低渗储层溶解气驱压裂油井流入动态

Inflow performance of fractured oil wells driven by solution gas in low permeability reservoirs

目前低渗油藏流入动态模型大多是在稳态条件下建立,而实际由于低渗储层孔渗条件差,压力波动传播过程慢,在达到渗流边界之前的很长时间内,油藏流体均以非稳态的形式在地层中流动。基于前人建立的致密油藏压裂井瞬态线性流模型,综合考虑脱气条件下油相的渗流能力以及储层的应力敏感效应,建立了一种新的低渗储层溶解气驱压裂油井的流入动态计算方法。该方法可以确定流入动态关系曲线的拐点,同时通过对不同渗透率以及不同脱气程度条件下的流入动态规律的对比分析,得到了低渗储层应力敏感效应越强、原始溶解气油比越大,产能拐点出现越早的影响规律。研究结果可以帮助确定油井的合理生产压差,对油田实际生产具有一定的指导意义。

The inflow performance models of low permeability reservoirs are mostly established under steady-state conditions.In reality,due to the poor porosity and permeability conditions,pressure fluctuations propagate slowly in low permeability reservoirs.Therefore,the reservoir fluids will flow in the formation in an unsteady pattern for a long time before reaching the flow boundary.Based on the transient linear flow model of fracturing wells in tight oil reservoirs established by the predecessors,and after comprehensively considering the flow capacity of the oil phase and the stress-sensitive effect of the reservoir under degassing conditions,a new method calculating inflow performance of fractured oil wells driven by solution gas in low permeability reservoirs was established.This method can determine the inflection point of the inflow performance relationship curve(IPR curve).Furthermore,through analyzing and comparing inflow performance laws under the conditions of different permeability and different degassing degrees,it is found that the stronger the stress-sensitive effect of the low permeability reservoir and the higher the original dissolved gas-oil ratio,the earlier the inflection point of production capacity occurs.The research results can help determine the reasonable production pressure difference of oil wells,which may provide a certain guiding significance for the actual production of oil fields.