Dense Aqueous Gravity Displacement for Heavy Oil Recovery
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Solution Overview
Problem
Conventional heavy oil recovery methods, such as water flooding and thermal recovery, face inefficiencies due to high mobility ratios and the presence of thief zones with high fluid mobility, leading to bypassing of oil and increased water requirements, which negatively impacts the overall recovery process.
Innovation Solution
The dense aqueous gravity displacement (DAGD) process involves injecting a dense aqueous fluid with a higher temperature than the immobile heavy oil, creating a gravity-driven displacement that mobilizes and separates the heavy oil, allowing it to rise and be produced, while managing fluid density and viscosity to optimize recovery, even in reservoirs with thief zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional water flooding is used to displace heavy oil, then the process is simple to implement, but the mobility ratio becomes too high causing oil to be bypassed and requiring many multiples of injected water volume
Solution Approach 1:
The invention changes the physical parameters of the injection fluid by using dense aqueous fluids with density greater than the heavy oil and elevated temperatures. This transforms the displacement mechanism from viscosity-driven to density-driven, fundamentally altering the mobility ratio and displacement efficiency while maintaining operational simplicity
Solution Approach 2:
Instead of using less dense fluids that rely on pressure differentials to push oil (conventional water flooding), the invention inverts the approach by using denser fluids that naturally displace oil through gravity-driven convection, reversing the traditional displacement paradigm
2Temperature
If steam injection is used for thermal recovery, then oil viscosity is reduced for mobilization, but thief zones with high fluid mobility cause the injected fluid to bypass the oil
Solution Approach 1:
The invention modifies the density parameter of the injection fluid to be greater than the heavy oil density, creating a stable density gradient that prevents bypassing by thief zones while maintaining the thermal effects needed for oil mobilization
Solution Approach 2:
The dense aqueous fluid creates a more uniform energy distribution throughout the reservoir by sinking and heating from below, eliminating the preferential flow paths that occur with steam injection and creating equipotential conditions that improve sweep efficiency
3Productivity
If large volumes of injected water are used in conventional flooding, then oil displacement is achieved, but water requirements increase many multiples of movable oil volume
Solution Approach 1:
By changing the density parameter of the injection fluid to be greater than the oil density, the invention achieves more efficient displacement where the volume of injected fluid required is significantly reduced compared to conventional flooding, as the density-driven mechanism is more effective at mobilizing oil
4Ease of operation
If high mobility ratio conditions exist in thief zones, then injected fluid flows easily through the zone, but the oil is bypassed and recovery efficiency decreases
Solution Approach 1:
The invention changes the density relationship between injection fluid and oil, creating a situation where the denser injection fluid sinks and displaces oil from below, preventing bypassing by thief zones and improving recovery efficiency while maintaining fluid flow
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
DAGD enhances the efficiency of heavy oil recovery by creating an expanding zone of mobilized oil, reducing the need for large volumes of injected water and improving the mobility ratio, thereby increasing the volume of recoverable oil and reducing operational inefficiencies.
Implementation Method 1
The aqueous injection fluid has, during at least a portion of the recovery process, a density greater than the density of the immobile heavy oil and a temperature greater than the temperature of the immobile heavy oil
Implementation Method 2
injecting an aqueous injection fluid into the formation through an injection well into an injection zone that is in fluid communication with the immobile heavy oil
Implementation Method 3
the density of heavy oil, when heated to a temperature sufficient to mobilize the oil, is greater than the density of the hot aqueous condensate formed from the injected steam, so that the mobilized oil collects at the bottom of the steam chamber by gravity drainage
Implementation Method 4
the aqueous injection fluid has, during at least a portion of the recovery process, a density greater than the density of the immobile heavy oil
Data Source
AI summary
Methods are provided that facilitate the production of hydrocarbons from subterranean formations, involving the mobilization of an immobile heavy oil in situ by gravity displacement. In effect, heavy oil is mobilized by dense aqueous gravity displacement (DAGD), in a process that generally involves injecting a dense, heated aqueous injection fluid into the formation into an injection zone that is in fluid communication with immobile heavy oil. The injection well is operated so that the injection fluid mobilizes and displaces the immobile heavy oil, to produce an expanding upper zone of mobilized heavy oil amenable to production.