Study On Polymer Flooding Performance Of Horizontal Wells In Heavy Oil Reservoirs

More recoverable reserves of heavy oil reservoirs have been found than recoverable reserves of conventional light crude oil reservoirs,and the production of conventional light crude oil is declining as drilling in the world.In common heavy oil reservoir,except for water flooding,most of them will use the method of thermal recovery for exploitation.However,the thermal recovery method is also limited by the reservoir and other conditions.So,the technology of horizontal wells has emerged in polymer flooding.In the oil displacement theory,polymer flooding can effectively improve the viscosity of water and the oil-water flow ratio;Horizontal wells can increase the oil discharge area and sweep coefficient,so the technology of horizontal wells has become one of the effective ways to improve the development effect of polymer flooding in heavy oil reservoirs.In this paper,the related dynamic characteristics of horizontal well are studied by using the physical simulation and reservoir numerical simulation method,combining with the geological characteristics,fluid properties and well pattern of the actual reservoir,and using the similarity principle in polymer flooding.The research achievements and understandings are as follows:(1)With the increase of well spacing,the anhydrous oil recovery period is prolonged and the recovery rate is higher.The recovery of polymer flooding in physical experiments is: well spacing 26cm(73%)> well spacing 20cm(65%);well spacing14cm(58%).After water breakthrough,the water cut increases rapidly.However,after entering the high water cut period,the water cut increases more slowly.(2)By means of numerical simulation,the parameters optimization of well pattern,well spacing,crude oil viscosity and reservoir porosity are studied in heavy oil reservoir.The quantitative and qualitative analysis are carried out for each parameter.The optimal parameter scheme of one for injection and one for production of horizontal well is determined,which the well spacing is 260 m,0.6PV polymer drive and well length400m;The smaller the viscosity of crude oil,the greater the permeability,the earlier the injection time,the more conducive to improve the oil recovery.(3)With the advance of polymer injection time,the recovery is gradually increases,and the water injection can be greatly saved.The better the reservoir development,the higher the permeability,the better the relationships from injection to production rates,the better the effect of reservoir spread and the greater the decrease of remaining oil saturation after polymer flooding.With the increase of the injection of polymer volume,the recovery rate gradually increased from 38.84% to 45.05%,but the increase began to slow down.Because the utilization of polymers gradually became worse and the recovery rate gradually stabilized.(4)Based on the black oil model of eclipse software,the paper carries out the numerical simulation calculation.Numerical simulations show that the injection and production well pattern of polymer flooding can linear drive in horizontal wells.And,delaying the breakthrough time of water injection,increase the sweep efficiency and increase the oil recovery in polymer flooding.The pressure drop of horizontal section affects the oil displacement efficiency in well.