Research Water Control And Mechanism Of Nitrogen Foam System In High Temperature And High Salinity Bottom Water Reservoir

Bottom water reservoir is widely distributed at home and abroad and has abundant reserves.Bottom water coning has seriously affected the effective mining time and production efficiency of the reservoir,especially the water control of high temperature and high salt bottom water reservoir is a difficult problem in the field of oil and gas field development in recent years.The example shows that nitrogen foam has a certain effect on the conventional reservoir control cones.In this paper,the water control of nitrogen foam system in high temperature and high salt(110-115℃,22.38×10~4mg/L)bottom water reservoir was studied.In this paper,the Waring Blender method was used to optimize the concentration of 0.3%main agent PJ from negative ion and amphoteric ion surfactants.The bubble volume was319mL and the half-life of the solution was 389s.The high temperature and high salt nitrogen foam system was determined by the combination of different foam stabilizer:"PJ+N20(2:1)",its bubble volume was 335mL,and the solution was semi decanting.The period is 2277s.The influence of high temperature,high salinity,long term hot salt and adsorption on foam system is further analyzed.Through the study of the"PJ+N20(2:1)"nitrogen foam system under the experimental condition(115℃),the high temperature long core(single core,parallel core)flow experiment to detect the sealing capacity and displacement efficiency of the nitrogen foam system.The optimum parameters of the foam flow control are obtained by the blocking experiment:the gas to liquid ratio 1:1,the injection speed 3.8m/D,and the injection velocity.The input 0.5PV is used to evaluate permeability,the influence of crude oil on plugging capacity,and the effect of interlayer and heterogeneity on oil displacement.By using the visualized device of simulating the water pressure cone of the reservoir condition,the shape,the density distribution of the foam(bright blue)and the migration of the foam in the oil well are observed,and the recovery rate of different stages is obtained.The effect of nitrogen foam control cone is evaluated by the physical simulation experiment.And get the best injection production parameters:the timing of conversion 95%,injection position of water cone,the middle of soak time 3d,wells 2.5m/D system.Using the STARS module of CMG numerical simulation software to establish the model,the parameters of the water control cone are designed in orthogonal design.The output input ratio is used as the evaluation index,and the optimum injection and production parameters are combined(1:1,injection amount 350000m/D,injection mode as foam slug,time 98%for injection,23 days of soaking time,800m/d injection speed.Well opening system 600m/D),parameters affect order and order of significance.After 30 years,the dynamic analysis of the density of foam shape and the distribution of water content in each stage has been carried out.The effective time is up to 5 years and 9 months.From the angle of numerical simulation,it is proved that the nitrogen foam has good effect on the water control of the high temperature and high salt bottom water reservoir,which lays a foundation for the field test.