Comprehensive Coupled Modeling Analysis of Stimulations and Post-Frac Productivity—Case Study of a Tight Gas Field in Wyoming

Settari, A.; Sullivan, R.B.; Rother, Robert J.; Skinner, Terry Kim

doi:10.2118/119394-ms

Cited by 14 publications

(1 citation statement)

References 11 publications

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“…A hydraulic fracture of infinite conductivity represented by the source and sink term has been investigated by Nghiem (1983). More sophisticated methods include coupled geomechanical modeling which computes reservoir deformation due to changes of the effective stress (Settari et al 1990(Settari et al , 1998(Settari et al , 1999(Settari et al , 2001(Settari et al , 2002(Settari et al , 2005(Settari et al and 2009. Mechanical simulation tools coupled with a reservoir simulator perform iterations between the stress-strain and fracture transmissibility.…”

Section: ) Numerical Well Testing and Hydraulic Fracturing Modelingmentioning

confidence: 99%

An Integrated Workflow for Reservoir Modeling and Flow Simulation of the Nikanassin Tight Gas Reservoir in the Western Canada Sedimentary Basin

Deng

Aguilera

Settari

2011

SPE Annual Technical Conference and Exhibition

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This paper presents an innovative workflow for characterization and reservoir simulation of the tight gas Nikanassin Group in the Western Canada Sedimentary Basin. Petrographic studies of the Nikanassin Group show the presence of (1) intergranular, (2) microfracture + slot, and (3) isolated (non effective) porosities. These porosities are handled with a mathematical triple porosity model for improved petrophysical analysis of the Nikanassin Group. Determination of pore throat apertures (r p35 ) facilitates facies mapping for reservoir simulation purposes. Numerical well testing of hydraulically fractured wells provides a way of tuning the static model with dynamic well testing information. In the case of open uncemented fractures and slots, numerical well testing indicates that the reduction of in-situ permeability can be more than two orders of magnitude. On the other hand in the case of partially cemented fractures and slots the reduction in permeability might be negligible. The approach permits an efficient representation of hydraulic fractures using transmissibility multipliers for the full field simulation of commingled tight reservoirs with multi-wells and multi-stage fractures.The result is a sound full field simulation model that permits a reasonable match of production and pressure histories, and forecasting of gas recovery under different well-spacing and depletion scenarios. As most Nikanassin tight gas wells are completed commingled, this research develops a procedure for production allocation of individual contributing formations.The study shows that there is a very large gas potential in the Nikanassin Group, particularly in the Lower Monteith Formation that can be exploited by reducing significantly the well spacing. The finding is significant as the tight gas Nikanassin Group extends for more than 15,000 km2 within Alberta and British Columbia, which suggests the potential for drilling thousands of wells in the region.

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Section: ) Numerical Well Testing and Hydraulic Fracturing Modelingmentioning

confidence: 99%

An Integrated Workflow for Reservoir Modeling and Flow Simulation of the Nikanassin Tight Gas Reservoir in the Western Canada Sedimentary Basin

Deng

Aguilera

Settari

2011

SPE Annual Technical Conference and Exhibition

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Reservoir stress path characterization and its implications for fluid-flow production simulations

Segura

Fisher

Crook

et al. 2011

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The reduction of fluid pressure during reservoir production promotes changes in the effective and total stress distribution within the reservoir and the surrounding strata. This stress evolution is responsible for many problems encountered during production (e.g. fault reactivation, casing deformation). This work presents the results of an extensive series of 3D numerical hydro-mechanical coupled analyses that study the influence of reservoir geometry and material properties on the reservoir stress path. The stress path is defined in terms of parameters that quantify the amount of stress arching and stress anisotropy that occur during reservoir production. The coupled simulations are run using an explicit coupling code between Elfen (Rockfield Software Ltd) and Tempest (Roxar). It is shown that the stress arching effect is important in small or thin reservoirs that are soft compared to the bounding material. In such cases, the stresses will not significantly evolve in the reservoir, and stress evolution occurs in the over and side-burden. Stiff reservoirs do not show stress arching regardless of the geometry. Stress anisotropy reduces with the bounding material Young's modulus, especially for small reservoirs, but as the reservoir extends in one or the two horizontal directions, the reservoir deforms uniaxially and the horizontal stress evolution is governed by the reservoir Poisson's ratio. Furthermore, the effect of the stress path parameters is introduced in the calculation of pore volume multiplier tables to improve non-coupled simulations, which otherwise overestimate the average reservoir pore pressure drawdown when stress arching is taking place.

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Numerical Study of PDL-Induced Fracture-Face Damage Using a Fracturing Mimicator

Gdanski

2010

SPE Asia Pacific Oil and Gas Conference and Exhibition

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Simulations with a fit-for-purpose fracture-cleanup model have previously explored the impact of matrix relative-permeability quality on cleanup and productivity in tight-gas sands. Gas-water relative-permeability curves that have a crossover in the range of 0.1% of rel-perm have a region of "rel-perm jail." Previous simulations demonstrated that water invasion in such situations can cause cleanup problems. However, a low rel-perm quality should also act as a fluid-loss-control mechanism during fracturing, thereby preventing deep invasion in the first place. The fracture-cleanup model was upgraded to mimic fracturing treatments to explore the impact of rel-perm quality on fluid efficiency, fluid invasion, and cleanup. The model explored certain aspects of pressure-dependant leakoff (PDL) that might bypass rel-perm jail restrictions. The causes and prevention of poor-performing fracturing treatments in tight-gas sands have plagued the industry, with many mechanisms suggested and various solutions attempted as cures. Verifying the mechanisms and solutions often requires a trial- and-error approach because of the physical and chemical complexities involved. This model has a unique capability of exploring physics of flow and chemical physics of overall complexity that cannot be effectively studied in the laboratory. The upgraded model was used to study a new mechanism by which PDL might induce fracture-face damage. Fracturing and PDL were successfully modeled using the method of pressure-dependant porosity and permeability for the fracture and matrix. Details of the method are presented. Simulations show that in the absence of PDL, poor quality rel-perms provide effective fluid-loss control and should prevent deep-matrix invasion. Under certain circumstances, PDL can bypass the fluid-loss-control mechanism causing rel-perm-induced matrix damage once the fracture has closed. Fortunately, there is currently no strong evidence that this damage mechanism is common.

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Comprehensive Coupled Modeling Analysis of Stimulations and Post-Frac Productivity—Case Study of a Tight Gas Field in Wyoming

Cited by 14 publications

References 11 publications

An Integrated Workflow for Reservoir Modeling and Flow Simulation of the Nikanassin Tight Gas Reservoir in the Western Canada Sedimentary Basin

An Integrated Workflow for Reservoir Modeling and Flow Simulation of the Nikanassin Tight Gas Reservoir in the Western Canada Sedimentary Basin

Reservoir stress path characterization and its implications for fluid-flow production simulations

Numerical Study of PDL-Induced Fracture-Face Damage Using a Fracturing Mimicator

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