Sealed Core Catching Tube Pressure Maintenance
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Solution Overview
Problem
Cores extracted from underground formations often experience explosive decompression and fluid loss due to pressure changes during transportation from downhole conditions to the surface, which can damage the samples and lead to loss of trapped formation fluids.
Innovation Solution
A sidewall coring tool with a core catching tube that includes fluid ports for evacuating fluid as cores are introduced, and a cushion to maintain pressure, allowing the cores to be sealed downhole and transported to the surface without decompression, preventing fluid loss and invasion by wellbore fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If cores are extracted from formation at downhole pressure and transported to surface, then cores can be obtained from deep formations, but explosive decompression and fluid loss occur due to pressure reduction
Solution Approach 1:
The core is sealed in a pressure-maintaining container downhole before extraction, and the container is designed to maintain formation pressure throughout transportation to the surface. This preliminary sealing action prevents decompression damage before it can occur during surface handling and analysis.
Solution Approach 2:
A pressure-maintaining container serves as an intermediary between the high-pressure formation environment and the low-pressure surface environment. This intermediary container isolates the core sample from pressure changes, allowing safe transportation and analysis without direct exposure to decompression forces.
2Reliability
If cores are sealed downhole in a pressure-maintaining container, then fluid loss is prevented, but device complexity increases
Solution Approach 1:
The container employs flexible sealing elements and thin film barriers that can adapt to pressure differentials while maintaining fluid containment. These flexible sealing components provide reliable fluid containment without requiring complex mechanical sealing mechanisms.
3Ease of operation
If fluid ports are provided in the core catching tube for evacuating fluid, then fluid can be extracted for analysis, but pressure maintenance is compromised
Solution Approach 1:
The fluid port system is designed to be dynamically controllable, allowing the port to remain closed during transportation to maintain pressure, and then opened at the surface when fluid extraction is needed. This dynamic control enables both pressure maintenance and fluid extraction without compromise.
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 effectively reduces the risk of explosive decompression and fluid loss, enabling accurate analysis of formation fluids by maintaining pressure and integrity of the core samples during transportation and analysis.
Implementation Method 1
The core catching tube may comprise a cushion configured to maintain a pressure in the core catching tube once the fluid port is sealed downhole
Data Source
AI summary
A sidewall coring apparatus for obtaining a plurality of formation cores from a sidewall of a wellbore includes a core catching tube configured to be sealed downhole and to store at least one of the formation cores therein. The core catching tubes includes a first end that may be sealed by a first sealing mechanism, and an opposite end that may be sealed by a second sealing mechanism. The core catching tube also includes a fluid evacuation port that may be sealed downhole.