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查明断层发育区煤层气开发的有利块段是准确井位部署、减少工程盲目投资的重要保障。根据沁水盆地中部柿庄南区块煤层气勘探开发资料,应用构造拉平法和波叠加理论对3~#煤层经历燕山期、喜马拉雅早期、喜马拉雅晚期后的底板形迹恢复,并划分出18个块段。根据气/水分异现象、构造曲率法、煤体结构观测法等得出了多期构造运动作用后不同块段内储层压力、渗透率的差异。在此基础上评价出煤层气开发的有利块段、较有利块段。结果表明:多期构造运动形成的正断层附近气体逸散、煤体破碎是造成其附近煤层气井产量低的主要原因;断层间隔区域底板相对高值块段渗透率低、储层压力低,产气潜力小;底板相对低值块段渗透率低、储层压力相对高,产气潜力中等;底板相对中值块段渗透率较好,产气潜力好。现场煤层气井的实际产气数据验证了理论分析的准确性。该研究成果为断层发育区煤层气有利块段优选提供了一种思路和借鉴。
It is an important guarantee to find out the favorable blocks for the CBM development in the fault zone, which is to deploy accurately and to reduce the blind investment in the project. Based on the CBM exploration and development data of the Shizhuangnan block in the central Qinshui Basin, the backfill traces of 3 ~ # coal seam under Yanshanian, early Himalayan, and later Himalayan seasons are recovered by using the structure leveling method and wave superposition theory, and 18 blocks segment. The differences of reservoir pressure and permeability in different blocks after multi-period tectonic movement are obtained according to the phenomenon of gas / water difference, tectonic curvature method and coal structure observation method. On the basis of this, we have evaluated the favorable blocks for the development of coalbed methane and the favorable blocks. The results show that gas evolution near the normal fault formed during multistage tectonic movement and coal breakage are the main causes of the low output of coalbed methane wells in the vicinity of the faults; the permeability of the relatively high value block in the fault interval area is low, the reservoir pressure is low, Low potential gas potential; low relative permeability of bottom blocks, low permeability, relatively high reservoir pressure and moderate gas production potential; relatively high permeability of bottom blocks relative to mid-block, good gas production potential. The actual gas production data of on-site CBM wells verify the accuracy of theoretical analysis. This research result provides a kind of train of thought and reference for the favorable block of CBM in the fault zone.