海上高温高压地层孔隙压力预测方法研究

Study on Pore Pressure Prediction Method in the Offshore High Temperature and High Pressure Formation

针对南海北部莺歌海盆地地层异常高压比较普遍的情况,利用改进的声波速度-密度交会图版,对其中东方13气田高温高压地层的异常高压形成机制进行分析。对于泥岩地层,分析认为其异常高压成因机制主要为欠压实作用、水热增压作用和化学压实作用,各机制对高温高压形成的贡献率随垂深不同而变化。基于该气田的特殊地质情况,建立了孔隙压力计算的组分模型,采用测井数据对孔隙压力进行计算。考虑到构造起伏的影响,认为砂岩储层孔隙压力是由泥岩传递和烃柱浮力作用产生的两部分孔隙压力组成,并建立了相关计算模型。

Abnormal pressure is generally developed in Yinggehai Basin in the northern South China Sea.The abnormal formation pressure mechanism is analyzed by using the improved acoustic velocity-density intersection plate model for the high temperature and high pressure formation in Dongfang 13 gas field.It is believed that the main pore pressure mechanism of the shale formation is under-compaction mechanism,hydrothermal pressurization and chemical compaction mechanism.The contribution of formation pressure mechanism to overpressure is a function of the depth.Based on the special geology and tectonics of Dongfang 13 gas field,the component model of pore pressure calculation is put forward,and the pore pressure is calculated by logging data.For the sandstone reservoirs,considering the effect of tectonic fluctuation,pore pressure is considered to be composed of the pressure produced by the mudstone transmission and the buoyancy of the hydrocarbon column.The relevant pressure calculation model of sandstone formation is established.