页岩气缝网优化的数值模拟
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摘要
为定量评价页岩气储层压裂缝网参数对产量的影响程度,运用页岩渗流机理,通过Eclipse建立页岩气水平井压裂后形成的复杂缝网模型,进行局部网格加密,分析了改变单因素(段间距、簇数、簇间距、次生缝间距、主缝长、次生缝长、主缝导流能力、次生缝导流能力、天然裂缝渗透率)对累计产量的影响,再对所有参数进行多因素正交方案设计,找出影响累计产气量的主控因素先后顺序并得到产量最大化的方案。结果表明,随着段间距、簇数与簇间距的增加,累计产气量随之减少;随着主缝与次生缝的长度增加,累计产气量随之增加;随着天然裂缝渗透率的增加,累计产气量随之增加;影响累计产气量的第一因素是天然裂缝渗透率,排在2到5位的依次是段间距、主缝长、簇间距与簇数,其他4个因素对累计产气量影响不大;正交方案设计中累计产量最多的方案为段间距40 m,3簇,簇间距40 m,次生缝间距30 m,主缝长530 m,次生缝长40 m,主缝导流能力7×10~(-3)μm~2·m,次生缝导流能力2×10~(-3)μm~2·m,天然裂缝渗透率0.000 8×10~(-3)μm~2,累计产量为2.94×10~8m~3。在实际生产中,尽可能提高主裂缝长度,压缩段间距、簇间距与簇数对页岩气产量有较大的提升。研究结果为页岩气压裂缝网部署提供了参考。
In order to quantitatively evaluate the influenced degree of the fracture network parameters of shale-gas reservoir fracturing on the production, with the help of the shale flow mechanism and Eclipse, the complex fracture network mode was established after fracturing of the horizontal well, the local grid refinement was conducted, the influences of changing the single-factor(segment/interval spacing, branch number and interval, secondary fracture spacing, primary and secondary fracture lengths, primary and secondary fracture conductivities, natural fracture permeability) on the cumulative production were analyzed, and then multi-factor orthogonal program design was engaged for all the parameters to find out the sequence of the primary controlling factor to the cumulative production and obtain the maximized program of the production. The results show that with the increase of the segment spacing, branch number and interval, the cumulative production declines on the contrary; with the rise of the lengths of the primary and secondary fracture, the cumulative production grows up as well; with the increase of the permeability of the natural fracture, so as the cumulative production. The first influencing factor to the cumulative production is the permeability of the natural fracture, the next is the segment spacing, length of primary fracture, branch spacing and interval; in the orthogonal program design, the largest cumulative production is that when the segment spacing is 40 m, the branches are three, the branch spacing is 40 m, the secondary fracture spacing is 30 m, the length of the primary fracture is 530 m, the length of the secondary fracture is 40 m, the conductivity of the primary fracture is 7×10~(-3)μm~2·m, the conductivity of the secondary fracture is 2×10~(-3)μm~2·m and the permeability of the natural fracture is 0.000 8×10~(-3)μm~2, the cumulative production is 2.94×10~8 m~3. In the actual production, the length of the primary fracture should be enhanced as much as possible, while for the segment and branch intervals, and furthermore the branch number, they are just on the contrary, thus the production of the shale gas can be greatly increased. The research results can provide the reference for the arrangement of the shale-gas fractured grid.
In order to quantitatively evaluate the influenced degree of the fracture network parameters of shale-gas reservoir fracturing on the production, with the help of the shale flow mechanism and Eclipse, the complex fracture network mode was established after fracturing of the horizontal well, the local grid refinement was conducted, the influences of changing the single-factor(segment/interval spacing, branch number and interval, secondary fracture spacing, primary and secondary fracture lengths, primary and secondary fracture conductivities, natural fracture permeability) on the cumulative production were analyzed, and then multi-factor orthogonal program design was engaged for all the parameters to find out the sequence of the primary controlling factor to the cumulative production and obtain the maximized program of the production. The results show that with the increase of the segment spacing, branch number and interval, the cumulative production declines on the contrary; with the rise of the lengths of the primary and secondary fracture, the cumulative production grows up as well; with the increase of the permeability of the natural fracture, so as the cumulative production. The first influencing factor to the cumulative production is the permeability of the natural fracture, the next is the segment spacing, length of primary fracture, branch spacing and interval; in the orthogonal program design, the largest cumulative production is that when the segment spacing is 40 m, the branches are three, the branch spacing is 40 m, the secondary fracture spacing is 30 m, the length of the primary fracture is 530 m, the length of the secondary fracture is 40 m, the conductivity of the primary fracture is 7×10~(-3)μm~2·m, the conductivity of the secondary fracture is 2×10~(-3)μm~2·m and the permeability of the natural fracture is 0.000 8×10~(-3)μm~2, the cumulative production is 2.94×10~8 m~3. In the actual production, the length of the primary fracture should be enhanced as much as possible, while for the segment and branch intervals, and furthermore the branch number, they are just on the contrary, thus the production of the shale gas can be greatly increased. The research results can provide the reference for the arrangement of the shale-gas fractured grid.
引文
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[15]程远方,李友志,时贤,等.页岩气体积压裂缝网模型分析及应用[J].天然气工业,2013,33(9):53-59.CHENG Yuanfang,LI Youzhi,SHI Xian,et al.Analysis and application of fracture network models of volume fracturing in shale gas reservoirs[J].Natural Gas Industry,2013,33(9):53-59.
[2]姜福杰,庞雄奇,欧阳学成,等.世界页岩气研究概况及中国页岩气资源潜力分析[J].地学前缘,2012,19(2):198-211.JIANG Fujie,PANG Xiongqi,OUYANG Xuecheng,et al.The main progress and problems of shale gas study and the potential prediction of shale gas exploration[J].Earth Science Frontiers,2012,19(2):198-211.
[3]王兰生.中国页岩气勘探开发面临的问题与对策[J].天然气工业,2011,31(12):119-122.WANG Lansheng.Bottlenecks and countermeasures in shale gas exploration and development of China[J].Natural Gas Industry,2011,31(12):119-122.
[4]董大忠,邹才能,杨桦,等.中国页岩气勘探开发进展与发展前景[J].石油学报,2012,33(增刊1):108-114.DONG Dazhong,ZOU Caineng,YANG Ye,et al.Progress and prospects of shale gas exploration and development in China[J].Acta Petrolei Sinica,2012,33(S1):108-114.
[5]MAYERHOFER M J,LOLON E P,YOUNGBLOOD J E,et al.Integration of microseismic fracture mapping results with numerical fracture network production modeling in the Barnett shale[R].SPE 102103,2006.
[6]MAYERHOFER M J,LOLON E P,WARPINSKI N R,et al.What is stimulated r eservoir volume[R].SPE 119890,2008.
[7]陈作.页岩气井体积压裂技术在我国的应用建议[J].天然气工业,2010,30(10):30-32.CHEN Zuo.Proposals for the application of fracturing by stimulated reservoir volume (SRV) in shale gas wells in China[J].Natural Gas Industry,2010,30(10):30-32.
[8]杜林麟,春兰,王玉艳,等.页岩储层水力压裂优化设计[J].石油钻采工艺,2010,32(增刊1):130-132.DU Linlin,CHUN Lan,WANG Yuyan,et al.Hydraulic fracturing optimization for shale reservoirs[J].Oil Drilling & Production Technology,2010,32(S1):130-132.
[9]陈守雨,刘建伟,龚万兴,等.裂缝性储层缝网压裂技术研究及应用[J].石油钻采工艺.2010,32(6):67-71.CHEN Shouyu,LIU Jianwei,GONG Wanxing,et al.Study and application on network fracturing technology in fractured reservoir[J].Oil Drilling & Production Technology,2010,32(6):67-71.
[10]陈守雨,杜林麟,贾碧霞,等.多井同步体积压裂技术研究[J].石油钻采工艺,2011,33(6):59-65.CHEN Shouyu,DU Linlin,JIA Bixia,et al.Research on the simultaneous volume fracturing of multiple wells[J].Oil Drilling & Production Technology,2011,33(6):59-65.
[11]吴奇,胥云,王晓泉,等.非常规油气藏体积改造技术:内涵、优化设计与实现[J].石油勘探与开发,2012,39(3):352-358.WU Qi,XU Yun,WANG Xiaoquan,et al.Volume fracturing technology of unconventional reservoirs:Connotation,optimization design and implementation[J].Petroleum Exploration and Development,2012,39(3):352-358.
[12]刘立峰,张士诚.通过改变近井地应力场实现页岩储层缝网压裂[J].石油钻采工艺,2011,33(4):71-74.LIU Lifeng,ZHANG Shicheng.Net fracturing by changing the surrounding in-situ stress in shale reservoirs[J].Oil Drilling & Production Technology,2011,33(4):71-74.
[13]蒋廷学,贾长贵,王海涛,等.页岩气网络压裂设计方法研究[J].石油钻探技术.2011,39(3):36-40.JIANG Tingxue,JIA Changgui,WANG Haitao,et al.Study on network fracturing design method in shale gas[J].Petroleum Drilling Techniques,2011,39(3):36-40.
[14]李小刚,苏洲,杨兆中,等.页岩气储层体积缝网压裂技术新进展[J].石油天然气学报,2014,36(7):154-159.LI Xiaogang,SU Zhou,YANG Zhaozhong,et al.New progress of volumetric network fracturing technologies for shale gas reservoirs[J].Journal of Oil and Gas Technology,2014,36(7):154-159.
[15]程远方,李友志,时贤,等.页岩气体积压裂缝网模型分析及应用[J].天然气工业,2013,33(9):53-59.CHENG Yuanfang,LI Youzhi,SHI Xian,et al.Analysis and application of fracture network models of volume fracturing in shale gas reservoirs[J].Natural Gas Industry,2013,33(9):53-59.