Cyclic Solvent Vapor and Steam Injection for Viscous Hydrocarbon Recovery
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Solution Overview
Problem
Thermal recovery processes for viscous hydrocarbons from subterranean formations face inefficiencies due to solvent loss and increased production costs, as existing methods often inefficiently utilize solvents and require large surface facilities for solvent separation and re-injection.
Innovation Solution
The method involves a sequence of injection cycles where a heated solvent vapor stream and a steam stream are alternately injected into a subterranean formation, with the steam stream vaporizing condensed solvent to enhance solvent utilization and reduce solvent loss, thereby improving the efficiency of solvent use and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a thermal recovery process utilizes a solvent as the thermal recovery stream, then the viscous hydrocarbons can be heated, dissolved, and diluted to enable production, but solvent loss to the subterranean formation increases production costs
Solution Approach 1:
The patent implements cyclic injection of solvent vapor followed by steam injection. The solvent is injected during a first time period to dissolve and mobilize viscous hydrocarbons, then steam is injected during a second time period to heat the formation and vaporize condensed solvent, preventing solvent loss and enabling its reuse in subsequent cycles
Solution Approach 2:
The patent utilizes phase transitions of the solvent between vapor and liquid phases. Solvent vapor is injected to contact and dissolve viscous hydrocarbons, then steam injection causes the solvent to condense into liquid form that can be recovered and reused, thereby minimizing solvent loss to the formation
2Reliability
If solvent is recovered and re-injected into the subterranean formation, then solvent utilization is maintained, but the volume of solvent produced increases surface facility size requirements and production costs
Solution Approach 1:
The patent extracts only the necessary thermal energy and mobilized hydrocarbons through steam injection, allowing condensed solvent to remain in the formation or be minimally produced. This reduces the volume of solvent requiring surface separation and re-injection infrastructure while maintaining solvent utilization through the cyclic process
Solution Approach 2:
The steam injection serves multiple functions simultaneously: it heats the subterranean formation to maintain thermal conditions for solvent effectiveness, vaporizes condensed solvent to prevent loss, and provides the energy needed for the cyclic process. This self-service approach reduces the need for separate solvent recovery and re-injection facilities
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 enhances the recovery factor and cumulative solvent-to-oil ratio, reducing solvent costs and improving the overall efficiency of viscous hydrocarbon recovery by optimizing solvent utilization within the subterranean formation.
Implementation Method 1
injecting a steam stream into the heated chamber... the steam stream vaporizing condensed solvent to enhance solvent utilization and reduce solvent loss
Implementation Method 2
injecting a heated solvent vapor stream into a heated chamber... injecting a steam stream into the heated chamber... thermal contact between the thermal recovery stream and the subterranean formation heats the subterranean formation
Data Source
AI summary
Thermal recovery methods for recovering viscous hydrocarbons from a subterranean formation. The thermal recovery methods include performing a plurality of injection cycles. Each injection cycle in the plurality of injection cycles includes injecting a heated solvent vapor stream into a heated chamber that extends within the subterranean formation and fluidly contacting the viscous hydrocarbons with the heated solvent vapor stream to generate mobilized viscous hydrocarbons. Each injection cycle also includes injecting a steam stream into the heated chamber. The thermal recovery methods further include producing a chamber liquid and/or mobilized viscous hydrocarbons from the subterranean formation.