Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Yu, Haisheng
Summary For an empty fracture, the fracture permeability (kf) is mainly influenced by the effect of viscous shear from fracture walls and can be analytically estimated if the fracture width (wf) is known a priori (i.e., , where β2 is the unit‐conversion factor). For an adequately propped fracture, the fracture permeability is mainly influenced by the proppant‐pack properties and can be approximated with the proppant‐pack permeability (, where kp is proppant‐pack permeability). It can be readily inferred that as the effect of viscous shear fades (or the proppant‐pack effect becomes pronounced), there should be a regime within which both the viscous shear and the proppant‐pack properties exert significant influences on the fracture permeability. However, the functional relationship between fracture permeability, viscous shear (or fracture width), and proppant‐pack properties is still elusive. In this work, we propose a new fracture‐permeability model to account for the influences of the proppant‐pack permeability, proppant‐pack porosity (ϕp), and fracture width on the fracture permeability. This new fracture‐permeability model is derived from a modified Brinkman equation. The results calculated with the fracture‐permeability model show that with different values of the Darcy parameter, the fluid flow can be divided into viscous‐shear‐dominated (VSD) regime, transition regime, and Darcy‐flow‐dominated (DFD) regime. If the Darcy parameter is sufficiently large, the effect of proppant‐pack permeability on fracture permeability can be neglected and the fracture permeability can be calculated with the VSD fracture‐permeability (FP) (VSD‐FP) equation (i.e., ). If the Darcy parameter is sufficiently small, the effect of viscous shear on fracture permeability can be neglected and the fracture permeability can be calculated with the DFD‐FP equation (i.e., ). Both the VSD‐FP and DFD‐FP equations are special forms of the proposed fracture‐permeability model. For the existing empirical/analytical fracture‐conductivity models that neglect the effect of viscous shear, one can multiply these models by the coefficient of viscous shear to make these models capable of estimating the fracture conductivity with large values of Darcy parameter.
- North America > United States > Texas (0.28)
- North America > United States > California (0.28)
- Research Report > New Finding (0.46)
- Research Report > Experimental Study (0.46)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.46)
Summary Cold heavy-oil production with sand (CHOPS) is a nonthermal primary process that is widely adopted in many weakly consolidated heavy-oil deposits around the world. However, only 5 to 15% of the initial oil in place is typically recovered. Several solvent‐assisted schemes are proposed as follow‐up strategies to increase the recovery factor in post‐CHOPS operations. The development of complex, heterogeneous, high‐permeability channels or wormholes during CHOPS renders the analysis and scalability of these processes challenging. One of the key issues is how to properly estimate the dynamic growth of wormholes during CHOPS. Existing growth models generally offer a simplified representation of the wormhole network, which, in many cases, is denoted as an extended wellbore. Despite it being commonly acknowledged that wormhole growth due to sand‐arch failure is likely to follow fractal statistics, there are no established workflows to incorporate sand‐arch stability constraints into the construction of these fractal wormhole patterns. A novel dynamic wormhole growth model is developed to generate a set of realistic fractal wormhole networks during the CHOPS operations. It offers an improvement to the diffusion limited aggregation (DLA) algorithm with a sand‐arch stability criterion. The outcome is a fractal pattern that mimics a realistic wormhole growth path, with sand‐arch failure and fluidization being controlled by sand‐arch stability constraints. The fractal pattern is updated dynamically by coupling compositional flow simulation on a locally refined grid and a stability criterion for the sand arch: the wormhole would continue expanding following the fractal pattern, provided that the pressure gradient at the tip exceeds the limit corresponding to a sand‐arch stability criterion. Important transport mechanisms including foamy oil (nonequilibrium exsolution of gas) and sand‐arch failure are integrated. Public field data for several CHOPS fields in Canada are used to examine the results of the dynamic wormhole growth model and flow simulations. For example, the sand production history is used to estimate a practical range for the critical pressure gradient representative of the sand‐arch stability criterion. The oil and sand production histories show good agreement with the modeling results. In many CHOPS or post‐CHOPS modeling studies, constant wormhole intensity is commonly assigned uniformly throughout the entire domain; as a result, the ensuing models are unlikely to capture the complex heterogeneous distribution of wormholes encountered in realistic reservoir settings. This work, however, proposes a novel model to integrate a set of statistical fractal patterns. The entire workflow has been readily integrated with commercial reservoir simulators, enabling it to be incorporated in practical field‐scale operations design.
- North America > United States (1.00)
- North America > Canada > Alberta (0.69)
- North America > United States > Texas > Permian Basin > Central Basin > 3000 Formation (0.99)
- North America > United States > Louisiana > Frog Lake Field (0.99)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Lloydminster Field (0.97)
Abstract Cold heavy oil production with sand (CHOPS) is a non-thermal primary process that is widely adopted in many weakly consolidated heavy oil deposits around the world. However, only 5 to 15% of the initial oil in place is typically recovered. Several solvent-assisted schemes are proposed as follow-up strategies to increase the recovery factor in post-CHOPS operations. The development of complex, heterogeneous, high-permeability channels or wormholes during CHOPS renders the analysis and scalability of these processes challenging. One of the key issues is how to properly estimate the dynamic growth of wormholes during CHOPS. Existing growth models generally offer a simplified representation of the wormhole network, which, in many cases, is denoted as an extended wellbore. Despite it is commonly acknowledged that wormhole growth due to sand failure is likely to follow fractal statistics, there are no established workflows to incorporate geomechanical constraints into the construction of these fractal wormhole patterns. A novel dynamic wormhole growth model is developed to generate a set of realistic fractal wormhole networks during the CHOPS operations. It offers an improvement to the Diffusion Limited Aggregation (DLA) algorithm with a sand-arch-stability criterion. The outcome is a fractal pattern that mimics a realistic wormhole growth path, with sand failure and fluidization being controlled by geomechanical constraints. The fractal pattern is updated dynamically by coupling compositional flow simulation on a locally-refined grid and a stability criterion for the sand arch: the wormhole would continue expanding following the fractal pattern, provided that the pressure gradient at the tip exceeds the limit corresponding to a sand-arch-stability criterion. Important transport mechanisms including foamy oil (non-equilibrium dissolution of gas) and sand failure are integrated. Public field data for several CHOPS fields in Canada is used to examine the results of the dynamic wormhole growth model and flow simulations. For example, sand production history is used to estimate a practical range for the critical pressure gradient representative of the sand-arch-stability criterion. The oil and sand production histories show good agreement with the modeling results. In many CHOPS or post-CHOPS modeling studies, constant wormhole intensity is commonly assigned uniformly throughout the entire domain; as a result, the ensuing models are unlikely to capture the complex heterogeneous distribution of wormholes encountered in realistic reservoir settings. This work, however, proposes a novel model to integrate a set of statistical fractal patterns with realistic geomechanical constraints. The entire workflow has been readily integrated with commercial reservoir simulators, enabling it to be incorporated in practical field-scale operations design.
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Cold Lake Field > Clearwater Formation > 995053 2D Cold Lake 2-10-63-2 Well (0.99)
- North America > United States > Louisiana > Frog Lake Field (0.98)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Lloydminster Field (0.97)