摘要
煤层气的压裂增产过程中,压裂缝通常会延伸至顶板,顶板水的越层窜流对煤层气的生产动态存在较大影响。针对煤层气生产过程中的越层窜流问题,建立了煤层与顶板水体的两种连通模型,运用数值模拟方法研究了煤层气藏内的越层窜流对生产动态的影响,绘制了不同水源产水的无因次特征曲线,通过特征曲线判断了煤层气井的产水特征。研究发现,排采制度对煤层气产水规律影响较小;当顶板水体与煤层直接接触时,裂缝在顶板水中的穿透比会延长见气时间,裂缝一旦穿透顶板,穿透比对排采动态影响不大。对于存在泥质隔层的情况,产气上升过程存在两阶段特征;当穿透比小于1/6时,产气先快后慢;穿透比大于2/6时,产气先慢后快,且穿透比对排采规律影响较小。
Hydraulic fractures always penetrate into the roof rock.The water cross-formational flow from roof rock could apparently affect the production performance of CBM(coalbed methane) reservoirs.According to the crossflow effect on CBM production,two connection models are established to describe the geology relation between coalbed and top aquifer.Then,the effects of top aquifer on methane production performance is studied by numerical simulation under different hydraulic fracture conditions.Further,the production performance is plotted by dimensionless method and the water sources of well are judged in a case study.The results show that production schedule has a slight influence on water production when the water comes from the inner layer.For the top aquifer without a barrier,the fracture penetration ratio in aquifer will delay the gas production.Once the fracture penetrates the aquifer,the penetration ratio has less effect on production.For the top aquifer with a barrier,there exist two stages of gas production increase.When the penetration ratio is under 1/6,the gas production will increase first quickly and then slowly.When the penetration ratio is above 2/6,the gas production will increase first slowly and then quickly,and the production performance is less sensitive to penetration ratio.
作者
杜佳
DU Jia(China United Coalbed Methane Corporation Limited,Chaoyang,Beijing 100015,China;Unconventional Oil&Gas Branch,CNOOC China Limited,Chaoyang,Beijing 100015,China)
出处
《西南石油大学学报（自然科学版）》
CAS
CSCD
北大核心
2020年第2期149-157,共9页
Journal of Southwest Petroleum University(Science & Technology Edition)
关键词
煤层气
排采动态
顶板水体
越层窜流
无因次曲线
coalbed methane
production performance
roof aquifer
water cross-formational flow
dimensionless curves
