摘要： 海上S油田水驱开发已进入高含水阶段,但仍存在大量剩余油,进一步提高采收率的潜力和方向未知.通过高倍数水驱实验对S油田在典型渗透率和原油黏度下的极限驱油效率进行评价,明确S油田水驱高含水期提高采收率潜力;并利用在线核磁共振测试,揭示S油田高含水期剩余油分布规律;其次,通过高倍数水驱和核磁共振驱油实验,探究S油田水驱后二元驱极限驱油效率和动用剩余油规律,明确水驱后二元驱提高采收率潜力.研究表明,S油田水驱后提高采收率潜力较大;高倍数水驱极限驱油效率最高达75.2%,相比高含水期,提高17.6～25.8 个百分点;高含水期剩余油主要分布在半径大于 10 μm和1～10 μm 的孔隙中,分别占 32.4%～55.1%和 35.1%～47.7%.注入二元体系后,降水增油效果显著,极限驱油效率提高至 84.8%,相比高含水期,提高 33个百分点,且后续水驱仅需不到 2 PV.二元体系通过提高波及体积和洗油效率,能够有效动用不同大小孔隙中的剩余油.海上S油田水驱后二元驱能够有效提高采收率,且显著降低开发时间成本.

关键词: 高倍数水驱, 核磁共振, 剩余油分布, 提高采收率潜力, 二元驱

Abstract: The offshore S oilfield has entered a high water cut development stage,yet a significant amount of residual oil remains,indicating potential for further enhanced oil recovery.This study evaluates the ultimate oil displacement efficiency of the S oilfield under typical permeability and crude oil viscosity conditions through high multiple waterflooding experiments,thus clarifying the EOR potential during this period.Using online nuclear magnetic resonance testing,the distribution pattern of residual oil during the high water cut stage is revealed.Additionally,by conducting high multiple waterflooding and online nuclear magnetic resonance displacement experiments,the study investigates the ultimate oil displacement efficiency and the mobilization pattern of residual oil in the offshore S oilfield after waterflooding,thereby determining the EOR potential with binary flooding post-waterflooding.The research indicates significant potential for enhancing oil recovery after water flooding in the offshore S oilfield.The ultimate oil displacement efficiency with high multiple water flooding reaches up to 75.2%,which is 17.6 to 25.8 percentage points higher compared to the high water cut stage.During the high water cut stage,residual oil is mainly distributed in pores with radius>10 μm and 1～10 μm,accounting for 32.4%～55.1%and 35.1%～47.7%,respectively.After injecting the binary system,the water cut decreases,and oil production increases significantly,with the ultimate oil displacement efficiency rising to 84.8%,an increase of 33 percentage points,requiring less than 2 PV of subsequent water flooding.The binary system effectively mobilizes residual oil in pores of different sizes by increasing sweep volume and oil displacement efficiency.Therefore,binary flooding after water flooding in the offshore S oilfield can effectively enhance oil recovery and significantly reduce development time costs.

Key words: high multiple waterflooding, nuclear magnetic resonance, residual oil distribution, enhanced oil recovery potential, binary flooding

中图分类号: 

• TE53 P618.13