Downhole Sampling Tool Check Valve Piston Contamination
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Solution Overview
Problem
In well applications, fluid samples are often contaminated due to inadvertent premature closing or opening of the sampling chamber, which can affect the accuracy of compositional and PVT analyses.
Innovation Solution
A sampling tool with a tubular member, sampling piston, and check valve assembly is used, where a secondary piston and check valve assembly move together within the tubular member, allowing controlled fluid sampling by adjusting pressure to prevent contamination and ensure accurate sample collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sampling piston is used to draw fluid sample into the sampling chamber, then the fluid sample can be collected, but the sampling chamber may close prematurely or open inadvertently causing contamination
Solution Approach 1:
The sampling tool is divided into separate functional components: a sampling piston for drawing the sample, a check valve assembly for preventing backflow, and a secondary piston for maintaining pressure. This segmentation allows each component to perform its specific function independently, preventing premature closing or opening of the sampling chamber and thus preventing contamination while ensuring reliable sampling.
Solution Approach 2:
The check valve assembly acts as an intermediary mechanism between the sampling chamber and the external environment. It allows fluid to flow in one direction (into the sampling chamber) while preventing reverse flow, thereby maintaining the integrity of the sampled fluid and preventing contamination during tool withdrawal.
2Productivity
If pressure is increased to move the sampling piston, then the fluid sample can be drawn into the chamber, but the check valve assembly may close prematurely
Solution Approach 1:
The secondary piston and check valve assembly are merged into a single moving unit that acts together. When pressure is applied to the sampling piston, the secondary piston and check valve assembly move simultaneously as a coupled system, ensuring that the check valve opens at the correct moment to allow sampling while preventing premature closing. This merging of functions ensures coordinated operation that maintains both productivity and reliability.
3Reliability
If the sampling tool is designed with multiple moving parts, then the sampling function can be improved, but the device complexity increases
Solution Approach 1:
The secondary piston serves multiple functions simultaneously: it moves with the check valve assembly to control fluid flow, maintains pressure within the sampling chamber, and prevents premature closing of the check valve. By making this single component multi-functional, the design achieves reliable sample integrity maintenance without proportionally increasing device complexity, as one component performs multiple critical roles.
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 solution minimizes contamination and ensures accurate fluid sampling by maintaining the sample at downhole conditions, allowing for precise compositional and PVT analyses with minimal dilution.
Implementation Method 1
increasing a pressure of a fluid in the tubular member on a first side of the sampling piston and the check valve assembly, causing the secondary piston and the check valve assembly to move together
Data Source
AI summary
A sampling tool includes a tubular member and a sampling piston positioned within the tubular member. The sampling piston has a bore formed axially-therethrough. A secondary piston is positioned within the bore of the sampling piston. A check valve assembly is positioned at least partially within the tubular member. The secondary piston and the check valve assembly move together with respect to the tubular member.