A Study of the Vibration Characteristics of Flexible Mechanical Arms for Pipe String Transportation in Oilfields

Yan Wang,Ruijie Zhang,Sheng Gao,Yongliang Ren,Shuwen Lu

doi:10.3390/en15062030

Abstract

During the drilling and repairing of wells, the pipe string transfer equipment has a high work frequency. The movement accuracy, response speed, and controllability of the equipment have significant impacts on the stability. In this paper, we propose an analysis method of mechanical arms to lift pipe strings using a rigid–flexible coupling model. With the mechanical arm as a flexible body and the mechanical hand as a rigid body, a numerical calculation model of the rigid-flexible coupling of the system was established based on the Lagrangian equation. ADAMS and Ansys software were applied to numerical simulations of this system to investigate the lifting characteristics, the influence of the operation parameters and structure parameters, and the contact collision analysis of the mechanical arm. The conditions of rigid–flexible modeling for the multi-body system and the main factors affecting the vibration characteristics of the flexible arm are described. We conclude that the arm should be modeled as a rigid body if the structure parameter [w/l] (elastic deformation/length) is between 1/650 and 1/1000, the system can be modeled as a rigid–flexible coupling if [w/l] is between 1/400 and 1/650, and the arm should be modeled as a flexible body and the influence and compensation of the control method should be considered if [w/l] is between 1/250 and 1/400.

Highlights

During the drilling and repairing of wells, the round trip and discharge operations of the drilling rod, casing, and pipe string are usually carried out
We described the main factors affecting the vibration characteristics of a flexible arm and modeling conditions of a multi-body system
XOY is the fixed coordinate system, xOy is the dynamic coordinate system, w(x,t) is the elastic deformation at any point P(X,Y) at time t on the flexible arm, l is the length of the flexible arm, E is the elastic modulus of the material, I is the moment of inertia of the section to the neutral axis, ρ is the arm’s density, θ is the rigid body angle of the flexible arm, ml is the concentrated mass, and u is the control torque

Summary

Introduction

During the drilling and repairing of wells, the round trip and discharge operations of the drilling rod, casing, and pipe string are usually carried out. In the round-trip process, the discharge operation of a drill string needs to be repeated many times. The characteristics of this kind of equipment are a large work scope and harsh environment. The system can grab and lift different sizes of string (drill rod, casing, and drill collar), as well as cooperate with the gear rack rig well, which makes it suitable for small- and medium-sized rigs with low rig heights.

Methods

Findings

Discussion

Conclusion