A comparison between directly measured and inferred wave speeds from an acoustic propagation experiment in Currituck Sound.

An acoustic propagation experiment was conducted in Currituck Sound to characterize low-frequency propagation in a very-shallow-water estuarine environment. The water column properties were homogeneous over the study area, and the emphasis of this work is on understanding the propagation effects induced by the estuarine bed. During the experiment, low-frequency sound propagation measurements of waterborne sound and interface waves were acquired, and direct measurements of the compressional and shear wave properties were obtained at high frequencies.

Controls on Methane Occurrences in Aquifers Overlying the Eagle Ford Shale Play, South Texas.

Assessing natural vs. anthropogenic sources of methane in drinking water aquifers is a critical issue in areas of shale oil and gas production. The objective of this study was to determine controls on methane occurrences in aquifers in the Eagle Ford Shale play footprint.

Methane Occurrences in Aquifers Overlying the Barnett Shale Play with a Focus on Parker County, Texas.

Clusters of elevated methane concentrations in aquifers overlying the Barnett Shale play have been the focus of recent national attention as they relate to impacts of hydraulic fracturing. The objective of this study was to assess the spatial extent of high dissolved methane previously observed on the western edge of the play (Parker County) and to evaluate its most likely source. A total of 509 well water samples from 12 counties (14,500 km ) were analyzed for methane, major ions, and carbon isotopes.

Controls on Methane Occurrences in Shallow Aquifers Overlying the Haynesville Shale Gas Field, East Texas.

Understanding the source of dissolved methane in drinking-water aquifers is critical for assessing potential contributions from hydraulic fracturing in shale plays. Shallow groundwater in the Texas portion of the Haynesville Shale area (13,000 km ) was sampled (70 samples) for methane and other dissolved light alkanes. Most samples were derived from the fresh water bearing Wilcox formations and show little methane except in a localized cluster of 12 water wells (17% of total) in a approximately 30 × 30 km area in Southern Panola County with dissolved methane concentrations less than 10 mg/L.

In situ measurements of sediment acoustic properties in Currituck Sound and comparison to models.

In situ measurements of compressional and shear wave speed and attenuation were collected 30 cm below the water-sediment interface in Currituck Sound, North Carolina at two field locations having distinctly different sediment types: medium-to-fine-grained sand and fine-grained sand with approximately 10% mud content. Shear wave measurements were performed with bimorph transducers to generate and receive horizontally polarized shear waves in the 300 Hz to 1 kHz band, and compressional wave measurements were performed using hydrophones operated in the 5 kHz to 100 kHz band. Sediment samples were collected at both measurement sites and later analyzed in the laboratory to characterize the sediment grain size distribution for each field location.

Source and fate of hydraulic fracturing water in the Barnett Shale: a historical perspective.

Considerable controversy continues about water availability for and potential impacts of hydraulic fracturing (HF) of hydrocarbon assets on water resources. Our objective was to quantify HF water volume in terms of source, reuse, and disposal, using the Barnett Shale in Texas as a case study. Data were obtained from commercial and state databases, river authorities, groundwater conservation districts, and operators.

Comparison of acoustic and seismic excitation, propagation, and scattering at an air-ground interface containing a mine-like inclusion.

Finite element methods are utilized to model and compare the use of both a remote loudspeaker and a vertical shaker in the generation of sound and shear and interface waves in an elastic solid containing an imbedded elastic scatterer, which is resonant. Results for steady state and transient insonification are presented to illustrate excitation, propagation, and scattering mechanisms and effects. Comparisons of acoustic and vibratory excitation of the solid interface are made, with a view towards remote sensing of induced vibratory motion through optical measurement of the ground interface motion above the imbedded inclusion.

Frequency-wavenumber processing for infrasound distributed arrays.

The work described herein discusses the application of a frequency-wavenumber signal processing technique to signals from rectangular infrasound arrays for detection and estimation of the direction of travel of infrasound. Arrays of 100 sensors were arranged in square configurations with sensor spacing of 2 m. Wind noise data were collected at one site.