应力敏感性条件下储层参数对煤层气井单相流段产水量影响研究
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摘要
建立了考虑应力敏感性条件下煤层气井单相流段产水量模型,并依据研究区块某区块储层参数对2口煤层气井解吸前产水量数据进行拟合,在此基础上模拟了应力敏感性系数、渗透率、表皮系数和井筒半径对产水量的影响。结果表明:应力敏感性对煤层气井解吸前产水量变化具有重要影响,应力敏感性不同,产水量曲线形态不同;对特定煤层气井,存在最优井底流压值使日产水量最大;应力敏感性系数越大,产水量越少;应力敏感性系数大于1时,出现无效降压段,应力敏感性系数越大,无效降压段越长;日产水量随着渗透率、井筒半径的增加而增加,渗透率越高,井筒半径越长,压裂液返排效率越高,压降扩展范围越大;日产水量随着表皮系数增加而降低。
We established the water yield model for single-phase flow under the consideration of stress sensitivity of coalbed methane wells, then completed the history matching of water yield data of two wells on the basis of the basic physical parameters of a block, and then simulated the effects of four parameters such as stress sensitivity coefficient, permeability, skin factor and wellbore radius on water yield. The results show that the stress sensitivity has important influence on the change of the water yield before the desorption of coalbed methane well, and the water yield curve varies with the stress sensitivity. For a particular coalbed gas well, there is an optimum bottom-hole pressure value under where the water yield is maximum. The greater the stress sensitivity coefficient is, the less water yield is. When the stress sensitivity coefficient is greater than 1, there is an invalid descending pressure section, and the greater the stress sensitivity coefficient is, the longer the invalid descending pressure section is. With the increase of the permeability and the wellbore radius, the daily water yield rate increases and the higher of the permeability and the longer of the radius of the wellbore is, the higher the efficiency of fracturing fluid flowback, and the larger the pressure drop zone is. While the daily water yield decreases with the increase of skin coefficient.
We established the water yield model for single-phase flow under the consideration of stress sensitivity of coalbed methane wells, then completed the history matching of water yield data of two wells on the basis of the basic physical parameters of a block, and then simulated the effects of four parameters such as stress sensitivity coefficient, permeability, skin factor and wellbore radius on water yield. The results show that the stress sensitivity has important influence on the change of the water yield before the desorption of coalbed methane well, and the water yield curve varies with the stress sensitivity. For a particular coalbed gas well, there is an optimum bottom-hole pressure value under where the water yield is maximum. The greater the stress sensitivity coefficient is, the less water yield is. When the stress sensitivity coefficient is greater than 1, there is an invalid descending pressure section, and the greater the stress sensitivity coefficient is, the longer the invalid descending pressure section is. With the increase of the permeability and the wellbore radius, the daily water yield rate increases and the higher of the permeability and the longer of the radius of the wellbore is, the higher the efficiency of fracturing fluid flowback, and the larger the pressure drop zone is. While the daily water yield decreases with the increase of skin coefficient.
引文
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[13]Meng Meng,Zhengsong Qiu.Experiment study of mechanical properties and microstructures of bituminous coals influenced by supercritical carbon dioxide[J].Fuel,2018(219):223-238.
[2]李超,申建,赵锦程,等.沁南某高阶煤井区煤层气井气、水产出差异及其控制因素[J].中国矿业,2018,27(2):117-124.
[3]鲍清英,东振,张义,等.低煤阶应力敏感性机理及其对产气的影响-以二连盆地为例[J].煤炭学报,2017,42(3):671-679.
[4]陈刚,秦勇,杨青,等.不同煤阶煤储层应力敏感性差异及其对煤层气产出的影响[J].煤炭学报,2014,39(3):504-509.
[5]陈振宏,陈艳鹏,杨焦生,等.高煤阶煤层气储层动态渗透率特征及其对煤层气产量的影响[J].石油学报,2010,31(6):966-969.
[6]贾慧敏.高煤阶煤岩孔隙结构分形特征研究[J].石油化工高等学校学报,2016,29(1):53-56.
[7]陈振宏,王一兵,郭凯,等.高煤阶煤层气藏储层应力敏感性研究[J].地质学报,2008,82(10):1390-1395.
[8]田永东,武杰.沁水盆地南部高煤阶煤储层敏感性[J].煤炭学报,2014,39(9):1835-1839.
[9]张羽,张遂安,杨立源,等.煤样三维渗透率应力敏感性试验研究[J].煤田地质与勘探,2016,44(3):51.
[10]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.
[11]贾慧敏,胡秋嘉,刘忠,等.缝应力敏感性对煤层气井单相流段产水影响及排采对策[J].中国煤层气,2017,14(5):31-34.
[12]孟猛,邱正松,刘均一,等.注超临界CO2开发煤层气技术研究进展[J].煤炭科学技术,2016,44(1):187.
[13]Meng Meng,Zhengsong Qiu.Experiment study of mechanical properties and microstructures of bituminous coals influenced by supercritical carbon dioxide[J].Fuel,2018(219):223-238.