Sensitivity analysis of reservoir risk in marine gas hydrate drilling
Wantong Sun,
Jun Pei,
Na Wei,
Jinzhou Zhao,
Jin Xue,
Shouwei Zhou,
Liehui Zhang,
Bjørn Kvamme,
Qingping Li,
Haitao Li,
Lin Jiang,
Chao Zhang,
Cong Li
Affiliations
Wantong Sun
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China; State Key Laboratory of Natural Gas Hydrate, Beijing, 100027, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang, 524013, China; Corresponding author.
Jun Pei
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China; Corresponding author.
Na Wei
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China; State Key Laboratory of Natural Gas Hydrate, Beijing, 100027, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang, 524013, China; Corresponding author.
Jinzhou Zhao
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China; State Key Laboratory of Natural Gas Hydrate, Beijing, 100027, China
Jin Xue
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China
Shouwei Zhou
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China; State Key Laboratory of Natural Gas Hydrate, Beijing, 100027, China
Liehui Zhang
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China; State Key Laboratory of Natural Gas Hydrate, Beijing, 100027, China
Bjørn Kvamme
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China; State Key Laboratory of Natural Gas Hydrate, Beijing, 100027, China
Qingping Li
State Key Laboratory of Natural Gas Hydrate, Beijing, 100027, China; CNOOC Research Institutes Limited Liability Company, Beijing, 100027, China
Haitao Li
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China; State Key Laboratory of Natural Gas Hydrate, Beijing, 100027, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang, 524013, China
Lin Jiang
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China
Chao Zhang
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China
Cong Li
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China
It is easy to change the original temperature state of marine gas hydrate reservoir by drilling, which leads to uncontrollable decomposition of gas hydrate and release of large amount of gas. The decomposition gas will further escape and expand, and the reservoir will break and collapse due to its weak cementation characteristic, which will easily lead to a series of other potential risks. Therefore, in this study, based on the drilling process of marine gas hydrate, we establish the theoretical model and numerical calculation method of wellbore temperature field, analyze the influence on wellbore temperature of drilling fluid displacement, density, viscosity and injection temperature, and seawater depth. Then the sensitivity laws of reservoir risk in marine gas hydrate drilling are obtained. The results show that with the increase of drilling fluid displacement, density, viscosity and injection temperature, the temperature in lower well section and bottom hole will increase, making the increasing amplitude of temperature in hydrate reservoir larger and the scope of influence on hydrate reservoir stability bigger. Moreover, drilling is more likely to raise the temperature of reservoirs in shallow seawater depth, posing greater risks. Thus, engineering measures to avoid risks caused by rising reservoir temperature in marine gas hydrate reservoir drilling are presented. This study is of great significance to ensure the safety of marine gas hydrate reservoir drilling.
