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Differentiating formation compressibility and water-influx effects in overpressured gas reservoirs

Journal Article · · SPE Reservoir Engineering (Society of Petroleum Engineers); (United States)
DOI:https://doi.org/10.2118/25478-PA· OSTI ID:7148627
; ;  [1]
  1. Texas A and M Univ., College Station, TX (United States)

Numerous authors have presented studies of overpressured gas reservoirs that are based on a particular model. Effects of pressure- and time-dependent formation compressibility, shale or aquifer water influx, or solution gas in the water are usually included, with varying degrees of emphasis and simplifying assumptions. However, a straightforward method to evaluate performance from overpressured gas reservoirs has never been presented. The authors present a rearranged form of the material-balance equation that provides such a method. Roach arranged the material-balance equation that includes the effect of formation compressibility for an overpressured gas reservoir in a new form. References cited in this paper showed the utility of this method to predict future performance. Field case history studies illustrated the usefulness of this plotting technique when studying partial-waterdrive gas reservoirs. In this paper, the authors show how this technique may be used not only to estimate OGIP, effective compressibility, and water-influx values but also to interpret how each of these variables affects the reservoir performance history.

OSTI ID:
7148627
Journal Information:
SPE Reservoir Engineering (Society of Petroleum Engineers); (United States), Journal Name: SPE Reservoir Engineering (Society of Petroleum Engineers); (United States) Vol. 9:3; ISSN 0885-9248; ISSN SREEEF
Country of Publication:
United States
Language:
English