水下生产系统启动低温优化分析

Low Temperature Optimization Analysis of Start-up of Subsea Production System

文章进行了国外某深水气田初始启动反向充压计算、水下井口不同起井流量低温分析等,结果可用于指导海底管道预充压计算、水下设备最低设计温度选型等。水下井口启动时因采油树油嘴上游为关井压力和最低环境温度,开井时油嘴下游因焦耳—汤姆孙效应产生低温会对下游设备造成损坏,起井前海底管道需预充一定压力降低油嘴前后压差,使启动低温在水下设备所允许范围内,避免设备启动低温损坏;平台外输干气海管可作为充压气源协助开井作业。当缺少油藏井筒和开井程序等信息时,为确定设备最低温度,可根据不同起井气量的低温预估水下设备最低温度,为水下设备采办选型及相应的分析计算提供依据;分析开井过程中的甲醇注入时间和注入量,确定支持平台甲醇储罐容积和支持船次,以保障水下生产系统平稳安全开井。

This article analyzed the initial start-up re-pressurization calculation of a foreign subsea gas field,as well as the subsea wellhead low-temperature analysis of different start-up flow rates,to guide the pre-filled pressure calculation of subsea pipeline and the selection of the min.design temperature for subsea equipment.Before subsea production system initial start-up,the up⁃stream pressure of the Christmas tree choke is wellhead shut-in pressure and temperature is min.environmental temperature.When the well initial start-up,the downstream of the tree choke will generate low temperature due to Joule Thomson effect,which will cause damage to downstream equipment.Before the wells initial start-up,the subsea pipeline needs to be pre-filled with a cer⁃tain pressure to reduce the pressure difference upstream and downstream the tree choke,so that the start-up low temperature is within the allowable range of the subsea equipment,and to avoid low-temperature damage to the equipment during initial start-up;The platform dry gas export pipeline can serve as a pressurized gas source to assist in well start-up operations.When there is a lack of information such as reservoir wellbore and well opening program,in order to determine the minimum temperature of the equipment,the minimum temperature of subsea equipment can be es⁃timated based on the low temperature of different well start-up flow rates,providing a basis for the procurement and selection of subsea equipment and corresponding analysis and calculation.Ana⁃lyze the methanol injection time and required volume during wells restart,determine the support⁃ing platform methanol storage tank volume and supporting vessel demand,and ensure the smooth and safe well opening of the subsea production system。