ABSTRACT
Chemical Enhanced Oil Recovery (EOR) processes are being considered for large field applications with recent high price of crude oil. However, applications are generally directed towards onshore environment, with temperature less than 85°C, using fresh water as the injection water. Malaysian oil fields are located offshore, with high reservoir temperatures of more than 100°C and use sea water as injection water. This paper reports on laboratory results that were part of an R&D project investigating the feasibility of increasing oil recovery through chemical EOR processes for oil fields in Malaysia.
Chemical EOR processes investigated include surfactant, surfactant-polymer, alkaline-surfactant, and alkaline-surfactant-polymer. A unique 2-stage softening prepared seawater for the two processes using alkali. Thermal aging studies at 119°C were used to screen chemicals for stability and degradation. Interfacial tension and phase behavior tests of stable chemicals were used to select formulations. Linear corefloods and thermal degradation tests were used to select polymers. Oil recovery studies used field proportioned injected chemical volumes in radial corefloods.
Dilute surfactant processes without alkali recovered little incremental oil. This was attributed to heavy consumption loss of surfactant. Average incremental oil recovery in coreflood studies by alkali-surfactant flooding was 14.6% OOIP and by alkaline-surfactant-polymer flooding was 28.6% OOIP respectively. This proved that there is potential for chemical EOR application in Malaysia.
