--> Genesis of Lacustrine Carbonate Breccias and Their Implications for Hydrocarbon Exploration in Yingxi Region, Qaidam Basin

2018 AAPG International Conference and Exhibition

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Genesis of Lacustrine Carbonate Breccias and Their Implications for Hydrocarbon Exploration in Yingxi Region, Qaidam Basin

Abstract

Yingxi region is located in the northwestern part of the Qaidam Basin. In recent years, significant breakthroughs have made in the exploration of Paleogene carbonate rocks. Industrial oil and gas streams with a daily output of more than 1,000 tons (square) per day have been obtained, some of them even up to 10000 tons per day. In order to examine the development characteristics and hydrocarbon exploration direction of high-yield carbonate reservoirs in Yingxi region, based on the data of cores, thin sections, logging and seismic data of the high-yield intervals, the paper analyzes that the high-yield intervals are mainly carbonate breccia rocks. Three kinds of breccia reservoirs are identified according to breccia characteristics: penecontemporaneous breccia of sedimentary origin, with reservoir space of intergranular pores and dissolved pores; fault breccia and interlayer-slide breccia of tectonic origin, with complex reservoir space of different sizes of pore-hole-seam system. On this basis, it is pointed out that the exposed surface at the top of the submarine paleohighs in the depositional period is a favorable area for penecontemporaneous breccia reservoirs. The coupling zone between the late fault system and the carbonate intervals is a favorable area for fault breccias. The carbonate adjacent to the thick salt slide layers is a favorable area for interlayer-slide breccia. This is of great guiding significance to the exploration and exploitation of the deep-buried lacustrine carbonate reservoirs in Yingxi region.