摘要
川中地区侏罗系致密油藏主要依靠地层的天然能量进行开发,原油溶解气油比较高,具有较好的气驱能力,因储层渗流主要受喉道和微裂缝控制,渗流阻力大,油气井产量小,一次采收率低。为了提高油藏储量动用程度,需要更深入了解川中地区特低渗储层气驱油过程中的渗流机理。通过岩心人工造缝,对基质岩心和造缝后裂缝岩心的渗透率、相渗、饱和度等进行分析,并开展同一束缚水条件下的油气相对渗透率测试和溶解气驱渗流阻力实验研究。研究结果表明:(1)基质岩心和裂缝岩心均随岩心渗透率升高,两相共渗区饱和度升高,残余油饱和度降低;(2)岩心渗透率越低,流体渗流阻力影响时间就越早,脱气形成的气泡大小对其影响也越早;(3)当井底流压高于渗流阻力拐点对应回压时,溶解气驱存在有利压力区,且原油脱气对原油流动影响较小,可有效利用溶解气驱能量;(4)根据溶解气驱模型试算,依靠溶解气驱开采的油井,泄油半径较小,越靠近井筒,压力下降越快,压力分布呈非线性分布。通过对致密油藏储层渗流机理的研究,为致密油藏的开发方式优选和提高油井的稳产高产具有一定的借鉴意义。
Exploited by their own natural energy,the Jurassic tight oil reservoirs,central Sichuan Basin,feature a high solution gas-oil ratio,better gas drive,large flow resistance greatly induced from throat and microfracture,small output and low primary recovery.It is essential to probe into flow mechanisms during the drive for these ultra-low permeability reservoirs in order to intensively draw on their reserves.Thus,matrix cores and artificially fractured cores were used for discussion on permeability,relative permeability and saturation.In addition,some flow resistance experiments and relative-permeability tests were performed under the same irreducible water conditions.Results show that(i)for both matrix and fractured cores,the saturation in dual-phase flow zones increases and the residual-oil saturation decreases with the increase of permeability;(ii)the lower the permeability is,the earlier the resistance arises,and the earlier the gas bubble originates from degassing affects on permeability;(iii)when the bottomhole flowing pressure is larger than the backpressure at the resistance’s knee point,there is a favorable pressure zone for solution-gas drive,and the degassing has a slight impact on oil flow,allowing for energy utilization of drive with effect;and(iv)according to the trial simulation on the drive model,oil wells with solution-gas drive may exhibit small drainage radius,faster pressure drop near the wellbore,and nonlinear pressure distribution.All results provide certain reference for optimizing development modes together with maintaining and improving productivity in the tight oil reservoirs.
作者
李秀清
白蓉
周红飞
丰妍
余凯
郭蕊莹
李雪松
LI Xiuqing;BAI Rong;ZHOU Hongfei;FENG Yan;YU Kai;GUO Ruiyin;LI Xuesong(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)
出处
《天然气勘探与开发》
2024年第5期21-28,共8页
Natural Gas Exploration and Development
基金
中国石油集团公司攻关性应用性科技专项(编号:2023ZZ15)。
关键词
致密储层
油气相渗
溶解气驱
渗流阻力
Tight reservoir
Oil/gas relative permeability
Solution-gas drive
Flow resistance
