地面水平井不同层位压裂效果评价及气水产出特征分析

    Fracturing effects evaluation and gas water production characteristics analysis at different layers of surface horizontal wells

    • 摘要: 为实现对地面水平井分段压裂效果的精细化评价,梳理了朱集东煤矿地面U1与U2水平井段钻井施工层位特征,从压裂施工规模、压裂施工曲线和测压降数据角度,对比分析了U1与U2井各段不同层位的压裂效果;基于微地震监测,从裂缝网络的平面和缝高参数、裂缝类型角度,分析了U1与U2井压裂效果的差异,初步形成压裂施工参数与微地震监测结果相结合的地面水平井压裂效果评价工程技术方法;最后,对比分析了U1与U2井煤层气排采效果。结果表明:U1井阶段总液量、阶段总砂量、每米液量、每米砂量均低于U2井;U1井压裂效果好的段数仅为8段,少于U2井的10段,整体以平稳型曲线为主;U1井测压降压力波动较U2井更大,U2井的压裂效果均较U1井更好;从不同层位压裂数据来看,U1井顶板、底板压裂液量均值较煤层压裂液量大,阶段砂量较少,但整体相差不大;U2井顶板、底板压裂液量、压裂砂量均低于煤层压裂;U1与U2井顶板、底板压裂平稳曲线均小于煤层压裂;U1井顶板、底板压裂测压降数据均大于煤层压裂,U2井则相反;煤层压裂的缝网打开效果较顶板、底板更好;压裂裂缝区域的平面参数离散型较大,而从裂缝缝高、裂缝类型角度可以较好地验证和评价压裂效果;现阶段的U1与U2井气水产出规律均存在返排阶段、上产阶段、稳产阶段,从各阶段和整体的气水产出规律来看,U2井的产气效果较U1井更好,与“U2井的压裂效果较U1井更好”相一致。

       

      Abstract: To achieve a refined evaluation of the effect of hydraulic fracturing in surface horizontal wells, the characteristics of the drilling construction layers of the U1 and U2 horizontal sections in Zhujidong Coal Mine were analyzed. The fracturing effects of different layers in each section of the U1 and U2 wells were compared and analyzed from the perspectives of fracturing construction scale, fracturing construction curves, and pressure falloff data. Based on micro-seismic monitoring, the differences in the fracturing effects of the U1 and U2 wells were analyzed from the perspectives of the plane and height parameters of the fracture network and the types of fractures. A technical method for evaluating the effect of hydraulic fracturing in surface horizontal wells was initially formed by combining fracturing construction parameters with micro-seismic monitoring results. Finally, the drainage effects of coalbed methane in the U1 and U2 wells were compared and analyzed. The results showed that the total liquid volume, total sand volume, liquid volume per meter, and sand volume per meter in the U1 well were all lower than those in the U2 well. The number of good fracturing sections in the U1 well was only 8, which was less than the 10 in the U2 well, and the overall curve was mainly stable. The pressure fluctuation of the pressure falloff in the U1 well was greater than that in the U2 well, and the fracturing effect of the U2 well was better than that of the U1 well. From the perspective of fracturing data at different layers, the average fracturing liquid volume of the roof and floor in the U1 well was larger than that of the coal seam, and the amount of sand in the stage is relatively small, but the overall difference was not significant. In the U2 well, both the fracturing liquid volume and the fracturing sand volume of the roof and floor were lower than those of the coal seam fracturing. The stable curves of the roof and floor fracturing in both the U1 and U2 wells were less than those of the coal seam fracturing. The pressure falloff data of the roof and floor fracturing in the U1 well were greater than those of the coal seam fracturing, while the U2 well was the opposite. In most cases, the fracture network opening effect of the coal seam fracturing was better than that of the roof and floor. The plane parameters of the fracturing fracture area were more discrete, but the fracturing effect could be better verified and evaluated from the perspectives of fracture height and fracture type. The current gas and water production patterns of the U1 and U2 wells both included the drainage phase, the production increase phase, and the stable production phase. From the perspective of each phase and the overall gas and water production pattern, the gas production effect of the U2 well was better than that of the U1 well, which was consistent “the fracturing effect of the U2 well was better than that of the U1 well”.

       

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