非稳态分析在高温高压气井井筒水合物防治设计中的应用  

Application of unsteady state analysis in HTHP gas well hydrate prevention and control design

作　　者：杜孝友 于继飞 文敏 陈欢 邱浩 DU Xiaoyou;YU Jifei;WEN Min;CHEN Huan;QIU Hao(CNOOC Research Institute Co.,Ltd.,Beijing 100028;State Key Laboratory of Of fshore Oil Exploitation,Beijing 100028)

机构地区：[1]中海油研究总院有限责任公司,北京100028 [2]海洋石油高效开发国家重点实验室,北京100028

出　　处：《非常规油气》2021年第5期70-76,86,共8页Unconventional Oil & Gas

基　　金：国家自然科学基金项目“深水油气钻采井筒压力控制基础研究”(51734010);中海石油(中国)有限公司科技项目“深水高温高压井钻完井技术研究”(2017-KJZC-05)。

摘　　要：以保障井筒流动安全、减少气井修井作业为目的,针对海上高温高压气田地层压力高、初期关井压力高导致气井开关井操作工况下极易生成水合物,造成井筒堵塞问题,采用OLGA瞬态多相流软件进行高压气井关井、热启动、冷启动、初开井等非稳态工况的模拟分析,研究不同工况井筒温压及产量变化规律,进行水合物生成风险区域及时间判别,对存在水合物生成风险工况,以甲醇水合物抑制剂为例,进行工艺参数模拟计算。结果表明:1)在气井关井工况下,海水段井筒最先进入水合物生成区域,井筒需在18 h内完成甲醇注入,所需甲醇量为57.2 L;2)在冷启动工况下,需在启井48 min内持续注入甲醇,注入速度约为0.038 6 m^(3)/min,所需甲醇量共计1.86 m^(3);3)在初开井工况下,需在初开井20 min持续注入甲醇,注入速率需满足0.57 m^(3)/min,总甲醇注入量约为12 m^(3)。以上成果认识可对海上高温高压气井井筒水合物预测及防治提供一定指导意义。In view of high formation pressure and high shut-in pressure in offshore HTHP gas field, gas hydrate is easily generated under well startup and shut-in operation, which can result in wellbore blockage. In order to ensure the safety of wellbore flow and reduce well work-over operation, unsteady simulation analysis is carried out for shut-in, hot restart, cold restart and initial open-up of high pressure gas well. According to the variation law of wellbore temperature, pressure and production under different unsteady conditions, the risk area and time of hydrate are identified. Taking methanol hydrate inhibitor as an example, the simulation calculation is carried out. The results show that: 1) The wellbore cool down time is 18 h and methanol should be injected into the well within this time after shut-in;2) Under the cold restart condition, methanol should be continuously injected within 48 min of well opening, with the injection rate of about 0.038 6 m^(3)/min, and the total amount of methanol required is 1.86 m^(3);3) Under the initial well open-up condition, methanol should be continuously injected within 20 min of well opening, with the injection rate of 0.57 m^(3)/min, and the total amount of methanol injected is about 12 m^(3). The above results can provide some guidance for the prediction and prevention of hydrate in offshore high temperature and high pressure gas wells.

关 键 词：高温高压 天然气水合物 非稳态分析 开关井 水合物抑制剂 

分 类 号：TE355[石油与天然气工程—油气田开发工程]