Sealed Core Barrel Pressure Balancing
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Solution Overview
Problem
During the recovery of core samples from subterranean formations, the reduction in ambient pressure causes gases to expand and expel fluids, such as oil and water, leading to a loss of sample authenticity and data accuracy.
Innovation Solution
The apparatus employs a pressure-balancing system with elastomeric seals and fluid chambers to maintain sample pressure and retain expelled fluids, minimizing friction and damage to the sample, and allowing for the collection and analysis of fluid variations along the sample length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the core sample is recovered to surface without pressure balancing, then the recovery process is simple and fast, but the ambient pressure reduction causes gases to expand and fluids to be expelled from the sample
Solution Approach 1:
The core barrel is divided into multiple sealed chambers (first chamber, second chamber, third chamber) separated by pistons. Each chamber can independently maintain pressure balance for different portions of the core sample, allowing segmented pressure control during recovery to prevent fluid expulsion while managing the complex pressure balancing requirement
Solution Approach 2:
Pistons are introduced as intermediary elements between the core sample and the external environment. These pistons transmit and balance pressure forces, mediating the pressure differential that would otherwise cause gas expansion and fluid expulsion, thus maintaining sample integrity while enabling recovery
2Reliability
If seal means are provided to retain fluids in the sample, then fluid retention is improved, but friction between the seal means and sample increases causing sample damage
Solution Approach 1:
The harmful frictional contact between seals and the core sample is eliminated by extracting the seal placement from the sample surface. Instead of sealing against the sample, the seals are positioned on the chamber walls, retaining fluids through pressure balance without direct contact friction, thus maintaining fluid retention while preventing sample damage
Solution Approach 2:
Flexible seal elements (such as O-rings or elastomeric seals) are used on the pistons and chamber walls. These flexible seals conform to the chamber geometry and maintain pressure containment through elastic deformation rather than rigid frictional contact, enabling fluid retention while minimizing damage to the core sample
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 solution effectively retains fluids within the sample, maintaining sample integrity and enabling accurate geological and geophysical data collection by minimizing fluid loss and sample damage during retrieval.
Implementation Method 1
two or more pairs of seal means, each pair comprising a resilient seal means... the seal means can be manufactured from rubber or plastics material... some useful embodiments are formed from Viton
Implementation Method 2
a change in hydrostatic pressure occurs in the sample during transit from the subterranean formation (with a high ambient hydrostatic pressure) to the surface (with a relatively lower atmospheric pressure) and this causes fluids to be expelled from the core sample during recovery
Data Source
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AI summary
The present invention relates to an apparatus and method for recovering a sample (12) from a subterranean formation. The apparatus comprises a receptacle (10) for receiving a sample (12) and at least two seal means (41, 42) disposed on an inner surface of the receptacle (10). The seal means (41, 42) can be arranged to allow a portion of the core sample (12) therethrough during the sampling process and to retain fluids within the receptacle (10) during recovery of the sample (12). The seal means can be provided with one or more fluid pockets (94) configured to change shape as the volume of fluid therein alters in response to a pressure differential. A plurality of pairs of seal means (41, 42) can be spaced along the length of the inner surface of the receptacle (10).