泥页岩稳定性评价中人工模拟岩样的制备

改进了泥页岩稳定指数(SSI)评价实验方法中人工模拟实验岩样的制备方法。使用B28井岩粉制备岩样,优选SSI实验模拟岩样制备条件为:10.5 MPa下压制浆液,得到含水量14.03%的岩样模拟上部高含水量地层;10.5 MPa下压制风干岩粉,得到含水量1.91%的岩样模拟深部低含水量地层。优选SSI实验条件为:在65℃试液中浸泡8 h后,测定岩样的SSI值。扫描电镜(SEM)微结构分析表明,两种方法制备的岩样与实际泥页岩的微观孔隙尺度相近,高含水量模拟岩样的含水量与浅部实际地层泥页岩含水量(12%14%)相近,低含水量模拟岩样的含水量与深部实际地层泥页岩含水量(2%3%)相近。改进的SSI评价方法相对误差为2.91%,平行性较好,可有效评价防塌剂和防塌体系对泥岩地层的防塌效果及作用机理。

Artificial Shale Sample Preparation Method in Shale Stability Index(SSI) Evaluation Test

Artificial shale sample preparation method in shale stability index(SSI) evaluation test was improved.With shale powder in B28 well,the optimum preparation condition of shale sample in SSI test was obtained.The slug was suppressed under 10.5 MPa to get shale sample with 14.03% water content which simulated the formation of high water content,and dry shale powder was suppressed under 10.5 MPa to get shale sample with 1.91% water content which simulated rock samples with low moisture content of deep formation.The optimum experiment conditions of SSI test was established: immersing in test solution at 65 ℃ for 8 h and then measuring SSI value of the shale sample.The results of scanning electron microscopy(SEM) micro-structural analysis showed that the micro-pore scales of shale samples in the two preparation method were similar to that of actual rock shale.Water content of high water content shale sample was similar to that of actual shallow shale formations which was of 12%—14%.Water content of low water content shale sample was similar to that of actual deep shale formations which was of 2%—3%.Relative error of the improved SSI evaluation method was of 2.91% which showed good parallel of the method.The improved method could effectively evaluate anti-collapse effects of anti-sloughing agents and anti-collapse systems and help understand mechanisms.