Study On The Staged Injection Pressure And Technology Of Horizontal Well In H Oil Field

A large area of carbonate H oilfield early development of rapid postpartum also requires a long period of stable production,the depletion annual natural decline rate is high,the depletion development has been unable to meet the requirements of stable level,horizontal injection well has advantages of low pressure and injection wells long,it can effectively compensate formation energy.Displacement of reservoir oil to enhance oil recovery,it plays an important role in ensuring the stable and high yield.Water injection technology of horizontal well is a new and potential oil development technology,water injection technology of horizontal well has a very big advantage in the process of oilfield development,horizontal waterflooding can increase water injection,improve the swept volume and oil displacement efficiency,but also can increase the reservoir pressure,improve reservoir development effect.horizontal waterflooding can increase water injection,improve the swept volume and oil displacement efficiency,but it also can increase the reservoir pressure and reservoir development effect.Water injection engineering technology of horizontal well is a technical guarantee to overcome large-scale carbonate water injection development technology project.However,the heterogeneity of strata is serious,large permeability difference along wellbore of horizontal well,the high permeability area,flow resistance is small,and often premature flooding;low permeability area with high flow resistance,water injection is difficult,oil recovery is poor,seriously affecting the horizontal well waterflooding.To solve the problem of poor connectivity and heterogeneity of reservoir,water flooding is needed.According to the H oilfield reservoir(deep Nahr Umr reservoir is 3600 meters,Mishrif reservoir is 3000 meters),injected a large amount of(5000~10000stb),thickness(average thickness of 200~300 meters),water injection and oil production wells wells complex(directional wells,horizontal wells,directional wells,and dual branch wells)and the characteristics of water scarcity,to increase the H reservoir development effect,improve the recovery rate,to carry out the research on the sea supporting technology of H injection;the horizontal well long well section have been identified in the field under the conditions of well completion methods,this paper carried out research on water injection technology of horizontal well section.1.Through studying the compatibility of injected water with reservoir and fluid,and according to the standards of petroleum and natural gas industry,the main water source types and water quality indexes of H oilfield are counted.And through the core flow experiment,it is concluded that different formation conditions require different water quality standards.2.Because of the difference of water quality between injected sea water and conventional water injection,the methods and items of Seawater Pretreatment are analyzed and summarized.3.The key factor of protecting oil and water well casing is reasonable injection pressure.It is found that pipe loss and nozzle pressure loss are the main factors of water injection pressure loss.And through reasonable injection pressure formula,the reasonable injection pressure of pipe string of three specifications,62 mm,75.9mm and 100.5mm,are calculated under the condition of injection rate of 8000bbl/d and 6000bbl/d respectively.4.Because the carbonate reservoir of Mishrif with depth,strong heterogeneity,single well injection volume is high,around the affected oil well and well spacing,type diversity.So,the tracer into water injection well,can be obtained through tracking and monitoring,water injection exists in the reservoir,seepage velocity,moving direction of plane and vertical relationship and spread Unicom parameters,pore distribution,evaluation of water flooding effect formation property and water dynamic parameter.Through comprehensive comparative analysis and demonstration evaluation,Mishrif tracer test wells,M279,M306 and M325 wells are recommended as the 3 tracers for the first choice.And through the experiment of tracer in fresh water and experiments in sea water,we can find that three inorganic salts are recommended,and the water soluble chemical tracers are compatible with each other.5.According to the characteristics of water injection wells,water injection wells,from the mouth to the formation is divided into three sections,each section according to the characteristics of the flow,establish the relationship between the output and the pressure difference of each model,using the principle of node analysis,summarized the calculation method of injection pressure.According to the theoretical formula: the injection pressure = the bottom hole pressure of injection well,the pressure produced by liquid injection + the total friction,a computer model for calculating the water injection pressure of horizontal injection is compiled.