川东北地区须家河组“断缝体”气藏有利勘探目标和预测技术

上三叠统须家河组致密砂岩是川东北地区天然气勘探的重点领域之一，整体具有“埋藏深度大、储层致密，非均质性强，商业动用难度大”的特点。川东北地区须家河组发育“断缝体”气藏，通南巴构造带的通江-马路背地区是“断缝体”气藏勘探最有利区带，优势岩相和裂缝发育区是有效储层发育的有利勘探目标。利用动态构造识别技术、非线性岩性与物性反演预测技术以及综合裂缝预测技术等关键方法，有效地解决了烃源断层识别、相对优质储层预测以及裂缝预测等问题，实现储层“甜点”综合预测。这些技术在川东北“断缝体”气藏勘探中应用效果显著，储层厚度预测误差从16%降低到8%，裂缝预测吻合率从60%提高到85%；依据“断缝体”评价思路部署实施的4口井均取得了较好的效果，钻井成功率100%，提交天然气控制储量367.91×10⁸m³，落实了千亿方资源规模阵地，基本实现了川东北地区通江-马路背区块的高效勘探。

Exploration and prediction of promising fault-fracture reservoirs in the Xujiahe Formation,northeastern Sichuan Basin

Tight sandstone in the Upper Triassic Xujiahe Formation, northeastern Sichuan Basin, has been one of the exploration targets for natural gas in the area. However, the stone, as a whole, is rather tight, deeply buried and highly heterogeneous, making commercial development of gas from it quite a challenge. The formation contains many fault-fracture gas reservoirs in the Tongjiang-Malubei area of the Tongnanba structural belt, where certain lithological facies in well-fractured zones may be used as clues to the whereabouts of the reservoirs. By recognition of source rock-rooted faults based on dynamic structure restoration, nonlinear inversion and prediction of lithology and physical properties, and multi-scale fusion as well as five-dimensional pre-stack fracture prediction in OVT domain, we effectively addressed the recognition of source rock-rooted faults, the prediction of relatively high-quality reservoirs and fractures as well as "sweet spots"-several issues easily encountered in dealing with this type of reservoir. These techniques were applied well to the predication of fault-fracture reservoirs in the northeast Sichuan Basin with prediction error of reservoir thickness being reduced from 16% to 8% and predication accuracy of fractures being increased from 60% to 85%. Four wells were so successfully drilled according to the predication results that controlled reserves of 367.91×10⁸ m³ were booked with a possible gas resource base of 100 billion cubic meters readily on the way.