Integrated Numerical Simulation for a Giant, Asphaltene Riched, Carbonate Reservoir

Abstract Fah reservoir in Y oilfield is a giant, pore-typed, carbonate reservoir, which have high heterogeneity and asphaltene deposition during production process. In order to describe the heterogeneity of Fah reservoir, fomulas of pore throat radius, porosity and permeability under different mercury injection saturation was fitted. It shows 30% is the best percentile, and R30 method was presented for rock typing. Six rock types were divided according to pore throat radius, the porosity-permeability relationship was established for each rock type. The rock types of the non-cored wells are predicted by KNN (K nearest Neighbor) method. After the rock types of all wells have been obtained, 3D rock type model was built by sequential indicator simulation, and the 3D porosity could be established on the basis of the rock type model, logging interpretation and sesmic data. 3D permeability model was calculated according the relationship between porosity and permeability. Comparing core permeability and calculated permeability obtained by the rock types, it shown very good coincidency. During the oilfield development process of Fah reservoir, the asphaltene deposition is very serious, which cause the production decline. Therefore, it is quite necessary to carry out the asphaltene deposition study. Based on the experiment research, the phase behavior of the asphaltene was studied, and the asphaltene precipitation envelope diagram was drawn on the basis of the gas-liquid-solid three-phase equilibrium theory. A fine numerical simulation model to simulate asphaltene precipitation, flocculation, deposition and damage processes was established, the impact of asphaltene on recovery was studied and the recovery of 10 years was declined by 2.3% in considering asphaltenes. By controlling the bottomhole pressure, the asphaltene precipitation in the formation could be prevented. In order to study the asphaltene depostion in the wellbore and the surface pipeline, a reservoir, wellbore and surface pipeline integrated model was built by coupling the Eclipse and IPM software together, and the pressure and temperature from reservoir to separator can be predicted, then compared with precipitation envelope diagram, the location of asphaltene precipitation could be determined accurately.