Pulse-Echo Tubular Length Measurement
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Solution Overview
Problem
Downhole tubulars, such as drill strings and casing, stretch over time due to stress, leading to inaccuracies in depth measurements based on pipe tallies, which can result in operational errors and potential damage to nearby wells, especially in ultra-deep drilling scenarios.
Innovation Solution
The use of pulse-echo type measurements involving fluid pulses to determine the length of downhole tubulars, where a pulsar is deployed to send and receive fluid pulses, allowing surface processing circuitry to calculate the travel time and account for tubular stretch and fluid density variations, providing accurate length measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pipe tally-based depth measurements are used, then the measurement system remains simple and operational, but measurement precision deteriorates due to tubular stretching
Solution Approach 1:
The patent replaces the mechanical pipe tally system with an acoustic pulse-echo measurement system. Surface-generated acoustic pulses travel down the wellbore, reflect off the bottom of the tubular, and return to the surface where the travel time is measured. This substitution eliminates the need for physical pipe segment counting and provides continuous, accurate depth measurements that account for tubular stretching.
Solution Approach 2:
The system uses periodic acoustic pulse generation to continuously monitor tubular length and depth. By sending repeated pulses and measuring their round-trip travel times, the system can detect changes in tubular length due to stretching and provide real-time depth corrections without requiring complex mechanical measurement devices.
2Reliability
If traditional pipe tally methods are used, then operational procedures remain simple, but reliability deteriorates due to stretching-induced measurement errors
Solution Approach 1:
The pulse-echo system is self-calibrating and automatically compensates for tubular stretching. The surface system generates pulses, receives echoes, calculates travel times, and determines current tubular length without requiring manual intervention or complex operational procedures. The system serves itself by using the wellbore fluid and tubular structure as part of the measurement mechanism.
3Measurement precision
If pulse-echo measurements are implemented, then measurement precision improves by accounting for tubular stretch, but device complexity increases due to additional equipment
Solution Approach 1:
The pulse-echo measurement system serves multiple functions: it measures tubular length, monitors depth, detects tubular stretching, and provides real-time feedback for operational decisions. By using a single measurement approach for multiple purposes, the system reduces the need for separate measurement devices and procedures, thereby managing complexity while providing comprehensive measurement capabilities.
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 enhances the reliability of depth measurements, improving the accuracy of drilling operations and preventing damage to nearby wells by directly measuring tubular length and accounting for stretching and fluid density effects.
Implementation Method 1
transmitting a first fluid pulse along a wellbore to a downhole location; receiving the first fluid pulse at the downhole location; in response to receiving the first fluid pulse, transmitting a second fluid pulse back along the wellbore to a surface location
Implementation Method 2
determining a round trip travel time for the first and second fluid pulses; determining a length of the tubular based upon the round trip travel time
Data Source
AI summary
Systems and methods are disclosed for obtaining distance related wellbore parameters using pulse-echo measurements. For example, the depth of a wellbore may be computed and/or the length of a tubular string positioned in a wellbore may be determined. In an embodiment, a pulsar is deployed into a wellbore along a length of tubular. Once deployed, a fluid pulse is sent form a surface pulse generator and the transmission time is recorded. The downhole pulsar receives the fluid pulse and, in response, returns a second fluid pulse back to the surface. Surface processing circuitry receives the second fluid pulse and records the reception time. The processing circuitry then process the data to determine the total time for travel, thereby determining the length of the downhole pipe or other tubing.