Seth S. Haines

Hydraulic fracturing water use variability in the United States and potential environmental implications.

Abstract Until now, up‐to‐date, comprehensive, spatial, national‐scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale‐gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection‐induced earthquakes.

Seismoelectric numerical modeling on a grid

Our finite-difference algorithm provides a new method for simulating how seismic waves in arbitrarily heterogeneous porous media generate electric fields through an electrokinetic mechanism called seismoelectric coupling. As the first step in our simulations, we calculate relative pore-fluid/grain-matrix displacement by using existing poroelastic theory. We then calculate the electric current resulting from the grain/fluid displacement by using seismoelectric coupling theory. This electrofiltration current acts as a source term in Poisson’s equation, which then allows us to calculate the electric potential distribution. We can safely neglect induction effects in our simulations because the model area is within the electrostatic near field for the depth of investigation (tens to hundreds of meters) and the frequency ranges ( 10 Hz to 1 kHz ) of interest for shallow seismoelectric surveys.We can independently calculate the electric-potential distribution for each time step in the poroelastic simulation with...

Seismoelectric data processing for surface surveys of shallow targets

The utility of the seismoelectric method relies on the development of methods to extract the signal of interest from background and source-generated coherent noise that may be several orders-of-magnitude stronger. We compare data processing approaches to develop a sequence of preprocessing and signal/noise separation and to quantify the noise level from which we can extract signal events. Our preferred sequence begins with the removal of power line harmonic noise and the use of frequency filters to minimize random and source-generated noise. Mapping to the linear Radon domain with an inverse process incorporating a sparseness constraint provides good separation of signal from noise, though it is ineffective on noise that shows the same dip as the signal. Similarly, the seismoelectric signal and noise do not separate cleanly in the Fourier domain, so f - k filtering can not remove all of the source-generated noise and it also disrupts signal amplitude patterns. We find that prediction-error filters provide...

Design and Application of an Electromagnetic Vibrator Seismic Source

Vibrational seismic sources frequently provide a higher-frequency seismic wavelet (and therefore better resolution) than other sources, and can provide a superior signal-to-noise ratio in many settings. However, they are often prohibitively expensive for lower-budget shallow surveys. In order to address this problem, I designed and built a simple but effective vibrator source for about one thousand dollars. The ‘‘EMvibe’’ is an inexpensive electromagnetic vibrator that can be built with easy-tomachine parts and off-the-shelf electronics. It can repeatably produce pulse and frequency-sweep signals in the range of 5 to 650 Hz, and provides sufficient energy for recording at offsets up to 20 m. Analysis of frequency spectra show that the EMvibe provides a broader frequency range than the sledgehammer at offsets up to ;10 m in data collected at a site with soft sediments in the upper several meters. The EMvibe offers a high-resolution alternative to the sledgehammer for shallow surveys. It is well-suited to teaching applications, and to surveys requiring a precisely-repeatable source signature.

Blind Test of Methods for Obtaining 2-D Near-Surface Seismic Velocity Models from First-Arrival Traveltimes

ABSTRACT Seismic refraction methods are used in environmental and engineering studies to image the shallow subsurface. We present a blind test of inversion and tomographic refraction analysis methods using a synthetic first-arrival-time dataset that was made available to the community in 2010. The data are realistic in terms of the near-surface velocity model, shot-receiver geometry and the datas frequency and added noise. Fourteen estimated models were determined by ten participants using eight different inversion algorithms, with the true model unknown to the participants until it was revealed at a session at the 2011 SAGEEP meeting. The estimated models are generally consistent in terms of their large-scale features, demonstrating the robustness of refraction data inversion in general, and the eight inversion algorithms in particular. When compared to the true model, all of the estimated models contain a smooth expression of its two main features: a large offset in the bedrock and the top of a steeply...

Shear-wave seismic reflection studies of unconsolidated sediments in the near surface

We have successfully applied of SH-wave seismic reflection methods to two different near-surface problems targeting unconsolidated sediments. At the former Fort Ord, where the water table is approximately 30 m deep, we imaged aeolian and marine aquifer and aquitard stratigraphy to a depth of approximately 80 m . We identified reflections from sand/clay and sand/silt interfaces and we mapped these interfaces along our transects. At an aggregate study site in Indiana, where the water table is at a depth of 1 to 2 m , we imaged stratigraphy in alluvial sand and gravel, and observe a strong reflection from the 32-m -deep bedrock surface. In both cases, we exploited the high resolution potential of SH waves, their insensitivity to water content, and the possibility of reducing Love wave contamination by working along a roadway. We accomplished our results using only sledgehammer sources and simple data processing flows.

An automated cross‐correlation based event detection technique and its application to a surface passive data set

In studies on heavy oil, shale reservoirs, tight gas and enhanced geothermal systems, the use of surface passive seismic data to monitor induced microseismicity due to the fluid flow in the subsurface is becoming more common. However, in most studies passive seismic records contain days and months of data and manually analysing the data can be expensive and inaccurate. Moreover, in the presence of noise, detecting the arrival of weak microseismic events becomes challenging. Hence, the use of an automated, accurate and computationally fast technique for event detection in passive seismic data is essential. The conventional automatic event identification algorithm computes a running-window energy ratio of the short-term average to the long-term average of the passive seismic data for each trace. We show that for the common case of a low signal-to-noise ratio in surface passive records, the conventional method is not sufficiently effective at event identification. Here, we extend the conventional algorithm by introducing a technique that is based on the cross-correlation of the energy ratios computed by the conventional method. With our technique we can measure the similarities amongst the computed energy ratios at different traces. Our approach is successful at improving the detectability of events with a low signal-to-noise ratio that are not detectable with the conventional algorithm. Also, our algorithm has the advantage to identify if an event is common to all stations (a regional event) or to a limited number of stations (a local event). We provide examples of applying our technique to synthetic data and a field surface passive data set recorded at a geothermal site.

A Framework for Quantitative Assessment of Impacts Related to Energy and Mineral Resource Development

Natural resource planning at all scales demands methods for assessing the impacts of resource development and use, and in particular it requires standardized methods that yield robust and unbiased results. Building from existing probabilistic methods for assessing the volumes of energy and mineral resources, we provide an algorithm for consistent, reproducible, quantitative assessment of resource development impacts. The approach combines probabilistic input data with Monte Carlo statistical methods to determine probabilistic outputs that convey the uncertainties inherent in the data. For example, one can utilize our algorithm to combine data from a natural gas resource assessment with maps of sage grouse leks and piñon-juniper woodlands in the same area to estimate possible future habitat impacts due to possible future gas development. As another example: one could combine geochemical data and maps of lynx habitat with data from a mineral deposit assessment in the same area to determine possible future mining impacts on water resources and lynx habitat. The approach can be applied to a broad range of positive and negative resource development impacts, such as water quantity or quality, economic benefits, or air quality, limited only by the availability of necessary input data and quantified relationships among geologic resources, development alternatives, and impacts. The framework enables quantitative evaluation of the trade-offs inherent in resource management decision-making, including cumulative impacts, to address societal concerns and policy aspects of resource development.

Analysis of passive surface-wave noise in surface microseismic data and its implications

Tight gas reservoirs are projected to be a major portion of future energy resources. Because of their low permeability, hydraulic fracturing of these reservoirs is required to improve the permeability and reservoir productivity. Passive seismic monitoring is one of the few tools that can be used to characterize the changes in the reservoir due to hydraulic fracturing. Although the majority of the studies monitoring hydraulic fracturing exploit down hole microseismic data, surface microseismic monitoring is receiving increased attention because it is potentially much less expensive to acquire. Due to a broader receiver aperture and spatial coverage, surface microseismic data may be more advantageous than down hole microseismic data.

The role of water in unconventional in situ energy resource extraction technologies: Chapter 7 in Food, energy, and water: The chemistry connection

Global trends toward developing new energy resources from lower grade, larger tonnage deposits that are not generally accessible using “conventional” extraction methods involve variations of subsurface in situ extraction techniques including in situ oil shale retorting, hydraulic fracturing of petroleum reservoirs, and in situ recovery of uranium. Although these methods are economically feasible and perhaps result in a smaller above-ground land-use footprint, there remain uncertainties regarding potential subsurface impacts to groundwater. This chapter provides an overview of the role of water in these technologies and the opportunities and challenges for water reuse and recycling.