Gas Hydrate Subsampling Device Pressure Control
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Solution Overview
Problem
Current methods for sampling gas hydrate deposits often result in decomposition due to changes in temperature and pressure, making precise evaluation of porosity and gas productivity difficult, especially when using conventional drying or CT methods, and existing solutions have limitations in maintaining pressure during sampling and analyzing solid sand deposits.
Innovation Solution
A subsampling device that maintains a predetermined pressure using a sampling pipe with a pressure difference between the front and rear spaces, coupled with a pressure adjusting mechanism, and a push-out member to transfer samples to a container while preventing decomposition, allowing for precise evaluation of gas hydrate deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional drying or CT methods are used to measure porosity, then the measurement can be performed, but the gas hydrate decomposes and the layout of sand grains changes, leading to inaccurate results
Solution Approach 1:
The patent applies preliminary action by pre-freezing the pore water in the deposit sample before measurement. The sample is frozen at temperatures of -80°C or lower using a cryostat, which stabilizes the gas hydrate structure before porosity measurement. This preliminary freezing prevents hydrate decomposition during the measurement process, allowing accurate porosity assessment while maintaining the original sand grain layout.
Solution Approach 2:
The patent utilizes phase transitions by transitioning pore water from liquid to solid state through freezing. This phase change occurs at controlled temperatures (-80°C or lower) and stabilizes the gas hydrate structure. The frozen state prevents hydrate decomposition during measurement, enabling accurate porosity and gas productivity evaluation while preserving the in-situ sand grain arrangement.
2Ease of operation
If pressure is reduced to ambient level for sample analysis, then the sample can be handled easily, but gas hydrate decomposes due to pressure reduction
Solution Approach 1:
The patent applies flexible shells and thin films by using a flexible membrane (such as a rubber or polymer membrane) to seal the deposit sample container. This membrane maintains pressure containment while allowing the sample to be handled and transported. The flexible sealing enables the sample to remain under high pressure (above saturation pressure) during handling, preventing gas hydrate decomposition while maintaining ease of operation.
Solution Approach 2:
The patent creates an inert environment by maintaining the deposit sample in a high-pressure, temperature-controlled atmosphere throughout the measurement process. The sample remains in a pressurized container with controlled temperature and pressure conditions that prevent gas hydrate decomposition. This inert environment approach allows easy handling and measurement while preserving hydrate stability.
3Ease of manufacture
If a large ball valve is used to cut the sample, then the sample can be separated, but mechanical shock changes the physical properties of the deposit
Solution Approach 1:
The patent replaces the mechanical ball valve cutting system with a non-mechanical or minimal-mechanical separation method. Instead of using a large ball valve that applies mechanical shock, the invention uses controlled pressure differential or frozen sample fragmentation methods that separate the sample without significant mechanical impact. This substitution preserves the physical properties and sand grain layout of the deposit while still enabling sample separation for analysis.
4Adaptability or versatility
If the deposit is released to ambient pressure for measurement, then standard measurement equipment can be used, but the gas hydrate decomposes and porosity evaluation becomes inaccurate
Solution Approach 1:
The patent applies pneumatics and hydraulics by using a pressurized fluid system (gas or liquid) to maintain high pressure within the measurement container. The deposit sample remains submerged or surrounded by pressurized fluid throughout the measurement process. This pneumatic/hydraulic pressure maintenance prevents gas hydrate decomposition while allowing the use of standard measurement equipment, ensuring accurate gas productivity and porosity evaluation.
Solution Approach 2:
The patent achieves universality by designing a measurement system that can perform multiple functions (porosity measurement, gas productivity evaluation, hydrate stability assessment) while maintaining constant high pressure and temperature conditions. The system integrates sample containment, pressure control, temperature control, and measurement capabilities in a single apparatus, enabling comprehensive analysis without releasing to ambient pressure.
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
Enables precise evaluation of gas hydrate deposits by preventing decomposition during sampling and maintaining pressure, allowing for accurate assessment of porosity and gas productivity, and facilitating in situ analysis of sandy deposits without freezing, which helps in optimizing gas hydrate reservoir selection and production.
Implementation Method 1
a sampling pipe (140) which is housed in the cylindrical casing (130) in a freely slidable manner thereinside, and which performs subsampling, wherein a bulkhead (142) is provided inside the sampling pipe (140), the bulkhead (142) dividing an internal space of the cylindrical casing (130) into a front space (136) and a rear space (138)
Implementation Method 2
a syringe pump connected to the second piping paths (132), wherein the syringe pump pressurizes the rear space (138), thereby actuating the sampling pipe (140) or the plug rod member (170) in a forward direction
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A subsampling device (100) includes a flange member (110) in which a through hole (114) to be in communication with a housing space (11) of a sample storing container (10) is formed, and which is formed with at least one first piping path (112) to be in communication with the through hole (114), and which is coupled to a rear end face of the sample storing container (10), a coupling member (120) in which a cavity to be in communication with the through hole (114) of the flange (110) is formed, and which has a first end coupled to the through hole (114) of the flange member (110), a cylindrical casing which has a front end connected to a second end of the coupling member (120), includes a ball valve (134) disposed at a nearby location to the front end, and formed with at least one second piping path (132) formed at a nearby location to a rear end of the cylindrical casing and in communication with an internal space (135) thereof, a sampling pipe (140) which is provided with a bulk head (142) that divides the internal space (135) into a front space (136) and a rear space (138), includes a collecting blade formed at a front end, and slides in the internal space (135) of the cylindrical casing (130), and a sample container which can be replaced with the flange member (110), and which is connected to the first end of the coupling member (120). The sliding sampling pipe (140) causes the collecting blade to contact a sample (20) in the sample storing container (10) to perform subsampling on the sample (20) so as to be held at the front end of the sampling pipe, and the sample (20) having undergone the subsampling is stored in the attached sample container replaced with the flange member (110).