摘要
南海莺琼盆地深层气藏属于极高温(240℃)、高压、高含CO_(2)的“三高”气田,该环境对固井水泥石提出了严峻挑战。然而,现有研究对此极端条件下加砂水泥石的退化机理仍缺乏充分认识。因此,开展了240℃极高温和高压CO_(2)条件下的腐蚀实验,重点分析了水泥石的力学性能演变规律、水化产物以及微观结构演化规律。结果表明:水泥石的碳化腐蚀深度随着腐蚀时间的延长而增加;其抗压强度表现为先增后减,而渗透率则出现先降低后增加的变化规律。其碳化腐蚀机理在于腐蚀初期硬硅钙石(C_(6)S_(6)H)占主导并保持较高热稳定性和耐腐蚀性,生成的方解石和文石(CaCO_(3))填充孔隙,在降低渗透率的同时短暂提高了抗压强度。随着腐蚀的持续,C_(6)S_(6)H含量持续下降且形貌由交织网状结构转变为针片状,同时反应生成的CaCO_(3)溶解,导致渗透率显著上升,水泥石力学性能衰退。
The deep gas reservoirs of the Yingqiong Basin in the South China Sea represent a“three-high”field with extreme high temperature(240℃),high pressure,and high CO_(2)content,posing severe challenges to cement stone integrity.However,the mechanical property degradation mechanism of sand-modified cement stone under such extreme conditions remains unclear.To address this,corrosion experiments were conducted under extreme high temperature(240℃)and high-pressure CO_(2)conditions,focusing on the evolution of mechanical properties,hydration products,and microstructure.Results show that the carbonation corrosion depth increases continuously with time;compressive strength exhibits an initial rise followed by a decline,while permeability first decreases and then increases.The mechanism is attributed to the early dominance of xonotlite(C_(6)S_(6)H),which provides thermal stability and corrosion resistance,while newly formed calcite and aragonite(CaCO_(3))fill pores,reducing permeability and temporarily enhancing strength.At later stages,progressive consumption of C_(6)S_(6)H with morphological transition to needle-and sheet-like forms,together with CaCO_(3)dissolution,leads to increased permeability and pronounced mechanical property degradation of the cement stone.
作者
徐璧华
罗彪
袁彬
杨朔
李宝锋
XU Bihua;LUO Biao;YUAN Bin;YANG Shuo;LI Baofeng(National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Fengcheng Oilfield Operation Area,PetroChina Xinjiang Oilfield Company,Karamay 834000,Xinjiang,China)
出处
《材料导报》
北大核心
2025年第S2期138-142,共5页
Materials Reports
基金
国家自然科学基金青年科学基金(52204014,2023NSFSC0926)。
关键词
240℃极高温
高含量CO_(2)
碳化腐蚀
水泥石
抗压强度
extreme high temperature(240℃)
CO_(2)-rich concentration
carbonation corrosion
cement stone
compressive strength
