Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Equivalence between Brinkman, single and double continuum models in the description of single-phase flow in 2D vuggy porous media
Submission Author:
Marcio CARVALHO , RJ , Brazil
Co-Authors:
Daniel Vaz Campos, Marcos Vitor Barbosa Machado, Marcio CARVALHO
Presenter: Daniel Vaz Campos
doi://10.26678/ABCM.COBEM2023.COB2023-1252
Abstract
This article presents a comparative study between two porous media fluid flow description methods applied to heterogeneous reservoirs composed of architectural elements of high permoporosity, called fractures and karsts. Both are characteristic of Pre-Salt carbonate rocks, which are the main oil producing reservoirs in Brazil. The existence of these elements brings complexity in characterization and, hence, increases the uncertainty in field production prediction curves. The Reservoir Engineering numerical simulators that generate these curves model the flow behavior inside the cavities in an approximate manner due to the mathematical formulation applied. Besides, due to the kilometric scale in which they are usually applied, these models use cells that comprehend the three media (matrix, karst and fractures). This study evaluates the equivalence between black oil simulation and the Brinkman model, still not widely used, which is a physical model made of equations that represent porous media flow inside high porosity regions as well as at the porous matrix and its boundaries. With this objective, a two-dimensional single-phase Brinkman simulator was designed using the finite elements method to solve differential equations. The pressure propagation and flow velocity values obtained while simulating fluid flow inside selected layers from Lajedo Arapuá’s carbonate formation were compared to the ones obtained from a black oil simulator. Studies were performed using dual-continuum models seeking, through variation of the fracture effective permeability and the shape factor, convergence to the single-continuum reference model that was selected after Brinkman’s results comparative analysis. The results show small variation between the two methods when the karst system is composed of sparse and disconnected vugs, while conduit shaped karsts with complex configuration increase the variation in pressure wave propagation and flow velocity values between models, especially in scenarios where matrix permeability values were closer to karst permeability values in the black oil model. The dual-continuum analysis showed that it is possible to obtain, through homogeneous and even ten times coarser models, similar results to those obtained by a heterogeneous black oil model with karst system characterization. It was also possible to conclude that fracture effective permeability was sufficient as a fitting parameter in order to achieve equivalent results to those from the single-continuum model, using a threshold criteria.
Keywords
Vuggy porous media, Heterogeneous porous media, Brinkman equation
