Browsing by Subject "Swarm"

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Fracture spatial arrangement in tight gas sandstone and shale reservoir rocks
(2017-09-18) Li, John Zihong; Laubach, Stephen E; Gale, Julia F.W.
A new statistical analytical method was applied to quantify the spatial arrangement of fractures in sandstones and shales. Results show that spatial arrangements of fractures in the subsurface have a wide range of patterns and that fracture clusters are prevalent. The Upper Cretaceous Frontier Formation is a naturally fractured gas-producing sandstone in Wyoming. East-west-striking regional fractures sampled using image logs and cores from three horizontal wells exhibit clustered patterns, whereas data collected from outcrop have patterns that are indistinguishable from random. Image log data analyzed with the correlation count method shows clusters ~35 m wide and spaced ~ 50 to 90 m apart as well as clusters up to 12 m wide with periodic inter-cluster spacings. A hierarchy of cluster sizes exists; arrangement within clusters is likely fractal. Regionally, random and statistically more clustered than random patterns exist in the same upper to lower shoreface depositional facies. These rocks have markedly different structural and burial histories, so regional differences in degree of clustering are unsurprising. Application to shale reservoirs further link fracture clusters and spatial arrangements with reservoir mechanical stratigraphy: Vaca Muerta Formation shale shows strong control of fracture cluster locality by reservoir mechanical properties; Middle Devonian shales in the Horn River Basin identify spatial arrangement and cluster dimensions associated with preferred wellbore intervals; Marcellus Formation shale shows spatial arrangement controlled by mechanical bed thickness. Our results show that quantifying and identifying patterns as statistically more or less clustered than random delineate differences in fracture patterns that are not otherwise apparent but that may influence petroleum and water production, and therefore may be economically important.
The implementation of a heterogeneous multi-agent swarm with autonomous target tracking capabilities
(2013-12) Szmuk, Michael; Akella, Maruthi Ram, 1972-
This thesis details the development of a custom autopilot system designed specifically for multi-agent robotic missions. The project was motivated by the need for a flexible autopilot system architecture that could be easily adapted to a variety of future multi-vehicle experiments. The development efforts can be split into three categories: algorithm and software development, hardware development, and testing and integration. Over 12,000 lines of C++ code were written in this project, resulting in custom flight and ground control software. The flight software was designed to run on a Gumstix Overo Fire(STORM) computer on module (COM) using a Linux Angstrom operating system. The flight software was designed to support the onboard GN&C algorithms. The ground control station and its graphical user interface were developed in the Qt C++ framework. The ground control software has been proven to operate safely during multi-vehicle tests, and will be an asset in future work. Two TSH GAUI 500X quad-rotors and one Gears Educational Systems SMP rover were integrated into an autonomous swarm. Each vehicle used the Gumstix Overo COM. The C-DUS Pilot board was designed as a custom interface circuit board for the Overo COM and its expansion board, the Gumstix Pinto-TH. While the built-in WiFi capability of the Overo COM served as a communication link to a central wireless router, the C-DUS Pilot board allowed for the compact and reliable integration of sensors and actuators. The sensors used in this project were limited to accelerometers, gyroscopes, magnetometers, and GPS. All of the components underwent extensive testing. A series of ground and flight tests were conducted to safely and gradually prove system capabilities. The work presented in this thesis culminated with a successful three-vehicle autonomous demonstration comprised of two quad-rotors executing a standoff tracking trajectory around a moving rover, while simultaneously performing GPS-based collision avoidance.