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Title: Origin, diagnostics, and mitigation of a salt dissolution sinkhole at the US Strategic Petroleum Reserve storage site, Weeks Island, Louisiana

Abstract

A sinkhole was first observed in May 1992 over the edge of the two-level former salt mine that was converted for oil storage by the US Strategic Petroleum Reserve (SPR). Diagnostic studies that included geophysical, geochemical, drilling, and hydrological methods suggest a direct connection exists between the surface collapse area and the underground mine as shown by correlative measurements of sediment slump rates and brine influx into the mine. The dissolution of salt below the sinkhole that initiated the leak into the mine was likely caused by several confluent geologic processes, and exacerbated by mining-induced stresses that created fractures which served as hydrologic flowpaths. Modeling studies of mine stresses show that years may be required before tensional cracking begins to occur, but once begun can continue to develop, and relieve the stress in that specific regime. The crack regime creates the avenue for incursion of groundwater, very slowly initially, but gradually enlarging as undersaturated groundwater dissolves salt on the sides of the crack. Mitigation measures include increasing the mine pressurization, slowing the dissolution by injecting brine into the sinkhole throat, and freeze grouting to restrict hydrologic flowpaths.

Authors:
 [1];  [2]
  1. Sandia National Labs., Albuquerque, NM (United States)
  2. USDOE, New Orleans, LA (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
90361
Report Number(s):
SAND-95-0222C; CONF-951098-1
ON: DE95008505
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: 5. international symposium on land subsidence, The Hague (Netherlands), 16-20 Oct 1995; Other Information: PBD: 27 Jan 1995
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; GROUND WATER; WATER INFLUX; SALT DEPOSITS; DISSOLUTION; STRATEGIC PETROLEUM RESERVE; SALT CAVERNS; MINES

Citation Formats

Neal, J T, and Myers, R E. Origin, diagnostics, and mitigation of a salt dissolution sinkhole at the US Strategic Petroleum Reserve storage site, Weeks Island, Louisiana. United States: N. p., 1995. Web.
Neal, J T, & Myers, R E. Origin, diagnostics, and mitigation of a salt dissolution sinkhole at the US Strategic Petroleum Reserve storage site, Weeks Island, Louisiana. United States.
Neal, J T, and Myers, R E. 1995. "Origin, diagnostics, and mitigation of a salt dissolution sinkhole at the US Strategic Petroleum Reserve storage site, Weeks Island, Louisiana". United States. https://www.osti.gov/servlets/purl/90361.
@article{osti_90361,
title = {Origin, diagnostics, and mitigation of a salt dissolution sinkhole at the US Strategic Petroleum Reserve storage site, Weeks Island, Louisiana},
author = {Neal, J T and Myers, R E},
abstractNote = {A sinkhole was first observed in May 1992 over the edge of the two-level former salt mine that was converted for oil storage by the US Strategic Petroleum Reserve (SPR). Diagnostic studies that included geophysical, geochemical, drilling, and hydrological methods suggest a direct connection exists between the surface collapse area and the underground mine as shown by correlative measurements of sediment slump rates and brine influx into the mine. The dissolution of salt below the sinkhole that initiated the leak into the mine was likely caused by several confluent geologic processes, and exacerbated by mining-induced stresses that created fractures which served as hydrologic flowpaths. Modeling studies of mine stresses show that years may be required before tensional cracking begins to occur, but once begun can continue to develop, and relieve the stress in that specific regime. The crack regime creates the avenue for incursion of groundwater, very slowly initially, but gradually enlarging as undersaturated groundwater dissolves salt on the sides of the crack. Mitigation measures include increasing the mine pressurization, slowing the dissolution by injecting brine into the sinkhole throat, and freeze grouting to restrict hydrologic flowpaths.},
doi = {},
url = {https://www.osti.gov/biblio/90361}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jan 27 00:00:00 EST 1995},
month = {Fri Jan 27 00:00:00 EST 1995}
}

Conference:
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