胜利油田特低渗透油藏CO2驱技术研究与实践

胜利油田适合CO2驱的特低渗透油藏资源量丰富,但这类资源具有埋藏深、丰度低、非均质性强、混相压力高的特点,特低渗透油藏CO2驱面临混相难、波及系数低等技术难题。综合运用地质学、渗流力学和油藏工程等理论和方法,采用物理模拟和数值模拟相结合的手段,形成了CO2驱提高采收率油藏适应性评价体系、室内实验技术、油藏工程方案设计优化技术系列,配套了CO2驱注采工艺等技术。矿场试验表明,CO2具有较好的注入能力,增油效果明显:高89-1块CO2驱先导试验区CO2累积注入量为30.7×104t,累积增油量为6.9×104t,中心井区采出程度为18.6%,已提高采收率9.7%。樊142-7-X4井组超前CO2注入量为1.9×104t,地层压力由17 MPa恢复至33.7 MPa,实现混相,对应油井自喷生产,单井日产油量稳定在5~6 t/d,远高于注气前的1 t/d。

Research and application of CO2 flooding technology in extra-low permeability reservoirs of Shengli Oilfield

The resources of extra-low permeability reservoirs suitable for CO2 flooding is abundant in Shengli Oilfield,but the application of CO2 flooding faces technical bottlenecks such as being difficult to be miscible and low sweep efficiency due to formation characteristics of deep burial depth,low abundance,strong heterogeneity and high miscible pressure. The geology,fluid mechanics,reservoir engineering theory and methods are applied comprehensively. By combination of the physical experiments and numerical simulation,the evaluation system of adaptability,technologies of laboratory experiment and schedule optimization technology series of reservoir engineering of CO2 flooding for enhancing oil recovery are formed,and the injection-production technologies of CO2 flooding are further established. The field test shows that CO2 has good capability of injection and oil increment is obvious. The cumulative oil increment is 6.9×104 t at cumulative CO2 injection of30.7×104 t in pilot test area in Gao89-1 Block. The oil recovery is 18.6% in the central well block with enhanced oil recovery of 9.7%. The advanced injection of CO2 is 1.9×104 t,and the formation pressure recoveries from 17 MPa to 33.7 MPa in the Fan142-7-X4 well group. The miscible flooding is formed and the corresponding oil well produces fluid by natural flow exploitation. The daily oil production of single well is kept stable at 5-6 t/d,which is much higher than 1 t/d before CO2 injection.