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At least 1,351 records · Page 75Linked to original sources
USGS2000

Construction, completion, and testing of replacement monitoring wells MW 3-2, MW 6-2, MW 7-2, and MW 11-2, Mountain Home Air Force Base, Idaho, February through April 2000

In February and March 2000, the U.S. Geological Survey Western Regional Research Drilling Operation constructed replacement monitoring wells MW 3–2, MW 6–2, MW 7–2, and MW 11–2 as part of a regional ground-water monitor- ing network for the Mountain Home Air Force Base, Elmore County, Idaho. Total well depths ranged from 435.5 to 456.5 feet, and initial depth-to-water measurements ranged from about 350 to 375 feet below land surface. After completion, wells were pumped and onsite measurements were made of water temperature, specific conductance, pH, and dissolved oxygen. At each well, natural gamma, spontaneous potential, resistivity, caliper, and temperature logs were obtained from instruments placed in open boreholes. A three- dimensional borehole flow analysis was completed for MW 3–2 and MW 11–2, and a video log was obtained for MW 11–2 to annotate lithology and note wet zones in the borehole above saturated rock.

Idaho↗
USGS2001

A test of a mechanical multi-impact shear-wave seismic source

We modified two gasoline-engine-powered earth tampers, commonly used as compressional-(P) wave seismic energy sources for shallow reflection studies, for use as shear(S)-wave energy sources. This new configuration, termed ?Hacker? (horizontal Wacker?), is evaluated as an alternative to the manual sledgehammer typically used in conjunction with a large timber held down by the front wheels of a vehicle. The Hacker maximizes the use of existing equipment by a quick changeover of bolt-on accessories as opposed to the handling of a separate source, and is intended to improve the depth of penetration of S-wave data by stacking hundreds of impacts over a two to three minute period. Records were made with a variety of configurations involving up to two Hackers simultaneously then compared to a reference record made with a sledgehammer. Preliminary results indicate moderate success by the higher amplitude S-waves recorded with the Hacker as compared to the hammer method. False triggers generated by the backswing of the Hacker add unwanted noise and we are currently working to modify the device to eliminate this effect. Correlation noise caused by insufficient randomness of the Hacker impact sequence is also a significant noise problem that we hope to reduce by improving the coupling of the Hacker to the timber so that the operator has more control over the impact sequence.

Open-File Report↗
USGS2002

Preliminary gravity inversion model of Frenchman Flat Basin, Nevada Test Site, Nevada

The depth of the basin beneath Frenchman Flat is estimated using a gravity inversion method. Gamma-gamma density logs from two wells in Frenchman Flat constrained the density profiles used to create the gravity inversion model. Three initial models were considered using data from one well, then a final model is proposed based on new information from the second well. The preferred model indicates that a northeast-trending oval-shaped basin underlies Frenchman Flat at least 2,100 m deep, with a maximum depth of 2,400 m at its northeast end. No major horst and graben structures are predicted. Sensitivity analysis of the model indicates that each parameter contributes the same magnitude change to the model, up to 30 meters change in depth for a 1% change in density, but some parameters affect a broader area of the basin. The horizontal resolution of the model was determined by examining the spacing between data stations, and was set to 500 square meters.

Nevada↗
USGS2002

Directional borehole radar tests of an oil injection experiment at the Colorado School of Mines, Golden, Colorado

In October 2001, the U.S. Geological Survey conducted borehole radar surveys of an oil injection experiment at the Colorado School of Mines (CSM), in Golden Colorado using the prototype U.S. Geological Survey (USGS)-developed directional borehole radar system (DBOR). A explanation of the system can be found in Wright and others (2001). The USGS was invited to the CSM to deploy the prototype directional borehole radar system during an oil injection experiment conducted to investigate the applicability of radar to monitoring formation invasion from a horizontal borehole. This work was conducted by a student at the CSM and is summarized in Moita (2001). The purpose of this report is to release the data and to summarize the experiments conducted with the DBOR system. This report contains, (1) a description of the system as deployed in the experiments, (2) a description of the data collected and data parameters used, (3) a simple display of some of the data collected, and (4) a description of the DBOR data files.

Colorado↗