桑托斯盆地L油田盐下复杂岩性测井识别方法

Log Identification Method of the Complex Subsalt Lithology in L Oilfield of the Santos Basin,Brazil

巴西桑托斯盆地盐下巨型碳酸盐岩储层是当今全球海域油气勘探的热点,目前对该区域储层性质的研究程度还相对较低。该区域发育了碳酸盐岩、火成岩和砂泥岩等多种岩性的地层,不同岩性序列的地层相互影响重叠,导致直接利用测井曲线进行岩性判别存在着较大的多解性和不确定性,严重影响了区域储层解释,制约了勘探进程。结合岩心、薄片、综合地质录井和测井等资料,对桑托斯盆地碳酸盐岩、火成岩和砂泥岩的岩石学特征及沉积学特征进行了综合分析,并基于几种主要岩性的测井响应特征,将元素组分、物性及孔隙结构相结合,提出一种“三步法”进行地层岩性识别,识别精度较高,为储层精细测井评价打下坚实的基础。

As a hotspot of global offshore petroleum exploration,the giant subsalt carbonate reservoir in the Santos Basin in Brazil is still relatively insufficient in geological studies.Multiple lithologic formations are developed,such as carbonate,igneous,sandstone and mudstone rocks,and they overlap each other,so that multiple solutions and uncertainty appear when using logging data to identify lithology.This seriously influences regional reservoir interpretation and exploration progress.In this paper,through comprehensive analysis of cores,thin sections,mud and well logging data,the petrological and sedimentary characteristics of carbonate,igneous,sandstone and mudstone rocks in the Santos Basin are analyzed,then based on the logging responses,a three-phase method involving element composition,physical properties and pore structures is proposed for lithology identification.Applications show that the method can provide a high accuracy of lithology identification.It lays a solid foundation for fine reservoir evaluation in the study area.