塔北隆起奥陶系古岩溶的电成像测井识别  

IDENTIFYING THE PALEOCAVES IN ORDOVICIAN IN TABEI UPLIFT BY ELECTRO-IMAGING LOGS

作　　者：钟广法[1] 刘瑞林[2] 柳建华[3] 祁兴中[4] 马勇[3] 

机构地区：[1]同济大学海洋地质教育部重点实验室 [2]长江大学地球物理系 [3]中国石化西北石油局 [4]中国石油塔里木油田分公司

出　　处：《天然气工业》2004年第6期57-60,i002,共5页Natural Gas Industry

基　　金：中国石化西北石油局和中国石油塔里木油田分公司科研项目资助

摘　　要：基于电成像测井解释 ,结合岩心标定和常规测井约束 ,建立了塔北隆起下奥陶统溶洞及其充填物的电成像测井识别模式。在电成像测井图像上 ,未充填溶洞一般呈黑色 ,而充填溶洞则可呈现出黑、棕、黄、白等各种颜色 ,这取决于充填物的类型和特征。溶洞充填物主要有角砾岩、砂泥岩和结晶碳酸盐岩三种类型 :角砾岩呈斑状 ,其中浅色斑块解释为从围岩跨塌下来的角砾 ,斑块间深色部分为砂、泥质填隙物 ;洞穴砂、泥岩一般呈黑色—棕色高导显示 ,其中常见图像纹理 ,解释为各种层理构造 ;洞穴结晶碳酸盐岩因电阻率最高 ,图像呈白色 ,并可见纹层状生长构造。洞穴及其充填物与碳酸盐围岩浅棕—亮黄色中高阻电成像测井特征易于区别。研究表明 ,利用高分辨率电成像测井图像 ,结合岩心标定和常规测井资料 ,能够有效地识别碳酸盐岩地层中的古洞穴 ,并判断其充填与否及充填物的性质。On the basis of electro-imaging log interpretation, a pattern of identifying the paleocaves and their fillings in Lower Ordovician in Tabei Uplift by electro-imaging logs was set up in combination with core calibration and conventional log restraint. On electro-imaging logs, the unfilled paleocaves show black colour and the filled ones may display various colours as black, brown, yellow and white, which is dependent upon the type and property of the fillings. Three types of fillings in the paleocaves, i. e. breccias, sand shales and crystalline carbonate rocks, were found. The breccias display a mosaic structure, in which the light colour patches were interpreted as the carbonate breccias collapsed down from the cave walls and the dead colour parts among the patches as the sand-shaly fillings; the sand-shales show black and brown, having high conductivities, in which the image laminations were interpreted as various bedding structures, and the crystalline carbonate rocks display white colour and lamellar growth structure, because they are of the highest resistivities. According to the light brown-bright yellow medium-high resistivity imaging logging characteristics, the surrounding carbonate rocks are easy to be differed from the paleocaves and their fillings. Through investigation it was indicated that the paleocaves in carbonate strata can be effectively identified and whether they were filled and the fillings' properties may be determined by use of the high-resolution electro-imaging logs and in combination with the core calibration and conventional log data.

关 键 词：电成像测井技术 碳酸盐岩 喀斯特 测井解释 奥陶纪 砾岩 砂泥岩 

分 类 号：P631.8[天文地球—地质矿产勘探]