Application Of Drainage Gas Recovery Technology In Jilin Oilfield

With the increase of gas well production time,the bottom hole pressure of gas well will decrease.When the pressure of the gas well is low,the air flow in the gas well cannot bring the water from the bottom of the well to the surface,which causes the water in the gas reservoir to gather at the bottom of the well and generate backpressure,resulting in the decline of the gas well production and the failure to meet the mining demand.The Changling gas field in Jilin Oilfield is facing the problem of poor liquid carrying capacity and serious liquid accumulation at the bottom of the well.These problems limit the gas production capacity of gas wells and seriously affect the development effect.In this paper,the gas wells in Changling gas field are studied.Based on the analysis of a large number of domestic and foreign literature,data and successful experience of drainage gas production in other blocks,the source,characteristics and law of water production in Changling gas field are tracked and analyzed,and the productivity equation of water-producing gas wells is established.This paper discusses the influence of water production on gas well productivity,and proves that the productivity of water-producing gas wells conforms to the actual production of Changling gas wells.Then,the gas well IP,IC index,critical liquid carrying flow,field test and gas production curve dynamic analysis of wellbore effusion diagnosis and evaluation methods were carried out,and the typical gas well effusion was calculated,which provided a theoretical basis for drainage and gas production measures.Finally,based on the adaptability analysis of existing drainage gas production technology,the research on drainage and gas production technology of Changling gas field was carried out.The research results show that:(1)The classification criteria of formation water and condensate water in Changling gas field are determined as follows:when salinity is less than 10 000 mg/L and water-gas ratio is less than 0.13 t/104 m3,it is condensate water,and vice versa,formation water.At present,there are 14 gas wells producing formation water in Yingcheng Formation,and all gas wells in low position produce formation water.(2)The relationship between water-gas ratio and salinity is studied:there are 7 gas wells with synchronous change of water-gas ratio and salinity.Water-gas ratio is low,all below 1.5ml/104m3,water invasion is weak,and reservoir fractures are relatively undeveloped.There are 4 gas wells with water-gas ratio lag behind the change in salinity,and the water-gas ratio is relatively high,reaching more than 4.0m3/104m3.The water invasion is strong,and the reservoir fractures are relatively developed.(3)Comparing the productivity equation of conventional gas Wells and water-producing gas Wells,the productivity of gas wells under the condition of water-producing gas wells is calculated and analyzed.The results show that once the gas wells produce water,the oil pressure and production will decrease,but the decline rate of production is contrary to the decline rate of oil pressure.The existing productivity calculation without considering the effluent is higher than the actual production,and the aquatic productivity method is more consistent with the actual production.(4)It is determined that the drainage and gas recovery processes of Changling gas field are mainly:foam drainage,gas lift drainage,preferred column and machine drainage,and the feasibility and effectiveness of the process are verified by field application.(5)Through field tests in Changling Gas Field,the foam discharging C with good liquid carrying capacity and foaming capacity was optimized.The research results in the paper deepen the understanding of the water production characteristics of Changling gas field,and form the technologies of the judgment of bottom hole fluid accumulation characteristics,and drainage water and production gas,which provide strong support for efficient development of Changling gas field.