灰岩储层多级交替注入酸压酸蚀规律研究  

Acid-etching fracturing law of multi-stage alternating injection in limestone reservoirs

作　　者：路依鑫 齐宁[1] 周顺明 王转转 李雪松 苏徐航 王亮亮 LU Yixin;QI Ning;ZHOU Shunming;WANG Zhuanzhuan;LI Xuesong;SU Xuhang;WANG Liangliang(School of Petroleum Engineering,China University of Petroleum(East China),Qingdao City,Shandong Province,266580,China;Research Institute of Exploration and Development,Qinghai Oilfield Company,PetroChina,Dunhuang City,Gansu Province,736202,China)

机构地区：[1]中国石油大学(华东)石油工程学院,山东青岛266580 [2]中国石油青海油田分公司勘探开发研究院,甘肃敦煌736202

出　　处：《油气地质与采收率》2024年第2期119-127,共9页Petroleum Geology and Recovery Efficiency

基　　金：“基于蚓孔竞争机制的自转向酸酸蚀蚓孔描述及动态酸化模拟研究”(ZR201702180073)。

摘　　要：中国大部分灰岩储层埋藏深、低孔隙低渗透,受高温、高闭合压力、强非均质性等因素影响,常规盐酸酸压不易对其形成非均匀刻蚀,且改造效果差,影响了该类储层的高效开发。多级交替注入酸压技术可以通过酸液在前置液中多次形成黏性指进的方式来更好地实现裂缝壁面的非均匀刻蚀,但多级交替注入酸压酸蚀规律尚不清晰,注酸级数的界限尚不明确,目前酸压设计多依靠经验方法进行。针对以上问题,在双尺度连续酸化模型的基础上,综合考虑黏度变化与注酸级数的影响,建立了灰岩储层多级交替注入酸压模型。基于多级交替注入酸压模型,将酸岩反应动力学、酸蚀裂缝实验数据、酸蚀数值模拟研究结果相结合,分析了酸液黏度、注酸排量及注酸级数等因素对酸压改造效果的影响,明确了灰岩储层多级交替注入酸压的酸蚀规律与注酸级数界限,通过引入酸液突破体积对现场优化提供依据。研究结果表明,为改善裂缝壁面的非均匀刻蚀程度,获得酸蚀裂缝的高导流能力,在地层温度为90℃时纯灰岩储层采用盐酸与稠化酸交替注入工艺,在注酸排量为5 m^(3)/min时加入0.4%非离子型聚丙烯酰胺的稠化酸。在此基础上,最佳注酸级数以不超过三级为宜,此时酸液突破体积最小,适用于现场施工。The majority of limestone reservoirs in China are characterized by deep burial,low porosity,and low permeability and are influenced by factors such as elevated temperatures,high closure pressures,and strong heterogeneity.Conventional hydrochloric acid fracturing techniques often fail to achieve non-uniform etching on such reservoirs,resulting in poor transformation effects and hindering the efficient development of such reservoirs.The acid fracturing technology of multi-stage alternating injection was used to facilitate non-uniform etching of fracture wall surfaces by iteratively forming viscous fingering in the prepad.However,the law governing the acid-etching fracturing of multi-stage alternating injection remains unclear,and the acid injection stage boundaries are not determined.At present,acid fracturing design typically relies on empirical approaches.To address these gaps,this study built an acid fracturing model of multi-stage alternating injection for limestone reservoirs by considering the influence of viscosity variation and alternating stages based on a two-scale continuous acidification model.Based on the acid fracturing model of multistage alternating injection,the influence of acid viscosity,acid injection rate,and acid injection stages on the acid fracture effects was analyzed by combining the acid rock reaction kinetics,acid-etched fracture experimental data,and numerical simulation re‐sults.The acid-etching law of multi-stage alternating injection in limestone reservoirs and the acid injection stage boundaries were determined,and the breakthrough volume of acid fluid was introduced to provide the basis for site optimization.The findings sug‐gest that to enhance the non-uniform etching of fracture wall surfaces and obtain high conductivity of acid-etching fractures,an al‐ternating injection process involving hydrochloric acid and thickened acid should be adopted for pure limestone reservoirs at a for‐mation temperature of 90°C.0.4%HPAM-thickened acid should be added when the acid injection

关 键 词：多级酸压 注酸级数 酸蚀裂缝 稠化酸 灰岩 

分 类 号：TE357[石油与天然气工程—油气田开发工程]