The Study Of Low Permeability Reservoir Grading Evaluation

In this paper,combining with constant rate mercury injection,X-ray diffraction,nuclear magnetic resonance(NMR),physics simulation and filtration theory,the micro pore structure character,movable fluids,seepage character and reservoir sensitivity of ultra-low permeability reservoir in different oilfields were studied,and the comparison figure of different characterization parameters was completed.Comprehensive evaluation method of low permeability reservoir was established,and the classification evaluation technique was formed.The main research results are as followed:1.The characteristics of micro pore structure and movable fluid of ultra-low permeability reservoir by using constant rate mercury injection and NMR,and the core samples with different permeability come from different oilfields.Based on micro pore structure and movable fluid,the lower permeability limits of water flooding development were studied of different oilfields.2.Nonlinear seepage mechanism and seepage low were revealed through micro-tube experiments and the nonlinear seepage core experiments.The experiment flow of nonlinear seepage in ultra-low permeability reservoir was improved.and a new nonlinear seepage equation and seepage state equation of ultra-low permeability reservoir were put forward.Based on experiments and theory,the nonlinear seepage law of different permeability cores from different oilfields was studied;3.The whole core mineral composition and clay composition of low permeability reservoir in four oilfields were analyzed by using X-ray diffraction and physics simulation experiments.And the characteristic of reservoir sensitivity has been contrasted.4.Based on the study of the characteristics of reservoirs,the influence of development effect by different characterization parameters was analyzed,“five parameters method" of comprehensive evaluation in low permeability was put forward,and the classification evaluation technique was formed.