Delayed Crosslinking Fracturing Fluids via Boron Sequestration
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Solution Overview
Problem
Hydraulic fracturing fluids face issues with premature crosslinking due to dissolved boron species in produced water, leading to excessive viscosity increase, strain on pumping equipment, and reduced fluid injectivity in low-permeability zones, which complicates oil recovery operations.
Innovation Solution
An injectable solution comprising a crosslinkable polymer, a competing agent formed from a dialdehyde and a non-polymeric cis-hydroxyl compound, and produced water with dissolved boron species, where the pH is maintained below 6.5 to prevent immediate crosslinking, allowing delayed crosslinking upon injection into the subterranean reservoir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinking agents are added to fracturing fluid, then viscosity increases to improve proppant transport, but premature crosslinking occurs due to dissolved boron species in produced water causing excessive viscosity increase before injection
Solution Approach 1:
A competing agent (sugar alcohol or carbohydrate) is introduced as an intermediary substance that preferentially reacts with dissolved boron species in the produced water, preventing premature crosslinking of the fracturing fluid. This mediator absorbs the harmful boron crosslinking action while allowing controlled crosslinking to occur later at the injection site
Solution Approach 2:
The pH of the fracturing fluid is maintained below 6.5 to suppress premature crosslinking reactions. By controlling this critical parameter (pH), the fluid remains pumpable during handling and injection, while crosslinking is enabled under different conditions (higher pH) after injection into the formation
2Strength
If crosslinking occurs prematurely in produced water, then viscosity increases excessively, but this causes strain on pumping equipment and reduces fluid injectivity
Solution Approach 1:
The pH of the fracturing fluid is controlled to remain below 6.5 during handling and injection operations. This parameter control prevents premature crosslinking and excessive viscosity increase, maintaining the fluid in a pumpable state throughout the injection process
Solution Approach 2:
A competing agent is added that selectively reacts with dissolved boron species in the produced water, preventing premature crosslinking reactions. This mediator allows the fluid to maintain appropriate viscosity for pumping while still enabling controlled crosslinking to occur after injection
3Use of energy by moving object
If crosslinking is delayed too long, then injection energy requirements are reduced, but crosslinking must occur promptly after injection to maintain fracture conductivity
Solution Approach 1:
The pH of the fracturing fluid is maintained below 6.5 during injection to delay crosslinking, reducing viscosity and energy requirements. After injection, the pH increases naturally or through additives, triggering controlled crosslinking to occur within the optimal time window to ensure fracture conductivity is established
Solution Approach 2:
A competing agent is introduced that temporarily sequesters boron species during injection, allowing low-viscosity flow with reduced energy requirements. Once the fluid is injected into the formation, the competing agent releases the boron species, enabling crosslinking to proceed and establish the necessary fracture conductivity
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 delays the viscosity increase of the fracturing fluid, reducing the energy required for injection, minimizing equipment strain, and enabling effective penetration into low-permeability zones, thereby enhancing oil recovery by controlling the crosslinking process.
Implementation Method 1
a competing agent formed from a dialdehyde and a non-polymeric cis-hydroxyl compound
Implementation Method 2
delayed crosslinking in hydraulic fracturing fluids
Implementation Method 3
where the pH is maintained below 6.5 to prevent immediate crosslinking
Data Source
AI summary
Disclosed herein are compositions and methods for delaying crosslinking in injectable compositions for hydraulic fracturing and related applications. The compositions and methods are effective in injectable compositions comprising or substantially excluding dissolved reactive species. The compositions and methods provide delayed crosslinking at high temperatures and pressures, such as those encountered by hydraulic fracturing compositions injected into subterranean environments. Compositions include injectable solutions comprising a competing agent that is the reaction product of a dialdehyde having 2 to 4 carbon atoms with a non-polymeric cis-hydroxyl compound. Also provided are methods of making and using delayed-crosslinking compositions comprising crosslinker compositions containing zirconium complexes and the competing agents.