| Formation resistivity is one of the important parameters for reservoir interpretation evaluation.With the development of exploration technology,the fine oil field exploration has gradually become the major theme of exploration and anisotropic formation which contains holes and cracks fracture-glutenite has become the main direction of fine oil in the field of precise exploration.Based on the finite element software COMSOL,this paper studies the rock electrical characteristics of single and dual modal structural conglomerate formation in a constant current field and it is hoped that this study provides theoretical support for the evaluation and interpretation of conglomerate reservoir and lay the foundation for numerical simulation study of rock electrical properties of more complex electrical anisotropy formation.The main research contents and results in this thesis are listed as follows.The first part introduces the basic idea of finite element and the simulation process of COMSOL software.Conglomerate formation model based on numerical calculation software COMSOL is built.A study on the method of calculating the conglomerate formation resistivity in the constant current field is made and the flow track of the current in the formation model is analyzed.Besides,the study on physical meaning of Archie formula based on its physical prototype is made to deepen the understanding and lay the foundation for the research of rock electrical properties of conglomerate reservoir.The second part researches the rock electrical characteristics of single modal structural conglomerate formation.Single ellipsoid conglomerate formation model was established to study the influence of conglomerate angle and sphericity,conglomerate spatial location and the characteristics of pore throat on the conglomerate formation apparent resistivity and it can be seen that the changes of angle,sphericity and spatial location have an effect on the resistivity of a single direction and there is certain regularity,while the resistivity of different directions have different changing law.Then the pore-throat model is build based on the pore structure of single modal structural conglomerate formation to study the influence of the pore throat radius,pore throat matrix resistivity,conglomerate resistivity and pore extending direction to the conglomerate formation resistivity.Results show that fluid resistivity in the pore throat is themain factor to influence the formation resistivity and different fluid resistivity corresponding formation resistivity have different changing laws.The third part studies the rock electrical characteristics of dual modal structural conglomerate formation.The deposition method of dual modal conglomerate formation is analyzed and dual modal structural conglomerate formation model with different structures is built.The electrical properties of the dual mode conglomerate formation is studied from the microscopic structure to verify the consistency of the double modal conglomerate reservoir macroscopic rock electrical properties and microscopic rock electrical properties.Build capillary pore models about the double modal conglomerate equivalent pore formation and study the influence mechanism of complex pore to the rock electrical characteristics in the dual modal conglomerate reservoir.It can be concluded that pore minimum radius and current flow have great effects on formation resistivity.The fourth part studies the relationship between the dual modal pore with full water conglomerate formation resistivity and the parameters of Archie formula.Analysis of the relations among conglomerate formation resistivity,formation porosity and formation factor when the double modal conglomerate formation pore full of water.Build the dual modal conglomerate formation isotropy formation model and calculate lithology coefficient and the cementation index by means of numerical simulation.Build dual modal conglomerate formation anisotropy formation model,numerical simulate conglomerate formation resistivity tensor quantitative relationship with the formation of porosity.Results show that the formation factor is constant within a certain scope and its value is related to water resistivity.The fifth part studies the relationship between the dual modal pore with oil and water conglomerate formation resistivity and the parameters of Archie formula.Build the dual modal oil-wet and hydrophilic conglomerate formation model to study the relationship between oil saturation,resistivity increasing coefficient and formation resistivity when there is the pore with oil and water two phase,and lithology coefficient and the saturation index are calculated by means of numerical simulation.Then studies of the rock electrical characteristics of pore-throat with oil and water model is made to find that the matrix of oil-wet formation resistivity values is much greater than the matrix of hydrophilic formation resistivity. |
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