"UA-147338991-1"

Proactive Geosteering in SAGD / CSS Heavy Oil Sands
April 1, 2018
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May 13, 2016

Duvernay Formation covers an area of approximately 20% of the area of Alberta, or 130,000 square kilometres. The AER and Alberta Geological Survey have published resource estimates for formations in Alberta (Rokosh et al., 2012). In summary, the total in-place resource endowment for the Duvernay ranges from 350 to 540 trillion cubic feet of natural gas, 7 to 16 billion bbl of natural gas liquids, and 44 to 81 billion bbl of oil. These estimates support that the Duvernay shale contains a massive initial resource in place; however, the amount of this resource that can be economically recovered is dependent on drilling and completions optimization, cost reductions, expected liquids yields, commodity pricing, and social, environmental, and regulatory constraints.

The AER has subdivided the extent of the Duvernay depositional area into two geological plays: Duvernay Fox Creek is the larger play in the northwest and exists in the Devonian West Shale Basin, and Duvernay Innisfail is the smaller play in the southeast and exists in the Devonian East Shale Basin.

Geosteering Objective:

The geosteering objective was to optimize the wellbore position within Duvernay target zone.

Challenges:

  • Limited available subsurface and offset wells data.
  • The gamma ray was the only LWD logging curve available.
  • Difficult to identify the reservoir boundaries based on geological cuttings.

Tools Utilized:

  • Bulk gamma ray

Geosteering Summary:

The well was placed in Duvernay target zone, based on the interpretation of bulk gamma ray and its correlation with offset dynamic gamma ray log. The geological cuttings were found least useful in order to differentiate reservoir boundaries. The real-time gamma ray correlation with dynamic log on horizontal scale was helpful in determining the wellbore position. The geological curtain section was modeled with offset well gamma ray property-fill to identify the wellbore position within the stratigraphy.

The wellbore positioning based on the gamma ray log was very accurate and the control point taken at the end of well further confirmed the borehole position within the target zone.

The competency of our geosteering team lead to gain higher client’s confidence in remote geosteering jobs for upcoming wells.

Conclusion:

  • Knowledgeable personnel (Geosteering specialists)
  • Extensive knowledge of geological and drilling operations.
  • For optimum well placement, the client was proposed to use resistivity tool to geosteer the wells proactively within the target zone.
  • Group work.