Downhole Vibrator Using Reflected Pressure Pulses
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Solution Overview
Problem
Conventional methods for retrieving stuck objects (fish) in wellbores, such as over-pulling or jarring, often cause sand grains to interlock, making it difficult to dislodge the object, and existing tools are not effective at great depths due to insufficient force and frequency.
Innovation Solution
An apparatus and method utilizing a tubular with a bottom engagement tool and two flow control devices to generate high-frequency pressure pulses in a fluid, inducing vibrations in the stuck object by cycling the first flow control device to create upward and downward pressure pulses, and using a second flow control device to reflect these pulses and create additional forces, with the frequency set to match the tubular's resonant frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional methods such as over-pulling or jarring are used to dislodge a fish, then the fish can be pulled with high force, but sand grains interlock and wedge the fish more firmly in the wellbore
Solution Approach 1:
The patent applies high-frequency mechanical vibrations (10-10,000 Hz) to the fish through a vibrator device to dislodge it from sand interlocks. The vibrations prevent sand grains from interlocking while the fish is being pulled, allowing effective retrieval without the harmful wedging effect that occurs with conventional static force methods.
Solution Approach 2:
The patent uses periodic cyclic loading combined with high-frequency vibrations to dislodge the fish. The periodic application of force at controlled intervals, synchronized with the vibration frequency, prevents sand interlocking while progressively moving the fish along the wellbore.
2Length of stationary object
If traditional dislodging tools are used at great depths, then the tools can reach deep wellbores, but the force and frequency are insufficient to effectively dislodge the fish
Solution Approach 1:
The patent uses hydraulic fluid pressure to generate and transmit high-frequency pressure pulses through the tubular conveyance system to the vibrator device. The hydraulic system efficiently transmits energy to the fish regardless of depth, overcoming the limitation of insufficient force that plagues traditional mechanical tools at great depths.
Solution Approach 2:
The patent changes the frequency parameter of the applied force to high-frequency ranges (10-10,000 Hz) that are effective for dislodging fish at great depths. By adjusting the frequency and amplitude parameters of the vibrations, the system maintains effective dislodging capability regardless of the wellbore depth.
3Duration of action of moving object
If low frequency forces are applied to dislodge a fish, then the forces can be applied continuously, but the forces are less effective compared to high frequency vibrations
Solution Approach 1:
The patent employs periodic high-frequency pressure pulses generated by cycling valves to create vibrations in the fish. The periodic nature of the pressure pulse generation allows continuous operation while maintaining high frequency vibrations that are significantly more effective at dislodging fish than continuous low-frequency forces.
Solution Approach 2:
The patent transforms continuous low-frequency force application into high-frequency mechanical vibrations through the use of rapidly cycling valves that generate pressure pulses. This vibration mechanism maintains continuous operation while dramatically improving dislodging effectiveness compared to traditional continuous low-frequency methods.
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 dislodges stuck objects by generating high-amplitude, high-frequency vibrations, overcoming the limitations of traditional methods by applying forces that resonate with the tubular and the stuck object, allowing for efficient retrieval even at great depths.
Implementation Method 1
A first flow control device, such as a cycling valve, in the tubular cycles (closes and opens) at a selected frequency or rate and generates at each closing a first upward pressure pulse in a fluid flowing through the tubular and a downward pressure pulse in the fluid
Implementation Method 2
A second flow control device, above the first flow control device, in the tubular closes in response to the first upward pressure pulse during each cycle and generates a second upward pressure pulse in the fluid flowing through the tubular and a second downward pressure in the fluid
Implementation Method 3
Successive inducement of the first and second force in the fish generates vibrations in the fish. The selected frequency may be set to match a resonant frequency of the tubular.
Data Source
AI summary
In one aspect, an apparatus for inducing vibrations in an object in a wellbore is disclosed that in one embodiment includes a tubular conveyable in the wellbore and has at its bottom end an engagement tool that is configured to engage with or latch onto the object. A first flow control device, such as a cycling valve, in the tubular cycles (closes and opens) at a selected frequency or rate and generates at each closing a first upward pressure pulse in a fluid flowing through the tubular and a downward pressure pulse in the fluid, which induces a first force in the engagement tool and thus in the fish engaged with the engagement tool. A second flow control device, above the first flow control device in the tubular, closes in response to the first upward pressure pulse during each cycle and generates a second upward pressure pulse in the fluid flowing through the tubular and a second downward pressure in the fluid and a corresponding second force in the object. The selected frequency may be set to match a resonant frequency of the tubular. The first flow control device may be cycled to close on or before arrival of the second downward pulse at the first flow control device to generate a resonance in the tubular.