Affiliation:
1. School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China
2. CNPC Offshore Engineering Company Limited, Beijing 100028, China
Abstract
The study of wellbore stability in offshore gas hydrate reservoirs is an important basis for the large-scale exploitation of natural gas hydrate resources. The wellbore stability analysis model in this study considers the evolution of the reservoir mechanical strength, wellbore temperature, and pressure parameters along the depth and uses plastic strain as a new criterion for wellbore instability. The wellbore stability model couples the hydrate phase transition near the wellbore area under the effect of the wellbore temperature and pressure field and the ‘heat–fluid–solid’ multifield evolution characteristics, and then simulates the stability evolution law of the wellbore area during the drilling process in the shallow seabed. The research results show that, owing to the low temperature of the seawater section and shallow formation, the temperature of the drilling fluid in the shallow layer of the wellbore can be maintained below the formation temperature, which effectively inhibits the decomposition of hydrates in the wellbore area. When the wellbore temperature increases or pressure decreases, the hydrate decomposition rate near the wellbore accelerates, and the unstable area of the wellbore will further expand. The research results can provide a reference for the design of drilling parameters for hydrate reservoirs.
Funder
National Natural Science Foundation of China
China National Petroleum Corporation Technology Development Project
Subject
Energy (miscellaneous),Energy Engineering and Power Technology,Renewable Energy, Sustainability and the Environment,Electrical and Electronic Engineering,Control and Optimization,Engineering (miscellaneous),Building and Construction
Cited by
1 articles.
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