Analysis Of Mining Potential Of Low Permeability And Low Pressure Gas Wells

China's natural gas reserves are abundant,and one-third of natural gas resources are distributed in low permeability layer,which has great prospects for exploration and development.In the middle and late stages of low-permeability gas reservoir development,with the decrease of formation pressure,the gas wells produced different degrees of water production,and the gas well production decreased rapidly.Therefore,the analysis of the exploitation potential of such low-permeability low-pressure gas wells is of great significance for deepening gas reservoir awareness and enhancing oil recovery.In this paper,the inflow dynamics of the gas reservoir,the law of wellbore flow,the evaluation of formation pressure and the analysis of mining potential are taken as the research objectives.Firstly,determine a low-permeability low-pressure research block,combine the data of AOF test and pressure recovery test,establish the relationship between AOF potential and formation capacity,establish a gas well inflow dynamic model suitable for this block and predict the gas well productivity change,and The capacity model performs a sensitivity analysis.Then,the water production characteristics of the study block are analyzed.By dividing the flow pattern of the gas-water two-phase flow in the wellbore,the water-gas ratio limit of single-phase(pseudo-single-phase)flow and gas-water two-phase flow is set.The energy consumption characteristics of the vertical wellbore and the downhole throttling system are preferably the wellbore pressure drop and the downhole throttling calculation model,and verify the reliability of the model calculation.Secondly,the calculation model of formation seepage-wellbore flow coupling is established.The calculation method of bottomhole pressure for Kriging interpolation is established for the first time,and the method for evaluating the pressure of unclosed in formation is obtained.Realize the use of wellhead pressure to calculate formation pressure,and dynamically monitor the pressure drop law of the formation and the dynamic change of gas well productivity.Finally,combined with the geology and production dynamic data of a well group in the study block,the formation seepage-wellbore flow-ground gathering system well group model is established;the single well production is recalculated,and the gas geologic reserve,remaining recoverable reserves and remaining formation pressure are calculated.Evaluate the remaining mining potential of gas wells from the aspects of pressure and production.Combined the gas well productivity,optimize the working system and stable production measures of gas wells,and formulate a reasonable gas well development work system;at the same time,reduce the gas well pressure and output,and increase the gas wells.Analyze the reasonable timing and mining effect of pressure mining,predict the ultimate recovery rate,further verify the potential of gas well production and optimize the gas well production system.