川西坳陷须家河组二段优质储渗体预测

Abstract

川西上三叠系须家河组气藏埋深大，砂体超致密，优质储渗体预测是须家河组二段气藏勘探重点。相对优质储层与沉积相密切相关，层序地层格架分析是描述沉积体系的关键技术。本文通过分析地震剖面上典型地震反射结构，建立须家河组二段层序地层格架，划分沉积体系，预测有利沉积相带；用属性参数描述沉积相平面分布；结合区域构造演化、应力场分析技术，预测有效裂缝网络。有效裂缝叠加相对优质储层，可预测为优质储渗体发育有利区。研究结果表明：川西地区南北向断层网络、叠加河口坝，或者叠置河流相砂体，能够成为须家河组二段有效的优质储渗体。且预测结果与现有钻井吻合。The gas reservoir of the upper triassic Xujiahe formation in Western Sichuan buries deep and sand bodies are super tight, so the high-quality permeability reservoir prediction is the focus of the gas reservoir exploration. Relatively high-quality reservoirs are closely related with sedimentary facies and sequence stratigraphic analysis is the key technology to describe sedimentary system. By analyzing the typical seismic reflection structure in seismic section, this paper establishes sequence stratigraphic framework of the second members of Xujiahe, divides the sedimentary system, and predicts favorable sedimentary facies belt. Sedimentary facies distribution is described by using attribute parameter. Combined with regional tectonic evolution and stress field analysis, the paper predicts fracture network effectively. Effective fracture network superimposed relatively high-quality reservoir is predictable for favorable area in the development of the high-quality permeability reservoir. The results show that: In the region of western Sichuan, the NS fault network, superimposed mouth bar, or stacked fluvial sand body can become the second members of Xujiahe group of the high-quality permeability reservoir effectively. The predicted results are consistent with the existing drilling.