GEOLOGICAL MODEL EVALUATION THROUGH WELL TEST SIMULATION: A CASE STUDY FROM THE <i>WYTCH FARM</i> OILFIELD, SOUTHERN ENGLAND

Zheng, Shi-Yi; Legrand, Virginie; Corbett, Patrick William Michael

doi:10.1111/j.1747-5457.2007.00041.x

Cited by 12 publications

(4 citation statements)

References 11 publications

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“…The Wytch Farm field is approximately 18 km long and 3 km wide (Zheng et al, 2007), it is characterised by faulted and folded structures that resulted from rifting and extensional thrust faulting that affected the whole Wessex Basin in the early Cretaceous (Bowman et al, 1993). The field comprises of east-west trending gently dipping anticline divided by series of northerly dipping faulted blocks generated during early Cretaceous extensional thrust faulting in the entire Wessex Basin (Zheng et al, 2007;Hogg et al, 1999;McKie et al, 1998).…”

Section: Geology Of the Study Areamentioning

confidence: 99%

Data workflow for generating static geological model platform for petroleum prospect re-evaluation of Wytch Farm field, Wessex Basin, South Coast, United Kingdom

Osinowo

2020

Contrib. Geophys. Geod.

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The analyses and interpretation of the old existing 3D seismic and well log data of Wytch Farm field, Wessex Basin, south coast of the United Kingdom provided relevant information employed to generate static geological model platform. The platform which is requisite for building and distributing petrophysical and production data across the field could be useful for simulating the field's performance, history matching as well as generate future prediction/forecast needful to establish the reasons for the early water breakthrough and sudden production decline from a peak value of 115,000 bbl/day in 1997 to the present production rate of less than 19,000 bbl/day. Six major faults which extend throughout the entire length of the field and five horizon surfaces which correspond to the top of Greensand, Combrash, Mercia mudstone and the top and base of Sherwood Formations aided the generation of the static geological model platform across the Wytch Farm field. The volume of delineated saturated reservoir rock lying above the Oil Water Contact (OWC) and enclosed within fault assisted anticlinal structures indicate a Gross Rock Volume (GRV) of 2,007,000,000 m3 and thus suggest that Wytch Farm field may likely still hold hydrocarbon potential beyond the present daily production rate. This potential could be unlocked through adequate reservoir management that requires detailed information such as could be generated from static geological model of the field.

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Section: Geology Of the Study Areamentioning

confidence: 99%

Data workflow for generating static geological model platform for petroleum prospect re-evaluation of Wytch Farm field, Wessex Basin, South Coast, United Kingdom

Osinowo

2020

Contrib. Geophys. Geod.

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“…k v =0) multi-facies, high net:gross, braided fluvial reservoir (Zheng et al 2007) was selected in order to perform the well-test simulations. The model composed of 86*48*25 cells, each having dimensions of 25m*25m*1.9m in x, y and z directions, respectively.…”

Section: Geological Modelsmentioning

confidence: 99%

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

Hamdi

Jamiolahmady

Corbett

2011

SPE EUROPEC/EAGE Annual Conference and Exhibition

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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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“…A realistic pixel-based model of a commingled (i.e., k v ¼ 0) multifacies, high-net/gross, braided fluvial reservoir (Zheng et al 2007) was selected to perform the WT simulations. The model is composed of 86 Â 48 Â 25 cells, each with dimensions of 25 Â 25 Â 1.9 m in the x-, y-, and z-directions, respectively.…”

Section: Geological Modelsmentioning

confidence: 99%

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

Hamdi¹,

Jamiolahmady²,

Corbett³

2013

SPE Journal

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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 our knowledge, its combined effect with geology has rarely been studied. Our findings in the present report 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 WT 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, production rate, and drawdown time on the pseudopressure-derivative curves. The WT weighting kernel function and the calculated well-pressure sensitivity coefficients were implemented to demonstrate different trends of drawdown and buildup responses encountered in this study.The results clarified the idea 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, demonstrating the significant impact of some facies on the buildup and drawdown transient pressure response. The time-dependent sensitivity coefficients were calculated to show that the drawdown test is sensitive to effective permeability in near-wellbore regions, in which condensate is prone to build up with time. In the buildup, 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 WT interpretation of fluvial reservoirs.

show abstract

GEOLOGICAL MODEL EVALUATION THROUGH WELL TEST SIMULATION: A CASE STUDY FROM THE WYTCH FARM OILFIELD, SOUTHERN ENGLAND

Cited by 12 publications

References 11 publications

Data workflow for generating static geological model platform for petroleum prospect re-evaluation of Wytch Farm field, Wessex Basin, South Coast, United Kingdom

Data workflow for generating static geological model platform for petroleum prospect re-evaluation of Wytch Farm field, Wessex Basin, South Coast, United Kingdom

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

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

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