Tertiary Amine-Grafted Silica Nano-Plugging Agent for Wellbore Stability
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Solution Overview
Problem
Existing plugging agents fail to effectively stabilize the well wall during oil-gas field drilling in shale formations due to their inability to plug nano-scale cracks, leading to well instability and collapse.
Innovation Solution
A high-temperature-resistant tertiary amine-grafted silica nano-plugging agent is developed, prepared using a hydrazine compound, diallyl compound, enamine compound, silica particles, and an amino-containing silane coupling agent, which is incorporated into water-based drilling fluids to effectively plug nano-scale cracks and stabilize the well wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sulfonated asphalt or emulsified asphalt is used as plugging agent, then micro-scale cracks can be plugged effectively, but nano-scale cracks cannot be plugged due to particle size mismatch
Solution Approach 1:
The patent changes the particle size parameter of the plugging agent from micron scale (conventional asphalt) to nano scale (10-20 nm silica particles). This parameter change enables the plugging agent to match and effectively plug nano-scale crack dimensions in shale formations, resolving the size mismatch problem.
Solution Approach 2:
The patent creates a composite plugging agent by grafting tertiary amine functional groups onto silica nanoparticle surfaces. This composite structure combines the nano-scale size of silica particles with the chemical functionality of tertiary amines, enabling both physical plugging of nano-cracks and chemical interaction with crack surfaces for enhanced effectiveness.
2Reliability
If particles are deposited on the surface of nano-scale cracks, then some plugging effect is achieved, but the particles are easily flushed by drilling fluids resulting in discounted plugging effect
Solution Approach 1:
The patent modifies the surface chemical properties of silica particles by grafting tertiary amine groups, changing their interaction mechanism from simple physical deposition to chemical adsorption. This chemical functionality enhances particle adhesion strength to crack surfaces, preventing easy flushing by drilling fluids.
Solution Approach 2:
The tertiary amine functional groups act as intermediaries between the silica particle surface and the crack wall. These functional groups provide chemical interaction sites that mediate the bonding between particles and crack surfaces, significantly improving adhesion strength and plugging stability.
3Loss of substance
If conventional plugging agents are used, then filtration losses are reduced to some extent, but well wall instability and collapse still occur due to ineffective nano-crack plugging
Solution Approach 1:
The patent reduces particle size from micron to nano scale (10-20 nm), enabling penetration and effective plugging of nano-scale cracks. This parameter change simultaneously reduces filtration losses by blocking nano-pore pathways and improves well wall stability by preventing hydraulic splitting in nano-cracks.
Solution Approach 2:
The composite structure of tertiary amine-grafted silica nanoparticles provides both the nano-scale size needed for crack penetration and the chemical functionality needed for strong adhesion. This dual functionality simultaneously addresses filtration loss reduction and well wall stability improvement.
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 tertiary amine-grafted silica nano-plugging agent demonstrates excellent plugging performance, high-temperature resistance, and adaptability, significantly reducing well instability and filtration losses, thereby maintaining well stability and preventing reservoir contamination.
Implementation Method 1
reacting the silica particle with the amino-containing silane coupling agent for 5 h followed by vacuum distillation for 2 h to obtain a first crude product
Implementation Method 2
adding 0.48-0.53 mol of the hydrazine compound under stirring in the protection of nitrogen followed by heating to 30-40° C. for reaction for 8-12 h and vacuum distillation to obtain a secondary amine polymer
Implementation Method 3
adding 0.24-0.29 mol of the enamine compound into the fourth solution, followed by stirring at 60-68° C. for 36 h and vacuum distillation to obtain a third crude product
Implementation Method 4
vacuum distillation for 2 h to obtain a first crude product
Implementation Method 5
subjecting the crude product to rinsing with methylbenzene and filtration to remove unreacted silica particle, and vacuum drying for 2 h to obtain a modified nano-silica
Data Source
AI summary
Disclosed are a high-temperature-resistant tertiary amine-grafted silica nano-plugging agent and water-based drilling fluids, relating to oil-gas field drilling. The nano-plugging agent is prepared from a hydrazine compound, a diallyl compound, an enamine compound, silica particle, and an amino-containing silane coupling agent by stepwise reaction. The nano-plugging agent has a grain size of 58-280 nm.