火山岩气藏水平井压裂产能影响因素分析

Analysis of Influencing Factors of Fractured Horizontal Wells’Productivity in Volcanic Gas Reservoirs

为了进一步提高水平井压裂产能预测精度,研究了产能预测方法,同时进行了产能预测分析。采用复位势理论和叠加原理,考虑缝间干扰和应力敏感,建立了火山岩气藏水平井压裂产能模型。随着裂缝半长的增加,气井产能逐渐增加,单位裂缝半长产能增加百分数逐渐降低。当裂缝半长小于50m,单位裂缝半长产能增加百分数降低较快;当裂缝半长大于50m,降低减缓,在泄气面积、水平段长度一定的情况下,水平井压裂产能与裂缝条数成正比,然而裂缝条数增至5~8条后,因存在明显的缝间干扰,使气井产能增加趋于平缓。通过已完钻水平井验证,预测精度达到85%;同时分析了影响气井产能的裂缝长度、条数等因素,确定了适合大庆徐深气田的水平井压裂增产规模。

To further enhance the predictive accuracy of fractured horizontal wells’productivity,the productivity prediction methods were researched and the corresponding analysis was conducted at the same time.The producttivity model for fractured horizontal wells was established in volcanic gas reservoirs based on the complex potential the-ory and the superposition principle and taken the seam interference and the stress sensitivity into account.With the increasing fracture half-length,gas well's productivity rises gradually,however the increased productivity percent-age of unit fracture half-length drops.The percentage mentioned above drops faster as the fracture half-length is shorter than 50m,while it drops more slowly when the fracture half-length is longer than 50m.Under the certain drainage area and the length of horizontal intervals,the productivity of fractured horizontal wells is proportionate to the number of fractures.However,there exists obvious seam interference when the number of fractures rises to 5 8,as a result,the growth of gas wells'productivity tends to be moderate.Through test in drilled horizontal wells,the predictive accuracy of the new productivity model reaches as high as 85%.Meanwhile,the appropriate stimula-tion scale of fractured horizontal wells in Xushen gas field was confirmed after analyzing the length and number of fractures and other factors influencing the gas wells'productivity.