Downhole Tool Pump Rate Overshoot for Faster Detection
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Solution Overview
Problem
Conventional downlinking methods in drilling operations are slow due to fluid compliance and pressure drop issues, leading to delayed detection of pump rate changes at the downhole tool, and often exceed safety limits.
Innovation Solution
Adjusting the pumping rate to overshoot or undershoot a steady state rate, followed by adjustments to achieve the steady state, allowing for rapid detection of transitions by the downhole tool, while optimizing within operational limits to minimize time and avoid pressure extremes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional pump rate adjustment methods are used for downlinking, then safety limits are maintained, but detection time at the downhole tool is excessive
Solution Approach 1:
The system pre-calculates the optimal pump rate profile including overshoot/undershoot magnitude and duration before executing the downlink command. This preliminary calculation accounts for fluid compliance and pressure drop characteristics to determine the exact sequence needed to achieve rapid detection while staying within safety limits.
Solution Approach 2:
The pump rate is dynamically adjusted through a multi-stage sequence: initial overshoot or undershoot beyond the target steady state, followed by correction to achieve the desired flow transition. This dynamic approach exploits fluid compliance to accelerate detection while the subsequent correction ensures safety limits are not exceeded.
2Speed
If pump rate is increased rapidly to reduce detection time, then transition detection is faster, but pressure safety limits are exceeded
Solution Approach 1:
The downlink sequence employs periodic pump rate variations consisting of multiple phases: an initial rapid change (overshoot or undershoot), followed by a correction phase that returns the pump rate to appropriate levels. This periodic action creates detectable transitions while ensuring pressure remains within safety boundaries throughout the sequence.
Solution Approach 2:
The system changes the pump rate parameter in a controlled sequence that temporarily exceeds the steady state value (overshoot) or goes below it (undershoot), then corrects to the target value. This parameter change strategy exploits the compressibility of the drilling fluid to achieve faster detection while the correction phase ensures pressure safety.
3Loss of time
If pump rate adjustments are made to account for fluid compliance, then detection time is reduced, but control system complexity increases
Solution Approach 1:
The system incorporates feedback mechanisms that monitor pump rate, flow conditions, and pressure to verify successful downlink detection. This feedback allows the control system to adapt to actual fluid compliance characteristics and optimize subsequent downlink sequences, managing the complexity through intelligent control rather than hardware complexity.
Solution Approach 2:
The control system automatically calculates and executes the optimal pump rate sequence based on pre-programmed algorithms that account for fluid compliance. Once configured with basic well parameters, the system self-manages the complex overshoot/undershoot sequences without requiring complex real-time calculations or operator intervention, reducing operational complexity.
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 method enables faster transition detection by the downhole tool, optimizing drilling operations within safe parameters, allowing for quicker control of drilling parameters and reducing the risk of pressure-related safety issues.
Implementation Method 1
One common method of communication is called 'mud pulse telemetry'. Mud pulse telemetry involves sending signals, either downlinks or uplinks, by creating pressure and/or flow rate pulses in the mud. These pulses may be detected by sensors at the receiving location.
Data Source
AI summary
A method of downlinking to a downhole tool located in a borehole is provided. The downhole tool detects transitions in the flow velocity of fluid circulating in the borehole at the downhole tool. To provide for the detection of the transitions fluid is pumped into the drillstring so that it circulates in the borehole at the downhole tool and the the pumping rate of fluid into the drillstring is either increased to a rate which overshoots a steady state pumping rate needed to produce a transition or is decreased to a rate which undershoots a steady state pumping rate needed to produce a transition.