分水钻具的设计及其数值模拟分析

Design of Split-flow Drilling Tool and Its Flow Field Numerical Simulation

摘要:

岩（矿）心采取率低是单管取心钻进的主要问题。在钻进时由于冲洗液对岩心的冲刷作用，使岩（矿）心中的矿物颗粒不断被冲洗液带走，造成岩心缺失、岩心采取率过低。从钻具内部流速分布、冲洗液冲刷作用、岩心采取率、冲洗液携粉等角度出发，分析了单管钻进时造成岩心采取率过低的原因，采取分流、降速等方法，设计了一套可以在一定程度上提高岩心采取率的分水单管钻具，通过数值模拟，证明了该钻具在满足及时清除孔底岩粉的条件下，能使单管钻具中岩心周围冲洗液流速降低25%左右，进而解决常规单管钻进岩心采取率不足等问题。

Abstract:

The low core recovery is the main problem in single tube drilling. That tiny mineral particle of the core being taken away by drilling fluids continually causes the deficiency of core. The reasons for low core recovery is studied from the points of velocity profile, erosion action, core recovery and cuttings removal, and a set of single tube split-flow drilling tool has been designed with flow-distributing and area increasing to improve core recovery. The 3d-fem numerical simulation shows that this modified drilling tool can reduce the velocity of drilling fluids around core by about 25% under the condition of timely cuttings removal and solve the low core recovery.