RO/NF Desalination Control for Reservoir-Safe Injection Water
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Solution Overview
Problem
Existing desalination techniques produce low salinity water that may damage oil-bearing rock formations due to improper salinity levels, leading to formation damage, and can cause souring or scaling issues due to high sulfate anion and multivalent cation content, which are not optimally controlled for enhanced oil recovery.
Innovation Solution
A computerized control system integrated within a desalination plant to manage reverse osmosis and nanofiltration processes, blending systems, and valves/pumps, adjusting flow rates and pressures to produce injection water within a controlled salinity, sulfate, and multivalent cation envelope, mitigating formation damage and souring risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If desalination techniques are used to produce low salinity injection water, then enhanced oil recovery is achieved, but formation damage occurs due to improper salinity levels
Solution Approach 1:
The system dynamically adjusts multiple water composition parameters (salinity, sulfate content, multivalent cation levels) simultaneously to achieve the optimal composition window that enhances oil recovery while preventing formation damage. This involves continuous monitoring and adjustment of TDS, sulfate, calcium, and magnesium levels to match specific reservoir requirements.
2Productivity
If desalinated water is mixed with high salinity water to adjust salinity, then optimal salinity for oil recovery is achieved, but sulfate anion content becomes too high causing souring and scaling
Solution Approach 1:
The system selectively removes sulfate anions from the water stream using specialized filtration membranes that allow passage of water and monovalent ions while rejecting sulfate. This extraction of the harmful sulfate component enables achievement of optimal salinity through blending without introducing excessive sulfate that would cause souring or scaling.
Solution Approach 2:
The system applies different treatment approaches to different ionic components of the water. Specifically, sulfate removal is applied selectively to prevent souring and scaling, while salinity adjustment through controlled blending is applied to optimize oil recovery. This localized treatment of different chemical components resolves the contradiction between achieving optimal salinity and preventing sulfate-related problems.
3Productivity
If desalinated water is mixed with high salinity water to adjust salinity, then optimal salinity for oil recovery is achieved, but multivalent cation content becomes too high
Solution Approach 1:
The system independently controls multivalent cation levels (calcium, magnesium) separate from overall salinity adjustment. By using membranes with specific ion rejection characteristics and controlling the blending ratio of desalinated water to high salinity water, the system achieves optimal salinity while maintaining multivalent cation levels within the required envelope for preventing precipitation and scaling.
4Manufacturing precision
If complex blending and treatment processes are used to control multiple parameters, then optimal injection water composition is achieved, but system complexity increases
Solution Approach 1:
The system employs a multi-functional integrated treatment train where reverse osmosis and nanofiltration membranes perform multiple functions simultaneously: desalination, sulfate removal, and multivalent cation control. This universal approach allows a single processing system to control multiple water quality parameters (TDS, sulfate, calcium, magnesium) without requiring separate treatment units for each parameter, thereby managing complexity while achieving precise composition control.
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 produces low salinity injection water that minimizes formation damage and souring, ensuring optimal salinity and ion levels for enhanced oil recovery by continuously monitoring and adjusting desalination plant operations.
Implementation Method 1
a first reverse osmosis (RO) filtration unit configured to receive a first high salinity feed water and produce a first RO permeate and a first RO concentrate; a second RO filtration unit configured to receive a second high salinity feed water and produce a second RO permeate and a second RO concentrate
Implementation Method 2
a first nanofiltration (NF) filtration unit configured to receive a first feed water and produce a first NF permeate and a first NF concentrate; a second NF filtration unit configured to receive a second feed water and produce a second NF permeate and a second NF concentrate
Data Source
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AI summary
A control system configured to control operation of reverse osmosis (RO) array(s), nanofiltration (NF) array(s) and/or a blending system including a control panel (CP), regulatory controllers (RCs), and a supervisory controller (SC), wherein the SC is in signal communication with the CP, and with the RCs, wherein the SC is configured to: receive user inputs from the CP, and receive inputs from RCs regarding data from sensors, wherein the RCs are in signal communication with the plurality of sensors, wherein the RCs are configured to: receive data from the sensors, provide outputs to and receive permissions from the SC, and instruct devices in response to the received permissions from the SC, and wherein the SC is configured to: monitor trends in the inputs regarding and/or predict outcomes from data received from the RCs and determine the permissions for RCs based on the monitored trends and/or user inputs from the CP.