Solvent Inventory Management in Gravity Drainage Extraction
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Solution Overview
Problem
Current Enhanced Oil Recovery (EOR) methods for unconventional hydrocarbon resources like Canadian oil sands, such as SAGD and VAPEX, face inefficiencies in solvent usage, leading to high greenhouse gas emissions, capital costs, and slow extraction rates, with existing solutions like Nsolv and Thermal Solvent processes experiencing issues with solvent distribution and non-condensable gas trapping, which increases solvent-to-oil ratios and operational costs.
Innovation Solution
Increasing the bottom hole temperature of the injection well above the dew point of the solvent to maintain it as a vapor within the extraction chamber, creating a heated zone that vaporizes liquid solvent and reduces non-productive condensation, while ensuring the heated zone does not interfere with drainage or non-condensable gas removal, using methods like superheated injection, electric heaters, or co-injecting vapour energy carriers to manage solvent inventory and reduce solvent-to-oil ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the chamber grows in size and extraction surface area increases, then more solvent can process larger volumes of bitumen, but higher solvent injection rates are required leading to increased solvent inventory and solvent-to-oil ratio
Solution Approach 1:
The patent applies parameter changes by controlling temperature and pressure conditions to maintain solvent at or near its dew point, optimizing the phase behavior of the solvent to maximize condensation efficiency at the extraction interface while minimizing premature condensation in the chamber, thereby reducing the quantity of solvent required for a given extraction rate
Solution Approach 2:
The patent utilizes phase transitions by injecting solvent as a vapor that condenses to liquid at the extraction interface where bitumen is being extracted. This phase change releases latent heat to mobilize bitumen and the liquid solvent dissolves the mobilized bitumen for gravity drainage, thereby improving productivity without proportionally increasing solvent inventory
2Productivity
If solvent is injected at higher rates to maintain extraction rate as chamber grows, then extraction continues at required rate, but solvent-to-oil ratio increases leading to higher operational costs
Solution Approach 1:
The patent implements feedback control by monitoring chamber pressure, temperature, and solvent injection rate to maintain optimal operating conditions. The system adjusts solvent injection parameters based on real-time measurements of chamber growth and extraction performance, thereby maintaining efficient solvent utilization and preventing excessive solvent-to-oil ratio as the chamber expands
Solution Approach 2:
The patent changes operational parameters including solvent injection temperature, pressure, and rate based on chamber maturity and growth stage. By dynamically adjusting these parameters, the system maintains optimal solvent condensation efficiency at the extraction interface throughout the production lifecycle, preventing the solvent-to-oil ratio from increasing disproportionately with chamber size
3Reliability
If non-condensable gases are present in the chamber, then they occupy space and interfere with solvent-bitumen contact, but removing them requires additional equipment and process complexity
Solution Approach 1:
The patent extracts non-condensable gases from the chamber by providing a dedicated gas removal system that selectively removes non-condensable gases while allowing solvent vapor and condensed liquid to remain. This separation function improves solvent-bitumen contact efficiency by eliminating gas barriers at the extraction interface without requiring complex multi-functional equipment
Solution Approach 2:
The patent uses an intermediary gas removal system that acts as a mediator between the solvent injection system and the extraction interface. This separate gas removal pathway allows non-condensable gases to be evacuated without interfering with the solvent condensation and bitumen extraction processes, maintaining high contact efficiency while avoiding direct integration of gas removal into the solvent injection equipment
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 significantly reduces the solvent inventory and solvent-to-oil ratio, maintaining oil production rates while minimizing energy consumption and operational costs, by ensuring solvent vaporization occurs only at the extraction interface, thus optimizing solvent usage and reducing heat losses.
Implementation Method 1
heating an extracted volume of the chamber around the injection well to a temperature above the bubble point of the solvent to permit the liquid solvent passing therethrough to re-vapourize
Implementation Method 2
solvent condensation releases the latent heat of condensation. When this occurs in the chamber at the extraction surface, the heat flux from condensing solvent to the bitumen heats the bitumen
Data Source
AI summary
A method of managing a liquid solvent inventory in a condensing solvent gravity drainage extraction chamber includes growing the extraction chamber by injecting a solvent vapour under conditions which cause at least a portion of the solvent vapour to condense on a hydrocarbon extraction interface at a condensation temperature, then accumulating within the extraction chamber condensed liquid solvent which is draining through the chamber under the influence of gravity, which liquid solvent includes a hydrocarbon rich fluid production layer which is proximal to said extraction interface, and then heating a portion of the extraction chamber from a location near, in and/or above the injector to create a heated zone having a temperature above the condensation temperature without heating the hydrocarbon rich production layer to permit the hydrocarbon rich production layer to continue to drain to a production well.