Timothy C. Johnson

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Understanding and quantification of wellbore skin improves our ability to accurately measure or estimate hydrologic parameters with tests at wells such as pumping tests, flowmeter tests, and slug tests. This paper presents observations and results from a series of field, laboratory, and modeling tests which, together, explain the source of wellbore skin at(More)
Received for review December 14,1984. Accepted March 21,1985. Although the research described in this article has been funded wholly or in part by the U.S. Environmental Protection Agency through Contract 68-02-4033 to Northrop Services, I m Environmental Sciences, it has not been subjected to the Agency's required peer and policy review and therefore does(More)
The spectral induced polarization (SIP) technique is a promising approach for delineating subsurface physical and chemical property changes in a minimally invasive manner. To facilitate the understanding of position and chemical properties of reaction fronts that involve mineral precipitation in porous media, we investigated spatiotemporal variations in(More)
This paper describes a combined field, laboratory, and numerical study of electromagnetic borehole flowmeter measurements acquired without the use of a packer or skirt to block bypass flow around the flowmeter. The most significant finding is that inflow through the wellbore screen changes the ratio of flow through the flowmeter to wellbore flow.(More)
Marc L. Buursink,1,∗ Timothy C. Johnson,2,∗ Partha S. Routh3,∗ and Michael D. Knoll4,∗ 1Chevron Energy Technology Company, 1500 Louisiana Street, Houston, TX 77002, USA. E-mail: buursink@chevron.com 2Energy Resource Recovery and Management, Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415, USA 3Seismic Technology Development, Conoco Phillips,(More)
Major challenges exist in delineating bedrock fracture zones because these cause abrupt changes in geological and hydrogeological properties over small distances. Borehole observations cannot sufficiently capture heterogeneity in these systems. Geophysical techniques offer the potential to image properties and processes in between boreholes. We used(More)
Ground-penetrating radar GPR attenuation-difference tomography is a useful tool for imaging the migration of electrically anomalous tracer or contaminant plumes. Attenuation-difference tomography uses the difference in the trace amplitudes of tomographic data sets collected at different times to image the distribution of bulk-conductivity changes within the(More)
Biostimulation is increasingly used to accelerate microbial remediation of recalcitrant groundwater contaminants. Effective application of biostimulation requires successful emplacement of amendment in the contaminant target zone. Verification of remediation performance requires postemplacement assessment and contaminant monitoring. Sampling-based(More)
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