Study On The Technology Of Condensate Gas Well Deliquification By Gas-lift

Gas-condensate reservoir as an important unconventional gas reservoir developed fast with oil and gas reservoir exploration and development. Many problems urgent need to be solved in the development of condensate gas reservoir. These problems include condensate oil will appear and polluted the formation, the gas production will decreased when formation pressure below the dew point pressure. During the middle or last development phase, edge and bottom water encroached, after produced water, gas well take place liquid loading because of the small production and poor capacity of liquid carrying. The deliquification will be restricted in well depth due to the gas-condensate reservoir is deep lying. It is important for us to formulate production practice programs by studying on the problems of gas-condensate reservoir development.In view of pressure decreases in condensate reservoir development, oil/gas composition and statement alternate and the problem of condensate pollution,a binomial deliverability equation model for filtering flow is established based on non-Darcy deliverability equation.According to the model,formation water and condensate oil are taken into consideration,then a deliverability calculation model for oil/gas/water three-phase fluid flow is obtained.Wellbore applicable condition, exploitation condition, liquid producing capacity and flowing deepness for kinds of deliquification technology are analysed for hole depth feature, gas lift deliquification technology is adopted.This article mainly contains the following contents:1. Three kinds of oil gas hydrocarbon compound system’s EOS such as SRK、PR and BWS equation of states combined with gas-condensate state theory were used to calculate dew point pressure and multicomponent isothermal flash calculation.2. Demarcation to the dew point pressure and condensate seepage, seepage flow of condensate gas in reservoir can divided into three distinct regions, those three regions are described that:The first region that is far from the wellbore, the formation pressure higher than dew point pressure where gas and water can flow. The second region which pressure lower than the dew point pressure and the liquid keeps accumulating and does not flow until the critical liquid saturation is reached.The third region around the wellbore and formation pressure lower than dew point pressure where both oil and the gas phases are flowing if the system is2-phase.3. The functions can be calculated that the water production and the formation pressure, water saturation and formation pressure, relative permeability of condensate oil, water and condensate gas and formation pressure. It is based on binomial deliverability equation, material balance equation of gas reservoir, water influx calculation and isothermal flash calculation theory.4. Parameters such as mixture viscosity, mixture density, interfacial tension, superficial velocity which used in wellbore pressure distribution calculation of gas and water flow that can be modified. They were be used in the pressure distribution calculation of gas, oil and water phases wellbore flowing in condensate gas well.5. The least critical liquid carrying computational model combined with isothermal flash calculation model of condensate gas wellbore is used to analysis the least critical water carrying and the least critical oil carrying. Wellbore liquid loading diagnosis theoretical is provided for condensate gas well.6. Comprehensive analysis the similarities and differences spots of Gas-lift deliquification and gas-lift produce oil have, combined with the theory of gas-lift design, parameters of gas lift deliquification like the depth of gas injection, gas injection volume, gas lift valve distribution, the open pressure and close pressure of gas lift valve are designed.7. Based on the gas lift design theory, gas lift dynamic response analysis method is adopted to establish gas lift production adaptability plates and gas lift injection depth adaptability plates.8. Visual Basic computer programming language is used to design software of gas lift deliquification. The software contains some modules such as isothermal flash calculation module, pressure and temperature distribution calculate module, the least critical liquid carrying calculate module, gas lift design module.The main innovations are as following:1. In the process of condensate flow, fluids rate forecast model and computational method for condensate oil/gas and formation water in three vadose regions are established.2. Adaptiveness for gas lift deliquification technology is analysed and adaptiveness analytical map for gas lift drainage rate and flowing back depth, which provide some valuable evidences for deep gas lift in condensate wells.The article perfects the theory and methods of gas lift deliquification technology in condensate wells and laid the groundwork for efficiently and rational development in condensate gas reservoir.