Smart Water Polymer Flooding for Carbonate Reservoirs
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Solution Overview
Problem
Conventional polymer flooding processes for viscous oil recovery in carbonate reservoirs require high polymer dosages due to salinity issues, which are costly and limited by the availability of high salinity water, and are hindered by the interaction of polymers with divalent cations, leading to reduced viscosifying characteristics and mobility control.
Innovation Solution
The use of 'smart water' with tailored salinity and ionic composition, between 5,000 ppm and 7,000 ppm total dissolved solids, and a polymer such as copolymers of acrylamide and acrylate or acrylamide tertiary butyl sulfonate, reduces polymer concentration requirements by altering rock wettability and enhancing viscosifying characteristics, allowing for lower polymer volumes and improved mobility control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high polymer dosage is used to achieve adequate viscosity in high salinity water, then mobility control is improved, but operation cost increases significantly
Solution Approach 1:
The patent changes the chemical parameters of the injection water by reducing salinity from conventional high salinity levels to less than 5,000 ppm TDS. This parameter change allows polymers to maintain their viscosifying characteristics without requiring excessive dosages, thereby achieving adequate mobility control at lower polymer concentrations and reduced operation costs
Solution Approach 2:
The patent converts the harmful effect of salinity on polymer performance into a benefit by using low salinity water. The reduced salinity eliminates the detrimental interaction between divalent cations and polymer chains, allowing the polymer to function effectively at much lower concentrations, thus turning the previously harmful high salinity condition into a beneficial low salinity condition for cost-effective mobility control
2Stability of the object's composition
If high polymer dosage is used to overcome divalent cation interference, then viscosity is maintained, but polymer consumption increases
Solution Approach 1:
The patent changes the ionic composition parameter of the injection water by reducing divalent cation concentration to less than 300 ppm through water treatment and blending operations. This parameter change prevents divalent cations from binding to polymer carboxyl groups and causing coiling, thereby maintaining polymer viscosity at low concentrations and reducing polymer consumption by up to 50%
Solution Approach 2:
The patent introduces low salinity water as an intermediary medium that mediates between the polymer and divalent cations. This intermediary low salinity environment prevents direct harmful interactions between polymers and divalent cations, allowing polymers to maintain their extended conformation and viscosifying function at much lower dosages
3Reliability
If smart water with low salinity is used, then polymer effectiveness is improved, but water treatment complexity increases
Solution Approach 1:
The patent creates a universal low salinity water formulation with specific ionic composition (less than 5,000 ppm TDS, less than 300 ppm divalent cations) that can be used across different carbonate reservoirs regardless of specific conditions. This universal smart water formulation simplifies operations by providing a single effective solution that improves polymer effectiveness without requiring complex customized treatment for each reservoir
Solution Approach 2:
The patent performs preliminary water treatment and blending operations to prepare the low salinity smart water before polymer injection. By pre-treating the water to achieve the target ionic composition and storing it ready for use, the system eliminates the need for complex real-time treatment during injection operations, thereby improving polymer effectiveness while keeping water treatment complexity manageable
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 reduces polymer consumption by up to 50%, increases incremental oil recovery by 5 to 10%, and improves both microscopic and macroscopic sweep efficiency, resulting in more economical and effective polymer flooding operations for viscous oil recovery in carbonate reservoirs.
Implementation Method 1
a smart water, the smart water operable to alter a wettability of the in situ rock
Implementation Method 2
a polymer, the polymer operable to increase the viscosity of the composition
Data Source
AI summary
A composition for use in a polymer flooding operation in a viscous oil containing carbonate reservoir formation with in situ rock is provided. The composition includes a polymer, the polymer operable to increase the viscosity of the composition; and a smart water, the smart water operable to alter a wettability of the in situ rock, wherein the smart water has a total dissolved solids of between 5,000 ppm and 7,000 ppm, wherein the total dissolved solids comprises one or more salts; wherein the composition has a viscosity between 4 cP and 100 cP.