四川盆地涪陵地区页岩储层压力预测及高压形成机制分析

地层压力是反映页岩气保存条件的重要指标之一，是影响页岩气产能的重要因素。涪陵页岩气田构造特征复杂，地层压力变化大，如何准确预测地层压力对页岩气勘探开发尤为重要。在对现有地层压力预测方法系统分析的基础上，将Eaton法作为涪陵页岩气田地层压力预测的首选方法，并结合涪陵地区地质特征，通过"纵向分段、平面分区、多井联合"的方式对正常压实趋势线的建立过程进行质控，以提高单井孔隙压力预测的精度，通过广义线性反演为核心的高精度地震层速度处理技术提高三维孔隙压力预测精度。此外，基于声波速度-密度交会图以及有机质演化特征、构造地质特征，对涪陵地区页岩层段的高压成因机制进行探索性研究，认为涪陵地区志留系页岩层段的压力异常是由欠压实、生烃作用和构造挤压3种机制共同作用的结果。 

Formation pressure prediction and high pressure formation mechanisms of shale reservoirs in Fuling area,Sichuan Basin

Formation pressure is one of the important indicators to reflect shale gas preservation conditions, and is also an important factor affecting shale gas production. In the Fuling shale gas field, which has complex structure characteristics and variable formation pressure distribution, it is particularly important to accurately predict the formation pressure in shale gas exploration and development. The Eaton method was a preferred method for the prediction of formation pressure in the Fuling shale gas field based on the systematic analysis of the existing prediction methods. Combined with the geologic characteristics of Fuling area, the established method for normal compaction trend (NCT) lines was improved through vertical segmentation, plane partitioning and multi-well combination. It improved the accuracy of single well pressure prediction. The accuracy of 3D formation pressure prediction was improved by high-precision seismic layer velocity processing with generalized linear inversion. Based on the acoustic velocity-density intersection diagram and organic matter evolution characteristics and structural features, the paper explored the high pressure formation mechanisms of shale intervals in the Fuling area. It was concluded that the abnormal pressure in the Silurian shale formations in the Fuling area was the result of the combined effect of three mechanisms:undercompaction, hydrocarbon generation and tectonic compression.