New Solutions for Well-Test-Analysis Problems: Part 1—Analytical Considerations

Özkan, Erdal; Raghavan, R.

doi:10.2118/18615-pa

Cited by 340 publications

(103 citation statements)

References 6 publications

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“…In addition to acting as an effective way to verify the accuracy of the analytical solution, the numerical solution in this study has some advantages over the analytical solution in computing speed. However, the analytical solution also has its unique advantages in some respects: for example, wellbore storage and skin effect can be easily added to the analytical solution in Laplace domain [33][34][35], which may be extremely difficult for the numerical solution.…”

Section: Model Verificationmentioning

confidence: 99%

Analysis of Flow Behavior for Acid Fracturing Wells in Fractured-Vuggy Carbonate Reservoirs

Wang

Fan

Dong

et al. 2018

Mathematical Problems in Engineering

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This study develops a mathematical model for transient flow analysis of acid fracturing wells in fractured-vuggy carbonate reservoirs. This model considers a composite system with the inner region containing finite number of artificial fractures and wormholes and the outer region showing a triple-porosity medium. Both analytical and numerical solutions are derived in this work, and the comparison between two solutions verifies the model accurately. Flow behavior is analyzed thoroughly by examining the standard log-log type curves. Flow in this composite system can be divided into six or eight main flow regimes comprehensively. Three or two characteristic V-shaped segments can be observed on pressure derivative curves. Each V-shaped segment corresponds to a specific flow regime. One or two of the V-shaped segments may be absent in particular cases. Effects of interregional diffusivity ratio and interregional conductivity ratio on transient responses are strong in the early-flow period. The shape and position of type curves are also influenced by interporosity coefficients, storativity ratios, and reservoir radius significantly. Finally, we show the differences between our model and the similar model with single fracture or without acid fracturing and further investigate the pseudo-skin factor caused by acid fracturing.

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Section: Model Verificationmentioning

confidence: 99%

Analysis of Flow Behavior for Acid Fracturing Wells in Fractured-Vuggy Carbonate Reservoirs

Wang

Fan

Dong

et al. 2018

Mathematical Problems in Engineering

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“…Furthermore, the production solution in Laplace space for modeling a finite conductive fractured well with constant pressure production, can be obtained by [33][34][35]: (16) where q D is the dimensionless rate in Laplace space.…”

Section: Production Decline Type Curves Theorymentioning

confidence: 99%

Production decline type curves analysis of a finite conductivity fractured well in coalbed methane reservoirs

Wei

Wen²,

Duan

et al. 2017

Open Physics

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Production decline type curves analysis is one of the robust methods used to analyze transport flow behaviors and to evaluate reservoir properties, original gas in place, etc. Although advanced production decline analysis methods for several well types in conventional reservoirs are widely used, there are few models of production decline type curves for a fractured well in coalbed methane (CBM) reservoirs. In this work, a novel pseudo state diffusion and convection model is firstly developed to describe CBM transport in matrix systems. Subsequently, based on the Langmuir adsorption isotherm, pseudo state diffusion and convection in matrix systems and Darcy flow in cleat systems, the production model of a CBM well with a finite conductivity fracture is derived and solved by Laplace transform. Advanced production decline type curves of a fractured well in CBM reservoirs are plotted through the Stehfest numerical inversion algorithm and computer programming. Six flow regimes, including linear flow regime, early radial flow in cleat systems, interporosity flow regime, late pseudo radial flow regime, transient regime and boundary dominated flow regime, are recognized. Finally, the effect of relevant parameters, including the storage coefficient of gas in cleat systems, the transfer coefficient from a matrix system to the cleat system, the modified coefficient of permeability, dimensionless fracture conductivity and dimensionless reservoir drainage radius, are analyzed on type curves. This paper does not only enrich the production decline type

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“…In this context, we can compare to analytical solutions computed using Ozkan and Raghavan methodology [8].…”

Section: Numerical Examplesmentioning

confidence: 99%

Transmissibility Corrections and Grid Control for Shale Gas Numerical Production Forecasts

Artus¹,

Fructus²

2012

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Résumé -Corrections de transmissivités et contrôle des maillages pour les simulations numériques de production en faible perméabilité -En contexte de roche mère, la perméabilité effective du milieu est si basse que la nature de l'écoulement demeure principalement transitoire, même après des mois ou des années de production. A l'aide d'un simulateur numérique (maillage non-structuré, volumes finis) nous montrons que la non-linéarité du champ de pression au voisinage des puits horizontaux multi fracturés doit être prise en compte lors des prévisions de production. Un premier exemple, basé sur un PVT (Pressure Volume Temperature) linéaire, montre que les transmissivités classiques (linéaires) conduisent à surestimer la production de l'ordre de 5 % par rapport à la réponse analytique. Nous proposons une nouvelle approche de calcul des transmissivités, basée sur des intégrations numériques successives des distributions de points sources. Les résultats prennent en compte la non-linéarité du champ de pression et les interférences entre fractures. La précision des prévisions de production est alors nettement améliorée. Avec un PVT de gaz réel, les effets non-linéaires deviennent encore plus critiques à proximité des puits. Alors que les solutions analytiques sont insuffisantes dans ce cas, les simulations numériques sont plus précises, à condition toutefois que les maillages utilisés soient suffisamment fins. Afin de réduire les temps de calcul, les simulations de production à long terme sont en général effectuées sur des grilles grossières dont les transmissivités sont corrigées par des méthodes éprouvées de mise à l'échelle. Nous montrons néanmoins que la taille du maillage doit être soigneusement adaptée lorsque la perméabilité est faible. Une méthode d'ajustement automatique de la grille est testée qui prend en compte la perméabilité et la résolution temporelle du problème.

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New Solutions for Well-Test-Analysis Problems: Part 1—Analytical Considerations

Cited by 340 publications

References 6 publications

Analysis of Flow Behavior for Acid Fracturing Wells in Fractured-Vuggy Carbonate Reservoirs

Analysis of Flow Behavior for Acid Fracturing Wells in Fractured-Vuggy Carbonate Reservoirs

Production decline type curves analysis of a finite conductivity fractured well in coalbed methane reservoirs

Transmissibility Corrections and Grid Control for Shale Gas Numerical Production Forecasts

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