| Popis: |
The Ha'py Field is located offshore Egypt and is part of the Pliocene producing trend north of the Nile Delta. The original interpretation for the gas in place for the Ha'py Field by Amoco and others was 989 Bcf. Re-evaluation of the field increased the gas in place to 2045 Bcf proven. Subsequent production in the field has substantiated the large increase of the gas in place as a result of the re-evaluation. The initial underestimation of the gas in place was a result of the use of an incorrect log-derived porosity model. This porosity model is not compatible with the petrophysical water saturation relationship used. The incompatibility stems from the fact that petroleum engineers and petrophysicists have different definitions for the terms effective porosity and total porosity. The difference in definitions may lead a petrophysicist to improperly model the well logs to the available core analysis. In addition, the engineer may mis-apply the petrophysicist's results to the reservoir characterization. This improper application leads to a substantial underestimation of hydrocarbon pore volume. The higher the clay and shale content in the reservoir, the greater the error. Definitions will be clarified and explained as they apply to core analysis, reservoir engineering and petrophysics, along with examples using core analysis. Correct modeling of porosity data in these shaly reservoirs lead to the increased estimation of the gas in place. |
