Method for solving cutting parameters of PDC drill bit cutting teeth under wear condition

Abstract

The invention relates to a method for solving cutting parameters of PDC drill bit cutting teeth under wear condition and belongs to the kinematics field of oil-gas drilling tools. The method mainly comprises the steps of building a geometrical model of worn teeth, conducting axial plane projection on the worn teeth when drilling rate is zero and finding adjacent teeth, finding a null point on a cutting section, conducting bidirectional traversal starting from the null point and recording traversal path, dispersing the traversal path into points, and solving cutting parameters according to discrete points. By the adoption of the method, the cutting parameters of the worn teeth can be solved, and the problem that there is no algorithm for solving the cutting parameters of worn teeth currently is solved; solving precision is high and is 1e-5 mm; the cutting parameters of worn teeth can be accurately calculated; the stress change trend and wear trend of cutting teeth can be predicted accurately by means of stress and wear models, and wear design of a PDC drill bit is supported.

Description

technical field [0001] The invention relates to a method for solving cutting parameters of cutting teeth of a PDC drill bit under wear conditions, and belongs to the field of kinematics of oil and gas drilling tools. Background technique [0002] Since the PDC bit was born in 1973, the proportion of the world's total oil and gas drilling footage has grown from 5% in 1988 to 90% now, and the drilling efficiency is about 5 to 10 times that of 20 or 30 years ago. However, with the development of drilling projects in deep, ultra-deep and complex formations, the wear and unevenness of the cutting teeth of PDC bits are more serious, and the early failure of individual teeth has become a cause of short life of PDC bits and low rock breaking efficiency. , one of the main reasons why it cannot adapt to deep complex and difficult-to-drill formations. Once a few cutting teeth are damaged in advance, the remaining cutting teeth will bear additional force, and the wear and vibration wil...

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Problems solved by technology

However, at present, research at home and abroad is mostly focused on the solution of the cutting parameters of the PDC bit cutting teeth before wear, and no research has been carried out on the cutting parameters of the PDC bit cutting teeth after wear, which will inevitably lead to the inability to accurately predict the force change of each cutting tooth trend and later wear trend, it is impossible to fundamentally solve the phenomenon of uneven wear, and it is impossible to achieve the purpose of improving the performance of PDC bits through the design of equal wear teeth

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