Hydrothermal (Thermobaric) Dolomite Reservoir Project

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Structurally-controlled hydrothermal dolomite (HTD), variably associated with productive leached limestones, is a major reservoir facies in North America, and is receiving increased exploration focus on a global scale. HTD is productive in the Devonian and Mississippian of western Canada, in the Ordovician of Ontario, Quebec and into Newfoundland in eastern Canada, in the Ordovician to Devonian in the Appalachian and Michigan Basins of the northeastern USA, and more controversially in the Ordovician to Silurian of Texas. Exploration along the rifted Atlantic margins of North and South America indicates that the HTD-leached limestone association may be common in structurally involved Jurassic-Cretaceous hosts. In the Middle East, emerging data suggest that structurally-controlled hydrothermal processes may be significant in Jurassic to Cretaceous reservoirs, including the world’s largest oil and gas fields.

Mt. Wapta

Vertical hydrothermal dolomite 'chimneys' (arrows) and stratiform dolomite in Middle Cambrian on west face of Mt. Wapta in southeastern British Columbia.

The HTD project places strong emphasis on understanding the origin, tectonic and structural setting, fabrics, and reservoir characteristics of HTD in western Canada, but also takes a global comparative view of HTD reservoirs and associated hydrothermal mineral deposits. When viewed from a global perspective, most hydrothermal dolomite and mineral deposits show a close association with extensional tectonic settings with elevated heat flow, and focussed flow through fault/fracture conduits (with a strong strike -slip fault component), but still with a significant facies influence on fluid flow, dolomitization, and reservoir character.


'Floating clast' dolomite breccia cemented by saddle dolomite, characteristic of dilational extensional space along fault, formed under conditions of high pore fluid pressure/pressure drops. Middle Cambrian outcrop, southwestern Alberta.

Major aspects of the project include:

  • Multi-client, non-exclusive project
  • Project leader/principal geologist: Graham Davies
  • Global in scope, utilizing western Canada core control
  • Comprehensive report on all aspects of hydrothermal dolomite reservoir trends: tectonic setting, structural controls, rock fabrics, geomechanics, fluid flow and faulting, significance of wrench /strike-slip faults, seismic signatures of sags, importance of basal sandstone aquifers, western Canadian and US hydrothermal dolomite reservoir trends, reservoir quality, and other controls and aspects.
  • Report documents and builds on the recognition that emplacement of hydrothermal dolomite is a process driven not only by temperature but by pressure (hence the alternative term 'thermobaric' dolomite), with a range of newly-defined fabrics as well as breccias and zebra structures formed under superhydrostatic to possibly supralithostatic fluid pressures.
  • Report also reviews hydrothermal dolomite plays in Cambro-Ordovician in Michigan, Appalachian and Permian Basins, from Anticosti Island through southern Ontario, the eastern US, and (albeit controversially) to west Texas.
  • Description of over 480 cores from 153 wells in hydrothermal dolomite or proximal limestone facies from Alberta, NE BC, Yukon, NWT, in hard copy and CD-ROM with selected thin-sections and core photographs.
  • Upgraded Hydrothermal Dolomite Map of western Canada (multiple copies).
  • Report contains 548 pages, 506 text figures, 24 tables, 568 references and 5 appendices. Also includes: new organic petrographic analyses, fluid inclusion, temperature data, mass spectrometry of fluid inclusions, and other analyses, leading to new insights on hydrothermal dolomite processes.
  • Cambrian field guidebook
  • Core seminars and field trips available
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