稠油油藏高温盐析调剖的孔渗表征方法研究

深层高温油藏在开采过程中,由于近井地带压力变化剧烈,地层水蒸发致使结晶盐析出,进而导致储层孔隙度、渗透率降低.为研究稠油油藏高温盐析调剖的孔渗变化规律,根据盐类溶解/沉淀原理及储层孔隙度渗透率关系和填砂管模型高温盐析实验结果,建立了考虑地层水蒸发、水中氯化钠析出和储层孔渗变化的综合盐析模型.研究结果表明:随着堵剂注入量增加,封堵率快速上升并趋于稳定;实验温度在200~500℃之间氯化钠堵剂具有较好的封堵效果;盐析调堵方法可以有效封堵储层气窜通道,改良吸气剖面,提高周期采油量.最后用实验结果对数学模型进行拟合修正,得到稠油油藏高温盐析调剖的孔渗表征方法.

Porosity and Permeability Characterization Method of High Temperature Salting Out Profile Control in Heavy Oil Reservoir

In the production process of deep high-temperature reservoir,due to the drastic pressure change in the near borehole zones,formation water evaporation leads to the precipitation of crystalline salts,which leads to the decrease of porosity and permeability of the reservoir.In order to study the porosity and permeability pattern of high-temperature salt precipitation profile control in heavy oil reservoirs,based on the salt dissolution/precipitation principle and the relationship between reservoir porosity and permeability,and the results of high-temperature salt precipitation experiments of the sand-packed pipe model,a comprehensive salt precipitation model considering formation water evaporation,precipitation of NaCl in water and reservoir porosity and permeability variation is established.The results show that,with the increase of plugging agent injection,the plugging rate increases rapidly and tends to be stable;the experimental temperature is between 200~500°sodium chloride plugging agent has a good plugging effect;the method of salt out plugging can effectively block the gas channeling channel of reservoir,improve the gas suction profile and increase the periodic oil production.Finally,the mathematical model is fitting correction by the experimental results,and the characterization method of porosity and permeability of high temperature salting out profile control in heavy oil reservoir is obtained.