面向页岩气开发的地震压裂模拟技术及应用

复杂地质条件下, 有效提高页岩气井的压裂效果是页岩气井增产、提效的重要手段。通常情况下, 用于压裂模拟的数值模拟计算采用的是有限元方法, 但是该方法在地层变形较大和断层裂缝较发育处存在网格畸变的问题, 导致压裂模拟结果与实际压裂结果不一致, 降低了页岩气开发效率。为此提出了一种能够综合利用地震、地质和测井等资料进行地震-地质-工程一体化压裂模拟的技术, 并采用物质点法进行数值模拟计算, 有效避免了上述问题。该技术主要利用成像测井数据构建反映裂缝程度的裂缝面密度曲线, 然后应用模糊数学算法对多种裂缝敏感属性进行排序优选, 并利用模糊神经网络算法进行天然裂缝的人工智能建模, 最终应用裂缝建模结果并结合物质点法进行水平井段压裂模拟, 得出有利的压裂区和压裂效果。该技术在J研究区进行了应用, 完成了典型井J1井和J2井的地震压裂模拟, 对比了J1井压裂模拟效果与实际压裂效果, 结果一致性较好。该方法可以为实际压裂施工提供方案设计指导, 对页岩气开发降本增效具有重要的现实意义。

Under complex geological conditions, effectively improving the fracturing results of shale gas wells is important to increase the production and efficiency of shale gas wells. Seismic fracturing simulation before fracturing in shale gas wells is a key measure for guiding fracturing engineering. In general, the finite element method is used for numerical fracturing simulations. However, this method has grid distortion problems in areas with strong formation deformations and enrichment fault fractures, resulting in inconsistencies between the simulation and actual fracturing results. This reduces the shale gas development efficiency. The seismic, geological, and engineering-integrated fracturing simulation technology proposed in this study can effectively avoid these problems using the material point method (MPM) for numerical simulation calculations. First, this technique uses seismic imaging logging data to construct the fracture surface curve, which reflects the fracture situation. Second, we used fuzzy mathematics to optimize the sensitive attribute of the fracture. Third, we used a fuzzy neural network to construct the natural fracture model. Finally, the MPM was used to obtain the results of the fracturing simulation. These four steps were the main methods for predicting the fracturing simulation around a well and eventually obtaining a favorable fracturing zone. This study applied seismic fracturing technology to the J study area and the seismic fracturing simulation of Well J1 and Well J2. This result was consistent with the actual fracturing effect. This technique is a seismic fracturing simulation technique used before the actual fracturing of shale gas wells and can provide design guidance for fracturing operations, which is of great practical significance for shale gas development to reduce costs.