Delayed Crosslinking Complex for Subterranean Fluids
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Solution Overview
Problem
Conventional subterranean treatment fluids viscosified with metal crosslinking agents exhibit rapid viscosity increase, leading to high friction and limited use in deeper wells, and often contain non-environmentally friendly components that are not compliant with stringent regulations.
Innovation Solution
Development of an environmentally friendly delayed crosslinking complex comprising a metal and a ligand with hydroxyl and carboxylic acid groups, which interacts with viscosifying agents to achieve controlled viscosity increase, reducing pipe friction and allowing for safer, more efficient pumping in deeper wells by delaying crosslinking until closer to the treatment site.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional crosslinking agents are used to viscosify treatment fluids, then viscosity increases rapidly within seconds, but this causes increased friction and reduced pumping rates
Solution Approach 1:
The crosslinking agent is pre-complexed with a ligand to form a delayed crosslinking complex that remains stable during transport. The complex only dissociates and activates crosslinking near the treatment site, allowing the fluid to maintain lower viscosity during pumping while achieving the desired viscosity increase at the target location.
Solution Approach 2:
A ligand acts as an intermediary between the crosslinking agent and the viscosifying agent. The ligand temporarily binds to the crosslinking agent, preventing immediate crosslinking reaction. This intermediary complex only releases the crosslinking agent when conditions are favorable (near the treatment site), thereby delaying the viscosity increase.
2Stability of the object's composition
If conventional crosslinking agents are used, then high viscosity is achieved quickly, but this limits use to shallower wells and increases pumping power requirements
Solution Approach 1:
The crosslinking system is prepared in advance as a stable complex that does not immediately activate. This allows the treatment fluid to be pumped to deeper wells where the complex will later dissociate and activate crosslinking at the target zone, enabling operation in deeper wells that would be impossible with immediate crosslinking.
Solution Approach 2:
The crosslinking system transitions from a dynamic equilibrium state (stable complex) during transport to an active crosslinking state near the treatment site. This dynamic behavior allows the fluid to adapt its viscosity characteristics based on location, maintaining pumpability during transport while achieving high viscosity at the target.
3Stability of the object's composition
If conventional crosslinking agents are used, then rapid viscosity increase occurs, but this creates safety risks from high friction pressures
Solution Approach 1:
The crosslinking agent is pre-prepared as a stable complex that does not immediately react. This preliminary stabilization prevents sudden viscosity increases and associated friction pressure spikes during pumping, thereby eliminating safety risks while still achieving the desired viscosity increase at the treatment site.
Solution Approach 2:
The ligand serves as a safety intermediary that buffers the crosslinking agent until conditions are appropriate. This intermediary prevents harmful rapid viscosity changes during transport, thereby eliminating friction pressure safety risks while maintaining the ability to achieve high viscosity at the target location.
4Stability of the object's composition
If conventional crosslinking agents are used, then high viscosity is achieved quickly, but this reduces productivity due to higher pumping power requirements
Solution Approach 1:
The crosslinking system is activated in advance as a stable complex during fluid preparation, but the actual crosslinking reaction is delayed until near the treatment site. This allows the fluid to maintain lower viscosity during pumping operations, thereby maintaining high pumping rates and productivity while still achieving the desired viscosity increase at the target location.
Solution Approach 2:
The ligand intermediary prevents immediate crosslinking during pumping operations, allowing the treatment fluid to be pumped at higher rates with lower power requirements. The crosslinking reaction is postponed to occur near the treatment site, thereby maintaining productivity during the pumping phase.
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 delayed crosslinking complex reduces pipe friction, lowers pumping power requirements by 20-40%, enables treatment of deeper and horizontal wells, and complies with environmental regulations by using food-grade materials, thereby reducing environmental impact.
Implementation Method 1
These viscosifying agents may be crosslinked through an applicable crosslinking reaction comprising a crosslinking agent. Conventional crosslinking agents usually comprise a metal complex (e.g., aluminum sulfate) or other compound that interacts with at least two polymer molecules to form a 'crosslink' between them.
Implementation Method 2
a delayed crosslinking complex comprising: a metal and a ligand, the ligand comprising at least one hydroxyl group and at least one carboxylic acid group
Data Source
AI summary
The present invention relates to environmentally friendly delayed crosslinking complexes that are useful in subterranean treatment fluids. One embodiment of the present invention provides a method of providing a treatment fluid having a first viscosity and includes: an aqueous base fluid, a viscosifying agent, a delayed crosslinking complex having: a metal and a ligand, the ligand having at least one hydroxyl group and at least one carboxylic acid group; and placing the treatment fluid in a subterranean formation. In some embodiments, the delayed crosslinking complex is compliant and/or the viscosifying agent is compliant.