AAPG Geoscience Technology Workshop

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The Application of Biostratigraphy to the Understanding of the Geology, Stratigraphy and Petrophysical Correlation of the Reservoir Intervals in the Karish and Tanin Fields, Levantine Basin and its Proposed Use for Real-Time Wellsite Critical Decision Making


The Karish-1 discovery well (2013) proved the Tamar sands at the Karish Main Field to be eroded and incomplete, owing to significant syn-depositional uplift. In order to better understand the Karish stratigraphy, a proprietary biostratigraphic study was undertaken with Petrostrat Ltd on behalf of Energean Oil & Gas. A review of the legacy biostratigraphy of the Karish-1 and Tanin-1 wells offshore Levantine Basin was undertaken, followed by a program of focussed new analyses across the critical potential reservoir units. The aim of this study was to provide a stratigraphical countdown to use for real-time wellsite biostratigraphy monitoring of drilling on the Karish Field, to give high confidence stratigraphic control, predominantly for optimal placement of the lower completion in the prolific C Sands. The legacy data focussed primarily on the micropalaeontology and nannopalaeontology and the subsequent definition/calibration of a number of the critical petrophysical units in the Karish and Tanin Fields (A, B, C, D Sands) proved to be poorly refined by that data. Therefore, a new infill analytical program was initiated which also included palynology analysis in addition to the Levantine Basin industry standard micro- and nannopalaeontology analyses. The results from the palynology study were very promising and in association/integrated with the updated micropalaeontology allowed the erection of a detailed event-based stratigraphy that permits a stratigraphical countdown during drilling. Biostratigraphy will be used at the wellsite in the upcoming Energean drilling campaign on Karish Main to provide real-time, cost and time effective critical decisions, including setting casing and coring points and general monitoring. Further, this data will be used refine the Oligo-Miocene stratigraphic framework offshore Israel and offer insights into the provenance of that stratigraphy, which will be key to unlocking further prospectivity in adjacent exploration acreage.