Downhole Sampling Packer Probe Contamination Cleanup
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Solution Overview
Problem
Current formation sampling methods face challenges in efficiently reducing contamination levels during wellbore fluid testing, leading to inaccurate representation of virgin formation fluid properties due to contamination from drilling fluids and mud cake.
Innovation Solution
A downhole tool equipped with an expandable packer and an extendable probe that performs pressure transient testing and fluid analysis to monitor contamination levels, accelerating the cleanup phase by initially using the packer to withdraw large amounts of fluid and then the probe to isolate virgin formation fluid for sampling when contamination levels meet predetermined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the probe is used to withdraw formation fluid for sampling, then the sample represents virgin formation fluid, but the cleanup time is excessively long due to contamination from drilling fluids and mud cake
Solution Approach 1:
The system divides the fluid withdrawal function into two separate components: the packer handles bulk fluid removal to reduce contamination, while the probe handles precise sampling of virgin formation fluid. This segmentation allows each component to optimize its specific function, reducing overall cleanup time while maintaining sample accuracy.
Solution Approach 2:
The packer performs preliminary cleanup by withdrawing large volumes of contaminated fluid before the probe is activated for sampling. This preliminary action removes the bulk of drilling fluid and mud cake contamination, allowing the probe to quickly obtain representative samples without requiring extended cleanup time.
2Productivity
If the packer is used to withdraw large amounts of formation fluid, then the contamination level is reduced quickly, but the probe cannot obtain accurate samples during this phase
Solution Approach 1:
The system separates the bulk fluid removal function (performed by the packer) from the sampling function (performed by the probe). During the cleanup phase, only the packer is active to maximize contamination removal rate. Once contamination reaches acceptable levels, the probe is activated for accurate sampling, ensuring both high productivity during cleanup and high precision during sampling.
Solution Approach 2:
The system dynamically transitions between different operational modes: initially using the packer for high-volume fluid withdrawal to reduce contamination, then switching to the probe for precise sampling when contamination levels become acceptable. This dynamic operation optimizes both contamination removal rate and sample accuracy at different stages of the process.
3Adaptability or versatility
If both the packer and probe are set to engage the wellbore wall simultaneously, then pressure transient testing can be performed, but the system complexity increases
Solution Approach 1:
The system integrates multiple functions into a single downhole tool assembly that can perform pressure transient testing, formation fluid sampling, and contamination monitoring. The packer and probe are both capable of engaging the wellbore wall and withdrawing fluid, allowing the system to adapt its configuration based on the specific operational requirements, thereby managing complexity while maintaining versatility.
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 significantly reduces the time required for contamination levels to reach acceptable levels, allowing for more accurate representation of virgin formation fluid properties and efficient sampling, thereby improving the reliability of formation evaluations.
Implementation Method 1
withdrawing large amounts of fluid through the expandable packer
Implementation Method 2
a fluid analyzer to monitor a contamination level of the first portion of the formation fluid
Implementation Method 3
performing pressure transient testing by setting the expandable packer and the probe to engage a wall of the wellbore and measuring a pressure response
Data Source
AI summary
A formation sampling method includes disposing a downhole tool comprising a packer and an expandable probe within a wellbore. The method also includes performing pressure transient testing by setting the expandable packer and the probe to engage a wall of the wellbore and measuring a pressure response at the expandable packer and the probe while withdrawing formation fluid into the downhole tool through the expandable packer. The method further includes monitoring a contamination level of the formation fluid during the pressure transient testing, and performing formation sampling with the probe in response to determining that the monitored contamination level meets a predetermined threshold.