深水油气田水下生产系统双管输送流动安全研究——以流花21-2油田为例

Research on flow assurance of double pipeline transportation in subsea production system of deepwater oil and gas field:A case study of LH21-2oilfield

深水油气田水下生产系统采用双管输送,海管路由和立管构型的不同、管汇生产井布置、各井产量的差异、流体物性及流型等因素都可能导致两侧管道输量分配不均,给管道安全流动带来风险。以流花21-2油田水下生产系统双管输送为例,采用OLGA软件建立了从水下井口到FPSO分离器的双管输送模型,分析了双管输送偏流和段塞流形成的原因,并对提高管道运行背压、压力与液位高选控制以及管道出口温差控制等3项措施对偏流和段塞流的控制效果进行了对比分析。结果表明:对气油比较低的油气田,提高管道运行背压可消除段塞流,但偏流仍严重;采用压力和液位高选控制,可有效减弱偏流和消除段塞流,气、液偏流率分别降至6.3%、9.6%,且管道输送系统和分离器运行稳定;而采用出口温差控制,对偏流和段塞流控制效果不佳。因此,流花21-2油田最终采用了压力和液位高选控制措施对该油田双管输送进行控制。本文研究为类似油气田双管输送工程设计和生产操作提供了借鉴。

Double pipeline transportation is adopted in subsea production system of deepwater oil and gas field.Factors such as different subsea pipeline route and riser configuration,well layout in manifold,different well production,fluid physical properties and flow regime will all result in uneven distribution of throughput in two pipelines and bring risks to pipeline flow assurance.Taking the double pipeline transportation of subsea production system in LH21-2 oilfield as an example,a double pipeline transportation model from subsea wellhead to FPSO separator is established by using OLGA software.The causes of bias current and slug flow in double pipeline transportation are analyzed,and the control effects of three measures(i.e.increasing back pressure of pipeline operation,high selection and control of pressure and fluid level,and temperature difference control at pipeline outlet)on bias current and slug flow are comparatively analyzed.The results show that:for oil and gas fields with a low gas/oil ratio,increasing back pressure of pipeline operation can eliminate slug flows,but bias current is still serious;high selection and control of pressure and fluid level can effectively reduce bias current and eliminate slug flow,the rate of gas and liquid bias current is reduced to6.3%and9.6%respectively,and the pipeline transportation system and separator are stable;while temperature difference control at pipeline outlet is not effective for both bias current and slug flow.Therefore,the measure of high selection and control of pressure and fluid level is adopted for double pipeline transportation system in LH21-2 oilfield.The research result in this paper provides a reference for design and operation of double pipeline transportation system in similar oil and gas fields.