冲缝筛管结垢速率模拟研究

Research on simulation of scaling rate in slotted screen pipe

为对防砂过程中因地层物性影响而导致冲缝筛管出现结垢问题进行准确的过程分析,基于FLUENT平台利用现场数据建立流道中的化学反应和沉积结垢的数值模型,评估管道缝宽、环境压力、温度、离子浓度与流速对冲缝筛管结垢速率的影响规律。结果表明:筛管结垢速率与管内温度和离子浓度成正相关,与管内流体流速成负相关,但环境压力影响不大,同时结垢主要产生在冲缝台阶以及冲缝套与打孔基管的接触面上,对产液的过流面积存在较大影响;结合正交分析得到4个敏感因素的主次顺序为:管内温度、管内流速、反应物浓度、环境压力,并确定最小结垢的组合方案;通过DPM模型探究CaCO_(3)颗粒的沉积规律,得到管内的沉积情况,并建立多因素垢层厚度的计算模型。在实际生产中为降低筛管结垢对油井产能的影响,可以通过降低管内的温度、离子浓度及适当地增大流速来抑制结垢过程的发生。

In order to conduct the accurate process analysis on the scaling problem of slotted screen pipe caused by the influence of stratum physical properties in the process of sand control,a numerical model of chemical reaction and deposition scaling in the flow channel was established by using the on-site data based on FLUENT platform,and the influence of pipe slit width,ambient pressure,temperature,ion concentration and flow velocity on the scaling rate of slotted screen pipe was evaluated.The results showed that the scaling rate of screen pipe was positively related to the temperature and ion concentration in the pipe,and negatively related to the flow rate of fluid in the pipe,but the ambient pressure had little effect.Meanwhile,the scaling mainly occurred on the punching step and the contact surface between punching sleeve and perforated base pipe,which had a great influence on the flow area of produced liquid.Combined with the orthogonal analysis,the order of the four sensitive factors was the temperature in the pipe,the flow velocity in the pipe,the concentration of reactants and the ambient pressure,and the combination scheme of the minimum scaling was determined.The deposition laws of CaCO_(3) particles were explored through DPM model,then the deposition situation in the pipe was obtained,and a calculation model of multi-factor scale layer thickness was established.In the actual production,in order to reduce the impact of screen pipe scaling on the productivity of oil wells,the scaling process could be suppressed by reducing the temperature and ion concentration in the pipe and increasing the flow velocity appropriately.