低煤阶煤储层敏感性分析及对煤层气排采的影响
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摘要
为实现低煤阶储层煤层气的高效开发,对大佛寺井田4煤进行了流速敏感性和压力敏感性实验分析,并研究了储层敏感性对煤层气排采作业的影响。结果表明:低煤阶煤储层存在流速敏感性,当渗流速度大于临界流速,储层渗透率有所下降。低煤阶煤储层具有强压力敏感性,且存在不可逆性;升压结束后,渗透率损害率高达90%以上;卸压后,渗透率不能恢复到初始水平,不可逆渗透率损害率达60%以上。为了降低储层敏感性对煤层气井的影响,就必须遵循缓慢、连续、稳定降压的排采原则。
In order to improve gas recovery of low rank coal reservoir, several researches, like the pressure and flow velocity sensitivity analysis and its corresponding influence on coalbed methane drainage have been conducted in Dafosi No.4 coal seam.Research results show that when flow rate is greater than the critical rate, reservoir permeability will decrease slightly. The low rank coal reservoir has strong pressure sensitivity and irreversibility. Test shows that huge pressure increase could cause 90% loss of permeability, and even after pressure release, permeability can never recover to the original degree and could cause 60% permanent loss. As a result, in order to decrease the influence of reservoir sensitivity on coalbed methane well, a slow, continuous and gradual pressure decreasing protocol should be applied.
In order to improve gas recovery of low rank coal reservoir, several researches, like the pressure and flow velocity sensitivity analysis and its corresponding influence on coalbed methane drainage have been conducted in Dafosi No.4 coal seam.Research results show that when flow rate is greater than the critical rate, reservoir permeability will decrease slightly. The low rank coal reservoir has strong pressure sensitivity and irreversibility. Test shows that huge pressure increase could cause 90% loss of permeability, and even after pressure release, permeability can never recover to the original degree and could cause 60% permanent loss. As a result, in order to decrease the influence of reservoir sensitivity on coalbed methane well, a slow, continuous and gradual pressure decreasing protocol should be applied.
引文
[1]范耀.彬长矿区大佛寺井田煤层气直井排采制度优化[J].煤炭技术,2015,34(11):176-178.
[2]林柏泉,李庆钊,原德胜,等.彬长矿区低煤阶煤层气井的排采特征与井型优化[J].煤炭学报,2015,40(1):135-141.
[3]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.
[4]白建平.高煤阶煤储层敏感性对煤层气井排采的影响[J].煤炭科学技术,2014,42(12):54-57.
[5]孟召平,侯泉林.煤储层应力敏感性及影响因素的试验分析[J].煤炭学报,2012,37(3):430-437.
[6]陈世达,汤达祯,高丽军,等.有效应力对高煤级煤储层渗透率的控制作用[J].煤田地质与勘探,2017,45(4):76-80.
[7]郭春华,周文,孙晗森,等.考虑应力敏感性的煤层气井排采特征[J].煤田地质与勘探,2011,39(5):27.
[8]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.
[9]张晓阳,吴财芳,刘强.基于排采速率的煤层气井排采制度研究[J].煤炭科学技术,2015,43(5):131-135.
[2]林柏泉,李庆钊,原德胜,等.彬长矿区低煤阶煤层气井的排采特征与井型优化[J].煤炭学报,2015,40(1):135-141.
[3]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.
[4]白建平.高煤阶煤储层敏感性对煤层气井排采的影响[J].煤炭科学技术,2014,42(12):54-57.
[5]孟召平,侯泉林.煤储层应力敏感性及影响因素的试验分析[J].煤炭学报,2012,37(3):430-437.
[6]陈世达,汤达祯,高丽军,等.有效应力对高煤级煤储层渗透率的控制作用[J].煤田地质与勘探,2017,45(4):76-80.
[7]郭春华,周文,孙晗森,等.考虑应力敏感性的煤层气井排采特征[J].煤田地质与勘探,2011,39(5):27.
[8]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.
[9]张晓阳,吴财芳,刘强.基于排采速率的煤层气井排采制度研究[J].煤炭科学技术,2015,43(5):131-135.