Semester

Spring

Date of Graduation

2021

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Timothy Carr

Committee Co-Chair

Paul Ziemkiewicz

Committee Member

Shikha Sharma

Abstract

An investigation of 74 Marcellus Shale wells across northcentral West Virginia indicates changes in produced water chemistry and quantity can be related to geologic conditions based on well logs and core data. These changes are determined by reviewing multiple produced water analyses for individual wells for periods up to ten years. Results show variations among the areas in this study. From west to east across central Harrison County to central Taylor County, then north into Monongalia County, gamma-ray logs show increasing intensity, especially in the middle and lower Marcellus. XRD mineralogy from core data shows increasing clay content from west to east with associated decreases in quartz. Produced water analyses show increases in barium concentrations from west to east, typically associated with increasing shale/clay minerals. Additionally, produced water samples show decreasing calcium and strontium concentrations moving west to east, suggesting that increased carbonate content, possibly as carbonate cement, is present in the western-most study areas. The geological differences across the area results in variations in produced water behaviors. Total dissolved solids (TDS) concentrations typically reach their maximum value during the second year of production. After this time, areas in Harrison County showed both increasing and decreasing TDS concentrations, while areas in Taylor and Monongalia showed almost exclusively decreasing concentrations over time. With TDS concentrations dropping below the maximum values, relative ratios of formation water vs. fracturing fluid can be determined in a given well as it ages. Normalized, cumulative gas production for these wells showed that the geologic differences observed in the produced water are reflected in different production rates across the study area.

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