Intensity analysis of frictional heat source during core tube sampling and drilling

Abstract

AbstractCurrently, the heat generated during coal core tube sampling causes rapid gas desorption, leading to substantial measurement errors in laboratory gas content assessments. Reducing these errors requires studying frictional heat from core tube friction against the hole wall and coal core temperature rise. Combining the independently developed device to simulate the thermal effect of coring and the COMSOL finite element analysis software, the intensity of the frictional heat source during the core tube sampling and drilling process was analyzed under different coring depth and rotational speed conditions. The research results show that: At constant speed, frictional heat intensifies as the core depth increases. However, the rate of temperature rise decreases with increasing core depth; when the coring depth is constant, the frictional heat is proportional to the rotational speed. For example, at a depth of 140 m and a rotational speed of 120 r/min, the intensity of frictional heat generated by drilling is 2.21 ∗ 10E6J. Similarly, at 180 r/min, the strength is 2.28 ∗ 10E6J, and at 240 r/min, the strength reaches 3.65 ∗ 10E6J; Under certain conditions, core tube wall temperature will not rise indefinitely but will stabilize to a certain value.