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柴达木盆地三湖地区第四系为弱成岩疏松砂岩地层,近几年围绕构造圈闭的勘探成效不大,岩性气藏将成为该区天然气储量的又一增长点。在层序地层分析基础上,分析了该盆地第四系独特的沉积条件及岩性气藏成藏条件:①盆地周边的构造坡折带是岩性圈闭的有利发育区;②构造背景上的斜坡带是岩性气藏发育区;③深层岩石的弱成岩作用有利于岩性圈闭的形成。根据对三湖地区第四系构造背景、沉积体系展布特征及岩性圈闭发育条件等的综合分析,得出三湖地区七个泉组发育有岩性尖灭带、盆地内沉积低隆起或鼻隆起带、斜坡带及透镜体等类型的岩性圈闭的认识。最后,提出了三湖地区岩性气藏的勘探技术对策:应加强保低频保振幅地震处理与综合解释,高分辨率露头层序的建立,测井资料的精细对比分析等工作。
The Quaternary in the Sanhu area of the Qaidam Basin is a weak diagenetic unconsolidated sandstone formation. In recent years, exploration around structural traps has had little success. Lithologic gas reservoirs will become another growth point for natural gas reserves in this area. Based on the analysis of sequence stratigraphy, the unique depositional conditions of Quaternary and the reservoir forming conditions for lithologic gas reservoirs are analyzed: (1) the structural slope break zone around the basin is a favorable development zone for lithologic traps; (2) on the tectonic setting The slope zone is a lithologic gas reservoir development area. (3) The weak diagenesis of deep rocks is conducive to the formation of lithologic traps. Based on the comprehensive analysis of Quaternary tectonic setting, distribution characteristics of sedimentary system and lithologic trapping development conditions in Sanhu area, it is concluded that there are lithic sharp-erupted zones in Qizuquan Formation in Sanhu area and low sedimentation in the basin Or nasogastric uplift, slope belt and lens body types of lithological traps. Finally, the exploration and technical countermeasures of lithologic gas reservoirs in Sanhu area are put forward. The seismic processing and integrated interpretation of the amplitude preserving bass frequency and amplitude preserving amplitude, the establishment of high resolution outcrop sequence and the fine contrast analysis of logging data should be strengthened.