Abstract
Inspired by the viscoelastic displacement theory and the advantages of preformed particle gels, we develop an innovative product called branched-preformed particle gel (B-PPG) for enhanced oil recovery. Due to its excellent viscoelastic properties, B-PPG can be used both in profile control and to improve sweep efficiency in heterogeneous reservoirs. Laboratory experiments indicate that B-PPG shows improved stability and long-term aging resistance under high temperature and salinity when compared with HPAM. The migration and displacement behaviors of B-PPG are studied by a series of sandpack core flow experiments. The results show that the B-PPG particles can migrate through the porous media, and the migration is a dynamic process of plugging and flooding. Besides, B-PPG can significantly create fluid diversion and increase the swept volume in low permeability zones. Moreover, micro visualization and oil displacement experiments are also carried out and prove that B-PPG can displace residual oil in small channels, leading to a high swept volume and enhanced displacement efficiency.
Highlights
Fossil fuels, such as oil and gas, currently supply most of the world's energy needs and will remain the dominant energy source for at least the decade or so.[1,2] At present, large fractions of the oil reserves in the world are located in mature oil elds whose production is declining
Inspired by the viscoelastic displacement theory and the advantages of preformed particle gels, we propose an innovative product called branched-preformed particle gel (B-PPG), which combines the excellent high viscosity characteristic of linear polyacrylamide with the outstanding pro le control ability of PPG
The experiment procedure is as follows: (1) the micromodel is saturated with brine water (30 000 mg LÀ1); (2) the micromodel is saturated with simulated oil; (3) brine water is slowly injected in the micromodel until no oil is produced from the outlet; (4) the hydrolyzed polyacrylamides (HPAM) solution is injected at the same rate until no oil is produced from the outlet; (5) the B-PPG suspension is injected at the same rate until the oil production becomes negligible
Summary
Fossil fuels, such as oil and gas, currently supply most of the world's energy needs and will remain the dominant energy source for at least the decade or so.[1,2] At present, large fractions of the oil reserves in the world are located in mature oil elds whose production is declining. Paper high salinities and high temperatures and may improve the development of oil elds that exhibit strong heterogeneity, high water-cut, and large porous channels.[18,19,20] despite the tremendous advantages that preformed particle gels present towards conformance control and reservoir heterogeneity, they seem incapable to improve the sweep efficiency of lower permeability areas because of their low viscosity These suspensions are heterogeneous, and the particles are subsided, which greatly impacts their injection and migration in channels. On the basis of these results, B-PPG can overcome the prior limitations of linear polymers, such as poor long-term thermal stability, poor salt resistance and low elasticity, and improve the viscosity, suspension stability and migration ability of PPG We believe that this novel product can be used as a new oil-displacing agent both to improve sweep efficiency and control the heterogeneous pro le. A simulated oil sample with viscosity of 16 mPa s and density of 942.7 kg mÀ3 at 85 C is prepared using degassed crude oil from Block Gudao in the Shengli Oil eld in China mixed with a certain proportion of kerosene
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