Downhole Overpull Generator for Deviated Wellbore Fishing
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Solution Overview
Problem
Conventional downhole fishing operations face challenges in generating sufficient overpull force in deviated wellbores due to curvature and friction, limiting the effectiveness of jar-based energy delivery for dislodging stuck objects.
Innovation Solution
The apparatus and method employ an overpull generator with a piston rod and fluid-actuated pistons to generate and store force, combined with a delay force release device and slinger, which applies an impact force to dislodge objects, overcoming frictional losses and enabling higher, controlled load application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional bottom hole assembly is used in a deviated wellbore, then the rig can pull up on the drill string, but the curvature and friction prevent sufficient energy generation for the jar
Solution Approach 1:
A downhole overpull generator is introduced as an intermediary device between the drill string and the jar. This device generates the required overpull force directly downhole by rotating a spool that winds a drum, thereby eliminating the energy loss associated with pulling through the curved wellbore section. The overpull generator acts as a local force generator that doesn't rely on surface pulling through the friction-prone wellbore curvature.
Solution Approach 2:
The conventional mechanical system of pulling the entire drill string from the surface to generate jar energy is replaced with a downhole mechanical system. The overpull generator uses a motor-driven spool and drum mechanism located downhole to generate the overpull force, substituting the surface-based mechanical pulling system with a localized downhole mechanical system that avoids friction losses in the wellbore curvature.
2Power
If the rig pulls up on the drill string to generate energy for the jar, then energy is stored in the slinger and drill string, but friction in deviated wellbores limits the effective force delivery
Solution Approach 1:
The overpull generator serves as an intermediary that creates the overpull force locally downhole. It rotates a spool that winds a drum, directly applying force to the jar assembly without requiring the drill string to be pulled through the friction-prone wellbore section. This intermediary mechanism delivers power directly to where it's needed, bypassing the friction problem.
Solution Approach 2:
The system transitions from a surface-based force application (pulling drill string from surface) to a downhole-based force application. By locating the force generation mechanism downhole, the system changes the spatial dimension of force application, allowing direct power delivery to the jar without the intermediate friction-prone path through the wellbore curvature.
3Adaptability or versatility
If conventional fishing operations are used in vertical wellbores, then the system is simple and effective, but it cannot generate sufficient overpull force in deviated wellbores
Solution Approach 1:
The overpull generator is designed as a multi-functional device that can operate in both vertical and deviated wellbores. It serves multiple functions: generating overpull force for the jar, driving the spool-drum mechanism, and adapting to different wellbore geometries. This universal design allows the same basic assembly to function effectively in various wellbore conditions without requiring complete redesign.
Solution Approach 2:
The bottom hole assembly is segmented into distinct functional modules: the overpull generator with its motor and spool, the drum mechanism, the jar assembly, and the slinger. This segmentation allows each component to be optimized for its specific function while maintaining overall system versatility. The modular structure enables the assembly to adapt to different wellbore configurations by maintaining the core overpull generation capability while adjusting operational parameters.
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 solution effectively dislodges objects in deviated wellbores by generating and applying a consistent, higher overpull force directly at the bottom hole assembly, enhancing the efficiency and reliability of fishing operations by minimizing friction-related losses and allowing for precise force application.
Implementation Method 1
fluid-actuated pistons to generate and store force
Implementation Method 2
A slinger and delay force release device are provided in the assembly. The slinger is configured to store the generated overpull force.
Implementation Method 3
the curvature and the associated friction between the drill string and the wall of the wellbore
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The present invention generally relates to an apparatus and method of jarring with an overpull generator (100). In one aspect, a method of dislodging an object (20) stuck in a wellbore (10) is provided. The method includes the step of running an assembly into the wellbore on a conveyance member (50) and attaching the assembly to the object, wherein the assembly comprises an overpull generator and a delay force release device (150). The method also includes the step of generating an overpull force in the wellbore by selectively activating the overpull generator. Additionally, the method includes the step of applying an impact force to the object by activating the delay force release device and releasing the generated overpull force, thereby dislodging the object stuck in the wellbore. In a further aspect, an assembly for dislodging an object stuck in a wellbore is provided. In yet a further aspect, an overpull generator for use in generating an overpull force in a wellbore is provided.