页岩气储层压力测井评价模型研究——以涪陵地区龙马溪组页岩为例

Model study on logging evaluation of shale gas pore pressure: a case study in fuling longmaxi formation

欠压实/构造抬升背景下附加生烃增压是形成页岩气储层异常高压的主要成因机制,单一成因机制的压力评价方法无法准确解决这类储层压力评价难题.本研究以页岩孔隙组分测井评价为基础,分析页岩储层压力与不同类型孔隙的成因关系,依据压实平衡原理,评价欠压实/构造抬升作用形成的"背景孔隙压力",进而推导I型高-过熟干酪根生烃附加增压测井评价模型,评价生烃作用形成的"附加孔隙压力",通过两部分孔隙压力叠加,实现上述双重成因作用下的储层压力测井评价.评价结果经实测资料检验,具有较高可靠性.该模型描述了页岩孔隙组分、埋深、有机质类型、成熟度、天然气赋存方式及储层封闭性等因素对储层压力的综合影响,为解决类似页岩气储层压力评价问题提供了新的思路与方法.

Additional hydrocarbon generating pressure based on the under-compaction and tectonic uplift is the main genetic mechanism that caused abnormal pore pressure of shale gas. The pore pressure evaluation method aimed at single genesis solve above pore pressure evaluation giving the inaccurate result. In this study, based on the logging evaluation of shale pore component, analyze the relationship between pore pressures and pore causes in shale reservoirs. Establish inorganic pore pressure logging evaluation model that affected by under-compaction and tectonic uplift, according to the principle of compaction balance. Then, derive and establish logging evaluation model for I-type high/over mature kerogen additional hydrocarbon generating pore pressure model. Combining the two parts of the model can evaluate pore pressure using logging for the above cases that affected by both hydrocarbon generating pressure and under-compaction and tectonic uplift. The reliability of the evaluation results tested by actual data. The model sets reflect the combined effect on pore pressure, such as pore component, buried depth, type of organic material, maturity, gas occurrence ways and reservoir sealing property, presents a set of new ideas and methods for similar shale gas reservoir to solve pore pressure evaluation problems.