Fractured shale reservoirs: Towards a realistic model

Journal Article · Sun Sep 01 04:00:00 EDT 1996 · AAPG Bulletin

DOI:https://doi.org/10.1306/64ED9F2E-1724-11D7-8645000102C1865D· OSTI ID:411932

Hamilton-Smith, T ^[1]

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1. Applied Earth Science, Lexington, KY (United States)

Fractured shale reservoirs are fundamentally unconventional, which is to say that their behavior is qualitatively different from reservoirs characterized by intergranular pore space. Attempts to analyze fractured shale reservoirs are essentially misleading. Reliance on such models can have only negative results for fractured shale oil and gas exploration and development. A realistic model of fractured shale reservoirs begins with the history of the shale as a hydrocarbon source rock. Minimum levels of both kerogen concentration and thermal maturity are required for effective hydrocarbon generation. Hydrocarbon generation results in overpressuring of the shale. At some critical level of repressuring, the shale fractures in the ambient stress field. This primary natural fracture system is fundamental to the future behavior of the fractured shale gas reservoir. The fractures facilitate primary migration of oil and gas out of the shale and into the basin. In this process, all connate water is expelled, leaving the fractured shale oil-wet and saturated with oil and gas. What fluids are eventually produced from the fractured shale depends on the consequent structural and geochemical history. As long as the shale remains hot, oil production may be obtained. (e.g. Bakken Shale, Green River Shale). If the shale is significantly cooled, mainly gas will be produced (e.g. Antrim Shale, Ohio Shale, New Albany Shale). Where secondary natural fracture systems are developed and connect the shale to aquifers or to surface recharge, the fractured shale will also produce water (e.g. Antrim Shale, Indiana New Albany Shale).

• Sponsoring Organization: USDOE
• OSTI ID: 411932
• Report Number(s): CONF-9610180--
• Journal Information: AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 9 Vol. 80; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
EXPLORATION
FLUID FLOW
FRACTURED RESERVOIRS
GEOLOGIC MODELS
HYDROCARBONS
SOURCE ROCKS