Karish Complex, Offshore Israel: Responsible Asset Stewardship Through Identification and De-risking of Upside Potential in a Stacked Turbidite Deposit

Abstract

The Karish Main field is located 75km offshore the northern coast of Israel, in water depths of approximately 1750m. The field was discovered in 2013 by the down-flank Karish-1 well, which to date is the only penetration of the structure. The discovery of lean gas and associated liquids was made within the Lower Miocene, with all reserves being reservoired solely within the prolific Tamar C Sands. The Karish Main Field is currently under development, with the fabrication of an 8 BCM/annum capacity FPSO and tieback to shore ongoing and a development drilling campaign to commence in early 2019. Since becoming Operator in December 2016, Energean Israel have recognised significant upside potential within the Karish Lease. Some of this potential (c.650bcf recoverable gas/8mmbbls liquids) exists within the Karish Main field, owing to the >300m structural relief being persistent from the Mesozoic through to the late Miocene, and the likely development of stacked reservoir quality sands throughout the Oligo-Miocene. Detailed reservoir mapping and integration of image log data, mud gas data, biostratigraphic data and formation pressures has been key to identifying these opportunities. The upside potential in the Karish Main structure includes, but is not limited to, moveable hydrocarbons within the stratigraphically shallower, thinly bedded, marginal B Sand deposits, as well as down-flank presence of the overlying A sands, with both units being the main producing units in the prolific Tamar field. Further upside exists in the immediately underlying Miocene D1-2 sands and early Miocene/late Oligocene D4 sands which have seismic support for a hydraulically separate accumulation. In line with responsible field stewardship, the upside potential of the Karish Main stacked reservoirs will be assessed with at least one deep Karish Main pilot hole, complete with a comprehensive data acquisition program, before sidetracking to a production hole to offtake from the Tamar C sands. Further, a Karish Main pilot hole will be used to explore the deeper potential of the Oligo-Miocene which may reservoir a separate, more liquid prone accumulation. Upon completion of all drilling objectives, the pilot hole will be used as an observation well, with permanent, wireless, downhole pressure gauges to de-risk late field life workover campaigns. The Energean 2019 development drilling campaign will be used as an opportunity not only to develop the Tamar C sands, but to appraise the overlying and underlying stratigraphic units, ultimately with the purpose of moving prospective and contingent resources to reserves and maximising ultimate recovery. Energean Israel have also committed to drilling an exploration well into the downthrown Karish North prospect (Tamar sands) in Q1 2019. Karish North has a direct hydrocarbon indicator which is identical to those proven as robust indicators of a gas-water contact interface in the Karish Main field. The Karish North prospect has historically been viewed as a two-way dip closure against a sealing pair of faults. Reprocessing of the 2010 survey to PSDM, fault seal analysis and spill point analysis now identifies the Karish North prospect to be a larger, anticlinal 3 way dip closure (1.8tcf recoverable gas/ 24mmbbls liquids), which incorporates the Karish East structure. Utilising bespoke technologies, maximising value adding data acquisition in the upcoming development drilling campaign and looking beyond pre-existing subsurface interpretations is providing material opportunities to increase recovery from the Karish Lease, offshore Israel, to the benefit of all stakeholders.

AAPG Datapages/Search and Discovery Article #90341 ©2019 AAPG Geoscience Technology Workshop, Exploration and Development of Siliciclastic and Carbonate Reservoirs in the Eastern Mediterranean, Tel Aviv, Israel, February 26-27, 2019