川南页岩气开采中分离器排污系统的冲蚀分析及改进方案  

Erosion Analysis and Improvement Scheme of Separator Blowdown System in Shale Gas Exploitation in the Southern Sichuan

作　　者：刘恩斌 唐浩 李党建 赵万伟 李文胜 LIU En-bin;TANG Hao;LI Dang-jian;ZHAO Wan-wei;LI Wen-sheng(Petroleum Engineering School,Southwest Petroleum University,Chengdu 610500,China;China United Coalbed Methane Co.,Ltd.,Taiyuan 030000,China;Natural Gas Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu 610213,China;CNPC Offshore Engineering Company Limited,Qingdao 266000,China)

机构地区：[1]西南石油大学石油与天然气工程学院,成都610500 [2]中联煤层气有限责任公司,太原030000 [3]中国石油西南油气田分公司天然气研究院,成都610500 [4]中国石油集团海洋工程(青岛)有限公司,青岛266000

出　　处：《科学技术与工程》2023年第29期12760-12766,共7页Science Technology and Engineering

基　　金：四川省自然科学基金(2023NSFSC0422)。

摘　　要：在页岩气开采过程中,井里采出的页岩气会携带大量的砂粒等杂质,在经过分离器气液分离之后,底部携砂污水在高压驱动下,会使高速流动的砂粒对排污阀造成严重的冲蚀。针对该问题,以川南长宁地区生产井为例,建立相应计算流体动力学(computational fluid dynamics,CFD)模型,基于ANSYS Fluent求解器,针对不同压力、砂质量流量和颗粒特性条件下,对排污阀的冲蚀情况进行模拟分析。模拟结果表明:分离器运行压力越大,砂量质量流量越大,冲蚀速率及年冲蚀厚度逐渐增大,并呈现线性相关关系;颗粒形状系数越小,砂粒粒径越大,冲蚀速率以及年冲蚀厚度急剧增大;运行压力为1.5~5.5 MPa时,年冲蚀厚度为8.6~76.1 mm,根据行业标准得知目前的排污系统存在快速减薄穿孔现象。为此提出了一种新型的排污系统改进方案,并对该方案进行验证模拟分析。模拟结果表明,当排污管内流速为12 m/s时,排污阀最大冲蚀速率为4.53×10^(-5) kg/(s·m^(2)),折算成年冲蚀厚度为0.9 mm,相较于未改进的排污系统,缓蚀率可达99.7%以上。In the process of producing shale gas,the shale gas extracted from the well will carry a lot of impurities such as sand particles.After gas-liquid separation by the separator,the bottom sand-carrying sewage is driven by high pressure,high-speed flow of sand will cause serious erosion to the discharge valve.In view of this problem,taking a production well in the Changning area of Southern Sichuan Province as an example,the corresponding computational fluid dynamics(CFD) model was established.Based on ANSYS Fluent solver,the erosion situation of the blowdown valve was simulated and analyzed under different pressure,sand mass flow rate,and particle characteristics.The results show that when the pressure of separator is higher,the mass flow rate of sand is higher,the erosion rate and the thickness of annual erosion gradually increase,and there is a linear correlation relationship.When the shape coefficient of particles is smaller,the diameter of sand particles is larger,the erosion rate and the erosion thickness increase rapidly.When the operating pressure is 1.5~5.5 MPa,the annual erosion thickness is 8.6~76.1 mm.According to the industry standard,it is found that the current sewage system has the phenomenon of rapid thinning and perforation.Therefore,a new improvement scheme of the sewage system was proposed,and the scheme was verified and simulated.The simulation results show that the maximum erosion rate of the blowdown valve is 4.53×10^(-5) kg/(s·m^(2)) when the flow rate is 12 m/s in the sewage pipe,and the equivalent annual erosion thickness is 0.9 mm.Compared with the unmodified sewage system,the corrosion inhibition rate can reach more than 99.7%.

关 键 词：页岩气 排污阀 颗粒冲蚀 CFD技术 形状系数 冲蚀速率 

分 类 号：X937[环境科学与工程—安全科学]