四川盆地公山庙油田中侏罗统沙溪庙组一段致密油藏流体渗流特征
Fluid flow behaviors in tight reservoirs of the Middle Jurassic Shaximiao 1 Member,Gongshanmiao oilfield,Sichuan Basin
周克明 1袁小玲 1刘婷芝 1余华洁 1缪海燕 1张琳羚 1王艳 1何家欢 1肖红林 2宋林珂 2张容3
作者信息
- 1. 中国石油西南油气田公司勘探开发研究院 四川成都 610041
- 2. 中国石油西南油气田公司致密油气勘探开发项目部 四川成都 610051
- 3. 中国石油川庆钻探工程有限公司地质勘探开发研究院 四川成都 610051
- 折叠
摘要
针对致密油藏岩石孔隙结构复杂、流体渗流阻力大、油气产量低、开发效益较差等问题,以四川盆地中部地区(简称"川中地区")公山庙油田中侏罗统沙溪庙组一段低渗透、特低渗透致密砂岩油藏为例,在储层岩石润湿性实验基础上,开展了流体低速渗流实验、恒速水驱油实验和自发渗吸实验等多项研究.研究结果表明:①川中地区公山庙油田沙一段致密油藏的储层岩石总体上呈弱亲水性特征,在完全饱和地层水条件下的水相渗流曲线为一条直线,且经过坐标原点,地层水单相渗流符合达西定律且不存在启动压力或启动压力梯度.②在通过油驱水建立束缚水饱和度的条件下,岩石孔隙表面吸附的水膜降低了油相渗流通道,两相渗流存在贾敏效应,增加了油相渗流的附加阻力.油相低速渗流曲线不过坐标原点,存在启动压力或启动压力梯度;储层岩石的渗透率越低,启动压力或启动压力梯度越大.③驱替速度和岩石渗透率对水驱油效果有较大影响,在较高的驱替速度下,注入水在大孔道中发生指进和沿裂缝发生水窜是造成水驱油效率降低的主要原因.④岩石渗透率对渗吸驱油效果有显著影响,且裂缝样品的渗吸驱油效率大于基质样品的渗吸驱油效率.⑤对致密油藏实施大规模压裂改造,所形成的高渗透缝网可有效降低流体渗流的启动压力或启动压力梯度,再辅以单井吞吐(水油渗吸交换)的开采方式,这种组合是保证致密油藏长期稳产的重要技术措施.研究成果对致密油藏以及页岩油的开发具有重要的借鉴意义.
Abstract
Tight oil reservoirs are characterized by complex pore structure,high resistance in fluid flow,and low production,resulting in poor development benefits.Thus,taken the low to ultra-low permeability tight sandstone oil reservoirs of of the Middle Jurassic Shaximiao 1 Member,Gong-shanmiao oilfield,central Sichuan Basin,as examples,numerous experimental studies,such as low-velocity fluid flow,constant-rate water flooding and spontaneous imbibition,were conducted on the basis of another one experiment on rock wettability.Experimental results show that(i)generally,the reservoir rocks of Shaximiao 1 Member represent a weak hydrophilic feature.When core samples are fully saturated with formation water,the water phase flow curve assumes a straight line passing through the coordinate origin.There is no start-up pressure or start-up pressure gradient in the forma-tion-water single-phase flow which is consistent with the Darcy's law;(ii)when establishing an irreducible water saturation via oil displacing water,water membrane adsorbed on pore surface may reduce oil-phase flow channels,whereas the Jamin's effect in two-phase flow may increase additional resistance to oil-phase flow.The low-velocity flow curve of oil phase does not pass through the coordinate origin,indicating the existence of start-up pressure or its gradient.The lower the reservoir permeability,the higher the start-up pressure or pressure gradient;(iii)both displacement rate and rock permeability exert great impacts on the performance of water flooding.At a higher rate,not only fingering of injected water in some larger pores but water channeling along fractures are the main controls on the decline of flooding efficiency;(iv)rock permeability may affect imbibition displacement obviously.And for fracture samples,the imbibition displacement efficiency is bigger than that in matrix samples;and(v)after large-scale fracturing in tight oil reservoirs,the induced fractures with high permeability can reduce start-up pressure and its gradient with effect.And as an important means,the single-well huff and puff(water-oil exchange by imbibition)may also ensure these reservoirs in the long-term stable production.The research results are significantly referential for the development of tight reservoirs or shale oil.
关键词
致密油藏/润湿性/渗透率/低速渗流/启动压力/渗吸实验/水驱油效率Key words
Tight oil reservoir/Wettability/Permeability/Low-velocity flow/Start-up pressure/Imbibition experiment/Water-flood-ing efficiency引用本文复制引用
基金项目
中国石油天然气股份有限公司2019年天然气开发前期评价项目(西南司计财2019-248)
出版年
2024
国家科技期刊平台
NSTL
万方数据