On-Demand Cement via Encapsulated Accelerator Release
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Solution Overview
Problem
The set time of cement slurries in the oil and gas industry is not controllable and is influenced by wellbore temperatures and the time of slurry formation, making it challenging to achieve desired cementing outcomes.
Innovation Solution
A cement slurry containing an accelerator composite with a shell encapsulating a core of an accelerator and a disintegrating agent, which includes phase change materials or gas-producing materials, is used. This composite allows for controlled release of the accelerator, decoupling the set time from wellbore temperatures and enabling on-demand setting of the cement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a cement slurry is used right after it is formed to remain pumpable, then the slurry maintains pumpability, but the set time becomes uncontrollable and is ruled by well conditions
Solution Approach 1:
The accelerator is segmented and encapsulated within a shell structure, separating it from the cement slurry matrix. This encapsulation allows the slurry to remain pumpable while the accelerator is contained and controlled, releasing only when the shell breaks under specific conditions.
Solution Approach 2:
The accelerator is prepared and encapsulated in advance within the shell structure before being mixed with the cement slurry. This preliminary encapsulation ensures the accelerator is ready for controlled release at the desired location and time, maintaining pumpability during transport.
2Reliability
If the set time is determined by wellbore temperature and slurry formation time, then the cementing process follows natural conditions, but the set time cannot be controlled according to user demand
Solution Approach 1:
The invention changes the controlling parameter for set time from wellbore temperature and formation time to the mechanical breakdown of the encapsulating shell. This parameter change allows set time to be controlled by the shell's structural failure point rather than environmental conditions.
Solution Approach 2:
The encapsulating shell acts as an intermediary between the accelerator and the cement slurry. It controls the release of the accelerator, mediating the set time according to design parameters rather than allowing direct influence from wellbore temperature and formation conditions.
3Loss of time
If an accelerator composite with shell encapsulation is used, then the set time can be controlled on demand, but the device complexity increases
Solution Approach 1:
The invention uses a shell structure that is simple in form but functional in purpose. The shell encapsulates the accelerator and provides controlled release through mechanical breakdown, achieving complex functionality with a relatively simple structural addition.
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 method allows for reduced set times and critical hydration periods, enabling safer and more flexible placement of cement slurries, as the set time can be controlled independently of wellbore conditions.
Implementation Method 1
the disintegrating agent comprising at least one of a phase change material or a gas-producing material
Implementation Method 2
the disintegrating agent comprising at least one of a phase change material or a gas-producing material
Data Source
AI summary
A method of cementing a wellbore includes injecting into the wellbore a cement slurry containing: an accelerator composite having a shell encapsulating a core including an accelerator and a disintegrating agent, the disintegrating agent including at least one of a phase change material or a gas-producing material; a cementitious material; and an aqueous carrier; and releasing the accelerator from the accelerator composite.