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in creator/contributor: "Nakao, Shinsuke"

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Pressure-transient behavior during cold water injection

During injection testing, pressures in geothermal wells sometimes decline after an initial period of increase despite continued injection. The injection tests carried out at the Yutsubo geothermal field in Kyushu, Japan exhibit this peculiar behavior. During injection testing of Yatsubo well YT-2, observed downhole pressures eventually began to decline despite sustained injection rates. We have carried out numerical simulation studies using a radial flow model to examine this behavior. Double p… more

Date: January 24, 1996

Creator: Nakao, Shinsuke & Ishido, Tsuneo

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Sensitivity study on hydraulic well testing inversion using simulated annealing

For environmental remediation, management of nuclear waste disposal, or geothermal reservoir engineering, it is very important to evaluate the permeabilities, spacing, and sizes of the subsurface fractures which control ground water flow. Cluster variable aperture (CVA) simulated annealing has been used as an inversion technique to construct fluid flow models of fractured formations based on transient pressure data from hydraulic tests. A two-dimensional fracture network system is represented a… more

Date: November 1, 1997

Creator: Nakao, Shinsuke; Najita, J. & Karasaki, Kenzi

Item Type: Report