A simple power-law model is presented for performance of gas reservoirs experiencing water influx using only cumulative production, reservoir pressure, and the gas deviation factor (i.e., the z-factor). The application of the model provides estimation of gas-in-place. The gas material balance relation including ONLY water influx is given in dimensionless form as:
The following empirical model is proposed for dimensionless water influx function (WeD):
Substituting this model into the gas material balance yields:

The proposed power-law water influx model was exhaustively validated using the Carter-Tracy and Van Everdingen-Hurst methods to simulate water influx and pressure-cumulative gas production behavior for an unsteady-state water-influx system. The results of these simulation cases were fitted using the proposed (empirical) power-law water influx model and for every case that was tested, the proposed model gave an essentially perfect correlation of the simulated reservoir performance behavior.

Keywords:
drillstem/well testing, drillstem testing, compressibility, influx, reservoir surveillance, resource in place estimate, estimates of resource in place, production control, permeability, viscosity
Subjects:
Well & Reservoir Surveillance and Monitoring, Reservoir Simulation, Formation Evaluation & Management, Reserves Evaluation, Drillstem/well testing, Estimates of resource in place
Copyright 2024, International Petroleum Technology Conference DOI 10.2523/IPTC-24407-MS
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