沁水盆地夏店区块煤层气藏气水分异特征

Gas-water differentiation characteristics of CBM reservoirs in Xiadian block, Qinshui basin

  • 摘要: 沁水盆地夏店区块煤层气藏属低孔低渗致密气藏,区块试采情况证实该区气水分布关系复杂。为了明确研究区气水分布规律,对夏店区块试采区煤层气地质条件、压裂和生产动态资料进行分析,阐明夏店区块试采区的气水分布特点,探讨气水分布差异主控因素。结果表明,研究区气水分异主要表现为2种情况,一是高部位产气、低部位产水的重力分异;二是局部井区受断层影响,出现高部位产水、低部位产气的气水倒置现象。根据气水分布特征,以构造形态为骨架,结合储层、压裂及生产动态资料,建立了封闭断层–褶曲、类气顶、开放断层控制、微构造控制、顶底板岩性控制等5种气水分布模式,明确了沁水盆地夏店区块气水分布主要受构造及压裂控制影响,同时提出差异化的井位部署建议,可以指导该区煤层气进一步的勘探开发。

     

    Abstract: The coalbed methane reservoirs at Xiadian block of Qinshui basin are of low porosity and low permeability. In order to define the gas-water distribution rule in the study area, CBM geological conditions, fracturing and production performance data in the pilot mining district of Xiadian block were analyzed to illuminate the gas-water distribution characteristics and discusses the control factors of gas water distribution differences. The results show that the difference of gas and water in the study area occurs mainly in two cases, one is the difference of the gravity, gas occurs in higher part, water occurs in lower part; the second is that locally affected by the fault, and the gas-water inversion phenomenon occurs, water appears in the higher part and gas appears in the low part. According to the characteristics of gas-water distribution, with structural form as skeleton, combined with reservoir fracturing and production performance data, five patterns of gas and water distribution, were set up, that is, closed fault fold, gas-like cap, open fault control, micro structure control, lithologic control of roof and floor, it was defined that gas and water distribution in this area was mainly affected by structure and fracturing, at the same time differentiated well placement was suggested, which can guide the further exploration and development of CBM.

     

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