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川西坳陷中浅层河道砂岩气藏的成藏模式众多,但不同成藏模式控制下的成藏区域或层系的开发效益存在明显差异。本文通过解剖川西坳陷中浅层河道砂岩气藏高效开发层系或区域的成藏地质条件,明确该区中浅层高效成藏模式为“香肠式”成藏,该成藏模式包括两个重要环节,即“香肠式”充注和“香肠式”圈闭。研究表明“香肠式”成藏必须同时具备以下几个基本条件:(1)条带状外形的河道砂体;(2)河道砂体一端存在明显的岩性尖灭;(3)河道砂体另一端延伸至中浅层源岩断层发育区内;(4)河道砂体一端直接相接的源岩断层的倾角小;(5)单斜背景下的岩性圈闭。通过后期钻井测试、试采证实,具备“香肠式”成藏条件的区域或层系,单井产能高,稳产时间长,且无水产出。类比分析,在地质条件相当的其他地区河道砂岩气藏的勘探开发中,该成藏模式可作为一种高效成藏模式来进行推广运用。
There are many accumulation modes of sandstone gas reservoirs in the middle and shallow channels in the western Sichuan depression, but there are obvious differences in the development benefits of the reservoir-forming zones or strata under the control of different accumulation modes. In this paper, through the dissection of the reservoir forming geological conditions of the middle and shallow channel sandstone gas reservoirs in the western Sichuan depression, the high-efficiency reservoir-forming model in this area is defined as “sausage”, which includes Two important links, namely “sausage type” charge and “sausage type” trap. The research shows that the formation of “sausage type” reservoirs must have the following basic conditions at the same time: (1) riverbed sand bodies with strip shape; (2) obvious lithological pinch out at one end of river sand bodies; (3) The other end of the sand body extends into the middle-shallow source rock fault zone; (4) the dip angle of the source rock fault directly connected with one end of the channel sand body is small; (5) lithologic traps in the monoclinic background. Through the late drilling test, trial production proved that the area or strata with “sausage type” accumulation conditions have high single well productivity, long stable production time and no water production. In analogy, during the exploration and development of channel sandstone gas reservoirs in other geological regions, the reservoir-forming model can be used as a highly efficient reservoir-forming model.