CO_(2)快速吞吐提高页岩油采收率现场试验  

Field tests and effect of CO_(2) rapid huff-n-puff to enhance shale oil recovery

作　　者：姚红生[1] 高玉巧[1] 郑永旺[1] 邱伟生 龚月[1] 钱洋慧 YAO Hongsheng;GAO Yuqiao;ZHENG Yongwang;QIU Weisheng;GONG Yue;QIAN Yanghui(Sinopec East China Oil&Gas Company,Nanjing,Jiangsu 210019,China)

机构地区：[1]中国石化华东油气分公司

出　　处：《天然气工业》2024年第3期10-19,共10页Natural Gas Industry

基　　金：江苏省重大科技示范项目“苏北地区二十万吨级CCUS重大科技示范工程”(编号:BE2022603);中国石化科技部项目“苏北高陡构造带页岩油直井有效开发关键技术与示范”(编号:P23151);中国石化科技部项目“苏北CCUS-EOR一体化技术研究”(编号:P21107)。

摘　　要：页岩油注CO_(2)吞吐提高采收率技术处于探索阶段,目前面临着CO_(2)与页岩储层及流体相互作用机制不明确、数值模拟技术不成熟、缺乏规模注采及低成本回收工艺等技术难题。为探索页岩油注CO_(2)提高采收率主控机理,以苏北盆地溱潼凹陷古近系阜宁组二段页岩油为对象开展了超临界CO_(2)水岩反应实验,分析了高温高压条件下页岩矿物溶蚀作用及其对孔隙度和渗透率的影响,并通过注CO_(2)恒质膨胀实验、最小混相压力测试评价了地层超压条件下注CO_(2)后原油高压物性变化特征,并在此基础上开展考虑多因素数值模拟研究优化了设计注入参数,最终通过矿场试验验证了技术可行性。研究结果表明:(1) CO_(2)水岩反应以碳酸质矿物溶蚀占主导,长英质矿物部分溶解,生成中大孔隙;(2)在地层原油中注入适量的CO_(2),显著萃取了原油中间烃组分,原油黏度从5.151 mPa·s下降到1.250 mPa·s,且CO_(2)首先萃取轻烃组分,随生产时间增加萃取组分逐渐变为重烃;(3)基于人工压裂与天然缝网混合介质组分数模模型,优化设计单井吞吐注气量1.7×10~4 t,注气速度500~600 t/d,焖井时间50 d;(4)低压侧加热的页岩油CO_(2)吞吐地面工艺,可依据CO_(2)注入地面工艺多参数数据模型,实现精准控温,避免注入管线冻堵及井下油管和套管材料低温脆断问题;(5)产出气CO_(2)浓度高于80%时,采用气相回收直注工艺,实现产出气回收成本降至104元/t。结论认为,CO_(2)快速吞吐有效提高了页岩油采收率,形成的机理认识和技术系列可为页岩油注CO_(2)吞吐开发提供参考和借鉴。The technology of CO_(2) huff-n-puff for enhancing shale oil recovery is still in an exploratory stage.There are some technical challenges,such as unclear mechanism of interaction between CO_(2) and shale reservoirs/fluids,immature numerical simulation techniques,and absence of large-scale injection-production and low-cost recovery processes.A shale oil well in the second section of the Funing Formation of the Paleogene in the Qintong Depression of the Subei Basin was taken as a case of study.To figure out the dominant mechanism of CO_(2) huffn-puff for enhancing shale oil recovery,this paper conducts an experiment on water-rock reaction with supercritical CO_(2) to investigate the dissolution of shale minerals at high temperature and pressure and its impacts on porosity and permeability.Then,the constant-mass expansion(CME) and minimum miscibility pressure (MMP) tests with CO_(2) injection are carried out to evaluate the changes in physical properties of crude oil at high pressure after CO_(2) injection into overpressured reservoirs.On this basis,multi-factor numerical simulation is conducted to optimize the injection parameters.Finally,a CO_(2) thermodynamics and fluid dynamics data template is established to optimize the surface process.The proposed technology is verified through field tests.The results show that the water-rock reaction with CO_(2) is dominated by the dissolution of carbonate minerals,and partial dissolution of felsic minerals,forming medium and large pores.By injecting appropriate volume of CO_(2) into formation oil,the intermediate hydrocarbon components of the crude oil are extracted significantly,allowing the viscosity of crude oil to decrease from 5.151 mPa·s to 1.250 mPa·s.Moreover,CO_(2) first extracts the light hydrocarbon components,and then the heavy hydrocarbons with the production time.Based on the compositional numerical model of mixed media (artificial fractures and natural fractures),the parameters of huff and puff in a single well are optimized with the injection rate being 1

关 键 词：页岩油 注CO_(2) 水岩反应 机理 混合介质组分数模 快速吞吐 地面工艺 现场试验 

分 类 号：TE357.7[石油与天然气工程—油气田开发工程]