高温水热增压实验研究及地质启示

Experimental analysis of aquathermal pressuring under high temperature conditions and its geological implications

郭志峰 刘震 刘鹏 柳万春

Guo Zhifeng Liu Zhen Liu Peng Liu Wanchun

中海油研究总院, 北京 100028 2. 中国石油大学(北京), 北京 102249 3. 陕西延长石油(集团)有限责任公司研究院, 西安 701169

CNOOC Research Institute, Beijing 100028, China 2. China University of Petroleum, Beijing 102249, China 3. Research Institute of Shaanxi Yanchang Petroleum(Group) CoLtd, Xi'an, Shaanxi 710069, China

超压形成机制是沉积盆地油气成藏研究的重要内容。针对温度和封闭条件2个关键因素，设计双轴承压孔隙流体高温水热增压实验，选取典型高温高压盆地的砂、泥岩样品，通过对比性实验发现，在泥岩封闭体系中，升温引起的水热增压导致流体温度与压力表现为指数关系，而非线性关系；在孤立体系中，砂岩孔隙流体水热增压幅度明显高于泥岩封闭体系；在泥岩封闭体系中，泥岩孔隙度微小差异会导致水热增压量存在巨大差异；在相同泥岩封闭条件下，砂岩孔隙度越高，水热增压幅度越大。实验得到两项地质启示：在高温盆地中，被泥岩封闭的砂岩储层内孔隙流体水热增压能够成为盆地超压形成的重要机制，且随着埋深增大，地温升高，指数关系的增压趋势使得水热增压作用更加显著；泥岩的封闭性能决定砂岩储层水热增压的有效性和增压幅度，砂岩储层孔隙度大小影响水热增压幅度的强弱。

Overpressure generation mechanism is very important for the research of hydrocarbon accumulation. We collected samples from typical wells in high temperature basins, made use of a double-axial pressurization testing system for pore fluid aquathermal pressuring, and measured the amplitude of aquathermal pressuring for different geological conditions. Results indicated that the relationship between temperature and pressure was not linear but exponential on the condition of high aquathermal pressuring in shale sealed systems, while the amplitude of aquathermal pressuring in isolated systems was higher than that in shale sealed systems. The fine variation of properties of sealed shales would lead to a large amplitude of aquathermal pressuring in shale sealed systems, and the greater porosity of sand samples would lead to larger amplitude of aquathermal pressuring. Experimental results induced two geological implications. In high temperature basins, aquathermal pressuring in shale sealed systems increases significantly with burial depth. It cannot be neglected and could be one of the main overpressure generation mechanisms. The quality of sealed shale decides the amplitude of aquathermal pressuring, and sand porosity could affect the amplitude of aquathermal pressuring, so in geological conditions, high porosity sand embedded in low porosity shale layers is more likely to lead to aquathermal pressuring.

“十二五”国家科技重大专项“南海北部深水区成藏组合评价研究”（2011ZX05025-002-05）资助。

https://doi.org/10.11781/sysydz201606836