沁水盆地煤系地层孔-裂隙特征测井反演

Logging inversion on pore-crack features of coal measure strata in Qinshui Basin

利用微分等效介质理论方法和Biot相恰理论方法,分别对沁水盆地固县井区山西组3号原生结构煤层及其上覆煤系地层孔隙纵横比和裂隙密度进行了反演。结果表明,3号原生结构煤层以近球形孔隙空间系统为主;上覆致密砂岩以裂缝性孔隙空间系统为主;上覆泥岩中存在孔隙及裂缝型多重孔隙空间系统。随着裂隙密度的增加,煤系地层裂缝孔隙度逐渐趋向于一个极大值,同时岩石体积模量发生显著降低,裂隙密度反演结果对指导煤系气勘探具有一定参考价值。

A differential equivalent medium theory method and Biot consistent theory method were applied to an inversion on the pore aspect ratio and crack density of No.3 primary structure seam and overlaying coal measure strata in Shanxi Group of Guxian well block in Qinshui Basin.The results showed that No.3 primary structure seam was mainly close spherical pore space system. In the overlaying mudstone,there was a pore and crack type multi pore space system. With the crack density increased,the crack and pore degree of the coal measure strata would steadily be a maximum in tendency and meanwhile,the rock volume modulus would be reduced obviously and the crack density inversion results would have a certain reference value to guide the exploration of the coal measure gas.