Study On Development Mode And Injection-production Parameters Of Horizontal Wells In Central Fuyu Oilfield

There are 228 horizontal wells in Fuyu oilfield,but most of them are in residential area and belong to water injection sensitive area.There are some problems such as imperfect injection-production relationship,insufficient energy and large production decline.The recovery rate is only 15.7%.Therefore,it is necessary to study the injection-production mode and energy supplement mode of horizontal wells,and make the best possible use of the remaining oil in the case of limited water injection conditions.Based on the geological model of the middle area of Fuyu Oilfield,the history of numerical simulation of water flooding is fitted with a relative error of 4.74%.The numerical simulation shows that the remaining geological reserves of the 3+4 and 6+7layers in this area reach 83.86×10~4t and 74.26×10~4t respectively,which are the main potential tapping targets of remaining oil.On the basis of remaining oil research,the injection-production mode of horizontal wells is numerically simulated.The comparison shows that the recovery rate of injection-production mode in the same well can reach 38.93%,which is 2.98%and 3.03%higher than that of exhaustive development and horizontal well pattern development,respectively.The main influencing factors of injection-production productivity of horizontal wells in the same well are injection-production ratio,injection intensity,length of horizontal section,length of packed section,coefficient of permeability variation and reservoir thickness.The ratio of injected section to produced section length is 1:1,and the length of packed section is 1/2 of the length of horizontal well.The optimum injection and production methods of four different horizontal wells,i.e.water injection,intermittent water injection,hot water injection and intermittent water injection,are further studied.Ideal numerical simulation shows that the recovery rates of these wells reach 40.90%,41.95%,41.97%and 42.64%respectively.Without considering economic factors,the recovery rate of intermittent hot water injection development mode is the highest,with the optimal water injection intensity of 0.05 pv/a,injection-production ratio of 0.95 and intermittent water injection-production ratio of0.95.The cycle is 2 years and the injection stoppage time is 1 year.The numerical simulation in the middle area of Fuyu oilfield shows that the recovery degree of four injection-production modes in the same well in 10 years are 29.34%,30.88%,30.35%and 31.47%respectively,and the output-input ratio is 1.16,1.37,0.96 and 1.09,respectively.It is recommended that intermittent water injection is the best horizontal well injection-production mode in the middle area of Fuyu oilfield.