A rapid evaluation method for the working state of pre-bent bottom hole assembly

Abstract

The invention provides a rapid evaluation method of pre-bending bottom hole assembly (BHA) working state. The structural parameters of a pre-bending BHA is determined by a special measurement tool, the mechanical parameters of the material used for the pre-bending BHA are determined through a material tensile experiment, combining with a weighted allowance method and a finite element method, the working state diagram of the pre-bending BHA is established on the basis of obtaining the steady-state dynamic response of the transverse vibration of the pre-bending BHA, so that the working state ofthe pre-bending BHA in the actual drilling operation can be quickly evaluated. By means of the method, the transverse vibration characteristic of the pre-bending BHA used in the actual drilling process can be obtained, so that the critical rotating speed and the working state diagram are obtained, and the working state of the pre-bending BHA can be quickly determined according to the critical rotating speed and the working state diagram. The method can be used for pre-drilling analysis to reasonably design the structure of the pre-bending BHA and the preferred drilling parameters, and can alsobe used for post-drilling analysis to find out the lose-efficacy preliminary reason of the pre-bending BHA (such as failure), and the engineering application significance is high.

Description

technical field [0001] The invention relates to the technical field of oil and gas drilling, in particular to a method for quickly evaluating the working state of a pre-bent bottom hole assembly (BHA, Bottom Hole Assembly). Background technique [0002] BHA with pre-bent structure and stabilizer (pre-bent BHA), due to its low cost and easy maintenance, is a commonly used drilling tool for directional wells and horizontal wells (such as slide steerable with single curved screw BHA). Since the end of the last century, this BHA has been used for anti-deviation and fast drilling operations of vertical wells. As a vertical and horizontal bending beam with a special structure, the motion of the pre-bent BHA in the wellbore has dual nonlinearities of geometry and contact, and its mechanical characteristics are very complex. Early experts and scholars studied the static characteristics of pre-bent BHA by using the theory of vertical and horizontal bending beams, and obtained the l...

AI Technical Summary

Problems solved by technology

However, due to the existence of the curved structure in the pre-bent BHA, there is a contradiction between the solution efficiency and the solution accuracy when using the finite element method to solve its statics (if the solution speed is fast, the number of elements required is small, and the accuracy will be reduced)

Therefore, it is not suitable for the rapid evaluation of the lateral vibration and working state of the pre-bending BHA

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