A Comprehensive Application of a Composite Reservoir Model to Pressure Transient Analysis

Olarewaju, J.S.; Lee, W. J.

doi:10.2118/16345-ms

Cited by 16 publications

(12 citation statements)

References 9 publications

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“…1 The solutions are found to be consistent with the literature data. Hence, the composite reservoir model is applicable for the gas producing reservoir.…”

Section: Field Applicationssupporting

confidence: 83%

“…The potential applications have been discussed in several papers. 1 However, the composite reservoir model has not been applied before for those recovery processes because variation of viscosities has not considered before.This paper illustrates how the composite reservoir model has been developed for the above specific applications. The variation of fluid viscosities corresponds with the fluids distribution.…”

mentioning

confidence: 99%

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Development of Composite Reservoir Model for Heterogeneous Reservoir Studies

Yu¹,

Yang²

1990

SPE Eastern Regional Meeting

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Oil and gas production across a producing reservoir may vary in a complex manner that is unrelated to anyone physical property. Such variations relate to properties which together can be called reservoir heterogeneity. Some forms of heterogeneity can sometimes be resolved by classical' geologic and engineering methods, but often the variability is not resolvable because of incomplete data, poor reservoir pressure analysis, or simply because the reservoir heterogeneity is beyond resolution as dictated by well spacing or well distribution. Thus, a new composite reservoir well testing model is a necessary tool to obtain more pertinent data for future studies. This composite reservoir model has the variation of fluid viscosities in two different zones. Hence, the fluids distribution information can be obtained with the pressure testing analysis. The composite reservoir can model reservoirs with a fluid bank, reservoirs with a water flooding front, and reservoirs with steam or a miscible flooding front.When the reservoir heterogeneity of different formations can be more accurately defined, then fracture stimulation and well specing can be planned in a more manageable fashion. The production manager and engineer will be able to optimize production and infill drilling. The above objectives will definitely help West Virginia's current and future energy challenges.References and illustrations at end of paper. 55The variation of flow regions in the lateral direction is very common for the most of the reservoir conditions, e.g., permeability, the mobility ratio and transmissibility. These variations either occur near the wellbore condition or away from the borehole. However, the fluid distributions within the· .reservoir formation have the most interest to us because we want to find out the potential of production: The regional variations in transmissibility and mobility ratio reflect the fluid distribution, particularly the reservoir condition after the extended period of production· and shut-in. A study of the regional variation in reservoir parameters is known as the composite reservoir modeling. This model study has been applied for pressure transient analysis to determine permeability variations.Actually, the composite reservoir model has a wide application other than just permeability variations because the composite reservoir is being modeled by two concentric zones of different fluid distributions and transmissibilties separated by a discontinuity. The composite reservoir can model reservoirs with a fluid bank, reservoirs with a steam front, and reservoirs with a miscible flooding front and other recovery processes. The potential applications have been discussed in several papers. 1 However, the composite reservoir model has not been applied before for those recovery processes because variation of viscosities has not considered before.This paper illustrates how the composite reservoir model has been developed for the above specific applications. The variation of fluid viscosities corresponds with the fluids distribu...

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“…1 The solutions are found to be consistent with the literature data. Hence, the composite reservoir model is applicable for the gas producing reservoir.…”

Section: Field Applicationssupporting

confidence: 83%

mentioning

confidence: 99%

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Development of Composite Reservoir Model for Heterogeneous Reservoir Studies

Yu¹,

Yang²

1990

SPE Eastern Regional Meeting

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“…A pumping well may fully or partially penetrate the aquifer and may be subject to well skin effects. In well hydraulics a flowing fully penetrating well can be appropriately simulated as a Dirichlet (the first type) boundary of a prescribed potential, and the associated models can be solved with the conventional integral transform technique [e.g., Jacob and Lohman , 1952; van Everdingen and Hurst , 1949; Hantush , 1964; Clegg , 1967; Hurst et al , 1969; Ehlig‐Economides and Ramey , 1981; Olarewaju and Lee , 1989; Mishra and Guyonnet , 1992]. On the other hand, a flowing partially penetrating well must be considered as a mixed boundary that involves two different types of boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

An integral transform approach for a mixed boundary problem involving a flowing partially penetrating well with infinitesimal well skin

Chang

Chen

2002

Water Resources Research

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[1] A flowing partially penetrating well with infinitesimal well skin is a mixed boundary because a Cauchy condition is prescribed along the screen length and a Neumann condition of no flux is stipulated over the remaining unscreened part. An analytical approach based on the integral transform technique is developed to determine the Laplace domain solution for such a mixed boundary problem in a confined aquifer of finite thickness. First, the mixed boundary is changed into a homogeneous Neumann boundary by substituting the Cauchy condition with a Neumann condition in terms of well bore flux that varies along the screen length and is time dependent. Despite the well bore flux being unknown a priori, the modified model containing this homogeneous Neumann boundary can be solved with the Laplace and the finite Fourier cosine transforms. To determine well bore flux, screen length is discretized into a finite number of segments, to which the Cauchy condition is reinstated. This reinstatement also restores the relation between the original model and the solutions obtained. For a given time, the numerical inversion of the Laplace domain solution yields the drawdown distributions, well bore flux, and the well discharge. This analytical approach provides an alternative for dealing with the mixed boundary problems, especially when aquifer thickness is assumed to be finite.

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“…Also, Uraiet and Raghavan [1980] used V w ( t ) for the determination of the average reservoir pressure before the onset of possible boundary effects. Olarewaju and Lee [1989] mentioned that V w ( t ) could be useful for production forecast.…”

Section: Introductionmentioning

confidence: 99%

Use of cumulative volume of constant‐head injection test to estimate aquifer parameters with skin effects: Field experiment and data analysis

Chen

Chang

2002

Water Resources Research

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[1] In a silty sand aquifer, constant-head injection tests (CHITs) were performed for the determination of aquifer parameters. In a CHIT the test well is overflowed by the injection of surface water. The difference between the injection flow and the overflow measured by an automated system directly yields the cumulative volume V w (t) that enters the aquifer. Therefore the method of using V w (t) in determining the aquifer transmissivity and the storage coefficient is developed, where well skin effects are taken into account. The semilog plot of t/V w (t) is useful in indicating whether well skin exists around the constant-head pumping well. If well skin is absent, the semilog plot of t/V w (t) shows a straight line at large times, from which the transmissivity and the storage coefficient can be determined. If well skin exists, the semilog plot of t/V w (t) exhibits two straightline sections occurring at small and large times, respectively. Then only the transmissivity can be determined from the slope of the large-time straight line. In this event, aquifer drawdown/buildup observed at observation wells is needed for the determination of the storage coefficient. In fact, both the transmissivity and the storage coefficient can be determined with aquifer drawdown/buildup normalized with respect to V w (t), regardless of well skin around the constant-head pumping well. Once T and S are known, the skin factor of the constant-head pumping well can be obtained from t/V w (t).

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A Comprehensive Application of a Composite Reservoir Model to Pressure Transient Analysis

Cited by 16 publications

References 9 publications

Development of Composite Reservoir Model for Heterogeneous Reservoir Studies

Development of Composite Reservoir Model for Heterogeneous Reservoir Studies

An integral transform approach for a mixed boundary problem involving a flowing partially penetrating well with infinitesimal well skin

Use of cumulative volume of constant‐head injection test to estimate aquifer parameters with skin effects: Field experiment and data analysis

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