Erosion Law of Drill Pipe in Whole Well During Gas Drilling

This paper uses the gas-solid two phase flow theory to establish the erosion model when drilling pipes are eccentric in the borehole,in the center of the borehole and in the borehole with increased diameter,and CFD software is also utilized for the corresponding analog. By comparing gas flow field in annular,erosion rate of drilling string and trajectory of cuttings,it turns out that erosion rate of drilling string is inversely proportional to the depth of borehole,and the maximum erosion rate is found near the tool joint windward surface. Also,it finds out that eccentricity of drilling pipe can exacerbate local erosion rate peak. The increase in diameter of borehole can intensify the erosion of cuttings on drilling string by analyzing erosion rate of shaft and drilling string as well as trajectory of cuttings in borehole with increased diameter.