任岚,于志豪,赵金洲,林然,吴建发,宋毅,谢孟珂
REN Lan,YU Zhihao,ZHAO Jinzhou,LIN Ran,WU Jianfa,SONG Yi,XIE Mengke

• 1:西南石油大学油气藏地质及开发工程国家重点实验室
• 2:中国石油西南油气田公司页岩气研究院
• 3:中国石油西南油气田公司蜀南气矿

摘要(Abstract)：

CO_2吞吐是一种提高致密油藏采收率的有效方法，然而由于注入的CO_2与地层水接触形成的碳酸与岩石矿物发生了溶蚀作用，从而改变了储层的流动特性。为了探讨碳酸溶蚀对储层流动特征的影响，以鄂尔多斯盆地三叠系延长组长6段野外露头致密砂岩为研究对象，开展了岩心流动实验，通过测量CO_2在地层水中的溶解度，对比了碳酸溶蚀前后致密砂岩的孔隙度、可动孔喉下限、液相渗透率、矿物组成和微观形貌。结果表明：溶蚀作用提高了孔隙度和液相渗透率，使流体流动能力增强；溶蚀后致密砂岩的可动孔喉下限减小，降低了束缚水饱和度；方解石、白云石和长石是主要的溶蚀矿物，溶蚀后岩心的溶蚀孔明显增多；压力越大CO_2在地层水中的溶解度越大，碳酸的酸性越强，矿物溶蚀程度越大；温度越高，溶蚀作用越弱。研究成果明确了碳酸溶蚀作用对致密砂岩储层流动特征的影响规律，为致密油藏CO_2吞吐技术应用提供借鉴。
CO_2 huff-and-puff is an effective method to improve recovery of tight oil reservoirs.However,carbonic acid formed by the contacting between injected CO_2 and formation water dissolves with rock minerals,changing the flow characteristics of tight reservoirs.In order to study inpact of carbonic acid dissolution on reservoir flow characteristics,the tight sandstone outcrops from Member Chang 6 of Triassic Yanchang Formation in Ordos Basin are taken as research object to perform core flowing experiments.CO_2 solubility in formation water is measured to compare porosity,cutoff of pore throat diameter for movable fluid,liquid permeability,mineral composition and micromorphology of tight sandstone before and after dissolution.The results show that dissolution increases porosity and liquid permeability,and fluid flow capacity is enhanced.Cutoff of pore throat diameter for movable fluid of tight sandstone decreases after dissolution,reducing irreducible water saturation.Calcite,dolomite and feldspar are main dissolution minerals,with dissolution pores significantly increased after dissolution.CO_(2) solubility in formation water increases with pressure increase,with more strong acidity of carbonic acid and more dissolution minerals.Dissolution gets weaker with temperature increase.The research clarifies the influence law of carbonic acid dissolution on flow characteristics of tight sandstone reservoir,and provides reference for application of CO_2 huff-and-puff technology in tight reservoirs.

关键词(KeyWords)： 致密砂岩;CO_2;溶蚀作用;孔隙度;可动孔喉下限;液相渗透率
tight sandstones;carbon dioxide;dissolution;porosity;pore throat diameter for movable fluid;liquid permeability

Abstract:

Keywords:

基金项目(Foundation): 国家自然科学基金青年科学基金项目“基于DEM-LBM流固耦合的深层页岩气水力裂缝长效支撑理论与方法研究”（52104039）;; 中国石油-西南石油大学创新联合体科技合作项目“多层叠置页岩储层地质力学参数场预测及缝网创建理论与优化技术”（2020CX030201）

作者(Author): 任岚,于志豪,赵金洲,林然,吴建发,宋毅,谢孟珂
REN Lan,YU Zhihao,ZHAO Jinzhou,LIN Ran,WU Jianfa,SONG Yi,XIE Mengke

DOI: 10.19597/j.issn.1000-3754.202110031

参考文献(References)：

• [1]邹才能，张光亚，陶士振，等.全球油气勘探领域地质特征、重大发现及非常规石油地质[J].石油勘探与开发，2010,37(2):129-145.ZOU Caineng,ZHANG Guangya,TAO Shizhen,et al.Geological features,major discoveries and unconventional petroleum geology in the global petroleum exploration[J].Petroleum Exploration and Development,2010,37(2):129-145.
• [2]邢雅文，冯赫青，尹峥，等.二连盆地额仁淖尔凹陷云质岩致密油成藏特征与勘探潜力[J].大庆石油地质与开发，2020,39(4):159-168.XING Yawen,FENG Heqing,YIN Zheng,et al.Accumulation characteristics and exploration potential of the dolomitic tight-oil reservoirs in E’rennao’er Sag of Erlian Basin[J].Petroleum Geology&Oilfield Development in Daqing,2020,39(4):159-168.
• [3]LAI J,WANG G W,RAN Y,et al.Impact of diagenesis on the reservoir quality of tight oil sandstones:The case of upper Triassic Yanchang Formation Chang 7 oil layers in Ordos Basin,China[J].Journal of Petroleum Science&Engineering,2016,145:54-65.
• [4]NELSON P H.Pore-throat sizes in sandstones,tight sandstones,and shales[J].AAPG bulletin,2009,93(3):329-340.
• [5]马铨峥，杨胜来，杨龙，等.准噶尔盆地吉木萨尔凹陷芦草沟组致密储层微观孔隙特征[J].大庆石油地质与开发，2020,39(6):13-20.MA Quanzheng,YANG Shenglai,YANG Long,et al.Characteristics of the micro-pore in Lucaogou-Formation tight reservoir of Jimsar Sag, Junggar Basin[J]. Petroleum Geology&Oilfield Development in Daqing,2020,39(6):13-20.
• [6]沈德煌，张义堂，张霞，等.稠油油藏蒸汽吞吐后转注CO2吞吐开采研究[J].石油学报，2005,26(1):83-86.SHEN Dehuang,ZHANG Yitang,ZHANG Xia,et al.Study on cyclic carbon dioxide injection after steam soak in heavy oil reservoir[J].Acta Petrolei Sinica,2005,26(1):83-86.
• [7]TANG Y Q,WANG R,LI Z,et al. Experimental study on spontaneous imbibition of CO2-rich brine in tight oil reservoirs[J].Energy&Fuels,2019,33(8):7604-7613.
• [8]周冰，金之钧，刘全有，等.苏北盆地黄桥地区富CO2流体对油气储-盖系统的改造作用[J].石油与天然气地质，2020,41(6):1151-1161.ZHOU Bing,JIN Zhijun,LIU Quanyou,et al.Alteration of reservoir-caprock systems by using CO2-rich fluid in the Huangqiao area,North Jiangsu Basin[J].Oil&Gas Geology,2020,41(6):1151-1161.
• [9]周翔，周丹，邓家胜，等.超临界CO2驱提高致密油藏采收率实验研究[J].特种油气藏，2021,28(3):118-123.ZHOU Xiang,ZHOU Dan,DENG Jiasheng,et al.Experimental study on improving recovery efficiency of tight oil reservoirs with supercritical carbon dioxide flooding[J].Special Oil&Gas Reservoirs,2021,28(3):118-123.
• [10]贾瑞轩，孙灵辉，苏致新，等.二氧化碳吞吐致密油藏的可动用性[J].断块油气田，2020,27(4):504-508.JIA Ruixuan, SUN Linghui, SU Zhixin, et al. Availability of CO2 huff and puff in tight reservoir[J].Fault-Block Oil&Gas Field,2020,27(4):504-508.
• [11]丁茜，何治亮，王静彬，等.生烃伴生酸性流体对碳酸盐岩储层改造效应的模拟实验[J].石油与天然气地质，2020,41(1):223-234.DING Qian,HE Zhiliang,WANG Jingbin,et al. Simulation experiment of carbonate reservoir modification by source rock-derived acidic fluids[J].Oil&Gas Geology,2020,41(1):223-234.
• [12]SMITH M M, SHOLOKHOVA Y, HAO Y, et al.CO2-induced dissolution of low permeability carbonates. PartⅠ：Characterization and Experiments[J].Advances in Water Resources,2013,62:370-387.
• [13]AMINU M D,NABAVI S A,MANOVIC V.CO2-Brine-Rock Interactions:The effect of impurities on grain size distribution and reservoir permeability[J]. International Journal of Greenhouse Gas Control,2018,78:168-176.
• [14]WANDREY M, FISCHERA S, ZEMKEA K, et al. Monitoring petrophysical, mineralogical, geochemical and microbiological effects of CO2 exposure-Results of long-term experiments under in situ conditions[J].Energy Procedia,2011,4:3644-3650.
• [15]FISCHER S,LIEBSCHER A,WANDREY M.CO2-brine-rock interaction:First results of long-term exposure experiments at in situ P-T conditions of the Ketzin CO2 reservoir[J].Geochemistry,2010,70(S3):155-164.
• [16]BERTIER P, SWENNEN R, LAENEN B. Experimental identification of CO2-water-rock interactions caused by sequestration of CO2in Westphalian and Buntsandstein sandstones of the Campine Basin(NE-Belgium)[J].Geochemistry Exploration,2006,89(1-3):10-14.
• [17]SALEM A M,SHEDID S A. Variation of petrophysical properties due to carbon dioxide(CO2)storage in carbonate reservoirs[J].Journal of Petroleum and Gas Engineering,2013,4(4):91-102.
• [18]LUQUOT L M,ANDREANI M P,GOUZE P P,et al.CO2 percolation experiment through chlorite/zeolite-rich sandstone(Pretty Hill Formation-Otway Basin-Australia)[J]. Chemical Geology,2012,294-295:75-88.
• [19]JEDDIZAHED J, ROSTAMI B. Experimental investigation of injectivity alteration due to salt precipitation during CO2 sequestration in saline aquifers[J].Advances in Water Resources,2016,96:23-33.
• [20]VARGAFTIK N B. Handbook of physical properties of liquid and gases[M]. Washington:Hemisphere Publishing Corporation,1983.
• [21]富畅，吴大可，黄旭.超临界CO2压缩因子实验数据的新拟合方程[J].贵州工业大学学报（自然科学版），2005,34(6):8-11.FU Chang, WU Dake, HUANG Xu. A new fitting equation for experimental data of supercritical CO2 compressibility factor[J].Journal of Guizhou University of Technology(Natural Science Edition),2005,34(6):8-11.
• [22]GARCIA-RIOS M,CAMA J,LUQUOT L,et al.Interaction between CO2-rich sulfate solutions and carbonate reservoir rocks from atmospheric to supercritical CO2 conditions:Experiments and modeling[J].Chemical Geology,2014,383(15):107-122.
• [23]WIGAND M,CAREY J W,SCHüTT H,et al.Geochemical effects of CO2 sequestration in sandstones under simulated in situ conditions of deep saline aquifers[J]. Applied Geochemistry,2008,23(9):2735-2745.
• [24]TUTOLO B M,LUHMANN A J,KONG X,et al. CO2 sequestration in feldspar-rich sandstone:Coupled evolution of fluid chemistry,mineral reaction rates, and hydrogeochemical properties[J].Geochimica et Cosmochimica Acta,2015,160(1):132-154.
• [25]KETZER J M, IGLESIAS R, EINLOFT S, et al. Water-rockCO2 interactions in saline aquifers aimed for carbon dioxide storage:Experimental and numerical modeling studies of the Rio Bonito Formation(Permian), southern Brazil[J].Applied Geochemistry,2009,24(5):760-767.
• [26]KAMPMAN N,BICKLE M,WIGLEY M,et al.Fluid Flow and CO2-fluid-mineral interactions during CO2-storage in sedimentary basins[J].Chemical Geology,2014,369(2):22-50.