四川盆地乐山—龙女寺古隆起深层海相碳酸盐岩测井评价技术

四川盆地乐山—龙女寺古隆起寒武系及震旦系埋藏深度大,基质物性较差,历经多次构造运动,储层非均质性强,致使测井解释工作难度大。为此,综合运用薄片、岩化、ECS元素测井和常规测井资料,对该类储层的特殊岩性与矿物进行了可靠的识别,进而得到准确的储层参数。研究表明:成像测井可以对各类裂缝进行精细识别及分类,利用声波扫描测井得到的各向异性及频散曲线,结合裂缝识别结果可对裂缝的有效性进行评价;常规测井结合成像测井能够对溶蚀孔洞及大型溶洞进行定性识别,采用BorTex及孔隙谱技术,可定量评价溶蚀孔洞的发育程度及孔洞连通性,而对大型溶洞的延伸情况则需要结合钻、录井显示及地震资料来综合判别;流体判别在排除钻井液侵入、导电矿物等影响因素后,可采用可动水指数法、双侧向比值法、视电阻增大率法、中子—密度与中子—声波重叠法、介电扫描等方法,结合储层纵横向流体分布情况来综合判别储层流体性质。测井技术的不断完善,为该区深层油气的勘探开发提供了技术保障。

Well log assessment technique in the analysis of the petrophysical properties of deep marine carbonate reservoirs in the Leshan Longnüsi Paleouplift in the Sichuan Basin

The Cambrian and Sinian reservoirs were buried deep with matrix of poor petrophysical properties in the Leshan Longnüsi Paleouplift in the Sichuan Basin, and are of great heterogeneity especially after experiencing so many tectonic movements. In view of this, reservoir parameters were achieved based on the correct identification of the special lithology and minerals through better use of lamina, lithification, ECS element logging and regular logging information. From a comprehensive study, the following findings were concluded. First, imaging logging was effective in accurately identifying and classifying various fissures. Second, the fissures were effectively assessed based on the combination of anisotropy and frequency dispersion curves obtained from the acoustic scanning with fissure identification results. Third, through combined application of regular logging and imaging logging, the effective qualitative identification was made of corroded pores and caves as well as large karst caves. Fourth, the quantitative identification was also performed of the development degree and connectivity of corroded pores and caves by use of the BorTex and porosity spectrum technologies while the extension of large karst caves was analyzed based on drilling, logging and seismic data. And finally, reservoir fluids were determined after exclusion of influences such as the invaded drilling fluid, conductive minerals, etc. by use of the methods including movable water index, dual laterolog ratio, apparent resistance increase rate, dielectric scanning, neutron density and neutron sound wave superposition, in combination with the distribution of horizontal and vertical fluids in reservoirs. The constant improvement of well log analysis provides technical support for the further exploitation of deep hydrocarbon reservoirs in this study area.