Epitrochoidal Cutter Path Analysis for Bent Housing Drill Bits

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The complex motion of a drill bit with a bent housing in directional drilling cannot be accurately described using a simple helical model, making it challenging to analyze and optimize drill bit performance and borehole direction.

Innovation Solution

The use of epitrochoidal functions to simulate the path of a drill bit cutter coupled with a bent housing, considering the rotational speeds of both the drill bit and the bent housing, allows for the determination of the cutter's path and drilling forces, enabling optimized drill bit design and borehole direction control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a simple helical model is used to describe drill bit motion, then the analysis is simplified, but the accuracy of motion description deteriorates

Engineering Contradiction:
Improveanalysis complexityVSAvoidmotion description accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent transforms the drill bit motion analysis from a simple helical model to a complex epitrochoidal model by changing the mathematical parameters used to describe the motion. This allows accurate representation of the coupled rotational movements while maintaining manageable analysis through systematic parameter definition

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a mathematical copy of the actual drill bit motion using epitrochoidal functions. This virtual model replicates the complex physical motion patterns without requiring physical measurement, enabling accurate analysis while avoiding the complexity of direct physical measurement systems

Inventive Principle:
Principle #26Copying

2Measurement precision

If the complex motion of drill bit with bent housing is accurately modeled using epitrochoidal functions, then the motion analysis precision is improved, but the computational complexity increases

Engineering Contradiction:
Improvemotion analysis precisionVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the complex drill bit motion into distinct rotational components - the rotation of the bent housing and the rotation of the drill bit relative to the housing. By separating these movements and applying epitrochoidal functions to each component, the system achieves accurate motion modeling while managing computational complexity through structured decomposition

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If rotational speeds of both drill bit and bent housing are considered in the simulation, then the drilling forces determination accuracy is improved, but the simulation complexity increases

Engineering Contradiction:
Improvedrilling forces determination accuracyVSAvoidsimulation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary computational framework that links the rotational speeds of the bent housing and drill bit through epitrochoidal functions. This intermediary mathematical model translates the coupled rotational movements into accurate drilling forces calculations without requiring direct complex interaction modeling between the rotating components

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS8386181B2System and method for bent motor cutting structure analysis
Publication Date: 2013.02.26 NAT OILWELL VARCO LP
  • US8386181B2 patent drawing
  • US8386181B2 patent drawing
  • US8386181B2 patent drawing

AI summary

Techniques for analyzing operation of drill bit in a borehole are disclosed herein. A method for analyzing operation of a drill bit in a borehole includes providing information describing the drill bit and a bent housing coupled to the drill bit. A path of a cutter of the drill bit is determined based on a ratio of a rotational speed of the bent housing to a combined rotational speed of the drill bit and the bent housing. The combined rotational speed is different from the rotation speed of the bent housing.