Jingan Oilfield Of Extra Low Permeability Reservoir In Six Different Medium Injection Oil Displacement Effect Evaluation Research

Easing the reservoir heterogeneity, increasing oil displacement efficiency and expanding swept volume are the main ways of EOR. Studise on seepage law of multiphase fluid, microscopic remaining oil and displacement mechanism of different agent have been carried out widely. But there is no systematic comparison on oil recovery improvement of different flooding agent to reservoir with ultra-low permeability and strong heterogeneity.This article takes Wuliwan Oil Field Chang6reservoir as research object and carries on experiment of water flooding, surfactant flooding, air flooding and air-foam flooding in real sandstone microscopic combination model. Experiment studies the oil displacement efficiency of different injection agent, the status and quantity of remaining oil, and evaluates the effect of each injection agent improving oil recovery.Through research, made the following findings:1. There are three seepage shape of the injected water within the model, uniform, reticular and finger-like. Finger-like seepage lead to large amount of clusters of residual oil and low displacement efficiency.2. Surfactant flooding, air-foam flooding and air flooding after water flooding can significantly improve the oil displacement efficiency and expand the swept volume.3. Final oil recovery increased by the rising of injection pressure and amount of agent.4. In weak heterogeneity reservoir, it’s better to change injection agent when residual oil than after water breakthrough.5. In strong heterogeneity reservoir, air flooding can not been impacted on the timing of changing flooding agent. For surfactant flooding and foam flooding, it better to change injection agent more later.6. When the reservoir permeability variation coefficient greater than1.2, the permeability mutation coefficient greater than3, and permeability contrast greater than70, the model sweep efficiency is low. It’s need to reduce the parallel reservoir heterogeneity to enhance oil recovery.The conclusions of this article provides reference for screening flooding agent and choosing injection time. It’s very important for EOR and prolong high and stable yield stage.