Low-Salinity Injection Water Blending for Reservoir Damage Control
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Solution Overview
Problem
Low salinity water-flooding techniques face challenges in maintaining optimal salinity for injection water to enhance oil recovery while preventing formation damage, souring, and scaling, especially when dealing with variable produced water quality and quantity, which can lead to suboptimal injection water composition.
Innovation Solution
An integrated system comprising a desalination plant with reverse osmosis and nanofiltration arrays, a blending system, and a control unit dynamically adjusts the operation to maintain the composition of blended low salinity injection water within predetermined limits, ensuring optimal salinity, ion ratios, and sulfate levels to prevent formation damage and souring, and manage scaling risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If desalination techniques are used to reduce salinity of injection water, then enhanced oil recovery is achieved, but the water may become too low in salinity and cause formation damage
Solution Approach 1:
The patent applies parameter changes by precisely controlling the salinity concentration of injection water within a specific range (200-10,000 ppm TDS) and adjusting the ratio of multivalent cations to optimize both oil recovery and prevent formation damage. This involves dynamic adjustment of blending ratios between produced water and makeup water based on real-time monitoring of water composition
Solution Approach 2:
The patent implements feedback control through continuous monitoring of injection water composition using sensors that measure salinity, ion concentrations, and other parameters. The control system automatically adjusts the blending process based on this feedback to maintain optimal parameters, ensuring enhanced oil recovery while preventing formation damage from overly diluted water
2Loss of substance
If produced water is blended with low salinity injection water to dispose of produced water, then produced water disposal is achieved, but the composition of injection water may become suboptimal
Solution Approach 1:
The patent applies dynamics by making the blending system adjustable and flexible. The blending ratio between produced water and makeup water can be dynamically changed based on the variable quantity and quality of produced water available. This allows the system to adapt to changing conditions while maintaining optimal injection water composition through real-time control
Solution Approach 2:
The patent uses parameter changes to compensate for variations in produced water quality. By adjusting the salinity, ion concentrations, and other parameters of the blended water through controlled mixing with makeup water, the system maintains optimal injection water composition despite the variable composition of produced water being disposed
3Object-affected harmful factors
If sulfate level in injection water is controlled to prevent souring and scaling, then reservoir souring and scaling are mitigated, but the control complexity increases
Solution Approach 1:
The patent applies universality by using a multi-functional control system that simultaneously manages multiple parameters including salinity, sulfate concentration, ion ratios, and blending ratios. The same control system and blending apparatus handle both produced water disposal and injection water composition control, reducing overall system complexity despite the multiple functions being performed
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 system effectively maintains the composition of blended low salinity injection water within a predetermined operating envelope, maximizing oil recovery while minimizing the risks of formation damage, souring, and scaling, even with varying produced water quality and quantity, ensuring robust control and rapid adjustments to maintain optimal injection water properties.
Implementation Method 1
a reverse osmosis (RO) array to produce an RO permeate blending stream
Implementation Method 2
a nanofiltration (NF) array to produce an NF permeate blending stream
Data Source
Figure 1
AI summary
An integrated system comprising: a desalination plant comprising a reverse osmosis (RO) array to produce an RO permeate blending stream and a nanofiltration (NF) array to produce an NF permeate blending stream; a blending system; a control unit; an injection system for one or more injection wells that penetrate an oil-bearing layer of a reservoir; and a production facility to separate fluids produced from one or more production wells that penetrate the oil-bearing layer of the reservoir and to deliver a produced water (PW) stream to the blending system, wherein the blending system is to blend the RO permeate and NF permeate blending streams with the PW stream to produce a blended low salinity water stream, wherein the control unit is to dynamically alter operation of the blending system to adjust amounts of at least one of the RO permeate blending stream and the NF permeate blending stream to maintain a composition of the blended low salinity water stream within a predetermined operating envelope.