Desert Peak Well B

Immediately after well B21-1 was determined to be successful plans were made to drill a confirmation well. This well, B21-2, is located on private land 4100 feet north of well B21-1 and about 190 feet from strat. test no. 5. Well B21-2 was spudded on November 23, 1976, and the rig was released on December 20, 1976. The well is 3192 feet deep and produces about 456,000 lbs per hour of fluid with a wellhead pressure of 64 psig (fig. 18). The reservoir temperature in well B21-2 is 392°F, 14°F less than in well B21-2. Production flow tests show both wells to be in the same reservoir.

A lithologic log of well B21-2 is shown on figure 19. The top 260 feet consist of Quaternary and upper Tertiary sediments and sedimentary rocks. Between 260 and 620 feet basalts and andesites of the Chloropagus Formation are present. In nearby strat. test no. 5 the rocks are intensely altered between depths of 200 and 400 feet. This intense alteration is not present in well B21-2. Recent subsurface hydrothermal alteration may be common at Desert Peak but it apparently has a patchy distribution. A deep water table is probably the reason for the lack of hot springs and alteration at the surface. The rhyolitic unit is present at a depth of 620 feet and has a thickness of 2165 feet. The rhyolitic units penetrated by wells B21-1 and B21-2 are grossly similar.

Pre-Tertiary rocks are present below 2785 feet. Well B21-2 penetrated only 407 feet into the Mesozoic section. The first reservoir fracture was encountered at a depth of 2868 feet and no cuttings returned to the surface between 2880 and 3192 feet. Geophysical logs were

FIGURE 16. Photographs of Desert Peak well B21-1 flowing. View looking northwest.
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