低渗透矩形油藏不稳定渗流压力动态分析

Dynamic Analysis of Unsteady Seepage Pressure in Low Permeability Rectangular Reservoirs

目前,低渗透矩形油藏地层渗流压力求解的研究比较成熟,但是对于渗流压力的动态分析及渗流压力影响因素分析的研究尚存在一些不足。针对低渗透矩形油藏难动用的难题,基于两参数连续模型,运用稳态逐次替换法,分别建立了定压和定产两种生产形式下的压力动态分析模型,并从地层物性和导压系数两个层面进行了相关因素分析。分析认为:无论在定产模型还是在定压模型中,压力传播距离与时间均为二次三项式关系,且压力传播快慢与产量、渗透率呈正相关,与流体黏度、井底流压、启动压力梯度呈负相关。实例计算表明:所建立的模型可靠,为矩形油藏注水开发,预计注水见效时间,提供一定的理论依据。

At present,the research on solution of seepage pressure in low permeability rectangular reservoir formation is relatively mature. However,there are still some deficiencies in the study of dynamic analysis of the seepage pressure and the influencing factors on seepage pressure. Aiming at the difficult problem of low permeability rectangular reservoir,based on the two- parameter continuous model,the dynamic analysis models for constant pressure or fixed production were established separately by using the steady state successive substitution method,and the related factors analysis was carried out from the aspects of the formation characteristics and the pressure coefficient. The analysis showed that whether in the fixed production model or in the constant pressure model,the relationship between the pressure propagation distance and time is quadratic trinomial,and the speed of pressure propagation is positively correlated with the yield and the permeability,but negatively correlated with the viscosity of the fluid,the bottom hole flowing pressure and the starting pressure gradient. Example calculation showed that the models are reliable,which can provide some theoretical basis for the rectangular reservoir development by water injection and for the calculation of expected effective time of water injection.