摘要
在四川盆地西部中浅层致密砂岩气藏中,气井压力、产量递减快,气井产水、井筒积液,严重影响生产。为此,在多口水平井投产初期、生产中期实施连续油管排水采气工艺,以延长气井的生命周期。随着气井产量的下降,连续油管井生产后期仍需开展泡排、气举等辅助排液措施,但部分井的泡排、气举效果欠佳。针对这一问题进行研究,优化了泡排介入时机的选择及泡排剂用量的计算,同时优选了经济可行的连续油管井气举类型及方式,从而提升了致密砂岩气藏低能量气井的排水采气效果。研究结果表明:①水平井携液临界流量的计算模拟结果显示,水平段较之垂直段、斜井段,水平段的携液临界流量最大,因而带液难度最大,低能量气井水平段处于泡状流态;当气井产量递减至携液临界流量时,需及时分步介入泡排工艺、继而是补充能量型的气举工艺,使气井能带液生产。②气液两相流压降模型中考虑泡沫流热阻力因素后,计算的单井泡排剂用量减少约15%~40%,消除了因药剂加注过量而导致井底泡沫堵塞情况。③产水量较大的常规连续油管井,选择排压高、作业连续、经济性好的移动压缩机气举工艺。④全通径连续油管井,适宜采用气流量大、携液能力强的CNG(压缩天然气)罐装气举工艺。现场应用表明,优化了17口连续油管井泡排药剂用量,平均单井次药剂量减少25%,消除了泡沫堵塞停产现象;优化了4口连续油管井的气举方式,排液增产效果显著。
In many tight sandstone gas reservoirs in western Sichuan Basin,which are featured by shallow to middle burial depth,most wells exhibit rapid pressure and production decline,water production,and wellbore liquid,which seriously affect the productivity.Therefore,a technology of coiled tubing(CT)drainage gas recovery has been used for horizontal wells at their initial and middle production stages to prolong the life cycle.With the production decline,some auxiliary drainage tools such as foaming and gas lifting were adopted at the later stage,but did not perform well in some wells.So,to select the foaming time and to calculate the foaming dosage were optimized,and the economically feasible lifting type and mode for CT wells were defined in order to improve drainage gas recovery in low-energy gas wells in these tight sandstone gas reservoirs.After the simulation calculation of liquid-carrying critical flow rate in a horizontal well,it is shown higher liquid-carrying critical flow rate in horizontal interval than that in vertical and deviated intervals,leading to great difficulty to carry liquid,and the horizontal interval in low-energy gas wells is in bubble flow state.When the flow rate decreases to the liquid-carrying critical one,it is necessary to promptly implement a foaming process step by step,followed by gas lifting for energy supplement,so as to allow the gas well to produce with liquid carrying.Taking the thermal resistance of foam flow into account,the gas-liquid two-phase flow pressure drop model derives the single-well foaming dosage about 15%-40%lower,thus avoiding foam blockage at bottomhole due to excessive volume.For conventional CT wells with higher water production,it is recommended to use the mobile compressor gas lifting,which is featured with high displacement pressure,continuous operation,and good economics.For full-scale CT wells,it is recommended to use the compressed natural gas(CNG)canned gas lifting,which has large gas flow and strong liquid-carrying capacity.In field application,the foam dosage in 17 CT wells was optimized,with the single-well foam dosage reduced by 25%,thus eliminating production suspension due to foam blockage.In addition,the lifting type and mode were optimized for 4 CT wells,obtaining a remarkable effect.
作者
蒋淮宇
Jiang Huaiyu(No.1 Gas Production Plant,Sinopec Southwest Oil&Gas Company,Deyang,Sichuan 618000,China)
出处
《天然气勘探与开发》
2022年第2期99-107,共9页
Natural Gas Exploration and Development
基金
国家科技重大专项“低压低产气藏复杂结构井排水采气关键技术”(编号:2016ZX05048-004-004)。
关键词
产水气井
连续油管
泡排剂用量
泡沫流
热阻力
气举模式
Water-producing gas well
Coiled tubing
Foaming dosage
Foam flow
Thermal resistance
Gas lifting mode
