页岩气储层品质测井综合评价

页岩气储层品质对压裂改造至关重要,直接影响到试油层位的优选和压裂施工的效果,进而影响页岩气产能的高低。为此,针对四川盆地南部地区海相页岩储层开展综合评价研究:首先,通过岩心实验数据与测井曲线相关性分析,优选铀含量、密度计算有机碳含量,优选声波、密度、铀含量计算储层孔隙度和有机孔隙度,建立多参数计算页岩储层参数模型,参数精度高;其次,利用页岩气水平井单段测试产量与储层参数开展主成分方法分析,优选页岩孔隙度、有机碳含量、脆性指数、总含气量,建立页岩气水平井储层品质综合评价模型,形成了页岩气水平井储层品质测井综合评价方法,评价结果与生产测井测试成果有着较好的对应性。研究结果表明:①声波能较好地表征无机孔隙度,铀含量能较好地表征页岩有机孔隙度;②水平井靶体应尽量控制在页岩储层品质好、脆性矿物含量高、脆性指数高的小层内,易于被压裂,形成的压裂缝网复杂,测试产气量贡献大。结论认为,页岩气水平井储层品质测井评价方法对水平井储层品质级别具有较好的指示性,为现场水平井靶体优化和优质页岩储层压裂分段优选提供了技术支撑,可以有效地指导现场生产。

A comprehensive logging evaluation method of shale gas reservoir quality

As a crucial factor for reservoir fracturing reconstruction, the quality of a shale reservoir could directly affect the optimization of a testing zone, the effectiveness of fracturing operation, and the level of reservoir test productivity. To this end, a case study was made on the comprehensive evaluation of marine shale reservoirs in the southern Sichuan. First, through correlation analysis of core laboratory data and well logging curves, uranium content and density curves were chosen to calculate the total organic carbon, acoustics, density and uranium curves to calculate reservoir porosity and organic porosity, and a multi-parameter model for calculating shale reservoir parameters was thus established with high precision. Second, based on the principal component method analysis between reservoir parameters and single-stage test production in horizontal wells, shale porosity, total organic carbon, brittleness index and total gas content were chosen to establish a comprehensive evaluation model for horizontal wells in shale reservoirs, and to set up a comprehensive method to evaluate shale quality by using log data, from which evaluation results and production logging results were found to have a good correspondence. This study suggests that acoustics curves can better characterize inorganic porosity, while uranium content can better characterize organic shale porosity; and that a horizontal well target should be controlled as far as possible in the single layer with a high brittle mineral content and a high brittle index, i. e., easier to be fractured and more complex fractures to be formed, the greater the contribution of test production. It is concluded that the logging evaluation method of a shale gas horizontal well could precisely indicate the quality of shale reservoirs, providing a technical support for target optimization of field horizontal wells and fracturing section optimization of high quality shale reservoirs, and effectively guide field production and development practices.