Lerette, John P.1, James A. MacEachern1
(1) Simon Fraser University, Burnaby, BC
ABSTRACT: Along-Strike Variations in Reservoir Characteristics of Macaronichnus Segregatis-Burrowed Upper Shoreface and Foreshore Sandstones, Lower Cretaceous Glauconite Formation, Alberta, Canada
An integrated subsurface study merges petrophysical core analysis data with sedimentological and ichnological analyses of the Lower Cretaceous (Albian) Glauconite Formation along the Hoadley Barrier system. This mature hydrocarbon-producing trend in west-central Alberta, Canada has experienced renewed interest, resulting from strengthening commodity prices. The study area extends 30km along depositional strike, encompassing the Strachan, Ferrier and Willesden Green fields. The succession comprises a series of stacked, northeast-southwest trending, regressive shorefaces and wave-dominated deltas that prograded northward into the Clearwater Sea. Part of the succession reflects high-frequency forced-regressive deposition during incremental but progressive transgression.
One major reservoir facies within Glauconite Formation shoreface successions occur within the upper shoreface and foreshore sandstones. Monospecific assemblages of Macaronichnus segregatis are associated with these fine- to medium-grained chert litharenites and sublitharenites, and extend along depositional strike of the Hoadley Barrier complex. It is hypothesized that although the grain-selective deposit-feeding behavior of Macaronichnus trace-makers may have enhanced primary porosity, it may have facilitated diagenetic quartz overgrowths, ultimately leading to reservoir degradation.
A computer program (CORECALC) has been developed to facilitate evaluation of reservoir and geophysical logging parameters from core analysis data. This is employed to assess along-strike variations in reservoir characteristics of this facies and to refine reservoir/reserve estimations. The resulting distributions are compared to more diversely bioturbated, cryptically bioturbated and largely unbioturbated shoreface sandstones elsewhere in the Hoadley Barrier complex. Such comparisons may help to determine the role(s) that deposit-feeding bioturbation might play in reservoir development and preservation.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.