Calcium Oxide Injection for Natural Gas Hydrate Decomposition
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Solution Overview
Problem
Current methods for exploiting natural gas hydrate, such as depressurization, face challenges like low gas production rates, instability of the reservoir structure, and insufficient heat supply, leading to inefficient decomposition and potential wellbore destruction during large-scale exploitation.
Innovation Solution
The method involves injecting hydraulic calcium oxide powder into a fractured fracture configuration within the natural gas hydrate reservoir, where it reacts with water to generate heat and form calcium hydroxide, enhancing decomposition efficiency and reservoir stability, and increasing permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If depressurization method is used to exploit natural gas hydrate, then gas production can be achieved, but gas production rate is low and reservoir structure becomes unstable
Solution Approach 1:
The patent changes the thermal parameter of the reservoir by injecting calcium oxide powder that reacts exothermically with water to generate heat. This thermal parameter change accelerates hydrate decomposition kinetics, thereby increasing gas production rate while the generated heat also compensates for decomposition cooling, maintaining reservoir temperature and structural stability
Solution Approach 2:
The patent introduces calcium oxide powder as an intermediary substance that mediates between the depressurization process and hydrate decomposition. The calcium oxide reacts with formation water to generate heat in situ, which serves as an intermediate thermal energy source to accelerate decomposition without directly heating the reservoir, thus improving gas production while preserving reservoir stability
2Productivity
If large-scale exploitation is conducted to increase gas production, then productivity improves, but reservoir structure becomes unstable and wellbore destruction occurs
Solution Approach 1:
The patent applies local quality by injecting calcium oxide powder specifically into the fractured fracture configuration where hydrate decomposition occurs. This creates a localized heat generation zone that accelerates decomposition at the production front while leaving the broader reservoir structure undisturbed, thereby increasing gas production without compromising overall reservoir strength
Solution Approach 2:
The patent implements beforehand cushioning by having calcium oxide powder ready in the fractured fracture configuration before large-scale exploitation begins. When decomposition starts, the calcium oxide immediately reacts to generate heat, cushioning against the cooling effect and preventing thermal shock that would otherwise weaken the reservoir structure during rapid production
3Productivity
If heat is supplied to accelerate hydrate decomposition, then gas production rate increases, but heat supply is insufficient and energy consumption increases
Solution Approach 1:
The patent implements self-service by using calcium oxide powder that reacts with formation water already present in the reservoir to generate heat in situ. The system serves itself by utilizing available formation water as the reactant, eliminating the need for external heat supply systems or additional energy input, thereby accelerating decomposition without increasing energy consumption
Solution Approach 2:
The patent uses calcium oxide powder as a composite thermal energy source that combines chemical energy storage with thermal energy release. The calcium oxide-water reaction provides a self-contained heat generation mechanism that accelerates decomposition by providing necessary activation energy without requiring external energy input, thus improving productivity while maintaining energy efficiency
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 approach significantly increases gas production rates, improves reservoir stability, and maintains permeability, making it suitable for large-scale commercial exploitation while reducing the risk of structural instability and wellbore destruction.
Implementation Method 1
reacts with water to generate heat
Implementation Method 2
via gas fracturing
Data Source
AI summary
A method for exploiting a natural gas hydrate reservoir includes drilling a borehole entering the natural gas hydrate reservoir; perforating the borehole to form perforations; fracturing the natural gas hydrate reservoir via the perforations by using a gas containing calcium oxide powder having a particle size 0.001 to 10 mm to generate a fracture; and collecting natural gas released by the natural gas hydrate. The method is easy to operate, cost-effective, and suitable for commercial applications.