Reservoir Simulation And Application Of CO₂-EOR In The Low-permeability Reservoir

Naturally fractured reservoirs have been widely distributed around the world.It is of great importance to study the effects of geology and injection strategies on Enhanced Oil Recovery?EOR?in this type of reservoirs.A fluid flow dynamic model of the Tensleep Sandstone,based on a 3D geologic model,was built to conduct numerical reservoir simulation studies on the post-development programs in the Tensleep reservoir.Firstly,based on the existing screening criteria of gas injection reservoirs in the literature,fuzzy integrated evaluation was employed to develop a new screening criteria model for judgments of gas injections in the low-permeability Tensleep reservoir.Secondly,we used Winprop package in the commercial CMG software to match the saturation pressure of the reservoir fluids and flash vaporization,constant composition expansion,and the swelling test.Thirdly,history matching of field-wide primary production data was conducted based on the realistic reservoir dynamic model.Based on the gas-oil conversion ratios and oil recoveries,numerical studies on effects of geologic parameters and injection strategies on CO₂-EOR of the Tensleep reservoirs were performed.Orthogonal experimental design was conducted to analyze effects of injection rates,gas-water ratios,slug sizes,shut-in gas-oil ratios,and the cumulative water injection before implementing CO₂ flooding.