临兴区块煤系地层多层合压可行性研究

针对煤系地层多层合压时煤与砂岩、页岩的差异较大，裂缝扩展针对煤系地层复杂，裂缝形态变化不可预知等问题，通过室内实验测量煤层顶底板地应力，建立多层有限元反演模型，进行煤层地应力反演计算，对不同类型地层合压的可行性进行分析。结果表明：反演计算结果误差小于5%,可信度较高；多层合压穿层条件为：裂缝为垂直缝、破裂压力相差小于5MPa、合压层相差小于18～20m;多储层合压时，上部储层条件较好，尽量避免压开下部煤层；下部煤层起裂时，支撑剂主要支撑下部煤层，对于上部地层而言，支撑效果相对差；煤层在上部，砂岩气层在下部，从煤层起裂可利用应力遮挡作用，增加在煤层中缝长。

Feasibility analysis of coal-measure strata multi-layer compression in Linxing block

Multi-layer combined pressure is a key technology to improve multiple types of gas-bearing gas layers. However, due to the large difference between coal lithology and sandstone and shale, fracture propagation is more complicated than single-layer fracturing, especially the existence of coal seams makes the change of fracture shape unpredictable, which brings technical difficulties to fracturing design and implementation. For this reason, through indoor experiments to measure the peostress of coal seam roof and floor, establish multi-layer finite element inversion model, carry out in-situ stress inversion calculation of coal seam, and the feasibility of the combined pressure of different types of formations is analyzed. The results show that the error of the inversion calculation result is less than 5%, and the credibility is high; the conditions of the multi-layer combined pressure penetration layer are: the fracture is a vertical fracture, the fracture pressure difference is small (<5MPa), and the combined pressure layer difference is less than 18-20m; When multiple reservoirs are combined, the upper reservoir is in better condition, try to avoid pressing the lower coal seam; when the lower coal seam cracks, the proppant mainly supports the lower coal seam, and for the upper strata, the supporting effect is relatively poor.Cracks from the coal seam can take advantage of the stress shielding effect to increase the length of the seam in the coal seam when the coal seam is in the upper part, and the sandstone gas layer is in the lower part. The research results can provide guidance for the calculation of the stress of each layer, the judgment basis and conditions of the combined pressure, and the selection of the crack initiation layer when the multi-layer combined pressure is calculated.