渤海高地饱压差油藏考虑应力敏感的产能评价方法

Method of Productivity Evaluation Considering Stress Sensitivity for Reservoir with High Formation-saturation Pressure Difference in Bohai

渤海高地饱压差油藏有着高地饱压差、储层压力变化幅度大等特点,为明确此类油藏应力敏感特性对于其储层产能的影响,论文以Q油田W组油藏为例,在岩心覆压气测渗透率实验的基础上,通过改变岩心有效应力,得出了岩心渗透率与所受有效应力的变化规律。实验表明岩心渗透率与其所受有效应力存在着乘幂式关系,将此变化规律应用于产能分析中,推导考虑应力敏感的稳态产能公式,并绘制产能图版进行对比分析。考虑应力敏感后的产能明显出现整体降低的现象,在不同的储层渗透率下,都存在一个相应的最优生产压差限,这对于渤海高地饱压差油藏合理生产制度的制定具有指导意义。

The reservoir in Bohai is characterized by high formation-saturation pressure difference and large variation of reservoir pressure.In order to clarify the influence of stress sensitivity on productivity of such reservoirs,this study uses the W group reservoir in the Q oilfield as an example and obtains the change patterns of core permeability and effective stress by changing the effective stress of the core on the basis of gas-logging permeability experiment.The experiment result shows that the relationship between permeability change and the effective stress appears to be exponential.This change pattern was applied to the productivity analysis.The steady-state productivity formula considering the stress sensitivity was derived,and the productivity chart was established for comparative analysis.Considering that the stress sensitivity leads to the obvious overall decrease in productivity,there is a corresponding optimal pressure difference limit of production under different reservoir permeabilities.This is of guiding significance for the formulation of a rational production strategy for reservoirs with high formation-saturation pressure difference in Bohai.