委内瑞拉卡拉高莱斯合同区疑难储层测井识别方法

由于20世纪50～60年代委内瑞拉卡拉高莱斯合同区测井系列不全、资料品质差,仅有16 in*和64 in电阻率及自然电位测井资料,因此对高阻水层、低阻油层以及气层等疑难储层的识别一直是个难题.通过生产实践并结合大量的试油资料和油藏综合分析,总结出采用16 in(Rxo)和64 in(Rt)电阻率比值(Rxo/Rt),并结合低阻油层和标准水层对比定量确定含油饱和度的方法来判断疑难储层.采用该方法对疑难储层识别取得很好效果,使得老井作业成功率由30%提高到80%以上,而且在卡拉高莱斯合同区找到了290多个潜在油层,不仅为老井挖潜提供了依据,也为油田增储上产做出了贡献.

Logging Identification Method of Doubtful Oil Layers in Caracoles Contract Area, Venezuela

Caracoles Contract Area in Venezuela, one of overseas projects operated by CNPC, is situated in the southern part of eastern Venezuela basin. It is composed of over 460 complex and small faulted block reservoirs. Due to 50-year development, most oil pay zones have been depleted while low-resistivity ones are not easily identified by traditional logging interpretation methods but still have much potential. Because of the poor quality and insufficiency of logging series measured before 1960s (only including R xo , R t and SP), there are still problems in recognizing high-resistivity aquifer layers, low-resistivity oil layers and gas layers. Based on the integration of abundant testing data and comprehensive reservoir analysis, this paper presents a method to identify the doubtful layers by using the ratio of R xo to R t and the contrast between low-resistivity oil layers and standard aquifer layers to quantitatively determine water saturation. The application of this method has brought forth good outcome. The successful rate of old well log operations increased from 30% to 80%. 290 extra potential oil layers are recognized in Caracoles Contract Area, which not only provides a base for development of oil potentialities in old wells but also makes a contribution to increase in reserves and oil production rate.