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Study On Micro Pore Structure And Seepage Flow In Ultra-low Permeability Of Daqing Oilfield

Posted on:2011-03-10Degree:DoctorType:Dissertation
Country:ChinaCandidate:X W WangFull Text:PDF
GTID:1100360308961395Subject:Fluid Mechanics
Abstract/Summary:PDF Full Text Request
In this dissertation, combining with mercury, constant rate mercury injection, nuclear magnetic resonance and physics simulation, the micro pore structure character of ultra-low permeability reservoir. Then, from the microscopic point of view, the percolation flow law of the single phase and two phase fluids percolation are studied. The main research results are as followed:1. Throat distribution, pore-throat ratio and sorting coefficient are the main factors that control reservoir properties. The sorting coefficient increases with permeability, and the relationship between the average throat radius and permeability are linear in logarithmic coordinates. The relationship between movable fluid percentage, movable fluid porosity and permeability are linear in semi-logarithmic coordinates, and movable fluid percentage and movable fluid porosity are important parameter of reservoir evaluation.2. The stress sensitivity and water sensitivity are strong in ultra-low permeability reservoir. The influence factors by throat radius and clay are analyzed. The degree of stress sensitivity and water sensitivity are higher with the smaller radius of throat and the higher clay content, and the production capacity is analyzed considering stress sensitivity.3. The flow characteristics at low velocity were studied by the self-designed micro-flux measuring instrument. Considering the throat distribution and capillary model, the thickness of fluid boundary layer under different pressure gradient was calculated, the mechanism and influencing factors of nonlinear percolation were discussed. The study showed that the percolation curve of ultra-low rocks was nonlinear, and apparent permeability was not a constant, which increased with pressure gradient. The absorption boundary layer decreased with the increase of pressure gradient, and changed significantly especially in low pressure gradient, which was the essence of bringing nonlinear percolation.4. The character of oil/water relative permeability, nonlinear percolation character at irreducible water state and residual oil state of ultra-low permeability cores are analyzed. A new method of testing movable oil saturation was established, and the difference between movable fluid and movable oil was analyzed. The main influencing factors of the movable oil saturation including wettability, displacement pressure and water cut were studied.5. Considering the character of nonlinear percolation, the formulae of calculating vertical fracture well productivity for steady-state flow, production decline equation and water-drive characteristic equation are put forward. The influence factors by nonlinear percolation parameters and reservoir properties parameters are studied, and production law of typical blocks are analyzed.
Keywords/Search Tags:ultra-low permeability reservoir, pore structure, nonlinear percolation, movable oil saturation, displacement
PDF Full Text Request
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