Experimental study of acid fracturing behavior in carbonate reservoirs with different fracture-cavity development

IF 6.1 1区工程技术 Q2 ENERGY & FUELS

Petroleum Science Pub Date : 2025-07-01 DOI:10.1016/j.petsci.2025.04.022

Song-Cai Han , Li-Le Li , Sen Hu , Chu-Hao Jing , Xu-Di Wu , Jun-Chao Yang , Tao Liu , Cai-Yun Xiao

{"title":"Experimental study of acid fracturing behavior in carbonate reservoirs with different fracture-cavity development","authors":"Song-Cai Han , Li-Le Li , Sen Hu , Chu-Hao Jing , Xu-Di Wu , Jun-Chao Yang , Tao Liu , Cai-Yun Xiao","doi":"10.1016/j.petsci.2025.04.022","DOIUrl":null,"url":null,"abstract":"<div><div>Heterogeneity in carbonate formations due to discontinuities (e.g., fractures and cavities) will bring about distinctive acid stimulation effects. However, the differences in fracturing behavior between homogeneous and heterogeneous carbonate formations remain unclear, complicating the optimization of acid fracturing strategies. In this paper, full-diameter carbonate rock samples with different degrees of discontinuity development are selected to investigate the fracturing behavior under different fluid types and injection schemes. Advanced techniques, including 3D CT scanning and 3D laser scanning, are employed to analyze fracture morphology and etching characteristics, respectively. Experimental results show that the coupled hydraulic-chemical effects play different roles in fracture induction between fracture-cavity developed and undeveloped carbonate rocks. Acid-fracturing stimulation consistently induces multiple types of complex fractures in fracture-cavity carbonate rocks, whereas it results in a single artificial fracture in less fracture-cavity carbonate rocks. Furthermore, localized etching patterns are prevalent in most fracture-cavity carbonate rocks, whereas homogeneous carbonate rocks exhibit regional or global etching characteristics. In both carbonate rocks, the stimulation effect of guar fluid is inferior to that of gelled acid but comparable to self-generating acid. Further findings are that alternating fracturing with guar and acid fluids in fracture-cavity carbonate rocks can sustain or even increase the injection pressure, facilitating the formation of new or depth-penetrating fractures. This phenomenon, however, is not observed in fracture-cavity undeveloped carbonate rocks. Potential interaction modes between induced fracture and natural fractures/cavities under different injection conditions are also identified. Finally, preferred fracturing schemes applicable to different carbonate formations are recommended based on the area, number and roughness of the induced fractures.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2937-2949"},"PeriodicalIF":6.1000,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Petroleum Science","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1995822625001505","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENERGY & FUELS","Score":null,"Total":0}

引用次数: 0

Abstract

Heterogeneity in carbonate formations due to discontinuities (e.g., fractures and cavities) will bring about distinctive acid stimulation effects. However, the differences in fracturing behavior between homogeneous and heterogeneous carbonate formations remain unclear, complicating the optimization of acid fracturing strategies. In this paper, full-diameter carbonate rock samples with different degrees of discontinuity development are selected to investigate the fracturing behavior under different fluid types and injection schemes. Advanced techniques, including 3D CT scanning and 3D laser scanning, are employed to analyze fracture morphology and etching characteristics, respectively. Experimental results show that the coupled hydraulic-chemical effects play different roles in fracture induction between fracture-cavity developed and undeveloped carbonate rocks. Acid-fracturing stimulation consistently induces multiple types of complex fractures in fracture-cavity carbonate rocks, whereas it results in a single artificial fracture in less fracture-cavity carbonate rocks. Furthermore, localized etching patterns are prevalent in most fracture-cavity carbonate rocks, whereas homogeneous carbonate rocks exhibit regional or global etching characteristics. In both carbonate rocks, the stimulation effect of guar fluid is inferior to that of gelled acid but comparable to self-generating acid. Further findings are that alternating fracturing with guar and acid fluids in fracture-cavity carbonate rocks can sustain or even increase the injection pressure, facilitating the formation of new or depth-penetrating fractures. This phenomenon, however, is not observed in fracture-cavity undeveloped carbonate rocks. Potential interaction modes between induced fracture and natural fractures/cavities under different injection conditions are also identified. Finally, preferred fracturing schemes applicable to different carbonate formations are recommended based on the area, number and roughness of the induced fractures.

查看原文本刊更多论文

不同缝洞发育程度碳酸盐岩储层酸压行为实验研究

碳酸盐岩地层由于不连续性（如裂缝和空腔）造成的非均质性将带来独特的酸刺激效果。然而，均质和非均质碳酸盐岩地层的压裂行为差异尚不清楚，这使得酸压裂策略的优化变得更加复杂。本文选取不同不连续发育程度的全径碳酸盐岩样品，研究不同流体类型和注入方案下的压裂行为。采用三维CT扫描和三维激光扫描等先进技术分别分析断口形貌和蚀刻特征。实验结果表明，缝洞发育与不发育的碳酸盐岩裂缝诱导中，水力-化学耦合作用的作用不同。在缝洞型碳酸盐岩中，酸压增产总是会形成多种类型的复杂裂缝，而在较少缝洞型碳酸盐岩中，酸压增产只会形成一条人工裂缝。此外，大多数缝洞型碳酸盐岩普遍存在局部蚀刻模式，而均质碳酸盐岩则表现出区域或全局蚀刻特征。在这两种碳酸盐岩中，瓜尔流体的增产效果不如胶凝酸，但与自生酸相当。进一步的研究发现，在缝洞型碳酸盐岩中，瓜尔液和酸性流体交替压裂可以维持甚至增加注入压力，促进新裂缝或深部裂缝的形成。然而，在缝洞型未发育的碳酸盐岩中没有观察到这种现象。在不同的注入条件下，还确定了诱导裂缝与天然裂缝/空腔之间潜在的相互作用模式。最后，根据诱导裂缝的面积、数量和粗糙度，提出了适用于不同碳酸盐岩地层的优选压裂方案。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Petroleum Science 地学-地球化学与地球物理

CiteScore

7.70

自引率

16.10%

发文量

311

审稿时长

63 days

期刊介绍： Petroleum Science is the only English journal in China on petroleum science and technology that is intended for professionals engaged in petroleum science research and technical applications all over the world, as well as the managerial personnel of oil companies. It covers petroleum geology, petroleum geophysics, petroleum engineering, petrochemistry & chemical engineering, petroleum mechanics, and economic management. It aims to introduce the latest results in oil industry research in China, promote cooperation in petroleum science research between China and the rest of the world, and build a bridge for scientific communication between China and the world.