川西地区超高压气井井下节流设计及投产技术  

Downhole throttling designed for ultra-high pressure gas wells in western Sichuan Basin and technologies of putting into production

作　　者：于洋 谢南星 孙风景 YU Yang;XIE Nanxing;SUN Fengjing(Engineering Technology Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610017,China)

机构地区：[1]中国石油西南油气田公司工程技术研究院,四川成都610017

出　　处：《天然气勘探与开发》2024年第1期46-54,共9页Natural Gas Exploration and Development

基　　金：“十三五”国家科技重大专项(编号:2016ZX05052)。

摘　　要：随着天然气勘探开发进程的深入,出现越来越多的超高压气藏。四川盆地西部地区(简称“川西地区”)部分超高压气井的原始地层压力已高达130 MPa、关井井口压力达110 MPa,传统的天然气水合物防治技术措施不足以满足超高压气井的安全生产需要。而井下节流技术作为一种高效的天然气水合物防治技术,可在提高采气集输系统安全性的同时降低地面建设成本,已在国内西南油气田、长庆油田、塔里木油田等得到广泛应用。川西地区超高压气井亟须开展井下节流工艺的现场应用。为此,从关键参数的计算方法入手,结合现场参数,对超高压气井的井下节流工艺设计方法及投产技术进行研究,为现场应用奠定基础。研究结果表明:①通过DAK法、LXF法、修正LXF法计算偏差系数与实测偏差系数的对比分析,推荐修正LXF法作为超高压气藏天然气偏差系数的计算方法。②井下节流工艺设计主要针对两个参数,即节流器下入深度、节流嘴直径;通过对应公式代入相关参数后的反复试算,可确定节流器下入深度,以满足节流后温度高于对应深度处的水合物生成温度;同时,结合压力、温度、预计产量等参数,优选节流嘴直径。③超高压气井从开井到井下节流器稳定发挥作用期间,井口面临高压节流,因此,在开井瞬间避免井口针阀冰堵,是下入井下节流器的超高压气井安全投产的关键。④针对不同区块的超高压气井,可通过瞬态软件模拟不同开井制度下井口压力、温度、产气量和水合物过冷度随时间的变化趋势,从而优选开井制度,保证超高压气井顺利投产。研究结果为川西地区超高压气井井下节流工艺的现场应用奠定了基础,提供了技术方法。Recent years have witnessed the growing emergence of ultra-high pressure gas reservoirs with the advancement of natural-gas exploration and development.In central Sichuan Basin,some gas wells with ultra-high pressure reveal the initial formation pressure up to 130 MPa and the shut-in wellhead pressure achieving 110 MPa,respectively.Traditional techniques and processes to control gas hydrate are inadequate to secure the safe production in such wells.In contrast,the technology of downhole throttling,as an efficient control means,can not only improve the safety of gas production,gathering and transmission system but reduce surface-construction costs.And it has been widely applied to Southwest Oil&Gasfield,and Changqing and Tarim Oilfields.It is also urgent to make a feasibility study on its applica-tion to ultra-high pressure gas wells in central basin.Thus,taken some methods to calculate key parameters into account and combined with in-situ parameters,both design and application of downhole throttling process were discussed for those wells with ultra-high pressure.More-over,deviation factors calculated from DAK,LXF and modified LXF methods were compared with the measured one,which indicates that the LXF method is more suitable for this sort of gas reservoirs;(ii)two parameters of both throttle depth and orifice diameter are involved in throttling design.The depth can be attained from repetitive calculation by putting relevant parameters into corresponding formula,so as to enable the temperature after throttling to be higher than the hydrate-generating temperature at the parallel depth.The diameter is selected with all consideration to pressure,temperature,and expected production;(iii)for these gas wells,during the period from well opening to sta-ble operation of the downhole throttle,wellhead is confronted with high-pressure throttling.As a result,preventing wellhead pin valve from ice blockage at the moment of well opening is critical for the safe production in a certain well where downhole throttles are landed;an

关 键 词：超高压 井下节流 偏差系数 图版法 DAK法 LXF法 投产 开井 

分 类 号：TE37[石油与天然气工程—油气田开发工程]