海上油田井筒电加热防蜡工艺设计方法

Design Method of Wellbore Electric Heating Wax-Prevention Technology for Offshore Oil Field

渤海油田油气井存在井筒结蜡导致井筒堵塞、油井产量降低甚至停产等问题,对正常生产影响很大。电加热防蜡工艺的实施关键是必须首先确定出井筒内的流体温度分布。目前常用的温度分布计算方法是基于传热过程和两相流动模型的迭代方法,计算中有关井筒中油管、套管和隔水管等的导热系数均采用材料的常用值,未考虑实际井筒结构和生产工况对传热性质的影响。为此,利用OLGA模拟方法,分析了电加热段长度对井筒内流体温度分布特性的影响规律,建立了基于软件模拟和理论计算相结合的井筒电加热防蜡工艺设计方法。该设计方法不仅考虑了井筒内的气体含量对流体流动的影响,还考虑了井筒油管和套管表面在出现结垢、腐蚀和冲蚀等现象时对径向传热特性的影响,使井筒内温度分布计算结果更加符合实际工况;提出了将井口至海底泥线间的常规油管更换为E级隔热油管的设计方案,使海上W0油田A8H井预投产初期的电加热功率由240 kW降低至90 kW。该方法可为海上油田前期设计阶段中防蜡工艺方案的确定提供技术参考。

Many oil and gas wells in Bohai Oilfield have problems such as wellbore blockage,oil well production reduction or even shutdown caused by wax deposits,which has a great impact on normal production.To address the problems,the OLGA simulation method is used to simulate the influence of the length of the electric heating section on the temperature distribution of the fluid in the wellbore.A wellbore electric heating wax-prevention process design method based on the combination of software simulation and theoretical calculation is established.This design method not only considers the influence of gas content in the wellbore on the fluid flow,but also considers the influence of scaling,corrosion and erosion on the surface of the wellbore tubing and casing on the radial heat transfer,so that the wellbore temperature distribution calculation results are more in line with the actual conditions.The design plan of replacing the conventional tubing from the wellhead to the submarine mudline with E-class insulated tubing is proposed,which could reduce the electric heating power of the Well A8H in the offshore W0 Oilfield from 240 kW to 90 kW.The method can provide a technical reference for the determination of wax prevention technology in the preliminary design stage of offshore oilfields.