Dynamic Blending of Low Salinity Injection Water
Find Innovative SolutionsGenerate Solutions
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 swelling of clays and proliferation of sulfate-reducing bacteria.
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, using valves and sensors to adjust the amounts of RO and NF permeate streams and optionally high salinity water to ensure optimal TDS, ionic strength, and ion ratios, thereby controlling sulfate levels and stabilizing clays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If desalination techniques are used to reduce salinity of injection water, then oil recovery is enhanced, but formation damage occurs due to swelling of clays
Solution Approach 1:
The patent applies parameter changes by precisely controlling the salinity (TDS) of injection water within a specific range (200-10,000 ppm) and adjusting the ratio of multivalent cations to maintain enhanced oil recovery while preventing formation damage. This involves dynamic adjustment of blending ratios between produced water and desalinated water to achieve optimal salinity parameters.
Solution Approach 2:
The system implements dynamics through real-time monitoring and adjustment of injection water composition using sensors and control units. The blending ratio between produced water and desalinated water is dynamically modified based on measured salinity and composition parameters, allowing the system to adapt to changing conditions while maintaining optimal parameters for both oil recovery and formation protection.
2Loss of substance
If produced water is blended with low salinity injection water to dispose of produced water, then disposal is achieved, but salinity control becomes difficult due to variable produced water quality and quantity
Solution Approach 1:
The patent implements feedback control through sensors that continuously measure salinity (TDS), sulfate levels, and composition of the blended injection water. These measurements are fed back to a control unit that automatically adjusts the blending ratio between produced water and desalinated water to maintain salinity within the optimal range (200-10,000 ppm TDS), ensuring stable composition despite variable produced water input.
Solution Approach 2:
The system achieves multi-functionality by using the same blending system to simultaneously accomplish produced water disposal and maintain optimal injection water composition. The control unit manages multiple parameters (salinity, sulfate content, cation ratios) through a single integrated control mechanism that adjusts blending ratios to satisfy multiple requirements concurrently.
3Object-affected harmful factors
If sulfate level in injection water is reduced to prevent souring and scaling, then reservoir protection is improved, but additional processing complexity is required
Solution Approach 1:
The patent merges sulfate control with the existing salinity control process by using the same blending system and control unit to manage both TDS and sulfate levels. The reverse osmosis and nanofiltration arrays are integrated into the existing desalination process, allowing simultaneous control of multiple parameters (salinity, sulfate, cation ratios) through a unified system rather than separate processing trains.
Solution Approach 2:
The system controls sulfate levels by adjusting the blending ratio between produced water and desalinated water to maintain sulfate below 100 mg/L (preferably below 50 mg/L). This involves modifying the concentration parameters of the blended stream to achieve protective sulfate levels while maintaining optimal salinity for oil recovery, all through parameter adjustment rather than additional complex processing.
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 optimal ranges, maximizing oil recovery while minimizing formation damage, souring, and scaling risks, even with varying produced water quality and quantity, by dynamically adjusting the blending ratios and compositions in real-time.
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
AI summary
An integrated system includes a desalination plant including a reverse osmosis (RO) array to produce an RO permeate blending stream and a nanofiltration (NF) array to produce an NF permeate blending stream. The integrated system also includes a blending system. Further, the integrated system includes a control unit. Still further, the integrated system includes an injection system for one or more injection wells that penetrate an oil-bearing layer of a reservoir. Moreover, the integrated system includes 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. The blending system is configured to blend the RO permeate and NF permeate blending streams with the PW stream to produce a blended low salinity water stream. The control unit is configured 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.