Dilute Polymer Salt Composition for Carbonate Reservoir Mobility Control
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Solution Overview
Problem
Water flooding processes for enhanced oil recovery in carbonate reservoirs are mobility constrained due to insufficient injection water viscosities, leading to poor sweep efficiencies at the reservoir scale.
Innovation Solution
An oil recovery composition comprising an aqueous solution of salts with a salinity of 4,000 to 8,000 ppm TDS and a dilute polymer, including sodium chloride, calcium chloride, magnesium chloride, sodium sulfate, and magnesium sulfate, is used, along with metal oxide nanoparticles and surfactants, to enhance oil recovery by increasing viscosity and improving sweep efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water flooding is used for enhanced oil recovery, then oil production increases and environmental safety is maintained, but mobility control is insufficient due to low injection water viscosity
Solution Approach 1:
The patent changes the chemical composition parameters of injection water by adding specific salts (calcium chloride, magnesium chloride, sodium sulfate, magnesium sulfate) to achieve a salinity of 4,000-8,000 ppm TDS. This parameter modification enables the polymer to achieve higher viscosity at lower concentrations, resolving the contradiction between maintaining environmental safety and improving mobility control
Solution Approach 2:
The patent creates a composite injection fluid system combining four key components: diluted polymer (250-750 ppm), salt mixture (4,000-8,000 ppm TDS), and specific ion concentrations. This composite approach synergistically enhances viscosity and mobility control while maintaining environmental compatibility, allowing effective sweep efficiency improvement without compromising the other attributes
2Ease of operation
If conventional water flooding is used, then the process is simple and environmentally safe, but sweep efficiency is poor due to mobility constraints
Solution Approach 1:
The patent modifies the chemical parameters of injection water by controlling salinity (4,000-8,000 ppm TDS) and specific ion concentrations. These parameter changes enhance polymer viscosity effectiveness, improving macroscopic sweep efficiency while maintaining relatively simple injection operations
Solution Approach 2:
The patent applies different chemical compositions to different functional requirements: the salt mixture addresses mobility control in high-permeability zones, while the diluted polymer provides viscosity enhancement. This localized functional assignment improves overall sweep efficiency without requiring complete process redesign
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
The solution significantly boosts oil recovery performance by increasing viscosity and mobility control, resulting in improved macroscopic sweep efficiency and economic benefits for oil recovery in carbonate reservoirs.
Implementation Method 1
The polymer may have a concentration of 250 parts-per-million (ppm) to 750 ppm. The one or more salts may include at least one of sodium chloride (NaCl), calcium chloride (CaCl2), magnesium chloride (MgCl2), sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4)
Data Source
AI summary
An oil recovery composition of an aqueous solution of one or more salts and dilute polymer and processes for enhanced oil recovery using the oil recovery composition are provided. An oil recovery composition may include an aqueous solution of one or more salts having a salinity of about 4000 parts-per-million (ppm) total dissolved solids (TDS) to about 8000 ppm TDS and a polymer having a concentration of 250 ppm to 750 ppm. The one or more salts may include at least one of sodium chloride (NaCl), calcium chloride (CaCl2), magnesium chloride (MgCl2), sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4). The polymer may include a copolymer of acrylamide and acrylamido tertiary butyl sulfonate (ATBS). The oil recovery compositions provided may be suited for enhancing oil recovery in carbonate reservoirs having in situ oil viscosities less than 3 centipoise (cP).