Abstract

BED 2 is a brown gas field located in the western desert, Egypt and commenced production 1982. The field has multiple reservoirs varying between carbonates, clean sand stone and shaly sand stone.

Baharyia formation is the main producing reservoir in the field. In the latest years of the field life, an unrealistic recovery factor was reached making the volume of the recovered gas exceeds the maximum volume that could be recovered from this reservoir.

Hence, a new further investigation and review for the previously calculated GIIP was initiated. The results of this study yielded that the main uncertainty in the volumetric calculations was the petrophysical evaluation subsequently a new unconventional petrophysical evaluation approach was performed.

The first step in the petrophysical evaluation was to use the core data to separate the rock into different rock types "hydraulic zones" by calculating the reservoir quality index (RQI) and the flow zone indicator (FZI). After that, an electro-facies model was created using the electric logs for the model input and the hydraulic zones derived from the core data as the model learning.

The resulted model matched the core data in all the four cored wells and hence it was applied to the un-cored ones.

After that, the created rock typing model was used to deduce the cut-off criteria per each rock unit which resulted a huge difference from the previously calculated cut-offs and hence the NTG ratio is doubled as three types of net sand were added to the petrophysical evaluation. The first type is a very silty highly laminated sand-shale reservoir while the second one was clean sand reservoir.

Conventional saturation calculation methods showed no match between the calculated volumes and production and hence different unconventional shaly sand analysis was used in calculating the saturation for the two different types of sands.

The new petrophysical evaluation resulted in doubling the volumes in Baharyia reservoir and so a perforation campaign was performed to confirm the new volumetric calculations, which showed a good match with the model results. Hence, a new well was drilled targeting the low quality sand and found them with high pressure almost near virgin pressure.

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