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基于储层特征不确定性的产能分析——以古交区块为例

Gas productivity based on reservoir uncertainty analysis in Gujiao Block

  • 摘要: 古交区块开发面临平均产气量低,井间产气效果差异大的问题,明确产能主控因素并提出针对性增产措施是区块后期开发的关键。基于古交区块储层物性及生产特征,建立了古交区块典型数值模拟模型。基于典型模型,结合储层参数分布范围,通过蒙特卡洛插值方法,建立了不同参数组合下的数值模拟模型。通过参数敏感性分析,确定产能主控因素。研究结果表明:含气量、割理渗透率是影响产气量的主控因素。排采制度的制定,应重点考虑储层含气性及割理渗透率大小。先定产水量后定井底流压排采时,割理渗透率增加,累计产气量先增加后减小;定井底流压排采时,割理渗透率与累计产气量为正相关线性关系。同一含气量条件下,定井底流压生产比先定产水量后定井底流压生产的最终累计产气量高。割理渗透率、裂缝渗透率是影响压降扩展和产气的主控因素。割理渗透率为9.7×10-10 m2,裂缝渗透率为3×10-9 m2时,压降主要受割理渗透率影响;割理渗透率为6×10-11 m2,裂缝渗透率为3×10-9 m2时,压降主要受裂缝渗透率影响。因此,后期开发过程中需加强渗透率及含气量监测,根据储层条件制定合理的排采制度。同时,古交区块平均渗透率为1×10-10 m2,井距为300 m,很难实现井间干扰,后期可考虑体积压裂增产改造方式提高储层整体渗透率或打加密井以实现稳产增产。该研究成果为煤层气井稳产增产提供了开发建议。

     

    Abstract: The development of the Gujiao Block faces the problems of low average gas production and large difference in gas production effect between wells. The key to the later development of the block is to clarify the main controlling factors of productivity and propose targeted measures to increase production.Based on the reservoir physical properties and production characteristics of Gujiao block, a typical numerical simulation model of Gujiao block was established. Based on the physical properties and production characteristics of the Gujiao Block, a typical numerical simulation model for the Gujiao Block was established. Based on the typical model, combined with the distribution range of reservoir parameters, a numerical simulation model with different parameter combinations was established by Monte Carlo interpolation method. Through parameter sensitivity analysis, the main factors affecting productivity and inter-well interference were obtained. The research results show that gas content and cleat permeability are the main factors affecting gas production. The formulation of the drainage system should focus on the gas-bearing nature of the reservoir and the cleat permeability. When water production is first determined and then bottom-hole pressure is fixed, the cleat permeability increases, the cumulative gas production increases first and thenLMdecreases; when the bottom-hole pressure is determined, the cleat permeability and the cumulative gas production have a positive linear relationship. Under the same gas content condition, the final cumulative gas production of constant bottom hole pressure production is higher than the final cumulative gas production after first setting the water production rate and then constant bottom hole flow pressure production. Cleat permeability and fracture permeability are the main factors affecting pressure drop expansion and gas production effect. When the cleat permeability is 9.7×10-10 m2 and the fracture permeability is 9.7×10-9 m2, the pressure drop is mainly affected by the cleat permeability; when the cleat permeability is 6×10-11 m2 and the fracture permeability is 3×10-9 m2, the pressure drop is mainly affected by the fracture permeability. Therefore, it is necessary to strengthen the permeability and gas content monitoring in the later development process and formulate a reasonable production system according to the reservoir conditions. Meanwhile, the Gujiao Block has an average permeability of 1×10-10 m2 and a well spacing of 300 m. It is difficult to achieve inter-well interference.In the later stage, volume fracturing stimulation can be considered to increase the overall permeability of the reservoir or to drill infill wells to achieve stable production and increase production. The research results provide development suggestions for stable and increased production of CBM wells.

     

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