The paper combines a brief case history of applications with supporting laboratory data, for using a new relative permeability modifier (RPM) in conjunction with a conventional acid stimulation treatment. This design was targeted at mature oil wells with high water cuts in Ecuador. The recommendation was proposed after mineralogical characterization of core samples, using scanning electron microscopy (SEM) followed by laboratory core flooding with treatment fluids. The methodology described in the paper comprises stimulation of certain areas of the sandstone formation with an acid followed by a RPM treatment to prevent the water from the stimulated water-bearing zones from entering the wellbore. Coiled tubing is used for effective placement of the treatment.
Conventional stimulation treatments in the Hollin sandstone formation in Ecuador result in high water cuts because of encroaching water from an active aquifer. The acidizing technique with RPM improved the economic life of many mature wells in the field. Both laboratory and field data indicate excellent results from the treatments. The overall water cut in the treated wells decreased (by 8 to 15%), while oil production increased (~200%). Coiled tubing enables accurate placement of the acid and RPM into the desired zones, with the benefits from this targeted treatment far outweighing the cost of using coiled tubing units.
Successful implementation of the laboratory core flood results in the field resulted in field-wide protocols aimed at oil wells producing water at unacceptable rates. The optimized stimulation treatment increases oil production and selective placement of RPM using coiled tubing decreased water cut, thereby prolonging the economic viability of mature wells.