Hookload Friction Calibration via Travelling Block Velocity
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Solution Overview
Problem
Existing well drilling systems face challenges in accurately measuring hookload due to frictional effects, particularly linear friction and Coulomb friction, which are not adequately addressed by current methods, and these methods are not applicable to all types of drilling rigs, especially those with and without motion compensators.
Innovation Solution
A method and apparatus for monitoring hookload that involves measuring raw hookload, determining the velocity of a travelling block, holding it stationary for a period, lowering it, calculating contributions from linear and directional velocity components, and correcting the raw hookload measurements using these calculations, implemented in an autodriller system with sensors and processors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing hookload measurement methods are used, then the measurement process is simple, but the measurement precision is insufficient due to unaccounted frictional effects
Solution Approach 1:
The patent applies preliminary action by performing friction calibration before actual drilling operations. The travelling block is held stationary and then lowered in a controlled manner to measure frictional effects under known conditions. This preliminary calibration allows the system to account for frictional contributions to hookload measurements before real drilling occurs, improving measurement precision without complicating the actual drilling operation.
Solution Approach 2:
The patent implements feedback by using the calibration measurements to create correction factors that are applied to subsequent hookload measurements. The frictional effects measured during calibration are fed back into the system as correction parameters, allowing continuous improvement of hookload measurement accuracy throughout the drilling operation.
2Measurement precision
If friction calibration is performed, then hookload measurement accuracy improves, but the time required for calibration increases
Solution Approach 1:
The calibration is performed as a preliminary action during drilling operations, specifically during drill-offs when the travelling block is naturally held stationary and then lowered. This allows friction characteristics to be captured during normal operational cycles rather than requiring separate dedicated calibration time, thereby minimizing time loss.
Solution Approach 2:
The patent ensures continuity of useful action by integrating friction calibration into the ongoing drilling process. The calibration measurements are taken during drill-off operations that are already part of the drilling cycle, and the correction factors are applied continuously during subsequent drilling operations, making the calibration process continuous rather than intermittent.
3Measurement precision
If linear and directional friction components are accounted for, then measurement precision improves, but the calculation complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the frictional effects into distinct components: a linear velocity-dependent component and a directional (Coulomb) component. Each component is measured and calculated separately during calibration, allowing the complex friction behavior to be broken down into manageable parts that can be independently characterized and then combined for the final correction.
Solution Approach 2:
The patent utilizes parameter changes by determining different friction characteristics for linear and directional components through controlled variations in block velocity and direction during calibration. By changing the velocity magnitude and direction parameters during calibration measurements, the system can independently characterize each friction component and apply appropriate correction factors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively accounts for both linear and directional friction components, providing accurate hookload measurements that improve drilling efficiency and precision, applicable to various drilling rig configurations, including those with and without motion compensators.
Implementation Method 1
The current invention accounts both for linear friction effects, and friction that depends only on the direction of motion—not its amplitude (Coulomb friction).
Implementation Method 2
friction that depends only on the direction of motion—not its amplitude (Coulomb friction).
Data Source
AI summary
A method and autodriller for monitoring hookload in a well drilling system that measures raw hookload; determines a velocity of a travelling block; holds the travelling block in a non-lowering state for a first period of time; lowers the travelling block for a second period of time; calculates contribution to hookload of a component linear in the block velocity; calculates contribution to hookload of a component linear in a direction (sign) in the block velocity; and corrects measured raw hookload by the calculated contributions.