Research On Erosion Failure Of Lower Drilling Tools In Gas Drilling

Researchers have studied the Gas drilling for long time, but with the limiting of the construction conditions it is not as widely used as the conventional drilling means. This article studies the erosion of the bottom hole of gas drilling, analyzed the rule of drill erosion by experimental study on erosion, erosion model and numerical simulation methods. I focus on the question of erosion failure for gas drilling bottom hole to carry out the following research work and get the corresponding conclusions:(1)At first, I research and development design automatic erosion test apparatus, and use it to study the erosion regular pattern of test piece. Then get the law of peeling paint for a long time after the erosion. In the quantitative study of test piece erosion,Rough estimates of the erosion rate of steel in Experiment.(2)Useing numerical simulation software to establish a erosion models of test piece and downhole drill model. Adjust the calculation settings of erosion parameter, the results in the simulation of the erosion of test piece is similar to the results of erosion Experiments. Design downhole drill model simulation set times and optimize the mesh model. I designed the inport and export conditions and environment variables according to the actual conditions.(3)Use DPM model to calculate the annulus flow field and drilling under different inport and export conditions. The results showed that:Erosion mainly on the face of tool joint, the signs of erosion is spirally on the face of drill and can be effected by different inport conditions. The changing of inlet velocity shows large influences on the annulus flow field and erosion rate, but the changing of inlet pressure shows little influences on that.(4)With changing the physical model of gas drilling bottom hole and environment variable settings, I calculate the drill erosion rate in different conditions. And founding that conditions make an important factor in the erosion rate of drill.