Bankruptcy risk model and empirical tests

We analyze the size dependence and temporal stability of firm bankruptcy risk in the US economy by applying Zipf scaling techniques. We focus on a single risk factor-the debt-to-asset ratio R-in order to study the stability of the Zipf distribution of R over time. We find that the Zipf exponent increases during market crashes, implying that firms go bankrupt with larger values of R. Based on the Zipf analysis, we employ Bayes's theorem and relate the conditional probability that a bankrupt firm has a ratio R with the conditional probability of bankruptcy for a firm with a given R value. For 2,737 bankrupt firms, we demonstrate size dependence in assets change during the bankruptcy proceedings. Prepetition firm assets and petition firm assets follow Zipf distributions but with different exponents, meaning that firms with smaller assets adjust their assets more than firms with larger assets during the bankruptcy process. We compare bankrupt firms with nonbankrupt firms by analyzing the assets and liabilities of two large subsets of the US economy: 2,545 Nasdaq members and 1,680 New York Stock Exchange (NYSE) members. We find that both assets and liabilities follow a Pareto distribution. The finding is not a trivial consequence of the Zipf scaling relationship of firm size quantified by employees-although the market capitalization of Nasdaq stocks follows a Pareto distribution, the same distribution does not describe NYSE stocks. We propose a coupled Simon model that simultaneously evolves both assets and debt with the possibility of bankruptcy, and we also consider the possibility of firm mergers.Comment: 8 pages, 8 figure

Seismic monitoring and verification for the Co2CRC Ottway Basin project

The Otway Project conducted under the Australian Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) is the first of its kind, where CO2 is injected into a depleted gas reservoir. The use of depleted fields for CO2 storage is likely to become widely adopted globally and, therefore, the project will provide important experience for monitoring under these conditions. However, such scenario is not favorable for the application of geophysical techniques for the purpose of CO2 monitoring and verification (M&V) because the injection of CO2 into a CH4 depleted reservoir is modeled to produce very subtle changes in elastic properties of the reservoir rock which may be very difficult to measure. Consequently geophysical program for the Otway site was design according to the expected time-lapse effects. It combines both surface and borehole seismic methods. Surface seismic should provide a global vision of the underground and an indirect confirmation of the CO2 containment by recording no differences between the successive time-lapse experiments. Vertical Seismic Profile (VSP) surveys are expected to provide an improved characterization of the reservoir and hopefully a direct indication of the fluid distribution and/or its potential upward migration along the reservoir bounding fault pattern. Indeed the results of the current analysis of both pre-base line (test) and base-line 2D and 3D VSP data are encouraging. The availability of vector wave field (three-component) data recorded in VSP surveys should significantly improve the outcomes of M&V program at Naylor site

An Early Look at a Time-Lapse 3D VSP

In 2007 Australian Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) started a project to evaluate the available technology for monitoring the movement of CO2 in an underground reservoir. In stage one of this project CO2 and methane are being produced in a nearby well, then the CO2/CH4 is being injected back down a second well into a depleted gas sand. The movement of the CO2 up-dip needs to be remotely monitored. One of the technologies being evaluated to monitor the movement of the CO2 is 3D VSP. The CRC-1 injector well is instrumented with 10 3C downhole accelerometers. A baseline 3D VSP survey was shot around this well in late 2007 and was followed by a repeat survey in 2010. We hope to monitor the movement of CO2 around the CRC-1 well by observing changes in the time-lapse signature

CO2CRC/Otway Project - Influence of Geological and Reservoir Parameters on expected time-lapse seismic signal

In the field of CO2 storage, one important goal is to be able to prove that the injected CO2 is safely stored, and that no leak is occurring. Time-lapse seismic is one of the most powerful tools available for this purpose. However, it is generally used in a qualitative way, to map the injected CO2. Several attempts have been made to use it quantitatively, which are based on the measured time-shifts throughout the seismic volume. Here, we assess the impact of geological and reservoir parameters on the predicted time-lapse signal, which is a first step towards quantification. Uncertainties occur when trying to evaluate the expected timelapse seismic signal. Porosity and permeability are constrained at the wells, but, as is standard in the E&P industry, statistics are used to distribute them throughout the reservoir volume, which is a source of uncertainty. Some reservoir parameters need to be measured, and are poorly constrained for CO2. Our results show that these parameters have an impact on seismic signal prediction, which is not overwhelming (generally below 30%)

Seismic methods in mineral exploration and mine planning: A general overview of past and present case histories and a look into the future.

Due to high metal prices and increased difficulties in finding shallower deposits, the exploration for and exploitation of mineral resources is expected to move to greater depths. Consequently, seismic methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration. These methods also can be used with varying degrees of success to directly target mineral deposits at depth. We review important contributions that have been made in developing these techniques for the mining industry with focus on four main regions: Australia, Europe, Canada, and South Africa. A wide range of case studies are covered, including some that are published in the special issue accompanying this article, from surface to borehole seismic methods, as well as petrophysical data and seismic modeling of mineral deposits. At present, high-resolution 2D surveys mostly are performed in mining areas, but there is a general increasing trend in the use of 3D seismic methods, especially in mature mining camps

Optical observations of the nearby galaxy IC342 with narrow band [SII] and Hα\alpha filters. I

We present observations of the portion of the nearby spiral galaxy IC342 using narrow band [SII] and H$\alpha$ filters. These observations were carried out in November 2011 with the 2m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper we report coordinates, diameters, H$\alpha$ and [SII] fluxes for 203 HII regions detected in two fields of view in IC342 galaxy. The number of detected HII regions is 5 times higher than previously known in these two parts of the galaxy.Comment: 9 pages, 3 tables, 4 figures. Table 3 corrected + small corrections in the tex