涪陵页岩气水平井工程甜点评价与应用

针对涪陵页岩气水平井多段分簇射孔压裂时加砂量符合率低、产气量低的问题,提出了寻找水平段工程甜点、并结合地质甜点进行压裂优化设计的方法。首先利用声波时差和密度测井资料,拟合得到涪陵页岩气藏横波时差计算模型,再结合密度、自然伽马等测井资料,利用地应力剖面计算软件求取涪陵页岩气藏水平井水平段的岩石力学参数,然后通过分析已压裂井段产气剖面测试结果与岩石力学参数的相关性,得到涪陵页岩气藏工程甜点参数为:水平应力差小于8 MPa、脆性指数0.45~0.50。焦页30-1HF井采用了工程甜点与地质甜点相结合的压裂设计方法,其压裂施工压力平稳,总液量和总砂量符合率较好,压后无阻流量88.54×104 m3/d,取得了较好的增产效果。现场试验表明,工程甜点与地质甜点相结合的压裂设计方法,能够提高涪陵页岩气水平井压裂的加砂量符合率和产气量,有助于实现页岩气的高效开发。 

The Evaluation and Application of Engineering Sweet Spots in a Horizontal Well in the Fuling Shale Gas Reservoir

Due to the fact that shale gas reservoirs possess heterogeneity, sectional perforation and multi-stage fracturing in horizontal wells in the reservoir may generate very different effects. The engineering sweet spot parameter can affect the crack initiation, extension and reconstruction of hydraulic fractures. Accordingly, the parameter can be used to guide the sectional perforation of shale gas horizontal wells, which can be helpful in improving the reservoir and productivity. With the P-wave transit time and density logging data, the calculation model of S-wave transit time was established for the Fuling shale gas reservoir, and the calculation method of determining the engineering sweet spot was defined for the Fuling shale gas reservoir based on the experimental results of rock mechanics. Combined with the test results for 73 gas production sections in six wells, including Well Jiaoye 7-1HF, the evaluation indicators for the engineering sweet spot in the Fuling shale gas reservoir were summarized, namely, that the horizontal stress difference was less than 8MPa, and the brittleness index ranged from 45% to 50%. Optimum design for fracturing the Well Jiaoye 30-1HF was conducted based on the engineering sweet spot data, and then total liquid volume and total sand content were matched well with stable operation pressure. Post-frac open flow was 88.54×104 m3/d, and better stimulation results were achieved.