Flow Restricted Impact Jar for Downhole Tool Strings
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Solution Overview
Problem
Drilling operations in deep, harsh environments often result in downhole tools becoming stuck, leading to equipment damage and operational disruptions during retrieval, with existing impact jars generating excessive stresses that can further damage tool strings.
Innovation Solution
A downhole-adjusting impact apparatus (DAIA) that differentiates between electrical characteristics to apply selectively varying impact forces, using a latching mechanism and spring stacks to adjust impact forces between 1,000 and 12,000 pounds, minimizing damage to stuck tool strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high tension loads are applied by the conveyance means to trigger the jar, then the jar can deliver impact to dislodge stuck tool string, but the impacts generate stresses exceeding operational parameters and damage other components of the tool string
Solution Approach 1:
The patent applies parameter changes by modifying the fluid flow characteristics through restricted ports in the piston. The flow restriction creates pressure differential control that regulates the impact force magnitude, transforming the uncontrolled high-stress impact into a controlled impact within operational stress parameters, thus resolving the contradiction between sufficient impact force and tool string integrity
Solution Approach 2:
The patent introduces fluid pressure as an intermediary between the tension load application and the impact delivery. The fluid medium transmits and modulates the force from the conveyance means through the restricted ports, acting as a buffer that controls stress transmission to the tool string components, preventing direct excessive stress while enabling controlled impact
2Productivity
If the impact jar uses unrestricted fluid ports, then fluid can flow freely to enable impact operation, but the rate of fluid flow cannot be controlled leading to excessive impact stresses
Solution Approach 1:
The patent changes the flow parameter by introducing restricted ports with specific geometries that limit fluid flow rate. This parameter modification controls the pressure build-up rate and impact force magnitude, enabling productive impact operation while maintaining stress levels within safe operational parameters through controlled fluid dynamics
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
The DAIA effectively dislodges stuck tool strings with controlled impact forces, reducing the risk of equipment damage and operational disruptions while maintaining tool string integrity.
Implementation Method 1
one or more flow restrictors operable to reduce a flow area of the ports
Implementation Method 2
using a latching mechanism and spring stacks to adjust impact forces between 1,000 and 12,000 pounds
Implementation Method 3
Tension load is applied to the tool string via the conveyance means to trigger the jar, thus delivering an impact intended to dislodge the stuck portion of the tool string
Data Source
Figure 1
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AI summary
An apparatus (200) for coupling between opposing first and second portions (140, 150) of a downhole tool string (100). The apparatus includes a housing (260) having a port (620) therein, a shaft (270) extending within at least a portion of the housing, and a flow restrictor (630) reducing a flow area of the port. The housing and the shaft move axially relative to each other. The port fluidly connects a space external to the housing with an annulus (610) defined between the housing and the shaft.