Study On Desanding And Anti-scaling Technology In Laojunmiao Oilfield Gathering And Transmission System

The sand sedimentation and high content of sand in produced liquid have a deep influence in production of Laojunmiao Oil Field.The serious sedimentation results in the sharp decrease of gathering and transporting efficiency which needs urgent measures to remove the scale.Apart from that,the crude oil is characterized by high sand content,thus sand and mud depositing in the three-phase separator.However,there exist no special desanding facilities in central processing facilities.The sand sedimentation,spoils the dehydration performance,is difficult to be removed by the flowing produced fluid and gathers in the facilities.Hence,the study of desanding and scale removal for Laojunmiao Oil Field gathering and transmission system is of significance.Aiming at the sedimentation in the pipeline,the produced fluid without additional chemicals,together with the fluid added by scale inhibitor of different concentration are tested to determine the best dosage.Software Fluent is utilized to simulate the desanding effect of settling tank at different temperature in that the oil filed prepares to introduce the facility.Experiments are conducted to obtain the fluid's physical property that lay the foundation of the subsequent sedimentation analysis and numerical simulation.According to the emulsion testing result,back-doped sewage cannot increase the demulsification efficiency but consumes a large amount of heat instead.The simulation result of software ScaleChem shows that the main scale is prone to be CaCO₃.When the concentration of cszgj-3,shows best descaling performance,is 20ppm,the scale inhibition rate of Ca²⁺is 71%and the scale inhibition rate of Mg²⁺is 73%.Based on the numerical simulation results,it is found out that it usually needs approximately 7-10hours to achieve the anticipated desanding efficiency.The optimal capacity of the tank is 3000m³.Moreover,the sewage back-doped method is not recommended if the heating method is adopted to increase the desanding efficiency.The paper also gives the method for calculating time interval for sand removal operation which may provide guidance for determining the desanding cycle.