摘要
CO_(2)是人类生产生活排放的主要温室气体之一,是导致全球气候变化的主要原因。CCUS技术是一项能够实现CO_(2)深度减排、缓解气候变化的重要途径。其中,CO_(2)-EOR技术具有广阔的前景,油藏作为碳封存的理想场所,在实现CO_(2)长期有效封存的同时,还能提高原油采收率,达到经济效益与社会效益共赢。确定目标油藏的碳封存潜力对于CO_(2)-EOR技术的大规模实施具有重要意义。当前,CO_(2)封存潜力评估方法较多,但只能针对特定油藏使用,缺乏标准的普适性方法。讨论了CO_(2)驱油与封存机理,总结了国内外权威机构提出的CO_(2)-EOR封存潜力评估公式,通过实例分析详细论证了方法的普适性,并对准确评价CO_(2)-EOR过程中碳封存潜力的下一步工作做出展望。CO_(2)驱油过程是通过引起原油体积膨胀、降低原油黏度、改善油水流度比、萃取轻质组分、混相效应等机理,提高原油采收率;而CO_(2)封存则主要是依靠地质构造俘获、束缚空间俘获、溶解俘获和矿化俘获4种机理,二者概念不尽相同。目前,比较权威且使用较多的CO_(2)封存潜力评估方法主要有4种:US-DOE、CSLF、USGS和RIPED&CUP评价方法。其中,US-DOE和USGS方法是以体积平衡理论为基础的估算方法,依托封存效率,通过多种封存机理的组合来估算CO_(2)封存量。CSLF方法以物质平衡理论为基础,估算结果与资源储备金字塔一致,但未考虑溶解俘获机理。RIPED&CUP方法实则是CSLF方法的改进版,在其基础上考虑了CO_(2)在地层流体中的溶解问题,使计算公式更贴合我国油藏实际条件,但在各阶段原油采收率的确定是难题。因此为保证估算结果的准确性,应根据油藏的地质特征选用最适宜的评价方法。为更精确地进行碳封存潜力评价,下一步应从明确油藏开发策略、考虑滞后效应、使用现场数据修正以及加强安全风险评估等方面开展工作。
CO_(2) is one of the main greenhouse gases emitted by human production and living activities,which is recognized as the main cause of global climate change.CCUS technology is an important way to achieve deep emission reduction of CO_(2) and mitigation of cli⁃mate change.Among them,CO_(2)-EOR technology has broad prospects.As an ideal place for carbon storage,oil reservoirs can not only achieve long-term effective storage of CO_(2),but also enhance oil recovery and achieve win-win of economic and social benefits.Determi⁃ning the carbon sequestration potential of the target reservoir is of great significance for the large-scale implementation of CO_(2)-EOR tech⁃nology.Nowadays,there are many methods to evaluate the storage potential of CO_(2)-EOR,but they can only be used for specific reservoirs and lack of standard universal methods.The mechanism of CO_(2)-EOR and sequestration was discussed,and the evaluation formula of CO_(2)-EOR storage potential proposed by domestic and foreign authoritative institutions was summarized in this paper.The universality of the method was demonstrated in detail through the analysis of examples,and the next step of accurately evaluating the carbon sequestration potential in the process of CO_(2)-EOR was prospected.During CO_(2) flooding,oil recovery is enhanced by expanding oil volume,reduc⁃ing crude oil viscosity,improving oil-water mobility ratio,extracting light components and miscible effect,while CO_(2) storage depends on four mechanisms:structural trapping,residual trapping,solubility trapping and mineral trapping.The two concepts are different.At present,there are four authoritative and widely used evaluation methods of CO_(2) storage potential:US-DOE,CSLF,USGS and RIPED&CUP meth⁃od.Among them,US-DOE and USGS methods are estimation methods based on volume balance theory,which rely on storage efficiency and estimate the capacity of CO_(2) storage through the combination of a variety of storage mechanisms.The CSLF method is based on the ma⁃terial balance theory,and the estimated results are consistent with the resource reserve pyramid,but the mechanism of solubility storage is not taken into account.RIPED&CUP method is actually an improved version of CSLF method,the dissolution of CO_(2) in formation fluid is considered in this method,which makes the calculation formula more suitable for the reality of reservoirs in China,but it is difficult to determine the oil recovery in each stage.Therefore,in order to ensure the accuracy of the estimated results,the most appropriate evalua⁃tion method should be selected according to the geological characteristics of the reservoirs.Besides,for evaluating carbon sequestration po⁃tential more accurately,the next step should be carried out from the aspects of defining the reservoir development strategy,considering the lag effect,using field data for correction and strengthening safety risk assessment.
作者
叶航
刘琦
彭勃
YE Hang;LIU Qi;PENG Bo(The Unconventional Petroleum Research Institute,Beijing Key Laboratory for Greenhouse Gas Storage and CO2-EOR,China University of Petroleum-Beijing,Beijing 102249,China)
出处
《洁净煤技术》
CAS
北大核心
2021年第2期107-116,共10页
Clean Coal Technology
基金
国家自然科学基金资助项目(51604288)
中国石油大学(北京)科研基金资助项目(ZX20200133)。
关键词
CO_(2)驱油
封存潜力
低渗透油藏
评估
采收率
CO_(2)flooding
storage potential
low-permeability reservoirs
evaluation
recovery efficiency
