Modeling MDT Tester Stresses Guides Barnett Shale Fracturing to Prevent Water Production | Schlumberger
Case Study
Barnett Shale, United States, North America, Onshore

Challenge: Assess the in situ stress regime of the Barnett Shale and surrounding formations, especially for the potential of hydraulic fracture growth into the underlying waterbearing Ellenburger carbonate.

Solution: Measure stress in situ by performing multiple, precisely placed fracture injections and monitoring closure with the MDT modular formation dynamics tester in select intervals isolated with the Dual-Packer Module.

Results: Developed an accurate, continuous in situ stress profile by calibrating the mechanical properties derived from sonic log data with multiple stress measurements by the MDT tester to model fracture geometry and confidently predict fracture height growth.

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Modeling MDT Tester Stresses Guides Barnett Shale Fracturing to Prevent Water Production

Single-trip testing accurately calibrates sonic data for continuous stress profile used to predict fracture height growth

Fracture growth into water-bearing Ellenburger

The Ellenburger carbonate formation underlying the Barnett Shale can be water bearing and permeable. Consequently, Barnett wells often produce water from the Ellenburger after stimulation. To minimize water production, an operator needed an accurate in situ stress profile across the Barnett and the bounding formations to model fracture geometry and growth potential.

Multiple stress measurements on one trip

The MDT modular formation dynamics tester tool injects fluid to create hydraulic fractures in the wellbore vicinity within an interval isolated between the inflatable elements of the Dual-Packer Module. The small, controlled injection volumes are ideal for targeting thin shale zones for evaluation. The pressure decline is monitored to determine the fracture closure pressure, which represents the minimum in situ stress. The fracture and measure procedure can be repeated many times on a single trip for multiple intervals in the well to provide a wealth of information.

Continuous stress profile and modeled fracture geometry

The MDT tester measurements of closure stress from the multiple tested intervals were used to calibrate a continuous stress profile derived from sonic logs. The continuous stress profile was input to a hydraulic fracturing simulator to confidently predict the fracture height growth and the potential for Ellenburger water production.

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The MDT modular formation dynamics tester efficiently performs multiple tests in one of many intervals isolated by the Dual-Packer Module
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The stress profile produced by a conventional earth model (black solid curve in Track 9) was too low for the high-clay- volume rocks. Correction of the model to account for anisotropy based on the MDT tester measurements raised the predicted stress for the shale (magenta curve) to support more accurate modeling of fracture placement.
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