Kolesar, Courtney
(2014)
STRONTIUM ISOTOPES TEST LONG-TERM ZONAL ISOLATION OF INJECTED AND MARCELLUS FORMATION WATER AFTER HYDRAULIC FRACTURING.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
The rapidly expanding use of high volume hydraulic fracture stimulation during development of unconventional gas reservoirs such as the Marcellus Shale in northeastern North America has lead to concerns about potential migration or displacement of high TDS (total dissolved solids) fluids from the target formation or overlying units into shallow aquifers. Typical water quality monitoring methods may be unable to differentiate between contamination sources, behave non-conservatively, or require the addition of synthetic chemical tracers. Natural strontium isotope signatures (87Sr/86Sr) can be used to distinguish produced waters from the Marcellus Shale from other potential regional contaminants. The research objective of this study, located at the National Energy Technology Laboratory Greene County Site in southwestern Pennsylvania, was to test the assumption that hydraulic fracturing is confined to the target formation, and that injected and formation waters do not migrate to overlying units. Strontium isotope compositions were determined for produced waters taken over a period of approximately four months before and fourteen months after hydraulic fracturing from horizontal wells drilled into the Marcellus Shale and from overlying vertical Upper Devonian/Lower Mississippian (UD/LM) gas-producing wells. Water samples from a nearby spring were also collected to analyze the local ground water geochemistry and test the sensitivity of Sr isotopes as an indicator of brine incursions into fresh water aquifers. The results indicate that there was no significant post-hydraulic fracturing migration of Marcellus-related fluids or displacement of UD/LM brines into shallower units during the study period, and demonstrated that Sr isotopes can detect very small incursions of brine (<0.001%) into groundwater, often at a more sensitive level than shifts in elemental concentrations. The large difference in Sr content between the Marcellus brines and the UD/LM brines allows for detectable isotopic shifts in UD/LM 87Sr/86Sr ratios with as little as ~1% incursion of Marcellus fluids. Strontium isotopes have the potential to serve as an excellent long-term monitoring tool.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
22 May 2014 |
| Date Type: |
Publication |
| Defense Date: |
28 March 2014 |
| Approval Date: |
22 May 2014 |
| Submission Date: |
11 May 2014 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Number of Pages: |
56 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Geology and Planetary Science |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Strontium, Isotopes, Marcellus, Flowback, Hydraulic Fracturing, Produced Water |
| Date Deposited: |
22 May 2014 19:38 |
| Last Modified: |
22 May 2019 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/21579 |
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