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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />'::::J <br />'-I <br />L-casing-collar locator log, which was recorded to the total well depth of 6075 <br />C.1 <br />c:) feet. <br />C) <br /> <br />The most abrupt lithologic change seen on the gamma and neutron logs is <br />at a depth of approximately 2000 feet. At that depth, the log character shows <br />a general lithologic change from a clay-poor material to a clay-rich material. <br />This change is depicted on Figure 2.9. This is interpreted to correlate to <br />the change in DS and flow contribution seen in the Carroll Well at about the <br />same depth, three miles to the northwest. <br /> <br />Below a depth of 2000 feet, clay-rich materials predominate. This may be <br />due to the presence of Conejos Formation volcaniclastic-facies rocks in HSU-3 <br />at this location, or it may be due at least in part to clay-rich alteration <br />products of more permeable rocks localized in a geothermally-active rift- <br />related fault zone. The drilling conditions reportedly encountered in the <br />Alamosa Geothermal Well indicate agreement with a generally clay-rich material <br />in HSU-3. The neutron, gamma, and temperature logs indicate, however, that <br />there are sporadic sand- or gravel-rich zones within the predominantly clay- <br />rich HSU-3 materials. <br /> <br />The casing-collar locator log verified that slotted intervals of casing <br />were placed at approximate depth intervals of 5440 feet to 5520 feet, and 5720 <br />feet to 6040 feet. <br /> <br />Neither the fluid-resistivity log nor the spinner log proved to be very <br />helpful in defining the characteristics of HSU-3. The well appears to be <br />hydraulically isolated from the formation, possibly due to the low <br />permeability of the formation, or possibly due to residual drilling-mud cake <br />on the borehole walls in the two slotted intervals. The reported drilling <br />problems and lack of well development following drilling points to the latter <br />reason as the more probable. <br /> <br />The temperature log of the Alamosa Geothermal Well proved to be very <br />helpful in defining the geothermal gradient and vertical ground water leakage <br />within HSU-3 precisely because of the apparent hydraulic isolation of the well <br /> <br />2-8 <br />