川西坳陷邛西构造须二段裂缝特征及期次探讨  

CHARACTERISTICS AND STAGES OF FRACTURES IN THE SECOND MEMBER OF XUJIAHE FORMATION IN QIONGXI STRUCTURE,WESTERN SICHUAN DEPRESSION

作　　者：陈颖莉[1] 顾阳[1] 陈古明[1] 蒋德生[1] 

机构地区：[1]中国石油西南油气田公司川西北气矿

出　　处：《天然气工业》2008年第2期46-50,共5页Natural Gas Industry

基　　金：中国石油西南油气田公司科研项目"邛西须二气藏高产井控制因素研究"(编号20040305-02-01)的部分成果

摘　　要：2002年随着邛西3井获得高产工业气流,揭开了川西坳陷邛西构造上三叠统须家河组须二段气藏勘探开发的序幕。该区须二段气藏为裂缝—孔隙性气藏,储层以致密碎屑岩为主,之所以能成为有效储层是因为与裂缝有着密切关系。通过对该地层裂缝类型、力学机制和特征参数的综合定量化分析,探讨了裂缝发育的机制、控制因素和期次。结果认为:邛西构造须二段主要发育近南北向、北东向、近东西向和北西向4组裂缝,近南北向的裂缝较北东向裂缝发育;区内裂缝以高角度构造剪切裂缝为主,次为近水平成岩裂缝、滑脱裂缝以及与异常高压有关的裂缝;构造裂缝主要在印支期、燕山晚期和喜马拉雅期形成,成岩裂缝的形成时期比较漫长,与异常高压相关的裂缝主要在白垩纪形成。裂缝的形成、发育期次和规模主要受控于区域构造事件,且两者具有较好的耦合关系;岩性、层厚、断层等因素也直接影响着裂缝发育的程度。Gas exploration and development began in the second member of Upper Triassic Xujiahe Formation in Qiongxi structure, western Sichuan depression, since the well Qiongxi-3 tested high rate gas flow in 2002. The gas reservoirs in the second member of Xujiahe Formation in the study area are of fractured-porous type and are dominated by tight clastic rocks, which become effective reservoirs due to the development of fractures. The mechanism, controlling factors and stagis of fracture development are discussed through comprehensive quantitative analysis of fracture types, mechanical mechanism, and characteristic parameters. Four sets of fractures, including near NS-trending, NE-trending, near EW-trending and NW-trending fractures, are mainly developed in the second member of Xujiahe Formation in Qiongxi structure and the near NS-trending fractures are better developed than the NE-trending ones. The factures in the study area are dominated by high angle structural shear fractures, followed by near horizontal diagenetic fractures, gliding fractures and anomalous pressure-related fractures. The structural fractures are mainly developed in the Indo-Chinese epoch, late Yanshan epoch and Himalayan epoch. The formation of diagenetic fractures has experienced a very long geologic history. The anomalous pressure-related fractures are mainly formed in the Cretaceous. The formation, development stage and scale of fractures are mainly controlled by regional tectonic events. In addition, lithology, layer thickness and faults also have direct influences on the development of fractures.

关 键 词：川西坳陷 晚三叠世 气藏 构造 裂缝特征 期次 

分 类 号：P548[天文地球—构造地质学]