PHYSICAL AND MECHANICAL FEATURES OF IMPLEMENTATION OF HIGH STRENGTH PROPERTIES OF THE WELDED JOINTS OF OVERLOADED DRILL PIPES
Abstract
The main purpose of the research presented in the article is to increase the efficiency of construction of deeply directional and horizontal wells.
Taking into account the high cost of drilling operations, as well as the increase in prices on the world market for rolled metal products, we proposed using similar pipes, but with welded threaded ends, as ordinary heavy-weight drill pipes. Welded joints are stress concentrators in themselves. Therefore, a perfect technology for welding drill pipes is needed, which can ensure trouble-free operation.
Herein we consider the method of determination of stress in the connection weld of heavy-weight drill pipe with welded field ends. Depending on the type of welding and thermal processing of the connection weld, the pattern of stress distribution before and after thermal processing is of science interest. We use the mathematical model that enables consideration of stress distribution on the stage of cooling taking into account the possible phenomenon of plastic deformation along with strengthening accompanied by increase of limit of liquidity.
This model used makes it possible to study the currents and residual thermo-mechanical fields formed during the cooling stage.
Such mathematical modeling of the process of heat treatment of a welded joint of heavy-duty drill pipes makes it possible, at various functional coefficients of heat transfer with the environment (gas, liquid), to evaluate how and on what the level the depended of flow and residual stresses of welded joints. Here, the important components for the tempering process are the welding method, the physical and mechanical characteristics of the seam materials, the hardening parameters and the heat transfer coefficients of the materials that make up the welded joint of the drill collars.
Such pipes, with welded threaded ends, make it possible to save expensive alloy steel. This, in turn, will help to reduce the cost of drilling operations.
