Hydrothermal Dolomite Reservoir Pore Types Observed in the Full Diameter Core from the West Bay Exploration Co. -West Bay 1-22 Wellbore, Napoleon Field, Jackson County, Michigan

Ron Budros
Innova Exploration, Inc., Traverse City, MI, [email protected]

Six, back-to-back, full-diameter cores covering 261’ from the Lower Trenton/Upper Black River Formations were taken in the West Bay Exploration Co. - West Bay 1-22 ( PN 59996) wellbore, an early development well in the Napoleon Field, a Trenton-Black River field discovered by West Bay Exploration Company in the Fall of 2008. A variety of reservoir pore types and combinations of pore types, results of hydrothermal dolomitization, were observed in the full diameter cores. The major pore types observed include: intercrystalline, intercrystalline with molds, intercrystalline with burrows, isolated/separate vugular, connected/bedded vugular, breccia and fracture. The various intercrystalline pore types, along with the separate vugular pore type, are facies dependent and contribute primarily to the reservoir storage. The bedded vugular, breccia and fracture pore types are facies independent and their occurrence is related to where the faulting/fracturing from the strike-slip system intersects the wellbore. The bedded/connected vugular pore type is a combination and contributes to both the storage and deliverability of the reservoir and the fracture pore type is important in flow capacity/deliverability of the reservoir. The breccia pore type in this wellbore is limited by cementation.

AAPG Search and Discovery Article #90154©2012 AAPG Eastern Section Meeting, Cleveland, Ohio, 22-26 September 2012