Research On Wax Control Technology Of Weizhou 6-9 Oilfield In Western South China Sea

Wax deposition in oil wells is a common problem in the production process of waxy oil wells.There are many factors affecting wax deposition in oil wells,including temperature,pressure,wax content,flow rate,wall characteristics and so on.The wax content of crude oil in Weizhou 6-9 oilfield in the west of South China Sea is 11.17-21.37%,the freezing point is 34-42,the wax precipitation point is 59.8,the bottom temperature is low,and the average water temperature of seawater is 15 C.With the decrease of wellbore fluid temperature and pressure,the light components of natural gas and crude oil dissolved in crude oil escape from crude oil,which reduces the wax dissolving ability of crude oil and causes serious wax deposition problem.Aiming at the problem of wax deposition in Weizhou 6-9 oilfield,the physical model of heat transfer in production wellbore,the coupled solution method of temperature and pressure are established.Combining the strength index and strength checking calculation method of insulating tubing,the reasonable depth of insulating tubing is optimized.The influence of chemical agents on wax control effect is evaluated,and the chemical agents suitable for Weizhou 6-9 oilfield are screened out.In the process of research,by analyzing and calculating the influence of the parameters of insulating pipe or insulating tubing on the temperature field of production wellbore,combining with the characteristics of wax precipitation in Weizhou 6-9 oilfield,and on the basis of conventional wellbore temperature field prediction model,considering the dynamic liquid level height and annulus fluid thermodynamic factors,a high-precision prediction model of wellbore temperature field in offshore oilfield is established,which is sensitive to single factor.Based on the analysis,the order and law of main and secondary factors affecting wellhead temperature of production wells with insulating pipes are obtained,and combined with the actual production situation on the spot,the design technology of comprehensive and multi-factor deep plan of production wellhead insulating pipes is established.At the same time,aiming at the high pour point,easy wax precipitation and viscous properties of the crude oil in Weizhou 6-9 oilfield,fluorinated ester polymers YFFL-220 and YFFL-222 with good pour point depression,viscosity reduction and wax control effects were synthesized by optimizing the formulation.The design idea of wax inhibitor injection was optimized by combining the experimental results,wellbore temperature field and pressure field,and the wellbore pressure temperature field and chemical agent were formed.Viscosity reduction technology of chemical agents based on experimental results of agent evaluation.