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Abstract
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Article Information:
Geo Mechanical Analysis of Casing Failure in Bedded Rock Salt Formation
Tongtao Wang, Xiangzhen Yan, Xiujuan Yang, Xuewen Cao and Hongduan Huang
Corresponding Author: Xiang Zhen Yan
Submitted: February 10, 2012
Accepted: March 12, 2012
Published: September 01, 2012 |
Abstract:
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There are many bedded rock salt resources in China which are serviced as the hosts of underground
natural gas storages. For the relatively thin nature of bedded rock salt and the local presence of other
sedimentary rock formations, the design and safety evaluation of well completion casing take greater challenges
to the engineers than that of casing in other type formations, i.e., limestone and carbonatite. The 2D and 3D
geomechanical models of casing-cement sheath-rock salt are established in the paper based on the field data
to obtain the creep loads in casing and find the main reasons causing casing failure. In addition, the effects of
non-salt layer dip angle, friction factor between salt and non-salt layers and non-salt layer thickness, etc., on
the stresses and deformations of casing are studied. The comprehensive results show hoop creep loads are the
main reasons causing casing failure rather than radial creep loads. The cement sheath can improve the safety
and optimize force state of casing even in perfect wellbore, which disagrees with Willson’s view that the
cement sheath can be neglected in a salt formation wellbore with high quality. The non-uniform factor of radial
creep loads in cement sheath is slightly smaller than that of original in-situ stresses, while that of radial creep
loads in casing is greatly smaller than it. The stresses and deformations of casing increase with increasing
thickness of non-salt layer and decrease with the increase of friction factor. When the non-salt layer dip angle
is with a value of 50 deg, the stresses and deformations achieve the max and subsequently decrease.
Key words: Bedded rock salt, casing, creep loads, failure analysis, numerical analysis, ,
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Cite this Reference:
Tongtao Wang, Xiangzhen Yan, Xiujuan Yang, Xuewen Cao and Hongduan Huang, . Geo Mechanical Analysis of Casing Failure in Bedded Rock Salt Formation. Research Journal of Applied Sciences, Engineering and Technology, (17): 3069-3077.
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ISSN (Online): 2040-7467
ISSN (Print): 2040-7459 |
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