Anionic Surfactant Injection Fluids for Unconventional Formation Stability
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Solution Overview
Problem
Unconventional reservoirs face formation damage due to unstable injection fluids precipitating out of solution, causing plugging and reduced well productivity under high temperature and high salinity conditions.
Innovation Solution
A low particle size injection fluid is created by combining a single-phase liquid surfactant package, primarily comprising an anionic surfactant with an aqueous-based fluid, to stabilize the fluid and reduce particle size to less than 0.1 micrometers, minimizing precipitation and enhancing fluid stability in unconventional formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If typical injection fluids with multiple chemical components and additives are used, then the injection fluid can transport proppant to fracture reaches, but the injection fluid becomes unstable under reservoir conditions causing formation damage
Solution Approach 1:
The patent removes problematic chemical additives from the injection fluid formulation. By using a simplified fluid composition without the typical dozen+ chemical components, the fluid achieves stability under reservoir conditions while maintaining proppant transport capability through alternative mechanisms.
Solution Approach 2:
The patent changes the physical parameters of the injection fluid by reducing particle size to less than 0.1 micrometers and adjusting fluid properties to be compatible with reservoir conditions (temperature, salinity, divalent ion concentrations). This parameter optimization enables both proppant transport and fluid stability.
2Quantity of substance
If injection fluids with suspended particles are used, then the fluid can be pumped in large quantities, but particles precipitate out causing plugging of matrix permeability
Solution Approach 1:
The patent extracts and removes suspended particles from the injection fluid through filtration or centrifugation before injection. This eliminates the source of formation damage while maintaining the ability to inject large fluid volumes for fracture stimulation.
Solution Approach 2:
The patent performs preliminary particle removal and fluid stabilization actions before the injection process. By preparing the fluid in advance to ensure sub-0.1 micrometer particle size and compatibility with reservoir conditions, the fluid prevents precipitation and plugging during injection.
3Reliability
If the injection fluid is stabilized for reservoir conditions, then formation damage is reduced, but the fluid composition becomes more complex
Solution Approach 1:
The patent simplifies the fluid composition by removing the typical dozen+ chemical additives. The stabilized fluid uses a minimal component list that is inherently more stable under reservoir conditions, achieving reliability without compositional complexity.
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 low particle size injection fluid maintains stability under reservoir conditions, reducing formation damage and increasing hydrocarbon recovery by minimizing particle plugging, thus improving well productivity.
Implementation Method 1
combining a single-phase liquid surfactant package comprising a primary surfactant with an aqueous-based injection fluid to form a low particle size injection fluid. The primary surfactant can comprise an anionic surfactant comprising a hydrophobic tail comprising from 6 to 60 carbon atoms.
Implementation Method 2
The low particle size injection fluid can have a maximum particle size of less than 0.1 micrometers in diameter in particle size distribution measurements performed at a temperature and salinity of the unconventional subterranean formation.
Implementation Method 3
The unstable injection fluid can cause a loss in well productivity due to formation damage (FIG. 1C). The term 'formation damage' in this context is used to refer to plugging off matrix permeability (which can be on the order of 100's of nano-Darcies) in the formation thus obstructing or hindering fluid flow, for example, due to the suspended particles in the injection fluid precipitating out of solution and causing the plugging.
Data Source
AI summary
Described herein are compositions and methods that stabilize an injection fluid when exposed to reservoir conditions, reducing formation damage and increasing the amount of hydrocarbon recovered. Specifically, the formulation is a single-phase liquid surfactant package which comprises an anionic surfactant and optionally one or more secondary surfactants.