煤粉对支撑裂缝导流能力的影响特征及其防控
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摘要
针对煤层气井的煤粉伤害问题,运用LD-1A导流能力测试系统模拟了煤层气井变排量、恒排量及间抽过程中煤粉在支撑裂缝中的运移沉积情况,分析了不同流速下煤粉对支撑裂缝导流能力的影响特征及伤害机理。实验表明:煤粉易滞留沉积在支撑裂缝底部严重影响导流能力,导流能力伤害率可达90%以上;在没有煤粉持续进入支撑裂缝的情况下,有效排出煤粉导流能力有增大的趋势;排采制度、煤粉质量含量、煤粉粒径对导流能力的影响特征存在明显差异;煤粉随水运移时对支撑剂窄口的疏通作用和聚集堵塞作用共同影响支撑裂缝导流能力。压裂前期使用小粒径支撑剂,尾追大粒径支撑剂,合理控制排采速度,使排采速度略小于煤粉运移的临界流速,并使用煤粉分散剂,有利于适量排出煤粉减小导流能力伤害。
In order to deal with the problem of coal powder damage in the process of CBM( coalbed methane),the well changing flow velocity,constant flow velocity and discontinuous flow production,the coal powder migration and deposition in proppant fracture were simulated with LD-1A proppant conductivity testing system. Influencing characteristics and damage mechanism of coal powder to proppant fracture conductivity under different flow velocities were analyzed.Experimental results show that coal powder easily deposits in the bottom of the proppant fracture and seriously damage the fracture conductivity.The damage rate of fracture conductivity is up to more than 90%.Fracture conductivity has an increasing tendency when coal powder discharge effectively in the condition that coal powder isn't added to proppant fracture continuously.Influencing characteristics of production system,coal powder content and diameter to flow conductivity have obvious differences.Coal powder plug and dredge in proppant narrow pore influence the proppant fracture conductivity together when migration with water.Proppant in smaller diameters was employed at the beginning of fracturing,then proppant in bigger diameters was used.Flow velocity is controlled reasonably to ensure that the flow ve-locity is less than coal powder migration critical velocity.And coal powder dispersion agent is employed for fracturing.They are good for coal powder discharging effectively and reducing the fracture conductivity damage.
In order to deal with the problem of coal powder damage in the process of CBM( coalbed methane),the well changing flow velocity,constant flow velocity and discontinuous flow production,the coal powder migration and deposition in proppant fracture were simulated with LD-1A proppant conductivity testing system. Influencing characteristics and damage mechanism of coal powder to proppant fracture conductivity under different flow velocities were analyzed.Experimental results show that coal powder easily deposits in the bottom of the proppant fracture and seriously damage the fracture conductivity.The damage rate of fracture conductivity is up to more than 90%.Fracture conductivity has an increasing tendency when coal powder discharge effectively in the condition that coal powder isn't added to proppant fracture continuously.Influencing characteristics of production system,coal powder content and diameter to flow conductivity have obvious differences.Coal powder plug and dredge in proppant narrow pore influence the proppant fracture conductivity together when migration with water.Proppant in smaller diameters was employed at the beginning of fracturing,then proppant in bigger diameters was used.Flow velocity is controlled reasonably to ensure that the flow ve-locity is less than coal powder migration critical velocity.And coal powder dispersion agent is employed for fracturing.They are good for coal powder discharging effectively and reducing the fracture conductivity damage.
引文
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[16]刘岩,张遂安,石惠宁,等.支撑剂嵌入不同坚固性煤岩导流能力实验研究[J].石油钻采工艺,2013,35(2):75-78.Liu Yan,Zhang Suian,Shi Huining,et al.Experimental research on flow conductivity of different firmness coal rock embedded by proppant[J].Oil Drilling&Production Technology,2013,35(2):75-78.
[17]周明松,邱学青,王卫星.水煤浆分散剂的研究进展[J].化工进展,2004,23(8):846-850.Zhou Mingsong,Qiu Xueqing,Wang Weixing.Advances in the dispersants of coal water slurry[J].Chemical Industry and Engineering Progress,2004,23(8):846-850.
[18]张劲,赵军,林鑫,等.用于煤层气改造的分散剂优选实验研究[J].煤炭学报,2011,36(4):598-602.Zhang Jin,Zhao Jun,Lin Xin,et al.Experimental study for screening of dispersion agents used in CBM stimulation[J].Journal of China Coal Society,2011,36(4):598-602.
[19]Nguyen P D,Dusterhoft R G,Clarkson B.Control of formation fines to provide long-term conductivity in weak,unconsolidated reservoirs[J].SPE17039,2005.
[20]Zhao Jianhui,Lai Xingping.Application of preblasting to high-section top coal caving for steepthick coal sea[J].Journal of Coal Science&Engineering(China),2011,17(2):113-118.
[2]邹雨时,张士诚,张劲,等.煤粉对裂缝导流能力的伤害机理[J].煤炭学报,2012,37(11):1891-1894.Zou Yushi,Zhang Shicheng,Zhang Jin,et al.Damage mechanism of coal powder on fracture conductivity[J].Journal of China Coal Society,2012,37(11):1891-1894.
[3]李仰民,王立龙,刘国伟,等.煤层气井排采过程中的储层伤害机理研究[J].中国煤层气,2010,7(6):39-43.Li Yangmin,Wang Lilong,Liu Guowei,et al.Study on coal reservoir damage mechanism in dewatering and extraction process of CBM wells[J].China Coalbed Methane,2010,7(6):39-43.
[4]刘岩,张遂安,曹立虎,等.煤粉在支撑裂缝中的运移与沉积规律[J].煤炭学报,2014,39(7):1333-1337.Liu Yan,Zhang Suian,Cao Lihu,et al.Rules of coal powder migration and deposition in the proppant fracture[J].Journal of China Coal Society,2014,39(7):1333-1337.
[5]白建梅,孙玉英,李薇,等.高煤阶煤层气井煤粉产出对渗透率影响研究[J].中国煤层气,2011,8(6):18-21.Bai Jianmei,Sun Yuying,Li Wei,et al.Study of the impact of coal dust yield on permeability rate in high rank CBM well[J].China Coalbed Methane,2011,8(6):18-21.
[6]邹雨时,马新仿,王雷,等.中、高煤阶煤岩压裂裂缝导流能力实验研究[J].煤炭学报,2011,36(3):473-476.Zou Yushi,Ma Xinfang,Wang Lei,et al.Experimental evaluation of conductivity of fracturingin medium and high-rank coal beds[J].Journal of China Coal Society,2011,36(3):473-476.
[7]Meszaros G Geosteering.Horizontal coalbed methane reservoirs:A case study[J].SPE 107714-MS,2007.
[8]Awoleke O,Romero J,Zhu D,et al.Experimental investigation of propped fracture conductivity in tight gas reservoirs using factorial design[J].SPE 151963,2012:1-15.
[9]刘升贵,胡爱梅,宋波,等.煤层气井排采煤粉浓度预警及防控措施[J].煤炭学报,2012,37(1):86-90.Liu Shenggui,Hu Aimei,Song Bo,et al.Coal powder concentration warning and control measure during CBM well drainage[J].Journal of China Coal Society,2012,37(1):86-90.
[10]张遂安,曹立虎,杜彩霞.煤层气井产气机理及排采控压控粉研究[J].煤炭学报,2014,39(9):1927-1931.Zhang Suian,Cao Lihu,Du Caixia.Study on CBM production mechanism and control theory of bottom-hole pressure and coal fines during CBM well production[J].Journal of China Coal Society,2014,39(9):1927-1931.
[11]Phillip B Kaufman,Robert W,Mark Ziegler,et al.Introducing new API/ISO procedures for proppant testing[A].Annual Techical Conference and Exhibition[C].SPE 110697,2007.
[12]Yan Tie,Li Wei,Bi Xueliang.An experimental study of fracture initiation mechanisms during hydraulic fracturing[J].Petroleum Science,2011,8(1):87-92.
[13]George E King.Thirty years of gas shale fracturing:What have we learn[J].SPE133456,2010.
[14]Rodvelt G,Toothman R,Willis S,et al.Multiseam coal stimulation using coiled-tubing fracturing and a unique bottomhole packer assembly[J].SPE72380,2001.
[15]陈振宏,王一兵,孙平.煤粉产出对高煤阶煤层气井产能的影响及其控制[J].煤炭学报,2009,34(2):229-232.Chen Zhenhong,Wang Yibing,Sun Ping.Destructive influences and effectively treatments of coal powder to high rank coalbed methane production[J].Journal of China Coal Society,2009,34(2):229-232.
[16]刘岩,张遂安,石惠宁,等.支撑剂嵌入不同坚固性煤岩导流能力实验研究[J].石油钻采工艺,2013,35(2):75-78.Liu Yan,Zhang Suian,Shi Huining,et al.Experimental research on flow conductivity of different firmness coal rock embedded by proppant[J].Oil Drilling&Production Technology,2013,35(2):75-78.
[17]周明松,邱学青,王卫星.水煤浆分散剂的研究进展[J].化工进展,2004,23(8):846-850.Zhou Mingsong,Qiu Xueqing,Wang Weixing.Advances in the dispersants of coal water slurry[J].Chemical Industry and Engineering Progress,2004,23(8):846-850.
[18]张劲,赵军,林鑫,等.用于煤层气改造的分散剂优选实验研究[J].煤炭学报,2011,36(4):598-602.Zhang Jin,Zhao Jun,Lin Xin,et al.Experimental study for screening of dispersion agents used in CBM stimulation[J].Journal of China Coal Society,2011,36(4):598-602.
[19]Nguyen P D,Dusterhoft R G,Clarkson B.Control of formation fines to provide long-term conductivity in weak,unconsolidated reservoirs[J].SPE17039,2005.
[20]Zhao Jianhui,Lai Xingping.Application of preblasting to high-section top coal caving for steepthick coal sea[J].Journal of Coal Science&Engineering(China),2011,17(2):113-118.