Study On The Variation Of CO₂ Diffusion And Rock Physical Properties In The Process Of CO₂ Flooding In H3 Block

At present,the research on the seepage of tight reservoirs is mainly focused on how to overcome the difficulties of tight lithology,low porosity,low permeability and low natural productivity.The tightness makes it difficult to develop the conventional water injection,and the recovery rate is very low,and the use of CO₂ oil displacement technology has greatly promoted the improvement of oil recovery and the realization of carbon dioxide storage.Therefore,it is of great significance to study the diffusion law of CO₂ and the change of rock physical characteristics to the corresponding reservoir protection and the guarantee of safety construction in the CO₂ flooding process.This paper mainly studies the basic physical properties and percolation properties of the core of H3 block in Changqing Oilfield by experiment.First,the pore structure of the H3 Block cores is classified.Secondly,the test was carried out on the acoustic parameter,electrical parameters and mechanical parameters of cores under different conditions.Then,the stress sensitivity characteristics of four types of cores with different lithology and different pore types are analyzed by testing.Finally,the diffusivity of CO₂ in a single liquid and saturated fluid porous medium under different temperatures and pressures was tested.Through the research,the testing shows the fitting relationship between core permeability properties and acoustic parameters,mechanical parameters and the rule that electrical parameters change with the saturation.The stress sensitivity of the four types of core has been demonstrated and it shows the relationship between the evaluation parameters and the initial permeability.The magnitude of the diffusion coefficient is obtained,and the variation of diffusion coefficient with temperature and pressure under different medium conditions is obtained.