Tubular Running Load Limits Using Torque-and-Drag Modelling
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Solution Overview
Problem
In deviated wells, tubular running operations face challenges due to complex frictional and side loads that impede progress and risk overloading components, making it difficult to manage loads effectively without direct downhole measurements.
Innovation Solution
A method and system for calculating a surface load limit using torque-and-drag analysis to optimize tubular running operations by determining a safe load that maintains component loads within specified limits, allowing for reduced operation duration and extended reach without requiring downhole measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If frictional forces are overcome by applying excessive load to the running string, then the string can advance into the well, but the components of the running string may be overloaded and damaged
Solution Approach 1:
The patent performs torque-and-drag analysis before the tubular running operation to predict frictional forces and determine safe load limits. This preliminary calculation allows the operator to apply the minimum necessary load to overcome friction without exceeding component capacity, thereby avoiding both stalled operations and overloading during the actual running operation.
Solution Approach 2:
The patent establishes a feedback mechanism where torque-and-drag analysis continuously monitors and compares applied loads against predicted frictional forces and component load limits. This feedback loop enables real-time adjustment of applied load to maintain optimal advancement while preventing component overload, resolving the contradiction between speed and strength.
2Strength
If the running string is moved slower to reduce frictional forces, then component overloading is reduced, but the operation duration increases
Solution Approach 1:
By performing torque-and-drag analysis before the operation, the patent determines the optimal speed and load profile that minimizes both frictional forces and operation duration. This preliminary planning allows the operator to run the tubular string at the fastest safe speed without excessive component loading, thereby reducing operation time while maintaining strength safety.
Solution Approach 2:
The patent changes operational parameters (speed, load, rotation rate) based on torque-and-drag analysis predictions. By optimizing these parameters to match the actual frictional conditions, the system achieves the shortest possible operation duration while keeping component loads within safe limits, resolving the time-strength contradiction.
3Measurement precision
If torque-and-drag analysis is performed with high precision to accurately determine load limits, then component overloading is prevented, but the complexity of the analysis increases
Solution Approach 1:
The patent replaces complex mechanical measurement systems with computational torque-and-drag analysis. Instead of using physical sensors and mechanical measurement devices downhole, the system uses mathematical models and computer calculations to determine load limits with high precision, thereby achieving accurate measurement without increasing physical device complexity.
Solution Approach 2:
The patent introduces torque-and-drag analysis as an intermediary between the operator and the running string conditions. This analytical intermediary processes available data (friction factors, wellbore geometry, string properties) to predict loads and determine safe operating limits, achieving high precision without requiring direct complex measurements at the wellsite.
4Force
If the running string is rotated to break friction, then axial frictional forces are reduced, but torque loads on the running string increase
Solution Approach 1:
The patent performs torque-and-drag analysis before the operation to predict the torque required to break friction and the resulting stresses on the running string. This preliminary calculation allows the operator to decide whether rotation is necessary and, if so, at what rate and for how long, thereby managing the trade-off between reducing axial friction and limiting torque stress.
Solution Approach 2:
The patent applies dynamic control of rotation during the tubular running operation, adjusting rotation rate and duration based on real-time monitoring and torque-and-drag predictions. This dynamic approach allows the system to break friction effectively while limiting the total torque exposure to safe levels, resolving the force-stress contradiction.
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
Enables optimization of tubular running operations by ensuring component loads remain within acceptable levels, reducing the risk of overloading and enhancing operational efficiency and depth reach.
Implementation Method 1
frictional forces on the running string act to impede its progress into the well
Implementation Method 2
Contact forces between a wellbore and a running string are referred to as side load
Implementation Method 3
forces acting on the running string during a tubular running operation include gravity (i.e., the weight of the running string itself)
Implementation Method 4
forces acting on the running string during a tubular running operation include gravity (i.e., the weight of the running string itself) and buoyancy, which results from the running string displacing fluid within the well
Implementation Method 5
Side load may result from the running string resting on the low side of the wellbore, from tension or compression pulling or pushing the running string to the side of a curved wellbore (the 'capstan effect')
Data Source
AI summary
A method for optimizing tubular running operations (TROs) on a drilling rig calculates a surface load limit of a running string, using each of one or more selected modelled kinematic conditions as input to torque-and-drag analysis (TDA) in the bottom-up direction to estimate a running string load distribution including an estimated load acting at the top of the running string, and for each selected component of the running string calculating a load buffer, identifying a limiting load buffer from among the calculated load buffers, calculating a surface load buffer based on the limiting load buffer, and calculating the surface load limit based on the surface load buffer. TROs may be optimized by taking steps as necessary to keep actual loads applied to the upper end of the running string within surface load limits. Optionally, TDA in the top-down direction may be iteratively performed to determine revised surface load limits.