鄂尔多斯盆地延长油气区延长组长7段陆相页岩含气性分析

Gas bearing analysis of continental shale of Chang 7 member of Yanchang formation in Yanchang oil & gas region of Ordos basin

通过气测录井、地化分析、现场解吸测试等手段,证实了气测录井资料定性判断页岩含气性特征具有较强的可行性,并针对延长油气区长7段陆相页岩选取了东西和南北两个方向进行了含气性定性分析;重新分析和确定了页岩现场解吸实验中的损失时间,对USBM法中提钻过程中的损失时间进行了修正,提出了改进的USBM法来恢复损失气量。通过现场解吸实验,定量刻画了长7段页岩含气量,总含气量为1.87~5.23 m^3/t,平均含气量为3.51m^3/t,其中解吸气含量为0.28~2.14m^3/t,损失气含量为0.49~4.34m^3/t,残余气含量为0.17~0.61m^3/t。延长组页岩整体含气量不高、含气丰度低,总含气量随着深度具有明显增加的趋势,与定性分析结果一致。

By means of gas logging, geochemical analysis and field desorption test, it is proved that it is feasible to qualitatively judge the gas-bearing properties of shale by gas logging data. For the continental shale of Chang 7 member in Yanchang oil & gas region, the qualitative analysis of gas-bearing properties is carried out in east-west and north-south directions. The lost time in field desorption experiment of shale is reanalysed and determined. The lost time in the process of lifting drill by USBM method is corrected, and an improved USBM method is proposed to recover the lost gas. Through field desorption experiments, the gas content of Chang 7 shale is quantitatively characterized. The total gas content is 1.87~5.23 m^3/t, and the average gas content is 3.51 m^3/t. The desorption gas content is 0.28~2.14 m^3/t, the loss gas content is 0.49~4.34 m^3/t, and the residual gas content is 0.17~0.61 m^3/t. The overall gas content of Yanchang formation shale is not high and its gas abundance is low. The total gas content has an obvious increasing trend with depth, which is consistent with the qualitative analysis results.