Experimental Study on Etched Fracture Conductivity in Carbonate Rocks for Supercritical CO2 Prepad Acid Fracturing#br#

doi:10.12388/j.issn.1673-2677.2024.04.008

Abstract

Abstract:

Previously，the carbonate reservoir of Majiagou Formation in Yan'an Gas Field adopted traditional acid fracturing treatments，which ended up with a limited acid-affected range and low post-frac well production. This necessitates the optimization of the acid fracturing practice. The reservoir outcrop samples of the Fifth Member of Majiagou Formation were collected for experiments，and the etched-fracture conductivity meter and 3D laser scanning technology were used for acid etching experiments and fracture conductivity measurement in the cases of supercritical CO₂ （SC-CO₂） prepad acid fracturing and conventional acid fracturing. The effects of prepad SC-CO₂ and SC-CO₂ soaking time on etched fracture morphology and conductivity were investigated. The results demonstrate that acid fracturing with prepad SC-CO₂，compared with the conventional method，opens natural fractures，enhances the penetration and diffusion of acid solutions into micro-fractures，and thereby improves acidizing effectiveness. After 12 h and 24 h of SC-CO₂ Soaking，the dominant acid etching pattern resembles grooves，with no significant changes in overall etching severity or types.The 48 h soaking ething is associated with the predominant bridge-pier-like etching marks，while the uniform etching is found dominant after 72 h soaking. The difference of fracture conductivity between conventional acid fracturing and SC-CO₂ prepad acid fracturing is minor under the closure pressure below 30 MPa，and yet，a substantial disparity emerges beyond this threshold. The fracture conductivity of SC-CO₂ prepad acid fracturing consistently exceeds that of conventional acid fracturing across the closure pressure range of the experiments. In cases of low closure pressure，the soaking duration is positively correlated with the etched fracture conductivity，whereas excessively prolonged soaking periods under high closure pressure can suppress fracture conductivity. Therefore，48 h well shut-in is recommended. The findings of this research provide theoretical support for the scheme development of compound acid fracturing in carbonate reservoirs.

Key words:

carbonate rock, supercritical CO₂, prepad acid fracturing, conductivity, acid etched fracture, CCUS

摘要：

延安气田马家沟组碳酸盐岩储层前期采用常规酸压改造，酸蚀范围有限，改造后单井产量低，需开展酸压工艺优化。选取马家沟组五段储层露头，采用酸蚀裂缝导流仪及三维激光扫描装置开展了超临界CO₂（SC-CO₂）前置酸蚀、常规酸蚀及导流能力实验，研究SC-CO₂前置和不同SC-CO₂闷井时间对酸蚀形态及裂缝导流能力的影响。实验结果表明，相比于常规酸蚀，SC-CO₂前置酸蚀开启了天然裂缝，增强了酸液进入微裂缝和扩散的能力，提高了酸蚀效果。SC-CO₂闷井12 h、24 h后的酸蚀形态以沟槽状为主，总体刻蚀程度和类型未发生较大改变；闷井48 h后酸蚀形态以桥墩状刻蚀为主；闷井72 h后酸蚀形态以均匀刻蚀为主。常规酸蚀和SC-CO₂前置酸蚀裂缝导流能力在闭合压力小于30 MPa时相差不大，超过30 MPa后导流能力出现明显的差距。SC-CO₂前置酸蚀的裂缝导流能力在整个闭合压力范围内都保持较高，始终高于常规酸蚀的裂缝导流能力。在低闭合压力下闷井时间与酸蚀裂缝导流能力呈正比，高闭合压力下过长的闷井时间会抑制裂缝导流能力，推荐闷井时间48 h。研究结果可为碳酸盐岩储层复合酸化压裂方案的制定提供理论支撑。

关键词:

碳酸盐岩, 超临界二氧化碳, 前置酸蚀, 导流能力, 酸蚀裂缝, CCUS

CLC Number:

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ZHONG Pengjun , LIU Chao , WEI Chengxiang , ZHOU Weiqin , TIAN Shouceng , WU Jinqiao. Experimental Study on Etched Fracture Conductivity in Carbonate Rocks for Supercritical CO2 Prepad Acid Fracturing#br#[J]. Xinjiang Oil & Gas, 2024, 20(4): 60-69.

钟朋峻 , 刘超 , 魏呈祥 , 周伟勤 , 田守嶒 , 吴金桥. 碳酸盐岩超临界二氧化碳前置酸蚀裂缝导流能力实验#br#[J]. 新疆石油天然气, 2024, 20(4): 60-69.

References

［1］邓长生，张毅，谢小飞，等. 延安气田定向井及水平井钻井和压裂技术优化［J］.录井工程，2019，30（4）：29-34.DENG C S，ZHANG Y，XIE X F，et al. Optimization of drilling and fracturing technology for directional and horizontal wells in Yan'an Gas Field［J］. Mud Logging Engineering，2019，30（4）：29-34.

［2］魏新善，陈洪德，张道锋，等. 致密碳酸盐岩储集层特征与天然气勘探潜力——以鄂尔多斯盆地伊陕斜坡东部奥陶系马家沟组为例［J］. 石油勘探与开发，2017，44（3）：319-329.WEI X S，CHEN H D，ZHANG D F，et al. Gas exploration potential of tight carbonate reservoirs：A case study of Ordovician Majiagou Formation in the eastern Yi-Shan slope，Ordos Basin，NW China［J］. Petroleum Exploration and Development，2017，44（3）：319-329.

［3］李伟，涂建琪，张静，等. 鄂尔多斯盆地奥陶系马家沟组自源型天然气聚集与潜力分析［J］. 石油勘探与开发，2017，44（4）：521-530.LI W，TU J Q，ZHANG J，et al. Accumulation and potential analysis of self-sourced natural gas in the Ordovician Majiagou Formation of Ordos Basin，NW China［J］. Petroleum Exploration and Development，2017，44（4）：521-530.

［4］陈星宇，杨兆中，李小刚，等. 酸蚀裂缝导流能力实验及预测模型研究综述［J］. 断块油气田，2012，19（5）：618-621.CHEN X Y，YANG Z Z，LI X G，et al. Overview of study on experiment and predicting model of acid etched fracture conductivity［J］. Fault-Block Oil ＆ Gas Field，2012，19（5）：618-621．

［5］肖兵，范明福，王延平，等. 低摩阻超高温压裂液研究及应用［J］. 断块油气田，2018，25（4）：533-536.XIAO B，FAN M F，WANG Y P，et al. Study and application of low-friction high-temperature fracturing fluid［J］. Fault-Block Oil & Gas Field，2018，25（4）：533-536.

［6］吴文川，于小荣，王涛，等. 酸压用微膨胀可降解凝胶暂堵剂的研制与应用［J］.油田化学，2023，40（1）：44-50.WU W C，YU X R，WANG T，et al. Development and application of degradable gel temporary plugging agent with micro-expansion for acid fracturing［J］. Oilfield Chemistry，2023，40（1）：44-50.

［7］齐宁，陈国彬，李振亮，等. 基于分步算法的裂缝性碳酸盐岩油藏大尺度酸化数值模拟［J］. 石油学报，2020，41（3）：348-362、371.QI N，CHEN G B，LI Z L，et al. Numerical simulation of large-scale acidification in fractured carbonate reservoirs based on a step-by-step algorithm［J］. Acta Petrolei Sinica，2020，41（3）：348-362，371.

［8］柳明，张士诚，牟建业. 碳酸盐岩酸化径向蚓孔扩展形态研究［J］. 油气地质与采收率，2012，19（2）：106-110、118.LIU M，ZHANG S C，MOU J Y. Dissolution pattern of radial wormhole model in carbonate acidizing［J］. Petroleum Geology and Recovery Efficiency，2012，19（2）：106-110，118.

［9］侯冰，木哈达斯·叶尔甫拉提，付卫能，等. 页岩暂堵转向压裂水力裂缝扩展物模试验研究［J］. 辽宁石油化工大学学报，2020，40（4）：98-104.HOU B，MUHADASI Y，FU W N，et al. Experimental study on the hydraulic fracture propagation for shale temporary plugging and diverting fracturing［J］. Journal of Liaoning Petrochemical University，2020，40（4）：98-104.

［10］HYUNSANG Y，YOUNGMIN K，WONSUK L，et al. An experimental study on acid-rock reaction kinetics using dolomite in carbonate acidizing［J］. Journal of Petroleum Science & Engineering，2018，168：478-494.

［11］伊向艺，吴元琴，李沁，等. 马家沟组碳酸盐岩储层酸岩反应速率影响因素实验研究［J］. 科学技术与工程，2012，12（26）：6575-6578.YI X Y，WU Y Q，LI Q，et al. Experimental study of influence factors about acid-rock reaction rate in carbonate reservoir of Majiagou Formation［J］. Science Technology and Engineering，2012，12（26）：6575-6578.

［12］ZHOU D W，ZHANG G Q，WANG Y Y，et al. Experimental investigation on fracture propagation modes in supercritical carbon dioxide fracturing using acoustic emission monitoring［J］. International Journal of Rock Mechanics and Mining Sciences，2018，110：111-119.

［13］ZOU Y S，LI N，MA X F，et al. Experimental study on the growth behavior of supercritical CO₂-induced fractures in a layered tight sandstone formation［J］. Journal of Natural Gas Science and Engineering，2018，49：145-156.

［14］张艳，楼一珊，牟春国，等. 超临界二氧化碳压裂过程中注入压力对致密砂岩力学特征的影响［J］. 石油钻采工艺，2019，41（2）：242-248.ZHANG Y，LOU Y S，MOU C G，et al. Effects of supercritical carbon dioxide fracturing on rock mechanics characteristics of tight sandstone gas reservoirs［J］. Oil Drilling & Production Technology，2019，41（2）：242-248.

［15］周琳淞，杜建芬，郭平，等. 超临界CO₂对疏松砂岩储层物性影响的实验研究［J］. 油田化学，2015，32（2）：217-222.ZHOU L S，DU J F，GUO P，et al. Influence of supercritical CO₂ on the physical property of unconsolidated sandstone reservoir［J］. Oilfield Chemistry，2015，32（2）：217-222.

［16］张毅. 超临界CO₂压裂在页岩气开发中的优势与挑战［J］. 现代化工，2021，41（1）：1-6.ZHANG Y. Advantages and challenges of supercritical CO₂ fracturing in shale gas exploitation［J］. Modern Chemical Industry，2021，41 （1）：1-6.

［17］苏建政，李凤霞，周彤. 页岩储层超临界二氧化碳压裂裂缝形态研究［J］.石油与天然气地质，2019，40（3）：616-625.SU J Z，LI F X，ZHOU T. Hydraulic fracture propagation behavious and geometry under supercritical CO₂ fracturing in shale reservoirs［J］. Oil & Gas Geology，2019，40（3）：616-625.

［18］ISAKA B L，RANJITH P G，RATHNAWEERA T D，et al. Influence of long-term operation of supercritical carbon dioxide based enhanced geothermal system on mineralogical and microstructurally-induced mechanical alteration of surrounding rock mass［J］. Renewable Energy，2019，136：428-441.

［19］程宇雄，李根生，王海柱，等. 超临界CO₂连续油管喷射压裂可行性分析［J］. 石油钻采工艺，2013，，35（6）：73-77.CHENG Y X，LI G S，WANG H Z，et al. Feasibility analysis on coiled-tubing jet fracturing with supercritical CO₂［J］. Oil Drilling & Production Technology，2013，35（6）：73-77.

［20］郭建春，詹立，苟波，等. 不同相态二氧化碳前置酸压碳酸盐岩裂缝形成规律［J］. 石油勘探与开发，2021，48（3）：639-645.GUO J C，ZHAN L，GOU B，et al. Formation of fractures in carbonate rocks by pad acid fracturing with different phases of carbon dioxide［J］. Petroleum Exploration and Development，2021，48（3）：639-645.

［21］陈晨，朱颖，翟梁皓，等. 超临界二氧化碳压裂技术研究进展［J］. 探矿工程（岩土钻掘工程），2018，45（10）：21-26.CHEN C，ZHU Y，ZHAI L H，et al. Research progress on supercritical carbon dioxide fracturing technology［J］. Exploration Engineering （Rock & Soil Drilling and Tunneling），2018，45（10）：21-26.

［22］邹雨时，李彦超，李四海. CO₂前置注入对页岩压裂裂缝形态和岩石物性的影响［J］. 天然气工业，2021，41（10）：83-94.ZOU Y S，LI Y C，LI S H. Influence of CO₂ pre-injection on fracture morphology and the petrophysical properties in shale fracturing［J］. National Gas Industry，2021，41（10）：83-94.

［23］李曜轩，张艳，王兴义，等. 超临界二氧化碳压裂作用下页岩的力学特征与孔隙度变化规律研究［J］. 当代化工，2020，49（4）：572-576.LI Y X，ZHANG Y，WANG X Y，et al. Study on mechanical characteristics and porosity variation of shale under supercritical carbon dioxide fracturing［J］. Contemporary Chemical Industry，2020，49（4）：572-576.

［24］SANCHEZ M，ABEL J T，IDRIS M，et al. Acid fracturing tight gas carbonate reservoirs using CO₂ to assist stimulation fluids：An alternative to less water consumption while maintaining productivity［C］. SPE Middle East Unconventional Resources Conference and Exhibition，Muscat，Oman，2015：SPE-172913-MS.

［25］MALIK A R，DASHASH A A，DRIWEESH S M，et al. Successful implementation of CO₂ energized acid fracturing treatment in deep，tight and sour carbonate gas reservoir in Saudi Arabia that reduced fresh water consumption and enhanced well performance［C］. SPE Middle East Oil & Gas Show and Conference，Manama，Bahrain，2015：SPE-172620-MS.

［26］牟建业，闫骁伦，张士诚，等. 二氧化碳在致密储层基质中的作用距离研究［J］. 新疆石油天然气，2024，20（3）：64-71.MOU J Y，YAN X L，ZHANG S C，et al. Research on CO₂ matrix penetration distance in tight reservoirs［J］. Xinjiang Oil & Gas，2024，20（3）：64-71.

［27］齐洪岩，吴承美，胡可，等. 准噶尔盆地吉木萨尔凹陷页岩油效益开发关键技术与实践［J］. 新疆石油天然气，2024，20（3）：15-22.QI H Y，WU C M，HU K，et al. Key technologies and practice of shale oil cost-effective development in Jimsar Sag，Junggar Basin［J］. Xinjiang Oil & Gas，2024，20（3）：15-22.

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Experimental Study on Etched Fracture Conductivity in Carbonate Rocks for Supercritical CO2 Prepad Acid Fracturing#br#

碳酸盐岩超临界二氧化碳前置酸蚀裂缝导流能力实验#br#

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