致密岩心带压渗吸的影响因素实验研究

1)中国石油勘探开发研究院, 北京 100083; 2)中国石化石油工程技术研究院,北京 100101

油气藏开发; 致密砂岩; 带压渗吸; 低场核磁共振技术; 渗吸置换效率; 边界条件; 初始含水饱和度; 层理方向; 矿化度; 鄂尔多斯盆地

Experimental study on influencing factors for forced imbibition in tight sandstone cores
JIANG Yun1, XU Guoqing2, SHI Yang1, ZENG Xinghang2, and WANG Tianyi1

1)Research Institute of Petroleum Exploration & Development, Petro China, Beijing 100083, P.R.China2)SINOPEC Research Institute of Petroleum Engineering, Beijing 100101, P.R.China

oil and gas field development; tight sandstone; forced imbibition; low-field nuclear magnetic resonance(LF-NMR)technology; oil recovery; boundary condition; initial water saturation; bedding direction; salinity; Ordos basin

DOI: 10.3724/SP.J.1249.2020.05497

备注

为研究不同因素对于带压渗吸效果影响,结合低场核磁共振技术,开展5 MPa压差(基质外部流体压力与孔隙压力之差)作用下的致密砂岩带压渗吸实验,研究边界条件、初始含水饱和度、层理方向和矿化度等因素对带压渗吸的影响.结果表明,接触面积越大,渗吸置换效率(也称采收率)越高; 初始含水饱和度越高,渗吸置换效率越低; 沿垂直层理方向钻取的岩心样品渗吸置换效率高于平行层理方向岩心样品; 矿化度越高,渗透压差越大,渗吸置换效率越低.研究结果为深入探讨带压渗吸作用,提高致密砂岩油藏采收率的内在机理提供参考.

As to study the effect of different factors on forced imbibition(FI)in tight sandstone, FI experiments under 5 MPa pressure difference(the difference between hydraulic fluid pressure and original pore pressure)were conducted in combination with low-field nuclear magnetic resonance(LF-NMR)technology. The effects of boundary conditions, initial water saturation, bedding plane(BP)direction and fluid salinity on FI were systematically investigated. The results showed that the oil recovery(OR)was higher for cores with bigger contact area, higher initial water saturation would result in lower OR. Cores with perpendicular BP direction had higher OR than that with parallel BP direction. Less water was imbibed into cores as the salinity increased, which resulted in lower OR. The results provide reference for understanding mechanism of OR improvement in tight sandstone reservoirs, which originated from FI.

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