Stepwise Salinity Reduction for Carbonate Reservoir Oil Recovery
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Solution Overview
Problem
Current waterflooding methods for carbonate reservoirs are inefficient due to the lack of effectiveness of low salinity water floods, as carbonate reservoirs do not contain clays, and existing methods require complex chemicals or gases, which are not suitable for existing infrastructure.
Innovation Solution
A process involving multiple water flooding steps with progressively lower salt concentrations, starting from a first water solution with a high salt concentration, including ions like sulfate, calcium, and magnesium, to improve hydrocarbon recovery in carbonate reservoirs without the need for complex chemicals or gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low salinity water flooding is used in carbonate reservoirs, then oil recovery is expected to improve based on sandstone reservoir experience, but oil recovery actually decreases due to lack of clays and reduced active ions
Solution Approach 1:
The water flooding process is divided into multiple sequential stages with progressively decreasing salinity levels. The first stage uses high salinity water (35,000-70,000 ppm) to establish baseline recovery, followed by a second stage using lower salinity water (17,500-35,000 ppm) to achieve additional recovery improvement. This segmented approach allows the system to benefit from both high and low salinity conditions at different times, resolving the contradiction by avoiding direct low salinity injection that would decrease recovery in clay-free carbonate reservoirs.
2Productivity
If complex chemicals or gases such as carbon dioxide, surfactants, polymers are used to improve oil recovery, then oil recovery can be enhanced, but the process complexity and infrastructure requirements increase
Solution Approach 1:
The method utilizes naturally occurring brine from the reservoir or easily sourced water that requires minimal chemical treatment. The salinity adjustment is achieved through simple mixing and dilution processes rather than complex chemical formulations. This self-service approach allows the system to improve oil recovery using readily available resources and simple infrastructure, avoiding the need for complex chemical injection systems while still achieving enhanced recovery.
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 process achieves a significant improvement in incremental oil recovery, with up to 9% additional hydrocarbon recovery compared to conventional methods, demonstrating its effectiveness in carbonate reservoirs without requiring complex chemicals or modifications to existing infrastructure.
Implementation Method 1
Waterflooding is a method of secondary recovery in which water is injected into a reservoir formation to displace mobile oil within the reservoir formation. The water from injection wells physically sweeps the displaced oil to adjacent production wells
Data Source
AI summary
A method for increasing oil production in a carbonate reservoir by conducting a step-wise reduction of salinity of the injected salt water that is injected into the carbonate reservoir. The method provides for increased oil production as compared to conventional waterflooding techniques.