Layered Reservoirs with Internal Crossflow - A Well-connected Family of Well-test Pressure Transient Responses

Corbett, Patrick William Michael; Hamdi, Hamidreza; Gurav, Hemant

doi:10.3997/2214-4609.20149287

Cited by 3 publications

(8 citation statements)

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“…Figure 3 shows that the drawdown and build-up and the corresponding derivative responses of the base case model. The data shows a ramp effect phenomenon, which is a monotonic increase of (pseudo-) pressure derivative response over at least one log cycle (Corbett et al 2011). This is a characteristic response of a reservoir with laterally decreasing of the mobility that is usually observed in heterogeneous carbonate reservoirs (Corbett et al 2010) and/or high net:gross commingled reservoirs in which the pressure wave is encapsulated within the reservoir layers.…”

Section: Resultsmentioning

confidence: 97%

“…The longer the correlation length, the larger the facies patches in the resultant model. This leads to a more uniform spatial pressure distribution and a shorter ramp response (Corbett et al 2011). Figure 10 & 11 show the effect of the correlation length on the test response of the base commingled gas condensate reservoir model.…”

Section: Effect Of Correlation Lengthmentioning

confidence: 91%

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Modelling the Interfering Effects of Gas Condensate and Geological Heterogeneities on Transient Pressure Response

2011

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Numerous publications have investigated the effect of gas condensate fluid on the transient pressure well-test (WT) response. However, to the best of authors' knowledge, its combined effect with geology has not been studied. Our findings presented here demonstrate that geology can complicate the WT response and make it difficult for interpretation. In this study the impact of geological heterogeneities on the WT response of a commingled braided-fluvial gas/condensate reservoir has been investigated. Numerical well-test data were generated for a single-well model with a commercial compositional reservoir simulator. Several sensitivity simulations were performed to explore the effects of correlation length, vertical permeability, relative permeability, production rate and drawdown time, on the pseudo-pressure derivate curves. The WT weighting Kernel function and the calculated well-pressure sensitivity coefficients were implemented to demonstrate different trends of drawdown and build-up responses encountered in this study.The results clarified that some geological heterogeneities and production parameters can alter pressure distribution and condensate saturation, and mask the native model WT signatures. In this exercise, it was demonstrated that ramp effect, a geologically complex phenomenon in high net:gross commingled reservoirs, is affected by the condensate formation. This interfering phenomenon is reflected on the derivative curves and is magnified in the presence of the shorter correlation lengths, the lower vertical communications and the higher production rates. We also examined the stepwise stripping of the reservoir heterogeneity, in order to show the impact of each facies on the build-up and drawdown transient pressure response.. The time dependent sensitivity coefficients were calculated to show that the drawdown test is very sensitive to effective permeability in near wellbore areas, where condensate is prone to build up with time. In the build-up, on the other hand, the condensate saturation is almost invariant with time and affects the early time region. This work leads toward better understanding of the influence of geology in gas/condensate well-test interpretation. IntroductionGas condensate reservoirs are those with their temperature lying between the critical temperature and cricondentherm of the system. In such systems, retrograde condensation occurs when the pressure falls below the initial dew point pressure (Muskat 1949). This causes the liquid phase to build up near the producing well, which in turn can dramatically reduce the well productivity even in lean gas condensate reservoirs in which the liquid dropout is as low as 1% (Afidick et al. 1994). It is now well documented that in the near wellbore area, simultaneous flow of gas and condensate is also affected by the combined effect of coupling (increase in k r by an increase in velocity or decrease in IFT) and inertia (a decrease in k r by an increase in velocity) (Danesh et al. 1994, Henderson et al. 1996, Whitson et al. 1999and Jamiola...

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Section: Resultsmentioning

confidence: 97%

Section: Effect Of Correlation Lengthmentioning

confidence: 91%

Modelling the Interfering Effects of Gas Condensate and Geological Heterogeneities on Transient Pressure Response

2011

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“…A simulation showing the location of the most sensitive parts of the formation at a particular time to the pressure response measured at the well. This effectively illustrates complex pressure diffusion (rather than simple radial flow) in a fluvial reservoir [13]. Figure 8.…”

Section: Dynamic Well Testingmentioning

confidence: 96%

“…They are systems with highly variable (showing many orders of magnitude permeability variation for the same porosity) internal properties. The paths (comprising both horizontal and vertical components) of pressure disturbance away from the well will depend very much on the 3D arrangement of the sand bodies and the floodplain characteristics -the reservoir plumbing (Fig.7) [13]. In this respect, fluvial reservoirs are some of the more complex (clastic) reservoirs encountered.…”

Section: Dynamic Well Testingmentioning

confidence: 99%

“…Figure 9. Shows various connectivity arrangements in fluvial reservoirs (between channels and floodplain) and an equivalent schematic pressure deriviative responses to the scenarios [13]. With subtle changes in lateral and vertical connectivity the response changes from a geoskin response (top) to a geochoke response (middle) or to a ramp response (lower).…”

Section: In Heterogeneous Formationsmentioning

confidence: 99%

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The Role of Geoengineering in Field Development

Corbett¹

2012

New Technologies in the Oil and Gas Industry

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Application of Compositional Simulation in Seismic Modeling and Numerical Well Testing for Gas Condensate Reservoirs

Hamdi¹,

Amini²,

Corbett³

et al. 2011

73rd EAGE Conference and Exhibition Incorporating SPE EUROPEC 2011

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Recognition of condensate blockage is important in reservoir monitoring and management since the secondary operations such as gas cycling might need to be triggered to re-pressurize the reservoir. This study addresses the monitoring of a realistic gas condensate reservoir by time-lapse seismic data and transient well test analysis. A compositional reservoir modelling is employed to perform the numerical well test simulation. However, implementing a compositional fluid flow simulation highlights the limitations of the current petro-elastic model (PEM). Therefore we have developed an approach to consider the compositional changes of the fluid in the petro-elastic modelling. The equivalent black-oil model results are cross-validated against the compositional PEM as well. Our results show that the original widely used Batzle & Wang approach should be modified for a gas/condensate system. We show that the response strength of the well testing and the 4D seismic are complementary in each particular flow period (drawdown and build-up) which can be coupled to give useful information for reservoir monitoring purposes.

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Layered Reservoirs with Internal Crossflow - A Well-connected Family of Well-test Pressure Transient Responses

Cited by 3 publications

References 0 publications

Modelling the Interfering Effects of Gas Condensate and Geological Heterogeneities on Transient Pressure Response

Modelling the Interfering Effects of Gas Condensate and Geological Heterogeneities on Transient Pressure Response

The Role of Geoengineering in Field Development

Application of Compositional Simulation in Seismic Modeling and Numerical Well Testing for Gas Condensate Reservoirs

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