Two-Stage Depressurization for Class 3 Gas Hydrate Reservoirs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Class 3 gas hydrate reservoirs pose a significant technical challenge due to the lack of mobile fluid zones, making conventional depressurization methods ineffective, and requiring expensive thermal or chemical stimulation for gas production.
Innovation Solution
A two-stage depressurization method is employed, where the first stage involves producing fluids from a hydrate interval at constant pressure to create a hydrate-free zone, and the second stage switches to constant mass rate production with well heating to maintain production and prevent secondary hydrate formation, utilizing conventional oilfield technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional depressurization methods are used on Class 3 hydrate reservoirs, then gas production can be achieved, but the method is ineffective due to lack of mobile fluid zones
Solution Approach 1:
The method applies preliminary thermal stimulation to create mobile fluid zones before implementing depressurization. This preliminary action transforms the reservoir conditions to enable subsequent effective gas production through depressurization, which would otherwise be ineffective in Class 3 reservoirs without mobile fluid zones.
2Productivity
If thermal stimulation is used to produce gas from Class 3 hydrate reservoirs, then gas production is enabled, but operational costs increase due to additional equipment and heat source requirements
Solution Approach 1:
The method uses self-service by utilizing the heat source from the produced gas itself to maintain reservoir temperature during depressurization. This eliminates the need for external heat sources and additional equipment, reducing operational complexity while enabling continuous gas production from Class 3 reservoirs.
3Productivity
If chemical stimulation is used to produce gas from Class 3 hydrate reservoirs, then gas production is achieved, but operational costs increase due to expensive chemicals and progressive dilution effects
Solution Approach 1:
The method eliminates chemical stimulation by using self-service depressurization where the produced gas provides the necessary energy for continuous production. This avoids all costs associated with expensive chemicals, injection equipment, and deals with dilution effects, making gas production from Class 3 reservoirs economically viable.
4Productivity
If thermal or chemical stimulation is used for Class 3 reservoirs, then gas production is possible, but efficiency decreases compared to depressurization methods
Solution Approach 1:
The depressurization method achieves self-service by using the energy from produced gas to maintain reservoir conditions for continuous production. This eliminates the energy losses associated with external thermal or chemical stimulation, maximizing production efficiency while enabling gas production from Class 3 reservoirs.
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 method enables efficient gas production from Class 3 hydrate reservoirs without thermal or chemical stimulation, achieving high production rates and reducing operational costs by creating a mobile fluid zone for gas and water extraction.
Implementation Method 1
Gas can be produced from gas hydrate reservoirs by inducing dissociation using one or more of the following three main methods: (1) depressurization
Implementation Method 2
Gas hydrates are solid crystalline compounds in which gas molecules are encaged inside the lattices of ice crystals
Implementation Method 3
The second stage includes producing fluid from the hydrate interval through the well at a constant mass rate once secondary hydrates form and heating the well at the hydrate interval while producing fluid from the hydrate interval at a constant mass rate
Data Source
AI summary
The present invention is directed to using depressurization methods to create mobile fluid zones for producing fluids from a Class 3 hydrate reservoirs through a well. Aspects of the present invention include a two stage method wherein the first stage includes producing fluid from a hydrate interval within the Class 3 hydrate reservoir through a well at a constant pressure and forming an interface, and the second stage includes producing fluid through the interface at a constant mass rate and heating the well.