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Title: Potential geologic hazards of Arctic gas hydrates

Abstract

Sediments of the Arctic region may contain enormous quantities of natural gas in the form of gas hydrates, which are crystalline substances composed of water and mostly methane gas. These ice-like substances are generally found in two distinct environments: (1) offshore in sediments of outer continental margins and (2) nearshore and onshore in areas associated with the occurrence of permafrost. Recently, US, Canadian, and Soviet researchers have described numerous drilling and production problems attributed to the presence of gas hydrates, including uncontrolled gas releases during drilling, collapsed casings, and gas leakage to the surface. When the drill bit penetrates a gas hydrate, the drilling mud, unless cooled significantly by the operator, will become highly gasified as the hydrate decomposes. The hydrate adjacent to the well bore will continue to decompose and gasify the drilling mud as long as drilling and/or production introduces heat into the hydrate-bearing interval. The production of hot fluids from depth through the permafrost and gas hydrate-bearing intervals adversely raises formation temperatures, thus decomposing the gas hydrates. If the disassociated, free gas is trapped behind the casing, reservoir pressures may substantially increase and cause the casing to collapse. In several wells in northern Alaska, the disassociated freemore » gas has leaked to the surface outside the conductor casing. An additional drilling hazard associated with gas hydrates results from the sealing attributes of hydrates, which may trap large volumes of over pressured free gas at shallow depths. Even though documented problems attributed to the presence of gas hydrates have been relatively few, it is likely that as exploration and development activity moves farther offshore into deeper water (>300 m) and to higher latitudes in the Arctic, the frequency of gas hydrate-related problems will increase.« less

Authors:
 [1]
  1. Geological Survey, Menlo Park, CA (USA)
Publication Date:
OSTI Identifier:
6795943
Report Number(s):
CONF-900605-
Journal ID: ISSN 0149-1423; CODEN: AABUD
Resource Type:
Conference
Journal Name:
AAPG Bulletin (American Association of Petroleum Geologists); (USA)
Additional Journal Information:
Journal Volume: 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; Journal ID: ISSN 0149-1423
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 58 GEOSCIENCES; ARCTIC REGIONS; PETROLEUM DEPOSITS; GAS HYDRATES; HAZARDS; EXPLORATION; RESERVOIR PRESSURE; WELL DRILLING; DRILLING; GEOLOGIC DEPOSITS; HYDRATES; MINERAL RESOURCES; POLAR REGIONS; RESOURCES; 030200* - Natural Gas- Reserves, Geology, & Exploration; 580000 - Geosciences

Citation Formats

Collett, T S. Potential geologic hazards of Arctic gas hydrates. United States: N. p., 1990. Web.
Collett, T S. Potential geologic hazards of Arctic gas hydrates. United States.
Collett, T S. 1990. "Potential geologic hazards of Arctic gas hydrates". United States.
@article{osti_6795943,
title = {Potential geologic hazards of Arctic gas hydrates},
author = {Collett, T S},
abstractNote = {Sediments of the Arctic region may contain enormous quantities of natural gas in the form of gas hydrates, which are crystalline substances composed of water and mostly methane gas. These ice-like substances are generally found in two distinct environments: (1) offshore in sediments of outer continental margins and (2) nearshore and onshore in areas associated with the occurrence of permafrost. Recently, US, Canadian, and Soviet researchers have described numerous drilling and production problems attributed to the presence of gas hydrates, including uncontrolled gas releases during drilling, collapsed casings, and gas leakage to the surface. When the drill bit penetrates a gas hydrate, the drilling mud, unless cooled significantly by the operator, will become highly gasified as the hydrate decomposes. The hydrate adjacent to the well bore will continue to decompose and gasify the drilling mud as long as drilling and/or production introduces heat into the hydrate-bearing interval. The production of hot fluids from depth through the permafrost and gas hydrate-bearing intervals adversely raises formation temperatures, thus decomposing the gas hydrates. If the disassociated, free gas is trapped behind the casing, reservoir pressures may substantially increase and cause the casing to collapse. In several wells in northern Alaska, the disassociated free gas has leaked to the surface outside the conductor casing. An additional drilling hazard associated with gas hydrates results from the sealing attributes of hydrates, which may trap large volumes of over pressured free gas at shallow depths. Even though documented problems attributed to the presence of gas hydrates have been relatively few, it is likely that as exploration and development activity moves farther offshore into deeper water (>300 m) and to higher latitudes in the Arctic, the frequency of gas hydrate-related problems will increase.},
doi = {},
url = {https://www.osti.gov/biblio/6795943}, journal = {AAPG Bulletin (American Association of Petroleum Geologists); (USA)},
issn = {0149-1423},
number = ,
volume = 74:5,
place = {United States},
year = {Tue May 01 00:00:00 EDT 1990},
month = {Tue May 01 00:00:00 EDT 1990}
}

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