川中地区震旦系灯影组四段裂缝特征及发育机理

为解析川中磨溪地区灯四段碳酸盐岩裂缝特征及发育机理,通过钻井岩心观察、成像测井及地震资料分析等地球物理方法,并结合包裹体均一温度测试、岩石力学实验及埋藏史进行综合分析。结果表明:磨溪地区灯四段发育张性缝、剪切缝及压溶缝,以张性缝发育为主,剪切缝及压溶缝规模较小;裂缝发育包括NW、NE、近WE和近NS向4个优势方位;裂缝充填程度高,充填物主要为白云石、泥质、沥青质、方解石和少量石英。灯四段裂缝形成于3期构造运动,第1期裂缝形成于灯桐湾运动Ⅱ幕(522.0～508.0 Ma),受印度板块向北俯冲和欧亚板块向东碰撞的影响,主要发育NW、NS及近WE向裂缝,包裹体均一温度为116.6～146.3 ℃;第2期裂缝形成于加里东运动时期(425.0～420.0 Ma),受扬子板块与华夏板块冲撞作用的影响,主要发育NE向裂缝,包裹体均一温度为138.0～176.0 ℃;第3期裂缝形成于燕山—喜山运动时期(75.2～75.0 Ma),受龙门山冲断褶皱的影响,主要产生微细剪切缝,包裹体均一温度为177.0～208.0 ℃。研究成果为灯影组碳酸盐岩储层的深入研究提供一定的理论依据与支持。

Fracture Properties and Development Mechanisms of Sinian Dengying-4 Member in Central Sichuan

Drilling core observation, imaging logging, seismic data and other data were used to comprehensively analyze the fracture properties and development mechanism of the Dengying-4 Member carbonate rock in Moxi of Central Sichuan by combining with uniform temperature test of inclusion. Result indicates that there is tensile fracture, small scale shearing fracture and small scale pressure-solution fracture in the Dengying-4 Member of Moxi, which is dominated by tensile fracture. There are four dominant fracture strikes, including NW, NE, WE and NS. The fractures show a high filling level and the corresponding filling materials are dolomite, muddy, asphaltene, calcite and a small amount of quartz. The fractures in the Dengying-4 Member result from three-stage tectonic movements. The first-stage fractures developed in the Act-II of Dengtongwan movement (522.0～508.0 Ma), which are dominated by NW, NS and WE fractures due to the northward subduction of the Indian plate and the eastward collision of the Eurasian plate, and the corresponding uniform temperature of inclusions is 116.6～146.3 ℃. The second-stage fractures developed in the Caledonian movement (425.0～420.0 Ma), which are dominated by NE fractures due to the collision between the Yangtze plate and the Cathaysia plate, and the corresponding uniform temperature of inclusions is 138.0～176.0 ℃. The third-stage fractures developed in the Yanshan-Himalaya movement (75.2~75.0 Ma), which are dominated by shearing micro-fractures due to the effect of Longmenshan thrust folds, and the corresponding uniform temperature of inclusions is 177.0~208.0 ℃. This research could provide certain theoretical reference and basis for the further understanding of carbonate reservoirs in the Dengying Formation.