The Effect of the Reservoir Quality on Formation Water Resistivity: Case Study in Neem Field, Block-4, Muglad Basin, Sudan
Mustafa El Tayib
Team Leader Petrophysics Team, Exploration Department, GNPOC
The reservoir quality in Muglad basin it varies from field to field and from formation to another depending on the depositional environment and the sedimentary sequences in the basin which range in age from Early Cretaceous to Tertiary. The presence of localized micro porosity, small pore-throats sizes, fine grains, poor grain sorting, deep drilling fluid invasion and the nature of the laminated sand-shale sequences of the reservoir units added a lot of challenge to the formation evaluation in Muglad Basin in the presence of fresh formation water and the low resistivity low contrast pay zones. This is reflected in a lack of resistivity contrast between oil and water bearing zones, occurrence of low resistivity pays, which might lead to missed pay zones or under estimation of fluid saturations and the reserve size.
In this study logs, cores and testing data for all the wells drilled in Neem field in concession of Blocks-4 Muglad basin was integrated to understand the effect of reservoir quality on the formation water resistivity in the oil and water bearing sand so as to help in computing the accurate Petrophysical parameters. It’s found that the reservoir quality have a very big effect on formation water properties and subsequently a very big effect on Petrophysical characteristics and reserve estimation, details of the findings is discussed in the study
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