A Study On Effective Permeability Of Fractured Oil Reservoir

Fractured reservoirs are characterized by the combination of two rock types，namely，reservoir matrix，and fractures reservoir matrix．Rocks have larger oilstorage capacity than fractures，whereas the fractures have larger flow capacitythan the reservoir matrix．Bulk volume in the matrix rocks is much larger than inthe fractures， while the fracture permeability is much larger than the matrixpermeability．Thus，the oil production from fractured reservoirs depends on bothmatrix rocks and fractures． Most of the oil fluid volume is stored within thematrix rocks occupying most of the reservoir space．However，the amount of oilproduced depends on how much oil fluid is in the fractures and the rate at whichthe oil fluid can enter the fracture network．Hence，accurate estimation of theeffective permeability of fractured oil reservoir is one of the most important tasksin the prediction of the oil production rate from the fractures oil reservoir．Currently， numerical simulation studies of fractured reservoirs includediscrete fracture network model，dual media model and the equivalent continuummodel approach．Equivalent continuous model combines the authenticity of thefracture which is represented by discrete fracture network model and thecomplexity of the calculation which can be offered by the dual media model，thispaper will use the equivalent continuous model for the simulation of fracturedreservoirs．Based on the secondary development of the porous media flow softwarecalculation：Saints，which can simulate the effective permeability of the doubleporous media under periodic boundary conditions and different flow directions，one can compare the numerical solution with the analytical solution to verify thevalidity of the numerical methods．In this way，one could use Saints to calculatevarious flow which is not only for the case of horizontal flow，but also for the caseof oblique flow，and calculate the effective permeability of fractured reservoirs under different conditions． The main work and results of this paper can besummarized as follows：Firstly， this paper uses Kazemi model to investigate the dual directionaleffective permeability of porous media． Based on this model， the analyticalsolution of dual directional effective permeability of porous media is derived．Inthe actual calculation unit，by setting the volume fraction occupied by fracturesand matrix，and then setting the porosity and permeability of fracture and matrixrespectively，the horizontal effective permeability of Ke1and vertical orientationeffective permeability of Ke2can be calculated，and then set the value of α betweenthe fluid and the horizontal direction， one can get the value of the directionaleffective permeability of Keunder different values of α．Secondly， one uses the software Saints， dividing into different gridsaccording to different volume fraction of fracture and matrix， and giving thepartial porosity and partial permeability of the corresponding grid．After a seriesof simulation steps， one can get a set of values for the effective permeabilityvalues within the given value of α，and by varying the angle value of α for the nextsimulation，the directional effective permeability of Kecan be calculated underdifferent values of α．Finally， after obtaining the dates of numerical results and theoreticalcalculation results of each group of parameter conditions，one can compare thetheoretical and numerical solutions，then check if the two results coincide in theform of charts to reflect，and analyze the application scope of parameters．...