A rational working system for gas wells in tight sandstone reservoirs with rich water,Dugui gas province,Dongsheng gasfield,Ordos Basin
Taken Dugui gas province as an example,the production traits were discussed for tight sandstone gas wells rich in water at various water/gas ratio to hold up the efficient development in such gas reservoirs.On this basis,the effect of stress sensitivity and pressure difference on the production was also analyzed.Moreover,production outcome was accessed for gas wells with different proration working systems,and differentiated proration plans and standards were proposed to condition the pressure-drop rate.Results show that(i)with the unique pore-throat assemblage dominated by micropore and fine throat,the reservoirs in the study area feature low to ultra-low porosity,low permeability and strong heterogeneity;(ii)the development in these wells is seriously affected by water production.The higher the water/gas ratio,the larger the production decline and pressure-drop rate,and the lower the elastic yield;and(iii)with the increasing division in produc-tion pressure,part of capillary water and bound-water membrane may turn into movable water.As a result,water produc-tion increases,both elastic yield and cumulative production decrease,creating further complication in stabilizing production to deteriorate the development.In conclusion,for this kind of tight sandstone reservoirs rich in water in the mode of deple-tion development,controlling the proration and pressure-drop rate is an important means for gas wells to prolong their sta-ble period and improve recovery.What's more,after the proposed differentiated proration plan and pressure-drop rate con-trol chart have been in practice,the coincidence rate achieves up to 87.5%.So,these plan and chart may be popularized to the development in similar reservoirs and provide better guidance for the efficient development.
Ordos BasinDongsheng gasfieldPermian Lower Shihezi FormationTight sandstone gas reservoir rich in wa-terProduction characteristicsControlWorking system
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