In-Situ Emulsification Viscosity Control for Water-Flooding Reservoirs
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Solution Overview
Problem
Water-flooding oil reservoirs face challenges due to heterogeneity issues caused by varying emulsion viscosities, which affect the sweep efficiency and oil recovery rates, particularly in high- and low-permeability areas, where emulsions with excessive viscosity hinder displacement and increase injection pressure.
Innovation Solution
An in-situ emulsification and viscosity increase system comprising an emulsifier, ultrafine colloidal particles, and a suspending agent is introduced, which forms a kinetically stable water-external emulsion with controllable viscosity, suitable for both high- and low-permeability areas, by dissolving or dispersing in mineralized water and pumped into the formation, achieving piston displacement and enhancing oil recovery rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If emulsion viscosity is increased to improve oil recovery, then oil recovery rate increases, but injection pressure increases and displacement efficiency decreases
Solution Approach 1:
The emulsion viscosity is made dynamically adjustable through temperature control. At injection temperature (high temperature), the emulsion maintains low viscosity for easy injection. Upon injection into the reservoir, temperature decreases and triggers viscosity increase to enhance oil recovery. This dynamic viscosity adjustment resolves the contradiction between injection ease and oil recovery enhancement.
Solution Approach 2:
The patent changes the temperature parameter to control emulsion viscosity. By formulating the emulsion with temperature-sensitive components, the viscosity transitions from low at injection temperature to high at reservoir temperature. This parameter change allows the system to achieve both easy injection and effective oil displacement without increasing injection pressure.
2Productivity
If emulsion viscosity is increased to improve displacement efficiency, then oil recovery increases, but emulsion stability decreases and phase inversion occurs
Solution Approach 1:
The emulsion viscosity is dynamically adjusted through temperature changes rather than static formulation. At injection temperature, the emulsion is stable and low-viscosity. After injection, temperature decrease triggers controlled viscosity increase while maintaining stability. This dynamic approach avoids phase inversion that occurs with static high-viscosity formulations.
Solution Approach 2:
Temperature acts as an intermediary parameter that controls both viscosity and stability. The temperature-sensitive components serve as mediators that coordinate viscosity increase with stability maintenance. This intermediary mechanism allows the emulsion to achieve high viscosity for effective displacement while preventing phase inversion through controlled thermal conditions.
3Productivity
If water content is increased to improve sweep efficiency, then displacement efficiency increases, but emulsion type changes and viscosity control becomes difficult
Solution Approach 1:
The patent uses temperature as a parameter that overrides water content effects on emulsion type. Even at high water content, the temperature-sensitive formulation maintains consistent emulsion characteristics and viscosity control. This parameter change approach allows the system to adapt to varying water content conditions while maintaining sweep efficiency and viscosity controllability.
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 system effectively controls viscosity, allowing for efficient displacement in both high- and low-permeability areas, increasing oil recovery rates and reducing heterogeneity, with a broad applicability to water-flooding oil reservoirs, regardless of temperature and mineralization levels, and offering economic benefits.
Implementation Method 1
The emulsifier and ultrafine colloidal particles form (ultra) low interfacial tension (an order of magnitude of 10−2 mN/m and below) with crude oil
Implementation Method 2
Remaining (residual) oil is emulsified in situ to form a kinetically stable water-external emulsion
Implementation Method 3
The viscosity of the emulsion is 1 ̃1.5 times the viscosity of crude oil under high water-content conditions
Implementation Method 4
In 1903, Ramsden discovered that colloidal-scale solid particles could stabilize emulsions
Implementation Method 5
when an internal phase volume fraction reaches a maximum accumulation fraction of spherical particles, the emulsion will undergo a catastrophic phase inversion, and the viscosity of the emulsion subjected to catastrophic phase inversion will change significantly
Implementation Method 6
An interfacial film was stabilized through the network of particles or colloids adsorbed at the interface
Data Source
AI summary
An in-situ emulsification and viscosity increase system with controllable viscosity consists of the following components in percentage by weight: 0.3˜1.5% of emulsifier, 0.05˜0.5% of ultrafine colloidal particles, 0.01˜0.1% of suspending agent and the balance of mineralized water. The emulsifier is one of or a combination of petroleum sulfonate, petroleum carboxylate, sodium dodecyl sulfate, sodium dodecyl benzenesulfonate, alkyl glycoside, aliphatic alcohol ether carboxylate, aliphatic alcohol ether sulfonate, hydroxysulfobetaine and alkanolamide. The ultrafine colloidal particles are one of ultrafine silicon dioxide, ultrafine montmorillonoid, ultrafine ferric oxide, ultrafine ferroferric oxide, ultrafine aluminum oxide and ultrafine titanium dioxide. The suspending agent is one of partially hydrolyzed polyacrylamide, amylose, carboxymethyl chitosan, hydroxymethyl cellulose, xanthan gum and sodium alginate. The system is applicable to a water-flooding oil reservoir with the viscosity of lower than 50 mPa·s, has a very broad coverage scope and outstanding economic benefits and can effectively promote efficient development of water-flooding oil reservoirs.