注CO_(2)提高页岩吸附气采收率实验——以鄂尔多斯盆地延长组长7页岩气为例  

Experiment of enhancing the recovery of the shale adsorbed gas by CO_(2)injection:Taking Yanchang-Formation Chang-7 shale gas in Ordos Basin as an example

作　　者：贾连超[1] 刘鹏飞[1] 袁丹[1] 雷甜 冉婧 王刚 JIA Lianchao;LIU Pengfei;YUAN Dan;LEI Tian;RAN Jing;WANG Gang(No.2 Gas Production Plant of PetroChina Changqing Oilfield Company, Yulin 719000, China;Xi’an Changdong Petroleum Technology Co Ltd, Xi’an 710014, China)

机构地区：[1]中国石油长庆油田分公司第二采气厂,陕西榆林719000 [2]西安长东石油科技有限公司,陕西西安710014

出　　处：《大庆石油地质与开发》2021年第2期153-159,共7页Petroleum Geology & Oilfield Development in Daqing

基　　金：国家科技重大专项“鄂尔多斯盆地大型低渗透岩性地层油气藏开发示范工程”(2016ZX05050)。

摘　　要：注CO_(2)提高页岩储层中吸附气采收率对页岩气井稳产及高效开发具有重要意义,由于常规实验方法无法定量表征吸附气和游离气的变化规律,导致CO_(2)与吸附气作用机理尚不明确。基于页岩核磁共振T2谱测试技术,对鄂尔多斯盆地长7段页岩开展了注CO_(2)解吸实验,从微观孔隙尺度研究了注CO_(2)后吸附态甲烷的解吸机理,通过引入解吸效率与解吸速率2个指标,定量评价了注CO_(2)提高吸附态甲烷采收率。结果表明:页岩气中注入CO_(2)后吸附态甲烷的解吸效率为82.12%,解吸速率为13.69%/h;CO_(2)不仅能够极大地提高页岩中吸附态甲烷的总体解吸效率,还能大幅提升其单位时间内的解吸速率;在CO_(2)注入后0~1.5 h内,CO_(2)能够快速、大量置换吸附态甲烷,造成吸附态甲烷物质的量快速下降,解吸后的大部分吸附态甲烷转变成了自由态,仅很小一部分变成了游离态。研究成果为鄂尔多斯盆地页岩气的高效开发提供了方法和借鉴。The CO_(2)injection to enhance the recovery of the adsorbed gas in shale reservoir is very important for the stable production and high-efficiency development of the shale gas wells.The conventional experimental methods cannot quantitatively characterize the change rules of the adsorbed gas and free gas,which result in the unclear mechanism of the interacting mechanism between the CO_(2)and adsorbed gas.Based on the nuclear-magnetic-resonance(NMR)T 2-spectrum testing technology of the shale,the CO_(2)injecting-desorbing experiment was carried out for Member Chang-7 shale in Ordos Basin,the desorbing mechanism of the adsorbed methane after the CO_(2)injection was studied from the viewpoint of the micro pore scale.By introducing two indexes of the desorption efficiency and desorption rate,the enhanced recovery of the adsorbed methane by CO_(2)injection was quantitatively evaluated.The results show that the desorption efficiency(82.12%)and desorption rate(13.69%/h)of the adsorbed methane after the CO_(2)injection in the shale can be quantitatively characterized;the CO_(2)injection can not only greatly improve the overall desorption efficiency of the adsorbed methane in the shale,but also can greatly improve the desorption rate in the unit time;within 0~1.5 h after the CO_(2)injection,CO_(2)can rapidly and massively displace the adsorbed methane,which leads to the rapid decrease of amount of the substance of the adsorbed methane.After desorption,most of the adsorbed methane is transformed into the free state(opposed to the combined state),and only a small part becomes the free state(opposed to the combined state).The study results have provided the method and reference for high-efficiency development of the shale gas in Ordos Basin.

关 键 词：页岩气 CO2 吸附气 核磁共振 鄂尔多斯盆地 

分 类 号：TE377[石油与天然气工程—油气田开发工程]