Overpull Force Calculation for Stuck Drill Strings
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Solution Overview
Problem
Conventional methods for calculating the overpull force required to remove a stuck drill string from a borehole do not accurately account for varying factors of friction and drag, leading to inefficiencies and potential equipment loss during drilling operations.
Innovation Solution
A method and system that receive input parameters such as torque and drag parameters, determine the percentage of liquid and solids in the drilling fluid, calculate friction parameters, and generate an updated overpull force by incorporating inside, insitu, and outside friction, as well as shear forces to accurately determine the necessary force to overcome stuck conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional overpull force calculation methods are used, then the calculation process is simple, but the accuracy of friction and drag accounting is insufficient
Solution Approach 1:
The friction calculation is segmented into three distinct components: inside friction (within the drill string), insitu friction (at the drill string-borehole interface), and outside friction (external to the drill string). This segmentation allows each friction type to be calculated separately using appropriate parameters and equations, improving overall calculation accuracy while maintaining a structured approach to complexity
Solution Approach 2:
The calculation methodology transitions from a single-dimension conventional approach to a multi-dimensional framework by incorporating fluid composition dimensions (liquid and solid percentages) and multiple friction dimensions (inside, insitu, outside). This dimensional expansion enables comprehensive accounting of all friction and drag factors affecting the drill string
2Productivity
If conventional overpull force calculation methods are used, then the calculation time is short, but the borehole operation efficiency is reduced
Solution Approach 1:
The system performs preliminary calculations of friction parameters, fluid composition analysis, and drag forces before the actual drill string retrieval operation. By pre-calculating the overpull force requirements with comprehensive friction and drag considerations, the system enables more efficient borehole operations while the automated calculation process minimizes time loss
Solution Approach 2:
The calculation system incorporates feedback loops that continuously refine the overpull force calculation by integrating multiple friction components and drag forces. This feedback mechanism ensures accurate results while the automated iterative process efficiently converges on the optimal solution, balancing calculation time with operational efficiency
3Reliability
If conventional overpull force calculation methods are used, then the equipment requirements are minimal, but the risk of equipment loss increases
Solution Approach 1:
The risk mitigation is achieved through segmentation of the calculation system into distinct modules: inside friction calculation, insitu friction calculation, outside friction calculation, and total drag integration. Each module independently evaluates specific risk factors, and their combined results provide a comprehensive reliability assessment for drill string removal operations
Solution Approach 2:
The system enhances reliability by adding multiple analytical dimensions beyond conventional single-factor calculations. By evaluating inside, insitu, and outside friction separately and integrating fluid composition effects (liquid and solid percentages), the system provides a multi-dimensional assessment that significantly improves the reliability of drill string removal while managing computational complexity through structured organization
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 provides a more accurate calculation of the overpull force, enhancing borehole operation efficiency by accounting for fluid and mechanical friction, reducing the risk of equipment loss and improving the reliability of drill string removal.
Implementation Method 1
calculating one or more of an inside friction parameter at the first depth, a first insitu friction parameter utilizing the percentage of liquid, a second insitu friction parameter utilizing the percentage of solids, a shear force at the first depth, or an outside friction at the first depth
Implementation Method 2
calculating one or more of an inside friction parameter at the first depth, a first insitu friction parameter utilizing the percentage of liquid, a second insitu friction parameter utilizing the percentage of solids, a shear force at the first depth, or an outside friction at the first depth
Implementation Method 3
calculating a total drag utilizing a mechanical drag and one or more of the inside friction parameter, the first insitu friction parameter, the second insitu friction parameter, the shear force, or the outside friction
Data Source
AI summary
The disclosure presents processes and methods for determining an overpull force for a stuck drill string in a borehole system. The fluid composition of a mud in the borehole at a specified depth can be broken down into a percentage of liquid and percentage of solids, as well as adjusting for material sag and settling factors. The fluid composition can be utilized to identify friction factors and drag in respective fluid composition zones. Each friction factor and drag can be summed to determine a total fluid drag on the drill string. In some aspects, the total fluid drag can be adjusted utilizing the relative positioning of casing collars and tool joints. The total fluid drag can be summed with the other force factors, such as a shear force and mechanical drag. The total drag can then be utilized as the overpull force applied to the stuck drill string.