--> Abstract: Mechanical Stratigraphy of the Middle Bakken, Mountrail County, North Dakota, by Mark D. Sonnenfeld and Lyn Canter; #90089 (2009)

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Mechanical Stratigraphy of the Middle Bakken, Mountrail County, North Dakota

Mark D. Sonnenfeld1 and Lyn Canter2
1Whiting Oil and Gas Corp., Denver, CO
2Orion Skinner

Facies successions and event stratification also yield a mechanical stratigraphy thought to impact fracture height and spacing.

• Bed-limited fracture distributions (=smallest-scale joint network) are controlled by intrinsic rock properties which dictate mechanical stratigraphy—this network enhances whatever matrix contribution potential exists, and even provides its own limited storage network. Stress origins could be regional tectonic, local tectonic, or localized hydrocarbon generation.

• Progressive vertical linkage of bed-limited fractures reflects kinematic history and will vary aerially according to extrinsic parameters such as curvature and fault-proximity—this “fault/fracture highway” network extends aerial drainage potential.

• Both are important for kh, the former perhaps more for issues of horizontal target zone selection, the later for wellbore azimuth. Facies D is a single, massive mechanical unit; as such it has the greatest fracture spacing. By contrast, Facies A, B, and C are composed of thin mechanical beds. Dolomitic, centimeter- to decimenter-bedded Facies A is the thinnest bedded and most fracture-prone. Linking core facies to MWD GR, drilling time, and mud gas enhances real-time tracking of horizontal wellbore trajectories. Facies A, B, and C remain the principal horizontal target due to greater porosity, fracture susceptibility and therefore permeability.

AAPG Search and Discovery Article #90089©2009 AAPG Southwest Section Meeting, Midland, Texas, April 26-29, 2009