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From Well Log to Formation Model: A Novel Laboratory Calibrated Methodology with Demonstration

Benge, Margaret (2024) From Well Log to Formation Model: A Novel Laboratory Calibrated Methodology with Demonstration. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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This work demonstrates how the characterization and modeling of both elastic and creep properties are essential to describe zones in layered rock formations as either low-stress targets for stimulation or high-stress barriers to fracture growth. Prediction of fracture height is critical for designing stimulation operations in oil and gas wells. Ideally, fractures are placed in target zones which will produce hydrocarbons and should not propagate into zones expected to be unproductive or to produce unwanted fluids such as water which in turn must be treated and/or disposed. The essential task in designing stimulation plans is predicting which zones have low horizontal stresses and which will be high-stress barriers to fracture growth. Despite this importance, there are gaps in current knowledge and a complete workflow from laboratory characterization to a finite element model which includes time dependent rock deformation is required.

While the research and methodology presented here also have application to CO2 or hydrogen storage, wastewater injection, and geothermal applications, the focus will be on hydrocarbon extraction. This thesis presents the results of a characterization-to-prediction workflow for the Caney shale, which is an emerging hydrocarbon resource in Oklahoma, USA. It begins with an investigation to enable critical evaluation of the Caney zonation into nominally “brittle” and “ductile” zones based on properties observed from well logs. It shows none of the zones are consistently “brittle” or “ductile” mechanical behavior based on the variety of definitions of these terms. However, the nominally ductile zones are weaker and more prone to creep.

A laboratory investigation of samples including strength, elastic, and creep properties, is then used in a finite element model of stress evolution. The model includes both elastic deformation and viscoplastic creep. Results predict the least creep-prone layers to have the lowest horizontal stresses, therefore comprising hydraulic fracturing targets. The most creep-prone layers attain a horizontal stress similar to the vertical stress and therefore are predicted to be high stress barriers to hydraulic fracture stimulation. In addition to defining stimulation target intervals, the model shows how as tectonic strain rate increases, there is a transition from creep-dominated stresses to stresses dominated by elasticity.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Benge, MargaretMaggie.B@pitt.edumab599
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorBunger,
Committee MemberBrigham,
Committee MemberLin,
Committee MemberHarbert,
Date: 11 January 2024
Date Type: Publication
Defense Date: 31 October 2023
Approval Date: 11 January 2024
Submission Date: 13 November 2023
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 192
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Civil and Environmental Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: In-Situ Stress, Formation Stresses, Creep, Shale, Caney, Proppant Embedment, Triaxial Properties, Mechanical Properties, Formation, Stresses
Related URLs:
Date Deposited: 11 Jan 2024 19:43
Last Modified: 11 Jan 2024 19:43

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  • From Well Log to Formation Model: A Novel Laboratory Calibrated Methodology with Demonstration. (deposited 11 Jan 2024 19:43) [Currently Displayed]


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