Crossover of the dispersion of flexural waves recorded in borehole cross-dipole measurements is interpreted as an indicator of stress-induced anisotropy around a circular borehole in formations that are isotropic in the absence of stresses. We have investigated different factors that influence flexural wave dispersion. Through numerical modeling, we determined that for a circular borehole surro...

Measuring the electrical field induced by a borehole Stoneley wave is a new method for characterizing a rock formation around a borehole. Our field measurements demonstrate that the Stoneley-wave-induced electrical field can be detected in sedimentary rocks (dolomite in our experiment), and that the amplitude of this electroseismic phenomenon can be used to detect isolated fractures and permeab...

For a robust way of estimating time shifts near horizontal boreholes, we have developed a method for separating the reflection responses above and below a horizontal borehole. Together with the surface reflection data, the method uses the direct arrivals from borehole data in the Marchenko method. The first step is to retrieve the focusing functions and the updown wavefields at the borehole lev...

Theoretical models for the thermal response of vertical geothermal boreholes often assume that the characteristic time of variation of the heat injection rate is much larger than the characteristic diffusion time across the borehole. In this case, heat transfer inside the borehole and in its immediate surroundings is quasi-steady in the first approximation, while unsteady effects enter only in ...

This paper presents a wellbore-stability study of the San Andreas Fault Observatory at Depth (SAFOD) research borehole located near Parkfield, California, USA. In the summer of 2005, the SAFOD borehole was drilled successfully through the active trace of the San Andreas Fault (SAF) in an area characterized by fault creep and frequent microearthquakes. In this study, we report how the analysis o...

The vadose zone beneath the USDOE’s Hanford Site in southeastern Washington State (Fig. 1) received approximately 1 trillion liters (450 billion gallons) of liquid waste, some contaminated with radioactive and hazardous contaminants. Today, Hanford is engaged in the world’s largest environmentalcleanup project, and a variety of conceptual and mathematical vadose zone models have been developed ...

In this paper we describe the design and implementation of a bot to play the arcade game Breakout. Instead of manually writing the bot, we use reinforcement learning techniques to learn a strategy by repeated sessions of Breakout where the learner is rewarded for advancing through the game and punished for losing. We show that our bot’s game performance increases with repeated plays, though it ...

Formation elastic properties near a borehole may be altered from their original state due to the stress concentration around the borehole. This could lead to a biased estimation of formation elastic properties measured from sonic logging data. To study the effect of stress concentration around a borehole on sonic logging, we first use an iterative approach, which combines a rock physics model a...

The great depth and relatively steep geothermal gradient (3⁄429oC=km) of the KTB deep crustal borehole, located in the Bavarian region of Germany, provides the basis for our study of diffusive argon loss in K-feldspar. The observed borehole temperature at 9 km is 3⁄4265oC which reaches well into the argon closure interval for K-feldspar (3⁄4125–350oC). Four microcline and two adularia samples d...

Access to clean water for drinking and sanitation is a human right. Today water scarcity is a large problem and inequality in access to safe water is a striking truth. In Mozambique, the US foreign aid agency Millennium Challenge Corporation introduced the Rural Water Point Installation Program to increase access to safe water and sanitation – a step towards reducing poverty. 600 water points –...