Combinational Membrane Technique to Support Low Salinity Water Flooding Lswf

Abstract

Oil reservoirs comprise layers of sandstone with oil and gas held in the spaces between the grains that make up the rock. Allowing an oil reservoir to produce oil through declining natural pressure results in relatively low recoveries (10 to 30%), therefore most fields inject water (waterflooding sweeps oil towards the producing wells) into the oil-bearing rocks which typically increase the oil recovery by 5 to 10%. This means only 30 to 40 % of the oil in place is extracted and to further increase recovery various enhanced oil recovery (EOR) techniques are required including: gas-lift, polymer flood, steam injection depending on the reservoir and oil characteristics. In some reservoirs membranes are already used for low sulphate seawater injection to minimizes potential scaling or souring issues due to interactions with the formation rocks or water, however, this is for production maintenance rather than EOR. Waterflooding was first practiced for the purposes of pressure maintenance after primary depletion and displacing oil by taking advantage of viscous forces and has become the most widely adopted improved oil recovery (IOR) technique. Its high availability and simple injection, as well as lower cost and capital investment, are the other key operational and economical features of water flooding. Historically, little attention has been given to the role of injected water chemistry on the displacement efficiency or its recovery. However, over the past decade, many studies have shown that injecting brine with a salinity in the range of 1000–2000 ppm can affect crude oil/brine/rock (COBR) interactions in a favorable manner to reduce the remaining oil saturation.