裂缝性潜山油藏注气提高采收率研究

【作者】 姚淑影；

【导师】 李传亮；

【作者基本信息】 西南石油大学 ， 油气田开发工程， 2011， 硕士

【摘要】 裂缝性潜山油藏属于典型的双重介质油藏,其主要的储渗空间是裂缝系统和基质岩块系统。由于这两个系统在储集和渗流能力上的差异,导致衰竭式开发和注水开发都难以获得理想的采收率。近年来,注气提高采收率技术的应用逐年增加,针对裂缝性油藏,目前国外已有许多较成功的现场应用。随着勘探技术的不断进行,我国裂缝性潜山油藏发现的比例逐年增加,正确认识这类油藏的地质和开发特征,积极开展注气提高采收率研究,对合理开发此类油藏具有极其的意义。本文在总结分析此类油藏的主要地质、开发特征和注气驱油机理的基础上,以兴古7潜山油藏为实例,对其展开注气可行性分析,并借助于油藏数值模拟技术对其进行注气潜力评价。该油藏为块状裂缝性潜山油藏,主要储集空间类型为构造缝和破碎粒间孔；单井递减分析表明单井产量递减中等偏快,油藏天然能量不足,注水试验未见效；油藏特征参数符合注气筛选标准；细管实验得到注CO2驱为混相驱,注干气驱为非混相驱；长岩心实验结果表明注气驱油效率最高。连续注气影响因素分析表明：CO2的合理注入速度为200-300t/d,注干气的采出程度对注入速度不太敏感；注CO2优于注干气。气水交替影响因素分析表明：注入速度对采出程度影响最大,其次为交替周期、注入井组、注气注水时间比。注气潜力评价结果为：连续注气和气水交替开发10年,整个油藏采收率分别提高2.9%和3.3%,主力生产层段-第Ⅱ层段采收率分别提高6.4%和9.3%,气水交替采收率提高程度优于连续注气,注气波及区域(第Ⅱ层段)受效明显,气水交替开发潜力较好。更多还原

【Abstract】 Fractured buried hill reservoir belongs to the typical dual porosity reservoir. The main storage and permeable media are the fissure system and matrix system. Fractured buried hill reservoir has the properties of serious heterogeneity due to the big discrepancy between fissure system and matrix system in storage and permeable capacity. It’s really difficult to get a ideal recovery factor in both primary recovery and waterflooding development. The application of gas injection EOR technologies keep on the trend of fast increasing and good application results have been achieved in recent years. Many successful field applications in overseas fracture buried hill reservoir has been reported. Plenty of fractured buried hill reservoirs are discovered in China as the advancement of exploration technology in recent years. Based on the good knowledge of the geological properties and development characteristic, it’s significantly important for conducting gas injection EOR technologies and numerical simulation study.The main geological properties, development features as well as gas injection displacement mechanism have been summarized for naturally fractured buried hill reservoirs by literatures review. The feasibility study for gas injection has been conducted in XingGu 7 (XG7) naturally fractured buried hill reservoir. Moreover, numerical simulation was conducted to evaluate the feasibility of consecutive gas injection and water alternate gas (WAG) injection in XG7 reservoir.The main storage media are structural fractures and fragmented interparticle pores. The decline curve analysis for single well shows moderate decline rate due to lack of natural energy. Moreover, the waterflooding pilot test doesn’t give us any encouraging results for water injection development. According to the screening criterion for gas injection EOR technologies, the reservoir properties of XG7 reservoir comply with this criterion. CO2 injection belongs to miscible flooding and dry gas injection is immiscible flooding. The long core experiment study shows gas injection displacement efficiency is the highest one. XG7 reservoir has good potential for gas injection study.The numerical simulation results for consecutive gas injection have shown the following observation. First, the optimized gas injection rate for CO2 is 200-300t/d. Second, the oil displacement efficiency is higher than that of dry gas. Third, the result of CO2 injection is much better than that of dry gas.The numerical simulation for WAG injection shows the following findings. Gas injection rate has the biggest impact on the final recovery factor. Then the weight factors from high to low are alternating time, injection pattern as well as gas/water injection duration ratio.The result of the gas injection evaluation in XG7 reservoir is as follows. The incremental recovery factors for consecutive gas injection and WAG are 2.9% and 3.3% respectively after 10 years injection, while for the main production zones are 6.5% and 9.3% respectively. WAG injection is much better than that of consecutive gas injection. The incremental recovery factor is bigger than that of the whole reservoir. Thus, the producers have good response to WAG injection in the swept area. Gas injection has good potential in XG 7 reservoir.更多还原