Calibrated by core and traditional well-log data, electrical image logs (FMI and EMI) are used to study the types, characteristics and distribution of paleocaves in the Ordovician carbonate reservoirs, including Lianglitage and Yijianfang Formations, in east Lungu area, Tarim Basin, Northwest China. The paleocaves are classified into three classes: speckled to patched caves, layered caves, sheet or reticular fractured caves. The identification of various caves on image logs is also discussed. To characterize the spatial distribution of paleocaves, quantitative parameters, including the thickness and the burial depth relative to paleokarst surface of a paleocave zone, and the distribution density of paleocave zones (defined as the percentage of the thickness of paleocave zones in that of a given stratal unit) are introduced. Results indicate that the thickness of about 90 percent of paleocave zones is less than 10 m, and 70 percent of paleocave zones occur within 200 m beneath the paleokarst surface (top of the Lianglitage Formation). The distribution density of paleocaves in the Yijianfang Formation is obviously much higher than that in the Lianglitage Formation. In lateral, the distribution density of paleocaves increases from southeast to northwest, which suggests that paleokarstification strengthened northwestwards.%在岩心刻度和常规测井标定基础上,根据FMI、EMI成像测井资料研究了塔里木盆地轮古东地区奥陶系良里塔格组和一间房组碳酸盐岩储层中溶洞的类型、特征及分布.将溶洞划分为斑点-斑块状溶洞、层状大洞、片状及网状缝洞等类型,提出了各类溶洞的成像测井识别标志.引入溶洞发育带的厚度、相对于古岩溶面的埋藏深度及分布密度(即溶洞发育带厚度占地层总厚度的百分数)等参数,研究了该区溶洞的空间分布.结果表明:90%左右的溶洞发育带的厚度都小于10 m,70%的溶洞发育带分布于良里塔格组顶部古岩溶不整合面以下200 m深度范围内;一间房组溶洞发育带的分布密度明显高于良里塔格组;总体上,自南东而北西,溶洞发育带的分布密度增大,指示古岩溶作用的强度朝北西方向逐渐增强.
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