresponding to peak value reduced to 50% of the original value, which caused the permeability to decline permeability more than the porosity. With the continuous compaction, oil-water two phase permeability reduced to nearly 50%, the residual oil saturation increased from 17.8% to 19.2% and irreducible water saturation increased from 18.5% to 21.2%.The research results show that with the increase of compaction, the pore and throat of unconsolidated sandstone are all compressed, leading to poor reservoir physical properties, and while the porosity drops slightly, the permeability drops in a power function, and the permeability was not recovered in the process of formation pressure recovery. Irreducible water saturation and residual oil saturation increase exponentially with the increase of effective stress, and oil phase permeability is linear downward with the increase of effective stress. Consequentely, this is the cause of decrease of oil well productivity due to insufficient water injection or injection water delay.
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Keywords:
- unconsolidated sandstone /
- compaction /
- permeability /
- porosity /
- seepage characteristics
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[1] 贺玉龙,杨立中.围压升降过程中岩体渗透率变化特性的试验研究[J].岩石力学与工程学报,2004, 23(3):415-419. He Yulong, Yang Lizhong. Testing study on variational characteristics of rockmass permeability under loading-unloading of confining pressure[J]. Chinese Journal of Rock Mechanics and Engineering, 2004, 23(3): 415-419. [2] 刘均一,邱正松,黄维安,等.不同渗透率储层应力敏感性试验对比[J].中国石油大学学报:自然科学版,2014, 38(2):86-91. Liu Junyi, Qiu Zhengsong, Huang Weian, et al. Experimental study on stress sensitivity in reservoirs with different permeability[J]. Journal of China University of Petroleum: Edition of Natural Science, 2014, 38(2): 86-91. [3] Gray D H, Fatt I, Bergamini G. The effect of stress on permeability of sandstone cores[R].SPE 531, 1963.
[4] 杨沛,陈勉,侯冰,等.裂缝性和基质性碳酸盐岩在堵漏前后的应力敏感性研究[J].石油钻探技术,2011, 39(6):31-34. Yang Pei, Chen Mian, Hou Bing, et al. The study of stress sensitivity for fractured and matrix carbonate rocks before and after sealing[J]. Petroleum Driling Techniques, 2011, 39(6): 31-34. [5] Houseknecht D W.压实作用和胶结作用对砂岩孔隙度降低之相对重要性的评估[J].海洋地质译丛,1988, 71(6):53-60. Houseknecht D W. The relative importance of compaction and cementation to sandstone porosity decrease[J]. Marine Geology Translations, 1988, 71(6): 53-60. [6] Schutjens P M T M, de Ruig H, van Muster J G, et al. Production-induced compaction of the Brent Field: an experimental approach[R]. SPE 28096,1996.
[7] Morita N, Whitfill D L, Nygaard D, et al. A quick method to determine subsidence reservoir compaction and in-situ stress induced by reservoir depletion[R]. SPE 17150,1989.
[8] 刘国勇,刘阳,张刘平.压实作用对砂岩储层物性的影响[J].西安石油大学学报:自然科学版,2006, 21(4):24-28, 41. Liu Guoyong, Liu Yang, Zhang Liuping. Experimental study on the effects of compaction on the properties of sandstone reservoir[J]. Journal of Xi’an Shiyou University:Natural Science Edition, 2006, 21(4): 24-28, 41. [9] 刘国勇,金之钧,张刘平.碎屑岩成岩压实作用模拟实验研究[J].沉积学报,2006, 24(3):407-413. Liu Guoyong, Jin Zhijun, Zhang Liuping. Simulation study on clastic rock diagenetic compaction[J]. Acta Sedimentologica Sinica, 2006, 24(3):407-413. [10] 张建国,程远方.砂拱及其稳定模型的推导及验证[J].石油钻探技术,1999, 27(1):40-42. Zhang Jianguo, Cheng Yuanfang. Sand arch stability model and its verification[J]. Petroleum Drilling Techniques, 1999, 27(1): 40-42. [11] 孙峰,薛世峰,葛洪魁,等.疏松砂岩应力损害分析评价[J].石油钻探技术,2008, 36(5):47-50. Sun Feng, Xue Shifeng, Ge Hongkui, et al. Numerical simulation of stress-induced wellbore damage in unconsolidated sandstone reservoirs[J]. Petroleum Driling Techniques, 2008, 36(5): 47-50. [12] 陈学国.三维地层压力预测方法及应用研究[J].石油钻探技术,2005, 33(3):13-15. Chen Xueguo. Technology and application of 3D formation pressure prediction[J]. Petroleum Drilling Techniques, 2005, 33(3): 13-15. [13] SY/T 5336—2006 岩心分析法[S]. SY/T 5336—2006 Practices for core analysis[S]. [14] SY/T 6385—1999 覆压下岩石孔隙度和渗透率测定方法[S]. SY/T 6385—1999 The porosity and permeability measurement of core in net confining stress[S]. [15 ] 路保平,张传进,秦红祥,等.岩石力学三轴应力测试系统及其应用[J].石油钻探技术,1995, 23(4):42-46, 61-62. Lu Baoping, Zhang Chuanjin, Qin Hongxiang, et al. Rock mechanics triaxial stress testing system and its application[J]. Petroleum Drilling Techniques, 1995, 23(4): 42-46, 61-62. [16] 路保平,鲍洪志.岩石力学参数求取方法进展[J].石油钻探技术,2005, 33(5):44-47. Lu Baoping, Bao Hongzhi. Advances in calculation methods for rock mechanics parameters[J]. Petroleum Drilling Techniques, 2005, 33(5): 44-47. [17] 路保平,张传进.岩石力学在油气开发中的应用前景分析[J].石油钻探技术,2000, 28(1):7-9. Lu Baoping, Zhang Chuanjin. Analysis of apllications of rock mechanics in oil gas development[J]. Petroleum Drilling Techniques, 2000, 28(1): 7-9. [18] 马文国,王影,海明月,等.压汞法研究岩心孔隙结构特征[J].实验技术与管理,2013, 30(1):66-69. Ma Wenguo, Wang Ying, Hai Mingyue, et al. Research of pore structure characteristics of cores based on mercury penetration experiments[J]. Experimental Technology and Management, 2013, 30(1): 66-69. [19] SY/T 5345—2007 岩石中两相相对渗透率测定方法[S]. SY/T 5345—2007 The determination method of two-phase relative permeability in rock[S]. [20] Ali H S, Al-Marhoun M A, Abu-Khamsin S A, et al. The effect of overburden pressure on relative permeability[R].SPE 15730, 1987.
[21] Guo Xiao, Ma Jing, Li Jiudi, et al. Effect of reservoir temperature and pressure on relative permeability[R]. SPE 158055, 2012.
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