青海风西N_(2)^(1)致密油藏注减氧空气驱油机理与效益开发模式的实验对比

Experimental Comparison of the Mechanism and Beneficial Development Model of Injection of Deoxygenated Air in N_(2)^(1) Tight Reservoir in Fengxi,Qinghai Province

青海油田风西N_(2)^(1)油藏特点独特,迫切需要开展效益开发模式研究。采用多维度测试技术,围绕风西N_(2)^(1)油藏特点,基于地层油欠饱和相态特征,揭示了油藏流体注减氧空气增容膨胀、多次接触混相、溶解气弹性膨胀及萃取轻烃等驱油机理,明确了减氧空气在风西N_2~1油藏中增能物理化学驱油的可行性。进一步利用现场岩心制作了长岩心测试岩石样品,使用井口取样复配了油样和水样,设计了衰竭式开发、水驱油开采、减氧空气驱、减氧空气-水交替驱等开发模式,依靠长岩心模拟技术开展对比测试分析,论证了风西地区N_(2)^(1)致密油藏早期注水、接续注减氧空气-水交替增能开发模式的科学合理性。所得认识为风西N_(2)^(1)油藏_1及与之同类型的致密、欠饱和低能量油藏早期补能开发方式选择提供了技术参考。

The unique characteristics of the Fengxi N_(2)^(1) reservoir in Qinghai oilfield necessitate the study of a beneficial development model.By examining the reservoir s characteristics and the under-saturated phase properties of formation oil,various oil displacement mechanisms have been identified,including deoxygenated air injection for volumetric expansion,multiple contact miscible methods,elastic expansion of dissolved gas,and extraction of light hydrocarbons.The feasibility of enhancing energy physicochemical displacement through deoxygenated air injection has been confirmed.Long core tests using field core samples,a combination of oil,water,and wellhead samples,have been conducted to design development models such as depletion development,water-driven oil exploitation,deoxygenated air flooding,and deoxygenated air-water alternating flooding.Comparative testing and analysis utilizing long core simulation technology have demonstrated the scientific rationale behind early water injection and subsequent injection of oxygen-reducing air-water alternating energy enhancement models for the N_(2)^(1) tight reservoir in the Fengxi area.This knowledge serves as a technical reference for selecting early recharge development methods for the Fengxi N_(2)^(1) reservoir and similar types of tight,under-saturated,low energy reservoirs.