摘要
新疆油田百21井区砾岩油藏低渗透层段剩余油富集,CO_(2)驱具有良好的应用前景。然而,储层非均质性叠加油气流度差异导致CO_(2)驱过程中极易发生气窜。水气交替作为矿场常用气窜控制方法,对该区CO_(2)驱的改善效果亟待研究。文章利用不同渗透率天然砾岩岩心,研究了百21井区非均质条件下水气交替对CO_(2)驱油特征和采收率的影响规律。结果表明,CO_(2)易与百21原油作用并将其驱替产出,注入速度和岩心渗透率增加,原油动用加快,但同时CO_(2)窜流加剧,导致产油速度迅速衰减。针对主力渗透率储层(液测渗透率3.1×10^(-3)~25.5×10^(-3)μm^(2)),以段塞体积比1∶1进行水气交替可有效抑制层内气窜,在CO_(2)驱基础上提高采收率34.1百分点~50.6百分点。然而,渗透率增大导致水气交替渗流阻力建立能力减弱,同时水相会削弱CO_(2)对原油的抽提作用,令产出油中C7—C14烷烃含量降低。当层间与层内非均质性共存时,水气交替控窜效果进一步降低,对气测渗透率级差为4.1的砾岩岩心组,采收率增幅不足7.0百分点;而具有更强流度控制能力的泡沫驱可显著改善开发效果,在其基础上令高、低渗透岩心采收率分别增加26.8百分点和12.2百分点。研究结果可为明确百21井区水气交替可行性提供理论支撑,并为类似非均质油藏CO_(2)驱控窜方式优选提供重要参考。
In the Ba-21 Block of Xinjiang oilfield,residual oil is predominantly concentrated in low-permeability zones,making CO_(2) flooding a promising enhanced oil recovery(EOR)technique.However,significant reservoir heterogeneity,combined with the mobility contrast between CO_(2) and crude oil,increases the risk of gas channeling.Water-alternating-gas(WAG)injection,a widely used method to mitigate gas channeling,requires further evaluation to determine its effectiveness in this setting.This study investigated the influence of WAG injection on the performance and oil recovery of CO_(2) flooding under heterogeneous conditions,using natural conglomerate cores with varying permeabilities representative of Ba-21 Block.The results showed that CO_(2) readily interacted with Ba-21 crude oil,enabling efficient displacement.However,elevated injection rates and permeability levels accelerated oil production while intensifying CO_(2) channeling,leading to rapid declines in oil output.For the main reservoir intervals(liquid permeability ranging from 3.1×10^(-3)μm^(2) to 25.5×10^(-3)μm^(2)),WAG injection with a 1∶1 slug volume ratio effectively suppressed intra-layer channeling,enhancing oil recovery by 34.1 percentage points—50.6 percentage points compared to continuous CO_(2) flooding.However,as permeability increased,the flow resistance established by WAG weakened,and the presence of water reduced the extraction efficiency of CO_(2).As a result,C7—C14 alkane content in produced oil decreased.When both interlayer and intralayer heterogeneities were present,the effectiveness of WAG in controlling gas channeling was further compromised.In conglomerate cores with a gas permeability contrast of 4.1,WAG improved recovery by less than 7 percentage points.In contrast,foam flooding,offering superior mobility control,significantly enhanced following WAG injection,increasing oil recovery by 26.8 percentage points and 12.2 percentage points in high-and low-permeability cores,respectively.These findings provided theoretical and technical support for assessing WAG feasibility in Ba-21 Block and offered valuable guidance for optimizing gas channeling control strategies in similarly heterogeneous reservoirs during CO_(2) flooding.
作者
徐崇军
刘佳幸
许亮
李明
罗强
蒲万芬
孙琳
董硕
孙鸿应
XU Chongjun;LIU Jiaxing;XU Liang;LI Ming;LUO Qiang;PUWanfen;SUN Lin;DONG Shuo;SUN Hongying(Exploration and Development Research Institute,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang 834000,P R of China;Xinjiang Oilfield Company-Southwest Petroleum University Enhanced Oil Recovery Engineering Joint laboratory,Karamay,Xinjiang 834000,P R of China;Xinjiang Key Laboratory of Conglomerate Reservoir,Karamay,Xinjiang 834000,P R of China;Key Laboratory of Carbon Capture,Utilization and Storage,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang 834000,P R of China;School of Petroleum and Gas Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,P R of China;Chengdu Tianfu Yongxing Laboratory,Chengdu,Sichuan 610000,P R of China;Changqing Oilfield Company,PetroChina,Xi’an,Shaanxi 710000,P R of China)
出处
《油田化学》
北大核心
2025年第3期489-495,共7页
Oilfield Chemistry
基金
国家自然科学基金面上项目“低渗油藏泡沫与原位乳化协同改善CO_(2)波及效率机理研究”(项目编号52474049)
四川省自然科学基金面上项目“深层稠油超临界CO_(2)泡沫驱体系构建及两相流度协同调控方法研究”(项目编号2024NSFSC0198)。
关键词
砾岩油藏
CO_(2)驱
气窜
水气交替
非均质性
conglomerate reservoir
CO_(2)flooding
gas channeling
water-alternating-gas
heterogeneity
作者简介
徐崇军(1969-),男,高级工程师,西南石油大学石油与天然气工程专业工程硕士(2009),研究方向为提高采收率技术研究与应用,通信地址:834000新疆维吾尔自治区克拉玛依市克拉玛依区准噶尔路19号新疆油田分公司勘探开发研究院,E-mail:xcjun@petrochina.com.cn。
