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Title: ER-12-1 completion report

Abstract

The objective of drillhole ER-12-1 was to determine the hydrogeology of paleozoic carbonate rocks and of the Eleana Formation, a regional aquitard, in an area potentially downgradient from underground nuclear testing conducted in nearby Rainier Mesa. This objective was addressed through the drilling of well ER-12-1 at N886,640.26 E640,538.85 Nevada Central Coordinates. Drilling of the 1094 m (3588 ft) well began on July 19, 1991 and was completed on October 17, 1991. Drilling problems included hole deviation and hole instability that prevented the timely completion of this borehole. Drilling methods used include rotary tri-cone and rotary hammer drilling with conventional and reverse circulation using air/water, air/foam (Davis mix), and bentonite mud. Geologic cuttings and geophysical logs were obtained from the well. The rocks penetrated by the ER-12-1 drillhole are a complex assemblage of Silurian, Devonian, and Mississippian sedimentary rocks that are bounded by numerous faults that show substantial stratigraphic offset. The final 7.3 m (24 ft) of this hole penetrated an unusual intrusive rock of Cretaceous age. The geology of this borehole was substantially different from that expected, with the Tongue Wash Fault encountered at a much shallower depth, paleozoic rocks shuffled out of stratigraphic sequence, and the presence ofmore » an altered biotite-rich microporphyritic igneous rock at the bottom of the borehole. Conodont CAI analyses and rock pyrolysis analyses indicate that the carbonate rocks in ER-12-1, as well as the intervening sheets of Eleana siltstone, have been thermally overprinted following movement on the faults that separate them. The probable source of heat for this thermal disturbance is the microporphyritic intrusion encountered at the bottom of the hole, and its age establishes that the major fault activity must have occurred prior to 102.3+0.5 Ma (middle Cretaceous).« less

Authors:
; ; ;  [1]
  1. and others
Publication Date:
Research Org.:
USDOE Nevada Operations Office, Las Vegas, NV (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
465859
Report Number(s):
DOE/NV/10845-36; DRI-45120
ON: DE97004833; TRN: 97:010153
DOE Contract Number:  
AC08-90NV10845
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Dec 1996
Country of Publication:
United States
Language:
English
Subject:
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; 54 ENVIRONMENTAL SCIENCES; NEVADA TEST SITE; BOREHOLES; GEOLOGIC FORMATIONS; HYDROLOGY

Citation Formats

Russell, C E, Gillespie, D, Cole, J C, and Drellack, S L. ER-12-1 completion report. United States: N. p., 1996. Web. doi:10.2172/465859.
Russell, C E, Gillespie, D, Cole, J C, & Drellack, S L. ER-12-1 completion report. United States. https://doi.org/10.2172/465859
Russell, C E, Gillespie, D, Cole, J C, and Drellack, S L. 1996. "ER-12-1 completion report". United States. https://doi.org/10.2172/465859. https://www.osti.gov/servlets/purl/465859.
@article{osti_465859,
title = {ER-12-1 completion report},
author = {Russell, C E and Gillespie, D and Cole, J C and Drellack, S L},
abstractNote = {The objective of drillhole ER-12-1 was to determine the hydrogeology of paleozoic carbonate rocks and of the Eleana Formation, a regional aquitard, in an area potentially downgradient from underground nuclear testing conducted in nearby Rainier Mesa. This objective was addressed through the drilling of well ER-12-1 at N886,640.26 E640,538.85 Nevada Central Coordinates. Drilling of the 1094 m (3588 ft) well began on July 19, 1991 and was completed on October 17, 1991. Drilling problems included hole deviation and hole instability that prevented the timely completion of this borehole. Drilling methods used include rotary tri-cone and rotary hammer drilling with conventional and reverse circulation using air/water, air/foam (Davis mix), and bentonite mud. Geologic cuttings and geophysical logs were obtained from the well. The rocks penetrated by the ER-12-1 drillhole are a complex assemblage of Silurian, Devonian, and Mississippian sedimentary rocks that are bounded by numerous faults that show substantial stratigraphic offset. The final 7.3 m (24 ft) of this hole penetrated an unusual intrusive rock of Cretaceous age. The geology of this borehole was substantially different from that expected, with the Tongue Wash Fault encountered at a much shallower depth, paleozoic rocks shuffled out of stratigraphic sequence, and the presence of an altered biotite-rich microporphyritic igneous rock at the bottom of the borehole. Conodont CAI analyses and rock pyrolysis analyses indicate that the carbonate rocks in ER-12-1, as well as the intervening sheets of Eleana siltstone, have been thermally overprinted following movement on the faults that separate them. The probable source of heat for this thermal disturbance is the microporphyritic intrusion encountered at the bottom of the hole, and its age establishes that the major fault activity must have occurred prior to 102.3+0.5 Ma (middle Cretaceous).},
doi = {10.2172/465859},
url = {https://www.osti.gov/biblio/465859}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Dec 01 00:00:00 EST 1996},
month = {Sun Dec 01 00:00:00 EST 1996}
}