页岩饱和含气量的计算及应用

储集层在一定物理化学条件下所能容纳的最大气量是有限的,结合测井解释数据和岩心测试数据,可求得储层平均孔隙度和含气饱和度,进而根据储层温度压力条件求得饱和游离气量。由于页岩中存在大量的纳米级孔隙,需要根据吸附相的体积进行游离气量的校正。在储层温度不高,试验条件允许的情况下,最大吸附气量则可以用Langmuir等温吸附方程来计算;若储层埋藏较深温度较高,则可以用Polanyi吸附势理论建立吸附量与温度压力的关系模型,结合较低温度的等温吸附数据,来预测实际储层温度压力下的吸附量。根据断裂、地层水等对页岩储层的破坏程度估算破坏系数K0,使计算的饱和含气量贴近储层实际含气量。建议计算时,对获取的源数据进行趋势面分析,分离出区域性分量,使数据能代表评价区的整体性质。

On Application of Method to Calculate Shale Saturated Gas Content

Max gas content the reservoir contains under a certain condition of physical chemistry is limited. Based on well logging interpretation data and core test data, average porosity of reservoir and gas saturation can be acquired and then saturated free gas content acquired according to pressure conditions of reservoir temperature. Because there are a lot of nanoscale holes in shale, correction of free gas content is needed according to the size of adsorbed phase. If reservoir temperature is not high and test condition is good, Langmuir isothermal adsorption equation can be used to calculate max adsorbed gas content. If reservoir is deep and its temperature is high, Polanyi adsorption potential theory can be used to ~t up relation rrxxtel between adsorbing capacity, temperature and pressure to forecast real adsorbing capacity under reservoir temperature and pressure on the basis of isothermal adsorption data under lower teng~rature. And then it is necessary to estimate the damage coefficiem KO according to how much destructiveness shale reservoir has suffered from fracture and formation water so that calculated saturated gas content may be closer to real reservoir gas content. The au- thor suggests that, in the process of calculation, trend--surface analysis of obtained source data should be conducted and regional component extracted to ensure that the obtained data can represent bulk property of assessment zone.