Developments of ASP/SP Flooding Formulations for Huabei Fault Block Reservoir

Abstract

Abstract Chemical combination flooding technology is one of the effective enhanced oil recovery (EOR) methods for high water cut sandstone reservoirs. Alkali-surfactant-polymer (ASP) flooding has been tested and applied in Daqing oilfield with significant EOR performance. When chemical combination flooding was extended to different reservoirs, one of key techniques is to develop chemical flooding formulations to fit the reservoir conditions. Huabei oilfield is a fault block reservoir with specific geological conditions and reservoir fluid properties other than Daqing oilfield. The average water cut was around 90% by water flooding. Chemical combination flooding is an alternative technique to enhance oil recovery. ASP and alkali-free surfactant-polymer (SP) combination flooding formulations were investigated for Huabei reservoir conditions based on polymers and surfactants screening tests, surfactant adsorption losses experiments and oil displacement core flooding experiments. The research results lay the foundation of pilot tests for chemical combination flooding applying to the fault block reservoir. Salt tolerant polymers including comb-shaped polymer KYPAM showed good viscosifying performances than conventional polymers when prepared with Huabei formation water. Petroleum sulfonates (PS) were selected for ASP and SP formulations. Ultralow interfacial tension between crude oil and ASP/SP solution prepared with formation water could be obtained at a widely range of surfactant concentrations from 0.05wt% to 0.3wt%. Adsorption losses of surfactants on core sand showed that the adsorption losses of surfactants were less than 1.00mg/g. Core flooding tests of chemical flooding proved that about 20%-23% incremental oil recovery over water flooding could be obtained by using ASP (1.0wt% Na2CO3 + 0.3wt% PS-1 + 1400mg/L KYPAM) or SP (0.3wt% PS-2 + 1200/1400mg/L KYPAM) flooding with an injection pore volume of chemical slug was 0.5PV. The experimental results were considered to be technical feasibility and effectiveness of chemical flooding EOR methods for the fault block reservoir, which might present further understanding for chemical EOR field application in Huabei fault block reservoirs.