Production Enhancement in Tight Carbonate Reservoir with Propellant Stimulation Technique: Case Study in the State of Kuwait

Abstract

The objective of this paper is to describe the production enhancement by the application of Propellant stimulation perforation during testing. During testing of a very tight carbonate reservoir (5% average porosity) the well productivity before and after propellant stimulation was studied for it's effectiveness. Propellant stimulation is achieved by burning the propellant material chemically and generating the gas by combustion. Gases generate a peak pressure that exceeds the fracture gradient of formation. High pressure gases injects at extremely high rates for a few milliseconds, resulting in creating micro fractures in the reservoir near the wellbore area which may result in good reservoir connectivity. Based on the subsurface information from offset wells, a vertical exploratory well drilled to delineate the potential of the target reservoir. Three sets of intervals were perforated in the target carbonate reservoir, in underbalanced condition and all intervals were tested together with Drill Stem Test (DST) tools. Matrix stimulation carried out using emulsified acid. During cleanup period, the flowing pressure continuously declined and finally only gas return was observed at surface. Flow period lasted for 30 hours. Production logging results showed that only the top perforation interval was contributing to the well flow. After detailed review of PLT results and open hole logs the middle perforations was selected for the propellant stimulation. Well was filled with 2% KCL brine and the middle section was stimulated thru’ tubing using 15ft. of 2″ propellant stimulation tool on wireline. Matrix stimulation repeated with diverter and emulsified acid for all the perforated interval. Flowed the well for cleanup followed by rate measurement for 15 hours showed improved flowing pressure and increased liquid rate. Second production logging results showed that both the top and middle perforation interval is contributing to the total flow. Middle perforation contributing to flow after use of matrix propellant stimulation. Propellant stimulation was successfully applied in tight carbonate reservoir. The production logs recorded pre & post of the propellant stimulation clearly indicates gain in oil production rate & improvement of flowing pressure in tight carbonate reservoir. During Shut-in survey, no cross flow was observed between the perforations and no flow behind casing. The data acquired using production logging will provide procedures for testing new exploration wells in similar reservoirs. Propellant stimulation is economical and enhances the effectiveness of standard acid stimulation in carbonate reservoirs. Propellant stimulation executed in tight carbonate reservoir of exploration well in State of Kuwait was remarkable success. This mechanism will aid to produce oil from the tight carbonate reservoirs.