摘要
以四川盆地焦石坝地区典型页岩气取心井为研究对象,基于排水集气原理的页岩气现场解吸仪,采用二阶解吸法,对所获得的11块龙马溪组富有机质页岩岩心样品进行解吸、取样和测试。结果表明:①页岩气现场解吸过程中存在甲烷和乙烷碳同位素分馏效应,甲烷分馏幅度较大,平均分馏幅度为25.2‰,其碳同位素分馏幅度主要受控于有机质含量;乙烷分馏幅度相对较小,平均分馏幅度为3.8‰,主控因素不明。②解吸过程中甲烷和乙烷碳同位素分馏过程存在2个阶段,甲烷碳同位素分馏过程分别为缓慢分馏阶段和快速分馏阶段,乙烷碳同位素分馏过程分别为波动分馏阶段和缓慢分馏阶段。③现场解吸过程中,甲烷碳同位素值随着现场解吸率的变大出现有规律的增大,根据这一现象,建立了甲烷碳同位素与解吸率的数学模型,即解吸率是甲烷碳同位素值以自然常数(e)为底的指数函数。上述研究是页岩气解吸/生产全过程4阶段(稳定不变—变轻—逐渐变重—变轻)变化中第Ⅲ阶段的部分认识,以期能为页岩气解吸/生产全过程研究提供借鉴,为页岩气勘探开发提供科学依据。
Taking typical shale gas core wells in the Jiaoshiba area of Sichuan Basin as the research object,the application of the spontaneous development of a shale gas field desorption instrument based on the principle of drainage and gas collection,using a special desorption method to analyze the 11 organic-rich shale samples.The rock samples were desorbed,sampled and tested.The study showed that:(1)The carbon isotope fractionation effect of methane and ethane existed during the on-site desorption of shale gas.The methane fractionation amplitude was relatively large,with an average fractionation amplitude of 25.2‰,controlled by organic content.The fractionation range of ethane is relatively small,with an average fractionation range of 3.84‰.(2)There are two stages in the carbon isotope fractionation of methane and ethane in the desorption process.The methane carbon isotope fractionation process is a slow fractionation stage and a fast fractionation stage.At the end of the desorption process,there is a rapid rise of some methane carbon isotope.The ethane carbon isotope fractionation process is divided into the wave fractionation stage and the slow fractionation stage.(3)During the on-site desorption process,the methane isotope value regularly becomes heavier as the on-site desorption rate increases.Based on this phenomenon,a mathematical model of methane carbon isotope and desorption rate is established,that is,the desorption rate is the methane carbon isotope value after Exponential function with natural constant(e)as the base.The above research may be part of the understanding of the third stage of the four stage change(stable-lighter-gradually heavier-lighter)in the whole process of shale gas desorption/production,in order to provide reference for the research of the whole process of shale gas desorption/production and provide scientific basis for shale gas exploration and development.
作者
杨振恒
范明
陶成
卢龙飞
钱门辉
YANG Zhenheng;FAN Ming;TAO Cheng;LU Longfei;QIAN Menhui(Wuxi Research Institute of Petroleum Geology,RIPEP,SINOPEC,Wuxi 214126,China;SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms,Wuxi 214126,China;Shale Oil and Gas Accumulation Mechanism and Effective Development of State Key Laboratory,Wuxi 214126,China;The State Energy Research and Development Center of Shale Oil,Wuxi 214126,China)
出处
《天然气地球科学》
CAS
CSCD
北大核心
2022年第8期1295-1303,共9页
Natural Gas Geoscience
基金
国家科技重大专项(编号:2015ZX05061001)
国家自然科学基金重大项目(编号:41690133)
国家自然科学基金重点项目(编号:U1663202)联合资助
关键词
焦石坝地区
富有机质页岩
解吸气
碳同位素分馏
指数函数
控制因素
Jiaoshiba area
Organic-rich shale
Desorbed gas
Carbon isotope fractionation
Exponential function
Control factor
