Low Salinity Waterflood and Low Salinity Polymer Injection in the Wara Reservoir of the Greater Burgan Field

Abstract

The Greater Burgan Field, first discovered in 1938, is the second largest oilfield in the world. Production from the Greater Burgan began in 1946 from the Wara reservoir via primary recovery. Recently, field-wide waterflood as a secondary recovery mechanism has been implemented. The current insight on the potential of hybrid low salinity water and polymer flooding in the Greater Burgan is presented. The goal of the Greater Burgan Study team in this enhanced oil recovery (EOR) evaluation program was to compare the benefits of using low salinity waterflood (LSW) and low salinity polymer (LSP) injection as tertiary oil recovery methods in the Wara sandstone reservoir of the Greater Burgan field. The efficacy of low salinity and low salinity polymer injection has been investigated in the laboratory and by conducting a series of single-well chemical tracer (SWCT) tests in one Wara producer. In the field trial carried out on Well A, three separate determinations of residual oil saturation (Sor) were made. The first SWCT test measured waterflood Sor after injecting a slug of high salinity water (HSW) that is compositionally comparable to the produced water utilized field-wide for waterflooding operations. The second and third SWCT tests measured the remaining oil saturation after LSW and LSP, respectively. Laboratory corefloods were also performed to evaluate LSW and LSP recoveries and their impacts on injectivity. The injection water salinity, injection design, oil viscosity, and polymer viscosity used in the laboratory experiments were identical to those used in the field SWCT tests. These SWCT test trial results establish a baseline waterflood Sor (i.e., after high salinity water injection) and show that further reductions in Sor may be achieved with low salinity waterflooding and low salinity polymer injection. The laboratory results showed no plugging or injectivity issues during LSW or LSP corefloods. Overall, LSW and LSP were shown to be technically workable tertiary processes in the Greater Burgan.

An Elongational and Shear Evaluation of Polymer Viscoelasticity during Flow in Porous Media

“…These economic constraints motivate companies to perform low-salinity pre-flush to optimize the process. Water pre-flush is commonly used to decrease the salinity of the formation brine, which is expected to improve polymer flooding performance [36,39,41].…”

“…Recently, the concept of the hybrid EOR method, using combined low-salinity water flooding with polymer flooding, has also shown promising results for oil recovery [41,42]. Low salinity also decreases the salinity of formation brine in a similar manner as pre-flush and polymer flooding and afterward retains good mobility control.…”

“…Al-Qattan et al [41] presented a single-well chemical tracer test (SWCT) performed in one Wara producer of the Greater Burgan Field (Kuwait). The reported connate water salinity was 160 g/L total dissolved solids (TDS).…”

Brine-Dependent Recovery Processes in Carbonate and Sandstone Petroleum Reservoirs: Review of Laboratory-Field Studies, Interfacial Mechanisms and Modeling Attempts

“…Additional tests were planned for other parts of the Burgan field with reservoir rock containing high clay content to further corroborate the established trend of recovery performance with clay content. In the same giant Burgan oilfield, Al-Qattan et al [226] reported another SWCT tests performed on Wara reservoir considering the radius of investigation of 4.8 m around the wellbore. They documented that low saline brine injection reduced Sor by 3% as compared high saline brine injection.…”

 Brine-Dependent Recovery Processes (Smart-Water/Low-Salinity-Water) in Carbonate and Sandstone Petroleum Reservoirs: Review of Laboratory-Field Studies, Interfacial Mechanisms and Modeling Attempts

“…Additional tests were planned for other parts of the Burgan field with reservoir rock containing high clay content to further corroborate the established trend of recovery performance with clay content. In the same giant Burgan oilfield, Al-Qattan, et al [197] reported another SWCT tests performed on Wara reservoir considering the radius of investigation of 15.6ft around the wellbore. They documented that low saline brine injection reduced Sor by 3% as compared high saline brine injection.…”