海上低渗油藏大井距精细注水技术应用实践

Fine Water Injection Technology and Application Practice of Large Well Spacing in Offshore Low Permeability Reservoir

针对南海西部北部湾盆地流沙港组储层以低渗、特低渗为主,砂体纵向多期叠置,横向变化快,连通性复杂,在开发过程中面临注采不受效、油井自然产能低、地层能量补充困难等难题,找出如何有效开发此类油藏的关键。从影响产能因素入手,采用储层精细描述技术,刻画优势砂体分布,指导井位部署;采用梯形井网技术,垂直物源钻井,顺物源布井,利用勾型井纵向增加生产厚度,水平段平面横穿多个河道,降低砂体叠置引起的注采风险,实现立体注水;采用后效体射孔技术,提高储层渗流能力,实现油井增产、注水井增注;深化注水水质对开发影响,采用纳米级水处理技术,降低储层伤害,实现油层保护。该精细注水配套技术系列推动了涠洲A油田流沙港组采用常规井网、300~500 m大井距的有效注水开发,这也对后续其它海上类似低渗油田的开发有重要的指导和借鉴作用。

The Liushagang Formation in the Beibu Gulf Basin of the western South China Sea has considerable proven geological reserves,but the reservoirs are mainly of low permeability and ultra-low permeability.The sandbodies are overlapped longitudinally and multi-stage.The lateral variation is fast and the connectivity is complex.In the process of development,the injection and production are ineffective;the natural productivity of oil wells is low;and the formation energy is difficult to supplement.How to achieve effective water injection is the key to good reservoirs.Based on this,the reservoir fine description technology is used to describe the distribution of dominant sand bodies and guide the well location deployment.The trapezoidal well pattern technology,vertical source drilling,along-source well distribution,the use of hook wells to increase the vertical production thickness,horizontal section across a number of rivers,reduce the risk of sand overlap caused by injection and production,to achieve three-dimensional water injection.We use post effect perforation technology to improve reservoir percolation capacity,and increase oil production and injection rate.We deepen the influence of water quality on development,adopt nanometer water treatment technology to reduce reservoir damage and realize reservoir protection.This series of fine water injection matching technology promotes the development of Liushagang formation in Weizhou A Oilfield by using conventional well pattern and large well spacing of 300~500 m,which also has important guidance and reference for the development of other offshore similar oilfields.