Analytical and experimental research on erosion wear law of drill pipe in gas drilling

Erosion of drill pipe caused by the rock particles in annular space is very serious in gas drilling. The aim of this paper is to study the erosion wear law of drill pipe by theoretical derivation and laboratory experiment. Based on the micro-cutting model of single rock particle, the erosion model of drill pipe is established to calculate the erosion wear loss. This model establishes the relationship between the erosion wear loss of drill pipe and drilling parameters, such as gas injection volume and rate of penetration (ROP). The laboratory experiment is carried out to verify and revise the erosion model, and the results show that when ROP is less than 20 m/h, the erosion wear loss of drill pipe is approximatively proportional to the square of gas injection volume and has positive correlation with ROP. However, it has negative correlation with ROP when ROP is faster than 20 m/h. In addition, it is also obtained that gas injection volume has more impact on drill pipe erosion compared to ROP based on the analysis of an engineering example, and high ROP will suppress the erosion wear of drill pipe. Therefore, under the premise of satisfying the drilling requirements, employing lower gas injection volume and higher ROP can reduce drill pipe erosion in gas drilling, which will save the drilling cost greatly.