川南地区龙马溪组页岩储层水接触角及其稳定性影响因素

针对页岩储层水接触角随时间变化特征不清且影响因素不明的问题,通过开展水接触角实验,探讨页岩储层水接触角及其稳定性的影响因素。研究结果表明:页岩水接触角与时间呈指数变化关系;页岩干样穿层水接触角主要受TOC含量影响,石英影响次之,且页岩干样穿层稳定性指数(CASI)主要受黏土矿物含量影响,TOC影响次之;流体与页岩相互作用会影响页岩表面性质,饱和流体后页岩垂直层理面的表面性质更加均质,平行层理面的非均质性增强。最后提出不同层理方向下与不同的流体饱和实验环境中页岩接触角稳定性指数预测公式。该研究对明确页岩储层中油气运移规律具有一定的指导作用。

Water Contact Angle and Its Stability Influencing Factors of Shale Reservoirs in Longmaxi Formation,Southern Sichuan

In response to the problems that the characteristics that water contact angle in shale reservoirs changes over time are unclear and the influencing factors are unknown, water contact angle experiments were conducted to analyze the influencing factors of water contact angle and its stability in shale reservoirs. The results of the study showed that the water contact angle of shale varied exponentially with time; the inter-bed water contact angle of the dry shale sample penetration was mainly affected by the TOC content, followed by quartz, and the inter-bed stability index (CASI) of dry shale sample was mainly affected by the clay mineral content, followed by TOC; the fluid-shale interaction affected the shale surface properties, and the surface properties of vertical bedding plane of shale were more homogeneous after the fluid was saturated, while the surface properties of the parallel bedding plane more inhomogeneous. Finally, a prediction formula for the stability index of shale contact angle in different bedding direction and different fluid saturation experiment environment was proposed. The study is indicative of the clarification of oil-gas migration in shale reservoirs.