多级压裂水平井周期性注气吞吐提高页岩油气藏采收率——以北美Eagle Ford非常规油气藏为例  

Cyclic gas injection huff-n-puff in multi-stage fracturing horizontal wells to improve recovery of shale oil and gas reservoirs: Taking Eagle Ford Shale in North America as an example

作　　者：王勇 汤勇[2] 李士伦[2] 刘昕[2] WANG Yong;TANG Yong;LI Shilun;LIU Xin(CNOOC International Limited,Beijing 100028,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China)

机构地区：[1]中国海洋石油国际有限公司 [2]“油气藏地质及开发工程”国家重点实验室·西南石油大学

出　　处：《天然气工业》2023年第1期153-161,共9页Natural Gas Industry

基　　金：国家自然科学基金面上项目“超低渗透油藏CO_(2)强化采油过程中多孔介质相态及微观渗流机理研究”(编号:51974268)。

摘　　要：在溶解气驱开发方式下,采用多级水力压裂水平井衰竭式开发页岩油气藏一次采油的采收率预测仅为5%~10%,因而如何提高采收率是一个不得不面对的棘手问题。近年来,对多级压裂水平井通过周期性注气吞吐来提高页岩油气藏采收率在北美Eagle Ford非常规油气藏的先导试验和大规模现场应用均取得了显著成效。为了加快中国非常规油气资源的高效开发利用,在调研相关文献的基础上,结合北美已有的成功经验,从作用机理、数值模拟和现场试验等多个方面对注气吞吐提高页岩油气藏采收率技术进行了论述,进而提出了有针对性的建议。研究结果表明:①大规模周期性注气吞吐作业能有效延长油井生命周期,提高页岩油气藏的采收程度,提高幅度是衰竭式的30%~70%;②对于溶解气油比低的油藏,注气吞吐提高采收率的机理是注入的气体扩散到压裂油藏中与剩余原油接触且溶解,使其体积膨胀,降低了原油黏度和表面张力,提高了原油的流动性,对于初始溶解气油比高的挥发油藏和凝析气藏,油相组分蒸发到注入的气体中是更重要的增油机理,而对于凝析气藏,在井筒附近的凝析油气化提高产量则是主要的增油机理;③上述增油机理决定了只有注入大量气体才能取得明显的效果,注入的天然气为甲烷含量90%的干气,北美注气吞吐大规模应用得益于比CO_(2)还便宜的低价天然气;(4)由于国内天然气价格较高,可以考虑采用CO_(2)吞吐,使用CO_(2)能减少温室气体的排放量,如其捕捉、存储和管输等问题能够得以解决,注CO_(2)吞吐应是国内首选。In the case of dissolved gas drive development, the prediction of primary oil recovery of depleted horizontal wells in shale oil and gas reservoirs by multi-stage hydraulic fracturing is only 5%-10%, so how to improve the oil recovery is a difficult problem to face. In recent years, the pilot test and large-scale field application of Cyclic Gas Injection Huff-n-Puff in Multi-Stage Fracturing Horizontal Wells to enhance shale oil and gas recovery have achieved remarkable results in The Eagle Ford Shale in North America. In order to accelerate the efficient development and utilization of unconventional oil and gas resources in China, based on the investigation of relevant literature and combined with the existing successful experience in North America, the technology of huff and Puff gas injection to improve shale oil and gas recovery is discussed from the aspects of action mechanism, numerical simulation and field test, and some specific suggestions are put forward. The results show that:(1)Large-scale gas injection Huff-and-Puff can effectively prolong the life cycle of wells and increase the ultimate oil and gas recovery by 30% to 70% compared with primary depletion development;(2) The reservoir with low dissolved gas oil ratio, gas injection huff and puff to improve recovery factor is injected into the mechanism of gas diffusion in the fracture reservoir in contact with the surplus oil and dissolved, make its volume expansion, lower crude oil viscosity and surface tension, improve the liquidity of crude oil, for the initial high dissolved gas oil ratio of volatile oil reservoirs and condensate gas reservoir, evaporation of oil phase components into injected gas is the more important oil increase mechanism, while for condensate gas reservoirs, evaporation of condensate near wellbore to increase production is the main oil increase mechanism.(3) The mechanism of oil increase above determines that only a large amount of gas injection can achieve obvious effects. The injected natural gas is dry gas with 90% methane

关 键 词：页岩油气藏 注气吞吐 多级压裂水平井 提高采收率 北美地区 Eagle Ford非常规油气藏 

分 类 号：TE377[石油与天然气工程—油气田开发工程] TE357