深水天然气水合物储层钻井多物理场耦合数值分析
Numerical Simulation Analysis of Multi-physics Field Coupling in Deepwater Gas Hydrate Reservoir Drilling
赵珂 1刘磊 1廖波 1王金堂 1陈龙桥 2孙金声3
作者信息
- 1. 中国石油大学(华东)石油工程学院,青岛 266580
- 2. 中国石油集团海洋工程有限公司,北京 100028
- 3. 中国石油大学(华东)石油工程学院,青岛 266580;中国石油集团工程技术研究院有限公司,北京 102206
- 折叠
摘要
在深水天然气水合物储层钻井过程中,钻井液易侵入储层导致井筒内温度和压力变化,引起水合物分解,造成井壁失稳.考虑钻井液作用下的水合物解离和井筒-储层传热传质,建立了深水天然气水合物储层多孔介质非稳态传热多场全耦合模型,并进行数值分析.结果表明,当钻井液侵入后,水合物储层的温度和压力呈现不同程度的上升,沿地层方向的温度变化率为0.618K/m,压力变化率为0.39MPa/m.水合物饱和度沿地层向下逐渐降低,平均变化率为0.06 m-1.水合物分解导致井筒周围力学强度下降,等效塑性应变增加,20 h后井筒周围塑性应变达到90％,井筒失稳风险增加.因此,在水合物储层钻井过程中,应降低钻井液温度,或进行井筒-储层传热和传质屏蔽,以实现安全高效钻井.
Abstract
During the drilling process in deepwater gas hydrate reservoirs,the drilling fluid is prone to intrude into the reservoir,leading to temperature and pressure changes in the wellbore,which causes hydrate decomposition and results in instability of the well wall.A multi-field full-coupling model of unsteady heat transfer in the porous media in deepwater natural gas hydrate reservoirs is established with the hydrate dissociation under the action of drilling fluids and the mass and heat transfer in consideration.The simulation results show that when the drilling fluid intrudes,the temperature and pressure of the hydrate reservoir appear to varying degrees of increase.The temperature change rate is 0.618 K per meter along the formation direction,and the pressure change rate is 0.39 MPa per meter.The hydrate saturation gradually decreases in the formation direction,and the average rate of change is 0.06 per meter.Hydrate dissociation leads to a decrease in mechanical strength and an increase in the equivalent plastic strain around the wellbore.The plastic strain around the wellbore reaches 90％after 20 hours,and the instable risk of the wellbore increases.During hydrate reservoir drilling,the temperature of the drilling fluid should be reduced,or wellbore-reservoir transfer shielding of mass and heat should be implemented to achieve safe and efficient drilling.
关键词
天然气水合物/钻井液侵入/井筒-储层耦合/多物理场耦合/井壁稳定Key words
natural gas hydrates/drilling fluid invasion/wellbore-reservoir coupling/multi-physics field coupling/wellbore stability引用本文复制引用
基金项目
国家重点研究发展项目(2021YFC2800803)
出版年
2024
NETL
NSTL
万方数据