Enhanced oil recovery by branched-preformed particle gel injection in parallel-sandpack models

• Branched-preformed particle gel (B-PPG) was used for oil recovery in heterogeneous models.
• Mechanisms of enhanced oil recovery by B-PPG were studied in parallel sandpack models.
• B-PPG is capable of elastic deformation and adjusting flows in heterogeneous media.
• B-PPG injection can effectively improve sweep efficiency and residual oil recovery.

Branched-preformed particle gel (B-PPG) is a newly developed chemical agent for enhanced oil recovery in heterogeneous reservoirs. In this paper, laboratory experiments are performed to characterize the morphology and rheological properties of a B-PPG suspension in water, investigate its transport behavior through heterogeneous porous media, and study its performance in enhanced oil recovery in heterogeneous reservoirs. In the flow and displacement experiments, parallel-sandpack models are used to represent the heterogeneous porous media. The experimental results show that the viscoelasticity of the B-PPG suspension makes it a promising agent for both conformance control and enhanced oil recovery in heterogeneous reservoirs. Both B-PPG flow and tertiary oil recovery tests in parallel-sandpack models demonstrate that injection of a B-PPG slug can effectively improve the sweep efficiency and recover more residual oil in the low permeability zones. For a more heterogenous model, the effect of B-PPG on the sweep efficiency becomes more noticeable. This is because the viscoelastic B-PPG particles not only increase the viscosity of the water phase, but also divert the flow to the unswept low permeability zones.

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