Estimating reservoir permeability with borehole radar

We would like to express our gratitude to C. Warren at Northumbria University for the valuable help in gprMax modeling and W. Filinger at The University of Edinburgh and J. Liu at the Delft University of Technology for their assistance in the high-performance computing. We acknowledge the Sinopec Petroleum E&P Institute for the permission to use the oil field logging and coring data. The research was funded by the National Natural Science Foundation of China (41674138, 41811530749, 41974165), the NWO Cooperation and Exchange Fund (040.22.011/7048), and the China Scholarship Council grant (201806415048). The work has been performed under the Project HPC-EUROPA3 (INFRAIA-2016-1-730897), with the support of the EC Research Innovation Action under the H2020 program, and used the Cirrus UK National Tier-2 HPC Service at EPCC (http://www.cirrus.ac.uk) funded by the University of Edinburgh and EPSRC (EP/P020267/1). DATA AND MATERIALS AVAILABILITY Data associated with this research are available and can be obtained by contacting the corresponding author.Peer reviewedPostprin

Geophysical methods to detect tunnelling at a geological repository site : Applicability in safeguards

ABSTRACT Generating power with nuclear energy accumulates radioactive spent nuclear fuel, anticipated not to be diversified into any unknown purposes. Nuclear safeguards include bookkeeping of nuclear fuel inventories, frequent checking, and monitoring to confirm nuclear non-proliferation. Permanent isolation of radionuclides from biosphere by disposal challenges established practices, as opportunities for monitoring of individual fuel assemblies ceases. Different concepts for treatment and geological disposal of spent nuclear fuel exist. Spent nuclear fuel disposal facility is under construction in Olkiluoto in Southwest Finland. Posiva Oy has carried out multidisciplinary bedrock characterization of crystalline bedrock for siting and design of the facility. Site description involved compilation of geological models from investigations at surface level, from drillholes and from underground rock characterization facility ONKALO. Research focused on long term safety case (performance) of engineered and natural barriers in purpose to minimize risks of radionuclide release. Nuclear safeguards include several concepts. Containment and surveillance (C/S) are tracking presence of nuclear fuel through manufacturing, energy generation, cooling, transfer, and encapsulation. Continuity of knowledge (CoK) ensures traceability and non-diversion. Design information provided by the operator to the state and European Commission (Euratom), and further to IAEA describes spent nuclear fuel handling in the facility. Design information verification (DIV) using timely or unannounced inspections, provide credible assurance on absence of any ongoing undeclared activities within the disposal facility. Safeguards by design provide information applicable for the planning of safeguards measures, e.g., surveillance during operation of disposal facility. Probability of detection of an attempt to any undeclared intrusion into the repository containment needs to be high. Detection of such preparations after site closure would require long term monitoring or repeated geophysical measurements within or at proximity of the repository. Bedrock imaging (remote sensing, geophysical surveys) would serve for verifying declarations where applicable, or for characterization of surrounding rock mass to detect undeclared activities. ASTOR working group has considered ground penetrating radar (GPR) for DIV in underground constructed premises during operation. Seismic reflection survey and electrical or electromagnetic imaging may also apply. This report summarizes geophysical methods used in Olkiluoto, and some recent development, from which findings could be applied also for nuclear safeguards. In this report the geophysical source fields, involved physical properties, range of detection, resolution, survey geometries, and timing of measurements are reviewed for different survey methods. Useful interpretation of geophysical data may rely on comparison of results to declared repository layout, since independent understanding of the results may not be successful. Monitoring provided by an operator may enable alarm and localization of an undeclared activity in a cost-effective manner until closure of the site. Direct detection of constructed spaces, though possible, might require repeated effort, have difficulties to provide spatial coverage, and involve false positive alarms still requiring further inspection

Radar Sub-surface Sensing for Mapping the Extent of Hydraulic Fractures and for Monitoring Lake Ice and Design of Some Novel Antennas.

Hydraulic fracturing, which is a fast-developing well-stimulation technique, has greatly expanded oil and natural gas production in the United States. As the use of hydraulic fracturing has grown, concerns about its environmental impacts have also increased. A sub-surface imaging radar that can detect the extent of hydraulic fractures is highly demanded, but existing radar designs cannot meet the requirement of penetration range on the order of kilometers due to the exorbitant propagation loss in the ground. In the thesis, a medium frequency (MF) band sub-surface radar sensing system is proposed to extend the detectable range to kilometers in rock layers. Algorithms for cross-hole and single-hole configurations are developed based on simulations using point targets and realistic fractured rock models. A super-miniaturized borehole antenna and its feeding network are also designed for this radar system. Also application of imaging radars for sub-surface sensing frozen lakes at Arctic regions is investigated. The scattering mechanism is the key point to understand the radar data and to extract useful information. To explore this topic, a full-wave simulation model to analyze lake ice scattering phenomenology that includes columnar air bubbles is presented. Based on this model, the scattering mechanism from the rough ice/water interface and columnar air bubbles in the ice at C band is addressed and concludes that the roughness at the interface between ice and water is the dominate contributor to backscatter and once the lake is completely frozen the backscatter diminishes significantly. Radar remote sensing systems often require high-performance antennas with special specifications. Besides the borehole antenna for MF band subsurface imaging system, several other antennas are also designed for potential radar systems. Surface-to-borehole setup is an alternative configuration for subsurface imaging system, which requires a miniaturized planar antenna placed on the surface. Such antenna is developed with using artificial electromagnetic materials for size reduction. Furthermore, circularly polarized (CP) waveform can be used for imaging system and omnidirectional CP antenna is needed. Thus, a low-profile planar azimuthal omnidirectional CP antenna with gain of 1dB and bandwidth of 40MHz is designed at 2.4GHz by combining a novel slot antenna and a PIFA antenna.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/120674/1/wujf_1.pd

EAC Guidelines for the use of Geophysics in Archaeology: Questions to Ask and Points to Consider.

These guidelines provide an overview of the issues to be considered when undertaking or commissioning geophysical survey in archaeology. As every project diff ers in its requirements (e.g. from fi nding sites to creating detailed maps of individual structures) and variations in geological and environmental conditions lead to diff erent geophysical responses, there is no single ‘best’ survey technique or methodology. Th is guide, in its European approach, highlights the various questions to be asked before a survey is undertaken. It does not provide recipebook advice on how to do a geophysical survey or a tick list of which technique is suitable under what conditions. Experienced archaeological geophysicists should be consulted to address the questions that are being posed. Using geophysical techniques and methods inappropriately will lead to disappointment and may, ultimately, result in archaeologists not using them at all. “If all you have is a hammer (or magnetometer), driving a screw becomes impossible”. Especially in the American literature the term ‘remote sensing’ is oft en used to describe geophysical as well as air and space based exploration of underground features (e.g. Wiseman and El-Baz 2007). By contrast, and in line with European traditions, a clear distinction is made here between ground-based geophysical techniques and remote sensing techniques. Th is is based on the imaging principles underlying the respective technologies. Ground based systems usually collect one spatially registered data sample from each sensor location (e.g. a single reading for each magnetometer, or a single trace from each GPR antenna). Remote sensing techniques, by contrast, collect spatially resolved data from a whole area of investigation from each sensor location, using either the system’s optical aperture (e.g. photography) or a scanning device (e.g. laser sampling). These guidelines are based on the experience of the authors in archaeological geophysics and infl uenced by various published sources

Applications of aerospace technology to petroleum extraction and reservoir engineering

Through contacts with the petroleum industry, the petroleum service industry, universities and government agencies, important petroleum extraction problems were identified. For each problem, areas of aerospace technology that might aid in its solution were also identified, where possible. Some of the problems were selected for further consideration. Work on these problems led to the formulation of specific concepts as candidate for development. Each concept is addressed to the solution of specific extraction problems and makes use of specific areas of aerospace technology

The use of seismic techniques to identify hazardous ground conditions associated with cavities

The identification of civil engineering hazards such as cavities, mine shafts, etc., is an integral part of site investigations carried out prior to the construction of roads, tunnels and other civil engineering structures. The use of geophysical methods to identify these hazards is becoming increasingly important. An investigation into the effectiveness of three seismic methods to delineate the possible anomalous ground conditions associated with the presence of cavities has been evaluated. The three methods are: surface, interborehole and a single hole method. The surface seismic method (refraction) was used successfully over a disused railway tunnel to identify the presence of a cavity, and a technique was developed to generate images of a theoretical model, which can be compared to a field survey. The interborehole seismic method was used across a disused railway tunnel to study the effect of a cavity on changes in seismic parameters, such as compressional wave velocity and attenuation. Both of these parameters were sensitive to the presence of a large cavity, and the successful application of the technique is demonstrated in the Maidstone survey, where the presence of loosely packed sand (due to sinkholes in the vicinity) was located under a house. The use of the single hole method for detecting cavities is a new technique (ACDER) in seismics, and it is analogous to methods of radar detection. A sparker source, directional receiver and associated instrumentation were developed in the laboratory before field trials at East Fleet. Of the three methods, the interborehole technique was the most successful, followed by the surface method. The single hole method looks promising but requires further work in the design of directional receiving transducers, followed by more field trials