As part of a program to evaluate coal resources of the quadrangle, thirty-one water wells in the Castle Rock area have been re-entered and geophysically logged; includes interpretation of formation boundaries and coalbeds. The wells were located in the Buick-Matheson area, in which Laramie Formation coals are relatively near the surface and the Ramah-Fondis area, where coals of the Denver Formation are generally at shallow depths. One well near the western edge of the Denver Basin was logged; the remainder are on the eastern side. Well depths averaged about 400 feet.
The standard geophysical logs run were natural gamma-density and natural gamma-neutron in wells cased with steel and natural gamma-density only in wells with plastic casing (PVC). Six wells had plastic casing. While interpretations were based primarily on these logs, backup information was also used which included the driller’s log for the well and other drills holes in the vicinity.
93 pages. 24 figures. 1 plate (1:200,000). Digital PDF download. OF-81-08D