Study On The Program Adjustment After Polymer Flooding For X Offshore Oilfield

With the successful implementation of chemical flooding in onshore oil field,especially the large-scale industrial application of polymer flooding,chemical flooding technology has become more and more mature.After a long time target block polymer injection,reservoir parameters have changed,after the polymer injection of remaining oil distribution becomes more and more complex,while the lack of actual test data of polymer flooding relative permeability curve of polymer flooding,fitting more difficult,need through indoor experiment and numerical simulation on the basis of understanding of polymer flooding residual oil distribution.Well,well after the adjustment has great changes in polymer flooding oilfield,the well network problems existing wells wells,resulting in block pressure distribution is not balanced,effective effect becomes worse;at the same time,part of the block polymer injection time,the oil production of poly benefit concentration,water return,tons of poly index increased oil;the geological characteristics,pattern adjustment,polymer injection timing,engineering different conditions and other factors,after polymer flooding flow caused by the change of polymer flooding is not balanced,increasing the difference of block,well group and single well injection effect.Aiming at the problem that the effect of polymer flooding is poor and the cost of polymer flooding is increasing in the offshore X oilfield,this paper explores the efficient development mode in the late stage of polymer flooding,which lays the foundation for the reduction of the efficiency.Firstly,the polymer flooding techniques in onshore and offshore oilfied are compared systematically in order to figure out the main factors which have obvious effect on polymer flooding efficiency and lead to water/polymer interaction problem.Secondly,valid characteristic model are established to figure out the mechanism and influencing factors of water/polymer interaction.After the mechanism is clearly understood and the influencing factors are thoroughly analysed,multiple reservoir engineering methods are used to get the quantitative evaluation of water/polymer interaction on the efficiency of polymer flooding.At last,appropriate adjust measures are broght out to improve the efficiency of polymer flooding and the development parameters are optimized by orthogonal design method.Firstly,the actual core target area,to carry out a peacekeeping three-dimensional model experiment,the polymer flooding reservoir parameters and phase permeability parameters of the system,determine the distribution of remaining oil after polymer flooding;produced by dynamic analysis of target blocks,carrying out research on distribution of remaining oil and fine history fitting on this basis,;the unbalanced injection EOR method research.In the whole research process,the indoor physical model experiment,reservoir engineering method,numerical simulation method and mathematical method are applied.The results show that with the increase of permeability,k_ro decreased,k_rw increased,S_wcc decreased,two span increases;the infiltration point moves to the left,the right endpoint value,S_or decreased;with the polymer concentration increased,k_ro increased,k_rw decreased,the two-phase span decreases;the infiltration point right,right endpoint value,reduce the long-term water S_or;flooding after scouring,k_rw increased,S_or decreased after long-term erosion;flooding polymer,k_rw slightly decreased,S_or decreased.The adjustment measures,expand the parameter optimization of polymer injection,2000mg/L,polymer injection amount is 0.6PV,the moisture content is 75%by using the polymer concentration in the A7region of B7 polymer concentration area was 2500mg/L,polymer injection amount is 0.5PV,the moisture content is 75%,AI+J polymer concentration is 2250mg/L,polymer injection amount 0.4PV,the moisture content can obtain the best development effect is 72%.Taking into account the actual development effect of oilfield.In the same water flooding parameters optimization,selection of A7 weakened to 0.5 times,the original water injection multiple polymer concentration is 2500mg/L,B7 reduced to 0.5 times,the original water injection multiple polymer concentration is 2000mg/L,AI+J reduced to 0.3 times,the original water injection multiple polymer concentration is 2250mg/L,can achieve the best development effect.