ABSTRACT

Thin bedded and shaly sand unconventional reservoirs have been recognized in the Abu Qir Fields and elsewhere in the offshore Nile Delta concessions. Various papers have set the stage for a debate on methodologies used for the identification and petrophysical characterisation of unconventional reservoirs. To date, however, unconventional reservoirs remain relatively unexploited and underdeveloped in the Mediterranean region offshore Egypt.

In the northern area of the Abu Qir Fields, thin bedded lithologies were initially recognised through core data and gas shows in the Kafr El Sheikh (KES) channel fill sequence. The identification of these reservoirs using conventional logs is challenging, as these facies' expression is masked by the insufficient log resolution and the elevated clay presence. This led to the need to acquire high resolution logs able to image these lithologies in the newly drilled wells and to create a methodology to recognize unconventional reservoirs using a vintage log dataset of the existing wells.

This paper describes the experimental methodology implemented in the Intra KES reservoirs to train a predictive neural network algorithm in order to identify unconventional pay zones using conventional logs. The work includes specific examples of integration of high resolution data (core and micro-resistivity image logs) with conventional logging data. Moreover, the integration of petrographic and mineralogical analysis with the core measurement dataset allowed to link the authigenic reservoir mineralogy to petrophysical properties and thus generate a robust petrophysical model.

Once applied to the reservoir modeling workflow, these unconventional facies proved to be of crucial importance both for a correct definition of the gas initially in place and to suitably describe the reservoir heterogeneity.

As a result of the predicted reservoir facies interval output generated by the methodology, a Drill Stem Test (DST) was performed on a well in the northern area of the Abu Qir Fields which confirmed the validity of the proposed approach, testing successfully movable gas from unconventional facies.

Future work aims at implementing this methodology on unconventional reservoirs tested elsewhere in the Abu Qir Fields and at evaluating the usage of hydraulic fracturing technique to the further development of these assets in the Mediterranean Sea offshore Egypt.

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