涪陵页岩气田高曲率区水平井压裂特征及调整对策

Fracturing Characteristics of Horizontal Wells and Adjustment Measures in High Curvature Area of Fuling Shale Gas Field

摘要:

涪陵页岩气田焦石坝区块西南部地区受多期地质构造运动叠加，构造变形强、断裂复杂。地震曲率属性显示主力气层段曲率体分布密集，虽然曲率仅表示地层弯曲变形程度，但对于页岩储层高曲率往往预示着该区域微裂隙、天然裂缝更加发育，这有利于页岩储层形成复杂裂缝网络。然而，如果天然微裂隙过早过多开启，造成压裂液大量滤失，在压裂改造过程中表现出裂缝扩展受限、砂比提升困难，与主体区相比压裂施工曲线表现出较大差异，施工难度大大增加。本文从曲率平面分布特征、曲率密度、方向性、延伸长度入手，定量化描述了曲率与压裂试气效果之间的关系；考虑区域构造、断层等因素影响，分析了几种不同高曲率带的压裂施工特征，并提出了相应的压裂工艺调整对策，为后期提高压裂改造效果、高效开发气田提供了经验参考。

Abstract:

The southwest of Jiaoshiba block in Fuling shale gas field is superimposed by multiple tectonic movements with strong deformation and complex fracture. The seismic curvature attribute indicates that the curvature of the main gas stratum is densely distributed. Although the curvature only indicates the extent of the strata bending deformation, the high curvature of the shale reservoir often predicts more micro-fractures development, which is favorable for shale reservoir forming a complex fracture network. However, if the natural micro-fractures were opened too much and too early, a large amount of fracturing fluid loss would be caused to result in limited fracture propagation and difficult sand pumping during the fracturing process. Compared with the main block, the fracturing curves show huge differences and the treatment difficulty greatly increased, too. Starting from the plane distribution of curvature, curvature density, directivity and the extension length, this paper tries to quantify the relationship between curvature and the effect of fracturing testing gas. Meanwhile, considering the influence of regional structure and fault impact, fracturing construction characteristics of different high curvature areas are analyzed and the corresponding adjustment measures are put forward, which provides the experience reference for the later-stage fracturing effect improvement and efficient gas field development.