摘要
为明确排采过程中煤层气的产出路径,以沁水盆地南部马必东区块3#煤层样品为研究对象,通过煤岩基质岩心与裂隙岩心的并联和串联实验,分析不同组合模式下气体体积流量、岩心渗透率与驱替压差的关系,探究压差作用下煤层气藏的产出机理。实验结果表明,煤层气在排采过程中存在由煤岩基质孔隙向天然微裂隙进而向人工裂隙运移的串联产出路径以及由煤岩基质孔隙+天然微裂隙+人工裂隙共同产出的并联产出路径。串联产出路径中气体产出主要受煤岩基质渗透率的影响,并联产出路径中气体产出主要受人工裂隙的影响。并联产出路径的等效渗透率远高于串联产出路径的等效渗透率。当岩心两端压差由4.5 MPa降至2 MPa时,并联产出路径的等效渗透率由串联等效渗透率的30倍降至16倍。因此,在煤层气井的排采过程中,需进一步考虑并联产出路径中煤层气的产出。
In order to clarify the gas production path of coalbed methane in the process of drainage,samples that collected from No.3 coal seam of Mabidong Block,southern Qinshui Basin are studied,and the parallel and series experiments com posed of fractured and matrix samples are designed to simulate the different combination mode of matrix and fractures.By analyzing the relationship between gas flow rate,core permeability and displacement pressure difference in each case,the mechanism of coalbed methane production at different driving pressure differences is explored.The experimental results show that the coalbed methane follows the series path from the matrix pores to the natural micro-fractures and then to the artificial fractures during the drainage process,and it also follows a parallel path that composed of the matrix,natural mi cro-fractures and artificial fractures.The production of gas in the series path is mainly affected by the permeability of the matrix,and the production of gas in the parallel path is mainly affected by the artificial fractures.The equivalent permeabil ity of the series path is much lower than that of the parallel path.When the pressure difference across the core is reduced from about 4.5 MPa to 2 MPa,the equivalent permeability of the parallel path is reduced from 30 times to 16 times the equivalent permeability of the series path.Therefore,in the process of drainage of coalbed methane wells,the influence of the parallel path on the production of coalbed methane should be further considered.
作者
张学英
王钧剑
王刚
王宁
刘振兴
宫贺宴
王伟光
ZHANG Xueying;WANG Junjian;WANG Gang;WANG Ning;LIU Zhenxing;GONG Heyan;WANG Weiguang(Huabei Oilfield Company of PetroChina,Renqiu City,Hebei Province,062552,China;School of Energy Resources,China University of Geosciences(Beijing),Beijing City,100083,China)
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2020年第2期137-142,共6页
Petroleum Geology and Recovery Efficiency
基金
国家科技重大专项“沁水盆地高煤阶煤层气高效开发示范工程”(2017ZX05064)
中国石油股份公司重大专项“高煤阶煤层气开发增产技术研究”(2017E-1404)
国家自然科学基金之青年科学基金项目“原位煤层气渗流机理微流控实验及数值模拟研究”(51804281)。
关键词
煤层气
产气路径
岩心串联
岩心并联
沁水盆地
coalbed methane
gas production path
series flow experiment
parallel flow experiment
Qinshui Basin
