IEG 환경지질연구정보센터

- 9 -

Geologic assessment of an unconventional bituminous carbonate reservoir: Grosmont Formation (Devonian), Alberta, Canada

Kum Ryong Ku

, Jong-Sun Hong

, Jino Park

, Dong-Chan Lee

, and Suk-Joo Choh

1

Department of Earth and Environmental Sciences, Korea University

2

Department of Earth and Environmental Sciences, Chungbuk National University

3

Department of Cultural Heritage Studies, Daejeon Health Sciences College

*e-mail address: [email protected]

요 약

The Grosmont Formation of Alberta, Canada is a part of an extensive Devonian carbonate platform system spanning over 75,000 km2 in the subsurface of the Western Canada Sedimentary Basin. The formation contains over 300 billion barrels of heavy oil (bitumen) which constitute about 20% of total heavy oil reserve of the Alberta. Understanding the geologic factors that might promote or hinder the recovery of such unconventional resource is a key for future commercial production from the formation. We present the initial result of the integrated geologic assessment of the main reservoir interval of the Grosmont Formation based on regional correlation of geophysical well logs and description of depositional and diagenetic facies of the reservoir interval from cores.

The formation is informally divided into 4 sub units: Lower Grosmont (LG), Upper

Grosmont 1 (UG1), Upper Grosmont 2 (UG2), and Upper Grosmont 3 (UG3). Each sub

unit is divided by regionally extensive shale and/or marl unit. The UG2 and UG3 units in

easternmost area of the subcrop are the primary reservoir interval of the formation. The

UG3 unit is interpreted to be deposited in shallow subtidal to intertidal condition with

subsequent heavy modification by diagenesis. Dolomitization, cementation, dissolution, and

extensive fracturing (possibly related to karstification) are main diagenetic modifiers of the

interval. The UG3 interval shows an average porosity of over 20%, permeability of

100~10000 md, and bitumen saturation of 70~100%. The application of SAGD-type

production methods to the Grosmont reservoir should consider the nature of the

heterogeneity of the reservoir interval as well as the natural barriers and conduits of the

injected steam.