Hydrodynamic behavior of Kangan gas-capped deep confined aquifer in Iran

Smart Technique in Water Shutoff Treatment for a Layered Reservoir through an Engineered Injection/Production Scheme

“…It is concluded that increasing the gas flow rate amplifies the ability of the gas to overcome the entry capillary pressure of the LP layer and induces a pressure gradient (hydraulic potential) that can mobilize the initially immobile water within the LP layer. This observation is a phenomenological explanation of the KGR challenge. − …”

“…It is found that saline water production from the LP lenses (that are located within the pay zone of high gas flow rate wells), ceases by decreasing the gas production rate to almost one-sixth of its normal value. − High gas flow rates impose large pressure gradient in the vicinity of the wellbore, which mobilizes the naturally immobile saline water content of the LP lenses − as shown schematically in Figure a.…”

“…During step 6 of the procedure, the gas flow rates were increased from 5 to 600 scm 3 min –1 in nine successive steps (i.e., 5, 10, 50, 100, 200, 300, 400, 500, and 600 scm 3 min –1 ). This wide range of flow rates is conducted because reports of the KGR challenge elucidated that increasing the gas production rate enhances the excess water production. − Besides, the challenge is mainly related to the near wellbore region in which the gas flow rates are much higher than normal reservoir rates; therefore, a high range of gas flow rate is performed. Gas injection at each flow rate was continued until no more water displacement was observed and the injection pressure reached its steady state condition (i.e., no more changes in phase saturations and pressure were observed).…”

“…The HP layer is usually considered as the excess water producer; however, in specific gas producing formations, excessive saline water is surprisingly produced from nonisolatable LP lenses that are usually fully water saturated due to capillary effects . Severe challenges due to the excess saline water production from such lenses have been reported recently in Kangan gas reservoir (KGR). − KGR is a volumetric wet gas reservoir located in the south of Iran, suffering from saline water production in approximately half of the wells. − The saline water production ceases upon decreasing the gas production rate to almost one-sixth of its normal aptitude. Detailed studies showed that by increasing the gas production rate, the pressure gradient in the vicinity of the well exceeds the capillary resistance and induces water flow within these lenses. − In this case, most currently proven technologies that are based on blocking the HP layer lose their applicability.…”

“…Severe challenges due to the excess saline water production from such lenses have been reported recently in Kangan gas reservoir (KGR). − KGR is a volumetric wet gas reservoir located in the south of Iran, suffering from saline water production in approximately half of the wells. − The saline water production ceases upon decreasing the gas production rate to almost one-sixth of its normal aptitude. Detailed studies showed that by increasing the gas production rate, the pressure gradient in the vicinity of the well exceeds the capillary resistance and induces water flow within these lenses. − In this case, most currently proven technologies that are based on blocking the HP layer lose their applicability. Considering the fluid flow behavior in heterogeneous porous media, it is stated that the selective injection of the gelant into the lower permeability lenses in competition with the adjacent HP layers is practically impossible, , and consequently the challenge requires innovative treatments.…”