Date of Graduation

8-2013

Document Type

Thesis

Degree Name

Master of Science in Geology (MS)

Degree Level

Graduate

Department

Geosciences

Advisor/Mentor

Dumond, Gregory

Committee Member

Zachry, Doy L.

Second Committee Member

Hays, Phillip D.

Keywords

Earth sciences; Arkansas; Boone formation; Compressive strength; Geomechanics; Hydraulic fracturing; Mississippi lime; Mississipian

Abstract

The Boone Formation in northwest Arkansas is a chert-limestone sequence analogous to the subsurface Mississippi Lime reservoir in parts of Oklahoma and Kansas. It has low permeability and produces via horizontal drilling and hydraulic fracturing. The response to stimulation by fracturing is dependent on the quantity of chert in the area. Chert nodules and laterally extensive chert layers in the sequence are variable. Locally, cm- to dm-scale chert bedding is continuous and comprises up to 50% of the outcrop. Elsewhere, the chert is nodular and intermittent.

Samples collected from representative outcrops spanning the thickness and aerial extent of the formation are being targeted to establish a geomechanical framework for the reservoir. Samples include end members of chert and limestone and interlayered limestone and chert facies with variable thicknesses and contact geometries. Each sample was cored, confined, and oriented perpendicular to bedding. Compressive strength testing of core plugs were performed to determine the stiffness of the rock, describe how each facies responds to loading and failure, determine how limestone rheology is influenced by the presence of chert, and characterize how rock properties influence the compressive strength of the sample. Rockwell Hardness testing was performed on the samples to understand the strength of the rock in an additional quantitative way.

The compressive strength of the samples and the Rockwell Hardness values of the samples were compared with each other and with the inherent properties of the rock (e.g. lithology, natural fractures, contact types, and facies) to understand and assess correlations and trends in an effort to understand the geomechanics of the Boone Formation.

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