A Triple-Continuum Numerical Model For Simulating ...

Object Details

View

XVI International Conference on Computational Methods in Water Resources (CMWR-XVI) Ingeniørhuset

A Triple-Continuum Numerical Model For Simulating Multiphase Flow in Vuggy Fractured Reservoirs
Paper
Author:Zhijiang Kang <kangzj@pepris.com> (Research Inst. of Petroleum Exploration and Development, SINOPEC, Beijing, China)
Yu-Shu Wu <yswu@lbl.gov> (Lawrence Berkeley National laboratory)
Jianglong Li <kangzj@pepris.com> (Research Inst. of Petroleum Exploration and Development, SINOPEC, Beijing, China)
Yongchao Wu <wuyc0314@pepris.com> (Research Inst. of Petroleum Exploration and Development, SINOPEC, Beijing, China)
Jie Zhang <kangzj@pepris.com> (Research Inst. of Petroleum Exploration and Development, SINOPEC, Beijing, China)
Guangfu Wang <kangzj@pepris.com> (Research Inst. of Petroleum Exploration and Development, SINOPEC, Beijing, China)
Presenter:Zhijiang Kang <kangzj@pepris.com> (Research Inst. of Petroleum Exploration and Development, SINOPEC, Beijing, China)
Yu-Shu Wu <yswu@lbl.gov> (Lawrence Berkeley National laboratory)
Date: 2006-06-18     Track: General Sessions     Session: General
DOI:10.4122/1.1000000746
DOI:10.4122/1.1000000747

The existence of vugs (empty holes or cavities) in naturally fractured reservoirs has long been observed and can be contributed significantly to reserves of underground natural resources, such as oil, natural gas, and groundwater. A new multi-continuum conceptual model has been developed for investigating multiphase flow behavior through vuggy fractured reservoirs. The conceptual model, based on geological data and observations of core examples from carbonate formations in China, has been implemented into a three-dimensional, three-phase reservoir simulator using a generalized multi-continuum modeling approach. In this conceptual model, vuggy fractured rock is considered as a triple-continuum medium, consisting of (1) highly permeable fractures, (2) low-permeability rock matrix, and (3) various-sized vugs. The matrix system may contain a large number of small or isolated cavities (of centimeters or millimeters in diameter), while vugs are larger cavities with sizes from centimeters to meters in diameter, which are indirectly connected to fractures through small fractures or microfractures. Similar to the conventional double-porosity concept, the fracture continuum is responsible for the occurrence of global flow, while vuggy and matrix continua, providing large-storage space, are locally connected to each other as well as directly interacting with globally connecting fractures. Note that vugs directly connected with fractures are considered as part of the fracture continuum. In the numerical implementation, a control-volume, integral finite difference method is used for spatial discretization, and a first-order finite difference scheme is adapted for temporal discretization of governing mass-balance equations for the three-phase fluids in each continuum. The resulting discrete nonlinear equations are solved fully implicitly by Newton iteration. The numerical scheme has been verified by comparing its results against those of analytical methods for the case of single-phase flow. In addition, to demonstrate the model’s application, the new conceptual model and the associated numerical modeling approach are used to obtain some insight into the behavior of flow through vuggy fractured reservoirs.