延川南地区深部煤层气U型水平井压裂参数优化设计

Optimal design of the parameters of U-shaped horizontal well for deep coalbed methane in southern Yanchuan

  • 摘要: 鄂尔多斯盆地东缘煤层气田具有高储低渗的特点,为提高深部煤层气单井产量,基于区域构造特征、煤层厚度、含气量及水文地质特征,从优化U型水平井压裂参数的角度,对水平井及其压裂参数进行设计。通过数值模拟对影响水平井产量的水平段长度、压裂缝等主要因素进行研究。结果表明:不考虑摩阻情况下,煤层气产量随水平段长度增加而增加,当水平段超过800m后,由于阻力作用,水平段长度每增加100m,产气量降低10%;压裂缝条数和半缝长对产气量影响较大,最佳的压裂缝条数为4~5条,最佳半缝长为80~120m;裂缝间距和裂缝渗透率对煤层气产量影响不大。依据数值模拟的最优参数对该区煤层气井S1进行压裂,在相同条件下,煤层气产量比未压裂的S2井提高了10倍以上。

     

    Abstract: The coalbed methane field in the east edge of Ordos basin has the characteristics of "high storage and low permeability". In order to improve the production of deep coalbed methane of single well, the U-shaped horizontal well and its fracturing mode were designed based on the regional structural features, coalbed burial depth, gas content and hydrogeological characteristics. Through numerical simulation, the main factors that affect the output of horizontal well(such as the length of horizontal section and the fractured cracks)were studied. The results show that with the increase of horizontal section length, the output of coalbed methane increases gradually, when the horizontal section exceeds 800 m, the gas production will be reduced by about 10% per every 100 m. The number of fractured cracks and the half length of fractured cracks have great influence on gas production. The optimal number of fractured cracks is 4-5, and the optimum half length is 80-120 m. Fracture spacing and fracture conductivity have little effect on coalbed methane production. Field fracturing test proves that according to the optimal parameters of numerical simulation, CBM well S1 in this area is fractured. Under the same conditions, CBM production is more than 10 times higher than that of well S2 without fracturing.

     

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