煤层气井排采参数影响因素及优化方法
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摘要
为进一步认识煤层气井排采影响因素,从煤层气储集层生产过程中可能出现的伤害出发,分析排采过程中各种伤害的机理,将伤害分为储集层应力敏感、近井地带伤害、煤粉运移和压降传递4个方面。根据最小化机理伤害的原则,针对煤层气不同生产阶段的压降速率进行理论研究和探讨,进而提出煤层气排采参数的优化方法。结果表明,在煤层气井生产初期,适当提高排采速度在不会引起严重的应力敏感效应的前提下,不仅能够有效增加排液效果,也能降低由于压裂作业对近井地带造成的伤害;而在煤层气井生产的中后期,建议采用间或增大压差的方式解放圈闭气,提高产量。对于易产煤粉储集层,在井底压力略大于临界解吸压力时,加大压差快速排水,不仅有助于已产出煤粉的排出,也能使气水两相流区域尽快出现,阻止储集层远端水的快速产出,达到抑制煤粉的目的。
In order to further understand the factors affecting the production of coalbed methane(CBD) wells, the possible damage mechanisms in the production process of coalbed gas wells including reservoir stress sensitivity, near-bore zone damage, pulverized coal migration and pressure drop transmission are analyzed. Based on the principle of minimizing the above mechanism damages, the pressure drop rates in different stages of coalbed methane production are studied theoretically in this paper and then the optimization method of coal seam gas well drainage is put forward. The results show that in the early stage of CBM production, the appropriate increase of production rate will not cause serious stress sensitivity effect, and not only the drainage effect can be effectively improved, but the damage to near-bore areas can be decreased; in the middle-late CBM production stage, it is suggested that the occasional increase of pressure difference should be adopted to release the trapped gas and improve production. For the reservoirs producing pulverized coal easily, when the bottom pressure of the well is slightly greater than the critical desorption pressure, increasing pressure difference for rapid drainage can promote the expulsion of the produced pulverized coal and make the gas-water two phase flow area appear as soon as possible, and the aims to prevent the rapid water production from the far-end of the reservoir and to suppress the pulverized coal can be realized.
In order to further understand the factors affecting the production of coalbed methane(CBD) wells, the possible damage mechanisms in the production process of coalbed gas wells including reservoir stress sensitivity, near-bore zone damage, pulverized coal migration and pressure drop transmission are analyzed. Based on the principle of minimizing the above mechanism damages, the pressure drop rates in different stages of coalbed methane production are studied theoretically in this paper and then the optimization method of coal seam gas well drainage is put forward. The results show that in the early stage of CBM production, the appropriate increase of production rate will not cause serious stress sensitivity effect, and not only the drainage effect can be effectively improved, but the damage to near-bore areas can be decreased; in the middle-late CBM production stage, it is suggested that the occasional increase of pressure difference should be adopted to release the trapped gas and improve production. For the reservoirs producing pulverized coal easily, when the bottom pressure of the well is slightly greater than the critical desorption pressure, increasing pressure difference for rapid drainage can promote the expulsion of the produced pulverized coal and make the gas-water two phase flow area appear as soon as possible, and the aims to prevent the rapid water production from the far-end of the reservoir and to suppress the pulverized coal can be realized.
引文
[1]景兴鹏,宋永辉.基于流体注入诊断法的煤层气试井技术研究[J].煤炭科学技术,2017,45(12):1-6.JING Xingpeng,SONG Yonghui.Technical research on test well of coalbed methane based on diagnostic fracture injection test method[J].Coal Science and Technology,2017,45(12):1-6.
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[12]SUN Z,SHI J,WANG K,et al.The gas-water two phase flow behavior in low-permeability CBM reservoirs with multiple mechanisms coupling[J].Journal of Natural Gas Science and Engineering,2018,52:82-93.
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[18]余杰,秦瑞宝,梁建设,等.煤层气“甜点”测井判别与产量预测--以沁水盆地柿庄南区块为例[J].新疆石油地质,2017,38(4):482-487.YU Jie,QIN Ruibao,LIANG Jianshe,et al.Sweet spot identification with well-logging data and production prediction for coalbed methane:a case study from southern Shizhuang block in Qinshui basin[J].Xinjiang Petroleum Geology,2017,38(4):482-487.
[19]杜彩霞,张遂安,刘程,等.煤层气规模开发条件下压力传播特征研究[J].煤炭科学技术,2016,44(12):179-183.DU Caixia,ZHANG Suian,LIU Cheng,et al.Study on reservoir pressure transmission feature of coalbed methane under condition of multi-well exploitation[J].Coal Science and Technology,2016,44(12):179-183.
[20]明盈,汤达祯,陶树,等.煤层气水平井产能预测模型及其适用性研究[J].煤炭科学技术,2016,44(12):113-117.MING Ying,TANG Dazhen,TAO Shu,et al.Study on productivity prediction model of horizontal coalbed methane well and its applicability[J].Coal Science and Technology,2016,44(12):113-117.
[21]魏迎春,张傲翔,姚征,等.韩城区块煤层气排采中煤粉产出规律研究[J].煤炭科学技术,2014,42(2):85-89.WEI Yingchun,ZHANG Aoxiang,YAO Zheng,et al.Research on output laws of pulverized coal during coalbed methane drainage in Hancheng block[J].Coal Science and Technology,2014,42(2):85-89.
[22]刘春花,刘新福,周超.煤层气井排采过程中煤粉运移规律研究[J].煤田地质与勘探,2015,43(5):23-26.LIU Chunhua,LIU Xinfu,ZHOU Chao.Migration patterns of coal powder in coal reservoirs during the well drainage[J].Coal Geology&Exploration,2015,43(5):23-26.
[2]贾慧敏,孙世轩,毛崇昊,等.基于煤岩应力敏感性的煤层气井单相流产水规律研究[J].煤炭科学技术,2017,45(12):189-193.JIA Huimin,SUN Shixuan,MAO Chonghao,et al.Study on singlephase flow water production law of coalbed methane well based on coal and rock stress sensitivity[J].Coal Science and Technology,2017,45(12):189-193.
[3]SUN Z,SHI J,ZHANG T,et al.The modified gas-water two phase version flowing material balance equation for low permeability CBMreservoirs[J].Journal of Petroleum Science&Engineering,2018,165:726-735.
[4]徐兵祥,李相方,杜希瑶,等.煤层气井解吸区预测模型研究[J].中国矿业大学学报,2013,42(3):421-427.XU Bingxiang,LI Xiangfang,DU Xiyao,et al.The predictive models of desorption region for coalbed methane wells[J].Journal of China University of Mining&Technology,2013,42(3):421-427.
[5]SUN Z,LI X,SHI J,et al.A semi-analytical model for drainage and desorption area expansion during coal-bed methane production[J].Fuel,2017,204:214-226.
[6]冯其红,舒成龙,张先敏,等.煤层气井两相流阶段排采制度实时优化[J].煤炭学报,2015,40(1):142-148.FENG Qihong,SHU Chenglong,ZHANG Xianmin,et al.Real-time optimization of drainage schedule for coalbed methane wells at gaswater two-phase flow stage[J].Journal of China Coal Society,2015,40(1):142-148.
[7]吴见,姜杉钰,张守仁,等.利用潜在产气效率指数预测柿庄区块煤层气开发有利区[J].新疆石油地质,2017,38(3):352-357.WU Jian,JIANG Shanyu,ZHANG Shouren,et al.Using potential gas production efficiency index to predict favorable areas for coalbed methane development in Shizhuang block,Qinshui basin[J].Xinjiang Petroleum Geology,2017,38(3):352-357.
[8]XU B,LI X,REN W,et al.Dewatering rate optimization for coalbed methane well based on the characteristics of pressure propagation[J].Fuel,2017,188:11-18.
[9]MATTAR L,ANDERSON D.A systematic and comprehensive methodology for advanced analysis of production data[R].SPE 84472,2003.
[10]CLARKSON C,SALMACHI A.Rate-transient analysis of an undersaturated CBM reservoir in Australia:accounting for effective permeability changes above and below desorption pressure[J].Journal of Natural Gas Science and Engineering,2017,40:51-60.
[11]ZHANG J,HUANG S,CHENG L,et al.A mathematical model for drainage and desorption area analysis during shale gas production[J].Journal of Natural Gas Science and Engineering,2014,21:1 032-1 042.
[12]SUN Z,SHI J,WANG K,et al.The gas-water two phase flow behavior in low-permeability CBM reservoirs with multiple mechanisms coupling[J].Journal of Natural Gas Science and Engineering,2018,52:82-93.
[13]ZHENG D,YUAN B,MOGHANLOO R.Analytical modeling dynamic drainage volume for transient flow towards multi-stage fractured wells in composite shale reservoirs[J].Journal of Petroleum Science&Engineering,2016,149:756-764.
[14]SUN Z,LI X,SHI J,et al.A semi-analytical model for the relationship between pressure and saturation in the CBM reservoirs[J].Journal of Natural Gas Science and Engineering,2018,49:365-375.
[15]CLARKSON C,MCGOVERN J.Optimization of coalbed-methanereservoir exploration and development strategies through integration of simulation and economics[J].SPE Reservoir Evaluation&Engineering,2005,8(6):502-519.
[16]CLARKSON C.Production data analysis of unconventional gas wells:review of theory and best practices[J].International Journal of Coal Geology,2013,109-110(2):101-146.
[17]YARMOHAMMADTOOSKI Z,SALMACHI A,WHITE A,et al.Fluid flow characteristics of Bandanna coal formation:a case study from the Fairview field,eastern Australia[J].Australian Journal of Earth Sciences,2017,64(3):319-333.
[18]余杰,秦瑞宝,梁建设,等.煤层气“甜点”测井判别与产量预测--以沁水盆地柿庄南区块为例[J].新疆石油地质,2017,38(4):482-487.YU Jie,QIN Ruibao,LIANG Jianshe,et al.Sweet spot identification with well-logging data and production prediction for coalbed methane:a case study from southern Shizhuang block in Qinshui basin[J].Xinjiang Petroleum Geology,2017,38(4):482-487.
[19]杜彩霞,张遂安,刘程,等.煤层气规模开发条件下压力传播特征研究[J].煤炭科学技术,2016,44(12):179-183.DU Caixia,ZHANG Suian,LIU Cheng,et al.Study on reservoir pressure transmission feature of coalbed methane under condition of multi-well exploitation[J].Coal Science and Technology,2016,44(12):179-183.
[20]明盈,汤达祯,陶树,等.煤层气水平井产能预测模型及其适用性研究[J].煤炭科学技术,2016,44(12):113-117.MING Ying,TANG Dazhen,TAO Shu,et al.Study on productivity prediction model of horizontal coalbed methane well and its applicability[J].Coal Science and Technology,2016,44(12):113-117.
[21]魏迎春,张傲翔,姚征,等.韩城区块煤层气排采中煤粉产出规律研究[J].煤炭科学技术,2014,42(2):85-89.WEI Yingchun,ZHANG Aoxiang,YAO Zheng,et al.Research on output laws of pulverized coal during coalbed methane drainage in Hancheng block[J].Coal Science and Technology,2014,42(2):85-89.
[22]刘春花,刘新福,周超.煤层气井排采过程中煤粉运移规律研究[J].煤田地质与勘探,2015,43(5):23-26.LIU Chunhua,LIU Xinfu,ZHOU Chao.Migration patterns of coal powder in coal reservoirs during the well drainage[J].Coal Geology&Exploration,2015,43(5):23-26.
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