边水油藏气体辅助重力驱适应区块筛选方法及应用

冀东油田边水油藏历经多年天然水驱开发后，目前处于高含水阶段，亟需改变开发方式，而气体辅助重力驱能够利用重力形成次生气顶，自上而下驱替原油，从而实现控水增油稳产。应用数值模拟方法，建立“一注三采”的边水油藏数值模拟模型，分析了水平渗透率、地层倾角、水体倍数和原油黏度对气体辅助重力驱开发效果的影响规律，结合重力准数量化分析了各影响参数与气驱采收率的关系，建立了边水油藏高含水后期气体辅助重力驱适应区块筛选标准及参数界限，并应用于冀东油田12个开发单元。结果表明：储层渗透率高、地层倾角大、原油黏度小的储层更适合天然水驱后气体辅助重力驱；建立水驱后气体辅助重力驱筛选标准为油藏渗透率大于700 mD、原油黏度小于3 mPa·s、倾角大于 10°、水体倍数大于 400 倍;水驱后气驱可提高采收率约 15% ；筛选结果为冀东油田C区块最适合水驱后气体辅助重力驱开发，其次为H区块和K区块。该方法对于油藏天然水驱后气体辅助重力驱适应区块筛选具有指导意义。

Screening Method and Application for Gas-Assisted Gravity Drainage Adaptation Blocks in Edgewater Reservoir

After naturally water flooding for several years in the thin oil reservoirs with strong edge water drive of Jidong Oilfield,the producing strategy needs to be changed due to high water cut. Gas assisted gravity drainage ( GAGD) can use gravity to form a secondary gas cap and displace oil from top to bottom to control water-cut and achieve production stabilization. The theoretical numerical models of the oil reservoir with strong edge-water drive are stablished to analyze the effect of the horizontal permeability,dip angle,volume of edge-water and crude oil viscosity on GAGD. Based on the dimensionless gravity number,the relationship between influencing parameters and gas flooding recovery factor is quantified to obtain the screening method of GAGD in the strong edge-water reservoir under high water-cut stage,which is further applied in 12 different blocks of Jidong Oil field. The results show that the reservoirs with high permeability, large dip angle and low oil viscosity are more suitable for GAGD after naturally water flooding. The screening criteria of GAGD after water flooding in the thin oil reservoirs with strong edge-water drive indicated that it's more suitable for GAGD for the oil reservoirs with the permeability higher than 700 mD, the oil viscosity lower than 3 mPa·s, the dip angle larger than 10°, the ratio of edge-water volume and oil reserves larger than 400. After water flooding, the oil recovery factor can be enhanced by about 15% through gas flooding. C block of Jidong Oilfield is most suitable for GAGD after water flooding, followed by H block and K block. This work can provide important reference for the potential block evaluation of GAGD in oil reservoirs after naturally water flooding.