Characterization of the Tayarat Heavy Oil Carbonate Reservoir, Kuwait

Stonard, Simon¹, Mariam Al-Saeed², Mona Al-Rushaid², Dave Sibley¹, Tony Lomando¹, Raphael Ramirez¹, Steve Haas¹, Jamal Al-Hamoud² (1) ChevronTexaco Kuwait, Ahmadi, Kuwait (2) Kuwait Oil Company, Ahmadi, Kuwait

An extensive heavy oil accumulation occurs within the Late Cretaceous (Tayarat) carbon­ate reservoir above the giant Burgan field in South East Kuwait. Recently KOC initiated a comprehensive data acquisition program to further evaluate this reservoir as part of long term resource assessment. Four new information wells were logged last year with a com­prehensive log and core program to support this effort.

The reservoir is lithologically complex being composed of dolomite, limestone, dolomi­tised limestone, secondary anhydrite/gypsum, clay, minor native sulphur and organic rich carbonate. The pore-system contains micro, macro and vugular porosity with localized frac­turing. Formation water salinity appears to vary both vertically and laterally.

Although the oil accumulation is associated with a specific definable trap, at the current well data density there is no definable single oil water contact. From acquired core and log data and from regional information oil properties in this formation vary to the extent that pri­mary oil production is possible in some locations and not others.

The ability to determine lithology, specify and quantify porosity types, estimate perme­ability and assess of the amount and properties of the hydrocarbon from logs with depth is critical. Use is made of geochemical, acoustic and image logs and core data for lithology/porosity determination, and the latest Multi-TE/TW NMR technology, resistivity and core derived geochemical data to assess saturation and most importantly hydrocarbon qual­ity with depth.

The integration of the log evaluation, geochemical and seismic data with local and regional geological concepts is used to assess the productive capability of the reservoir and subsequently locate potential sweet spots to drill and test.