Modelling the interfering effects of gas condensate and geological heterogeneities on transient pressure response

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Abstract

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.
Original languageEnglish
Title of host publicationSPE EUROPEC/EAGE Annual Conference and Exhibition
Subtitle of host publication23-26 May 2011, Vienna, Austria
PublisherSociety of Petroleum Engineers
Number of pages16
ISBN (Print)9781613994290
DOIs
Publication statusPublished - May 2011
EventSPE EUROPEC/EAGE Annual Conference and Exhibition - Vienna, Austria
Duration: 23 May 201126 May 2011

Conference

ConferenceSPE EUROPEC/EAGE Annual Conference and Exhibition
CountryAustria
CityVienna
Period23/05/1126/05/11

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    Hamdi, H., Jamiolahmady, M., & Corbett, P. W. M. (2011). Modelling the interfering effects of gas condensate and geological heterogeneities on transient pressure response. In SPE EUROPEC/EAGE Annual Conference and Exhibition: 23-26 May 2011, Vienna, Austria [SPE-143613-MS] Society of Petroleum Engineers . https://doi.org/10.2118/143613-MS