川西坳陷须家河组致密砂岩储层裂缝发育特征及其成因——以孝泉—新场—合兴场地区为例  

Characteristics and origin of fractures in tight sandstone reservoirs of the Xujiahe Formation in the Western Sichuan Depression: A case study in the Xiaoquan-Xinchang-Hexingchang area

作　　者：王春梅[1] 黄思静[1] 孙治雷[2] 胡作维[1] 黄可可[1] 佟宏鹏[3] 

机构地区：[1]成都理工大学沉积地质研究院 [2]青岛海洋地质研究所 [3]中国科学院广州地球化学研究所

出　　处：《天然气工业》2011年第8期43-47,132,共5页Natural Gas Industry

基　　金：国家科技重大专项子课题"四川盆地碎屑岩有利储集相带与储层成岩作用研究"(编号:2008ZX05002-004)

摘　　要：川西坳陷孝泉—新场—合兴场地区上三叠统须家河组储层具有埋藏深、致密、低孔隙度、低渗透率的特点,裂缝的发育程度对储层具有重要的意义。为此,通过岩心观察和显微镜下薄片鉴定,研究了裂缝的发育类型、发育密度、发育频率以及充填特征。结果表明:储层中以低角度裂缝发育为主,高角度裂缝欠发育;微裂缝对须二段储集空间的影响显著大于须四段,在须二段地层中,对储层渗透率有实质性影响的主要是一些相对宏观的裂缝。综合区域地质背景及前人的研究成果,认为差异压实导致的非构造作用是该区裂缝尤其是须二段裂缝形成的主要机制,但后期燕山、喜山构造运动产生的构造应力都可能叠加在原有的非构造成因的裂缝上,使之具有构造成因色彩。The reservoirs of the Xujiahe Formation in the Xiaoquan-Xinchang-Hexingchang area of the Western Sichuan Depression are characterized by great burial depth, tightness, low porosity and low permeability, thus the development degree of fractures is critical to reservoir quality. This paper studies the type, density, frequency and filling of fractures in the reservoirs through core observation and microscopic thin section analysis. Low angle fractures are predominant, while high angle fractures are rare. Influences of microfractures on reservoir space in the 2nd member are greater than that in the 4th member of the Xujiahe Formation. Only the relatively large fractures have substantial impacts on reservoir permeability of the 2nd member. In combination with regional geologic background and previous study results, the non-tectonic action from differential compaction is believed to be the major mechanism of fracture formation, especially in the 2nd member. However, tectonic stress generated during Yanshan and Himalayan movements might have some footprints on these non-tectonic fractures, making them appear like tectonic fractures.

关 键 词：川西坳陷 晚三叠世 致密砂岩储层 薄片鉴定 裂缝 非构造成因 构造成因 差异压实 

分 类 号：P618.13[天文地球—矿床学]