APPLICATION OF THE POLYMER FLOODING TO ENHANCE OIL RECOVERY IN A SPECIFIC KAZAKHSTAN’S OIL FIELD

Abstract

Oil and gas reservoirs at their initial state possess high energy that can be used for the extraction of natural resources for a long time. This period is called the primary production period. Primary recovery methods depend on the natural energy stored in the reservoir and nearby aquifer to produce oil. To generate oil (or gas), primary recovery relies on in situ fluids or rock expansion; particular techniques involve solution gas drive, gas cap drive, natural water drive, and rock compaction. In many reservoirs, a mixture of such recovery mechanisms exists, but one of them is usually dominant. Depending on the fluids and reservoir geometry, gravity can also help with recovery. However, primary recovery methods lose energy and oil production decreases with time. It is important to cover world energy demands, thus to keep oil production above economic limits secondary and tertiary recovery methods are applied. The specific Kazakhstan oilfield was produced by water flooding which is a secondary recovery method, which led to a high water cut. Additionally, the formation has high heterogeneity. Relying on previously mentioned factors, it was decided by the operating company to evaluate the applicability of polymer flooding through several laboratory tests. In this capstone project, rheology and thermal stability tests were performed for 4 different polymers. The purpose of this study is to find out the optimum polymer type with the most suitable concentration. Screening criteria are mainly according to the target viscosity of the polymer, which is 5 cp at reservoir conditions. The conducted experiments provided qualitative as well as quantitative results. All 4 polymers have demonstrated a proposed shear-thinning behavior. However, Polymer 1 showed abnormally high viscosity and that is why it was excluded. At the initial stage of thermal stability tests, roughly 10 days, viscosity degradation for all polymers was sharp. At the end of all evaluations polymers, 2 and 3 achieved a target viscosity of 5cp at concentrations of 1500ppm and 2100ppm respectively. Further experiments such as static and dynamic adsorption tests, core flooding, compatibility, and mechanical degradation experiments are suggested to fully examine the polymer behavior under reservoir conditions.