基于新模型低渗透油藏产能研究

Production capacity research for low permeability reservoir by new seepage model

针对低渗透油藏非线性渗流模型的缺陷和产能评价方面的不足,文中基于低渗透非线性渗流理论,从泊稷叶公式出发,考虑流体屈服应力和吸附边界层的影响,建立了具有理论基础的低渗透油藏非线性渗流新模型。基于新的渗流模型,考虑压力敏感效应、启动压力梯度的影响,建立了一种适用于定压边界的低渗透油藏直井产能评价数值模型,并对其影响因素进行分析。研究表明:随着水驱前缘位置的增大,产能提高很快,且受生产压差的控制,同一水驱前缘位置下,产能与生产压差近似为线性正相关,压力敏感系数越小,产能越高;保持适当的生产压差,减小渗透率对压力的敏感性,有助于提高单井产能;启动压力梯度越小,产能越高,采用压裂或超前注水,可减小或"消除"储层启动压力梯度的影响。

For defects in low permeability reservoir nonlinear seepage model and productivity evaluation, based on low permeability nonlinear percolation theory and Park Ji Ye formula, a low permeability reservoir nonlinear seepage model was established. This new model has considered the effect of the fluid yield stress and the adsorption of the boundary layer on seepage flow. Based on the new percolation model, a numerical model of productivity evaluation for vertical wells under constant boundary pressure condition was built. The impacts of pressure-sensitive effect and the threshold pressure gradient were taken into consideration in this new numerical model, and also the factors to productivity were analyzed. Studies show that： with the increasing of leading edge location, production capacity increases quickly, and the production is controlled by the producing pressure differential, under the same leading edge location condition, capacity is approximately in linear correlation with the producing pressure differential; on the contrary, with pressure sensitive coefficient decreasing, production capacity increases quickly. If producing pressure differential is maintained at proper value, then the effect of the pressure-sensitive on the permeability is reduced, which can help to improve well productivity; with the threshold pressure gradient becoming smaller, the production capacity becomes higher. The effect of the threshold pressure gradient on production capacity can be small or ＂eliminated＂ by using fracturing or advanced water injection.