Study On The Technical Limits Of Water Drive Gas Reservoir And Software Development

Gas reservoirs need to design reasonable limit indices when formulating development plans.Because the development of water-drive gas reservoirs will inevitably face the problems of formation water intrusion and gas well water production,the following technical limits indices will be researched in this paper for water-drive gas reservoirs: Bottom water gas reservoir critical production,reasonable production capacity,bottom hole pressure of water production gas wells,critical liquid carrying capacity and abandoned pressure.The coning mechanism of the bottom water-drive gas reservoir was studied and a combined seepage model of the bottom water coning of the gas reservoir was established.The part above the well bottom was considered as plane radial flow,and the part below the well bottom was considered as hemispherical flow.Based on this model,the critical production formula is deduced without considering non-Darcy flow.When considering the non-Darcy flow,the numerical solution is obtained by using the fourth-order Runge-Kutta method;the basic law of seepage mechanics and the law of conservation of mass are established.The mathematical model of gas-water two-phase flow was deduced,and the gas-water two-phase production capacity equation and the open-flow flow calculation formula were derived,considering the non-Darcy flow and the gas well surface effect,and the water-containing IPR curve was drawn.With the increase of water mass ratio,the IPR curve will move to the lower left;the evaluation optimizes the gas-water two-phase flow pressure calculation model commonly used for different gas-water ratios.The results show that the modified Cullender-Smith model and Hagedorn-Brown model have higher calculation accuracy in the case of high gas-water ratio,and the Beggs-Brill model is more applicable in the case of low gas-water ratio;Get a new single droplet model from improvements in droplet shape,interfacial tension and drag coefficient of the Turner single drop model.Based on the critical velocity of the new single droplet model,a new multi-droplet model was obtained based on Zhou multi-droplet model experimental data;Summarizes the empirical and theoretical methods for calculating the abandonment pressure of water-drive gas reservoirs.Through the above work,a method system for developing water-drive gas reservoir was formed and a software was designed.The software can assist in the design of development projects for water drive gas reservoirs,and has a guiding role in gas field development.