水平孔携岩能力影响因素数值模拟研究

Numerical simulation study on factors affecting cuttings-carrying capacity in horizontal holes

摘要:

梳状孔是目前煤层气开采的主要技术手段之一，水平孔作为梳状孔的主孔，研究其在不同条件下岩屑的分布情况，可作为钻进参数选择的重要依据。本文基于FLUENT流体力学模拟软件，分析了钻杆转速、钻井液粘度、环空返速、岩屑浓度、岩屑颗粒直径、钻孔偏心等因素对水平孔中携岩能力的影响。结果表明：随钻杆转速、环空返速、钻井液粘度递增，环空岩屑浓度峰值降低，对岩屑运移有利；而岩屑浓度、岩屑直径的增大导致岩屑浓度峰值增大，加大了携岩压力，这2个参变量的增大对运移岩屑是不利的。钻井液粘度、钻杆转速对岩屑的运移和分布起重要的决定作用，环空返速、岩屑浓度、岩屑直径作用次之。

关键词:水平孔;携岩能力;FLUENT;环空返速

Abstract:

The comb-like multi-lateral hole is one of the main technical methods for coalbed methane mining. Study of the distribution of cuttings under different conditions in the horizontal hole, which works as the mother hole of comb-like laterals, can be used as an important basis for the selection of drilling parameters. Based on FLUENT fluid dynamics simulation software, the paper analyzes the effects of drill string rpm, drilling fluid viscosity, annulus velocity, debris concentration, debris particle size and borehole eccentricity on the cuttings-carrying capacity in horizontal holes. The result can provide a scientific basis for rational selection of drilling parameters during the drilling process.

Key words:horizontal holes; cuttings-carrying capacity; FLUENT; annulus velocity