First Long-Term Polymer Injectivity (LTPI) Test in Magwa Field Targeting Medium Quality Formation in Wara, Great Burgan Field

Abstract

Abstract The Greater Burgan field Kuwait is the second largest oil field in the world and the largest sandstone field. Greater Burgan is divided into Ahmadi, Magwa, and Burgan fields. This paper describes the result of the first Long Term Polymer Injecticity Test (LTPIT) in Magwa field targeting wara reservoir with inferior rock quality comparing with the previous LTPI tests implemented in Burgan Field. These multiple LTPI tests located in different areas of the Greater Burgan Field are aimed to de-risk fast-tracked phased commercial polymer-flooding deployment in pursuit of production acceleration, reserves growth and cost optimization. An existing water injector in Magwa field was selected and connected to existing effluent water plant. Down-hole pressure and temperature gauges were installed for real-time surveillance monitoring of the pilot operation. Effluent water was treated at specific criteria and then mixed with the dry polymer to form the mother solution. This solution was diluted with treated water to achieve targeted injected polymer solution viscosity. Water-polymer solutions were injected using a high pressure non-shearing reciprocating pump. Injection rates, polymer concentration and viscosity were continuously monitored along with pressure and temperature. Samples from nearby producers to detect polymer breakthrough and measure polymer concentration were collected. A commercial simulation package CMG STARS™ was utilized for numerical simulation evaluation. Pre-selected sulfonated polymer was used to evaluate injectivity in medium quality zone at multiple rates and multiple polymer concentrations under sub-fracturing conditions. The rate and concentration for full-field application were determined. Target viscosity in-situ (4.7 cp) was achieved at lower concentration (1600 ppm). BHP pressure response to different injection rate and concentration was established. Polymer injection has the potential to improve conformance and establish more uniform zonal intake of injected fluids. The results show overall good polymer injectivity under matrix condition, however, dynamic modeling results incorporating pilot test data does not provide a cost-effective development strategy when compared to other parts of greater Burgan field. The result of the Long-Term Polymer injectivity test will be further integrated to design the polymer phase development in Greater Burgan Field, de-risking the commercial polymer flood development and therefore to save cost, time, and accelerate production in Wara reservoir.