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韩城区块煤储层间接压裂地质主控因素研究

Research on main geological controlling factors of coal reservoir indirect fracturing in Hancheng Block

  • 摘要: 为解决间接压裂技术在韩城区块适应性问题,采用控制变量法对影响间接压裂产气量的地质因素进行了定量研究,提出了在相同的条件下,增大射开顶板比例可在一定程度上提高间接压裂的改造效果。研究结果表明:影响间接压裂效果的地质主控因素为煤层顶板特性和煤体结构,其中当顶板为砂岩时,影响间接压裂效果的主要因素依次为层理、沉积韵律、泥质夹层、天然裂隙和砂体含水性;顶板为泥岩时,脆性指数的大小影响着间接压裂的改造效果,泥岩脆性指数大于40时,间接压裂对于增产才有效。而煤体结构对间接压裂的影响主要表现在:煤体结构越破碎,人工裂缝越不容易在煤层中延伸,且排采过程中更易产出煤粉,导致间接压裂增产效果变差。

     

    Abstract: In order to solve the adaptability problems of high-degree indirect fracturing technology in Hancheng Block, by adopting the method of control variables, geological factors influencing gas production of indirect fracturing was quantitatively analyzed, it was also proposed that in the same conditions improving the strengths of perforated roof could increase the optimizing effects of indirect fracturing. The results show that main geological controlling factors affecting the effects of indirect fra cturing by ordinal are sediment bedding, rhythm, shale intercalation, natural fracture and sand body aquosity; when roof is mudstone, brittleness index controls stimulati on effect of indirect fracturing, main geological controlling factors affecting the effects of indirect fracturing are roof of coal seam and structure of coal body.The effect of indirect fracturing is influenced when roof is sandstone, only if the brittleness index of mudstone is larger than 40, the indirect fracturing can play a role on increasing th e gas production. The impact of coal structure on indirect fracturing is mainly reflected as follows: if coal structure get fragmentized, it is more diffcult for artificial fractur e to extend in the coal seam, and it is prone to produce coal power during drainage, which has caused the effects of gas production caused by indirect fracturing.

     

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