USGS

Water Resources of Colorado

Analysis of Geophysical Logs from Six Boreholes at Lariat Gulch, Former U.S. Air Force Site PJKS, Jefferson County, Colorado

by Frederick L. Paillet, Richard E. Hodges, and Barbara S. Corland

Prepared in cooperation with the U.S. Air Force

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Open-File Report 02-364, 39 p., 10 figs.

This document also is available in pdf format: Adobe Acrobat icon OFR 02-364 (1.5MB)
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Abstract

This report presents and describes geophysical logs for six boreholes in Lariat Gulch, a topographic gulch at the former U.S. Air Force site PJKS in Jefferson County near Denver, Colorado. Geophysical logs include gamma, normal resistivity, fluid-column temperature and resistivity, caliper, televiewer, and heat-pulse flowmeter. These logs were run in two boreholes penetrating only the Fountain Formation of Pennsylvanian and Permian age (logged to depths of about 65 and 570 feet) and in four boreholes (logged to depths of about 342 to 742 feet) penetrating mostly the Fountain Formation and terminating in Precambrian crystalline rock, which underlies the Fountain Formation. Data from the logs were used to identify fractures and bedding planes and to locate the contact between the two formations. The logs indicated few fractures in the boreholes and gave no indication of higher transmissivity in the contact zone between the two formations. Transmissivities for all fractures in each borehole were estimated to be less than 2 feet squared per day.


Table of Contents

Abstract

Introduction

Background on Geophysical Logs

Natural Gamma

Normal Resistivity

Fluid Column

Acoustic Televiewer

Caliper

Heat-Pulse Flowmeter

Quality Control

Analysis

Lithology

Structure

Heat-Pulse Flowmeter

Flowmeter-Measurement Adjustments and Normalization

Interpretation of Lariat Gulch Logs

Borehole LGMW-001-P

Borehole LGMW-003-P

Borehole LGMW-004-F

Borehole LGMW-006-P

Borehole LGMW-010-F

Borehole LGMW-017-P

Overview of Lariat Gulch Logs

Summary and Conclusions

References Cited

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