Injection Water Salinity Control via RO-NF Blending
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Solution Overview
Problem
In sandstone reservoirs, low salinity water injection can lead to loss of injectivity due to formation damage caused by clay swelling and migration of fines, which existing methods have not adequately addressed.
Innovation Solution
An integrated system comprising a desalination plant, blending system, and control unit that dynamically adjusts the composition of injection water by blending reverse osmosis and nanofiltration permeate streams to gradually reduce salinity, monitoring pressure and flow rate in real time to prevent formation damage, and optionally adding fines stabilizing additives to manage potential formation damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low salinity water is injected into sandstone reservoirs, then waterflood efficiency is improved, but formation damage occurs due to clay swelling and fines migration
Solution Approach 1:
The system performs preliminary action by gradually reducing salinity over time before reaching the target low salinity level. The controlled reduction system adjusts injection water salinity in a stepwise manner, allowing the formation to adapt progressively rather than experiencing sudden salinity shock that causes clay swelling and fines migration.
Solution Approach 2:
The invention applies parameter changes by dynamically adjusting the salinity parameter of injection water over time. The controlled reduction system modifies the concentration parameter gradually, transitioning from high salinity to low salinity in controlled steps, thereby maintaining formation stability while achieving the desired waterflood efficiency improvement.
2Reliability
If salinity of injection water is reduced gradually to mitigate formation damage, then injectivity is maintained, but commissioning time is extended
Solution Approach 1:
The system implements dynamics by making the salinity reduction process adaptive and responsive. The controlled reduction system continuously monitors formation conditions and adjusts the salinity reduction rate dynamically, accelerating the process when conditions permit and slowing down when formation sensitivity is detected, thereby optimizing both time and injectivity preservation.
Solution Approach 2:
The invention applies feedback through continuous monitoring of injection pressure and flow rate during the commissioning process. The controlled reduction system uses this feedback information to adjust the salinity reduction rate in real-time, ensuring injectivity is maintained while minimizing commissioning time by avoiding unnecessary delays.
3Object-affected harmful factors
If blended water streams are used to control salinity and sulfate concentration, then formation damage is prevented, but system complexity increases
Solution Approach 1:
The system applies universality by designing a multi-functional controlled reduction system that simultaneously manages salinity reduction, sulfate concentration control, and injectivity monitoring. This integrated approach consolidates multiple functions into a single system, reducing overall complexity compared to separate systems for each function while still achieving comprehensive formation protection.
Solution Approach 2:
The invention uses blended water streams as an intermediary medium to achieve controlled salinity and sulfate delivery. By mixing different water sources with varying compositions, the system creates an intermediate solution that balances the need for low salinity/sulfate with the need to maintain formation stability, simplifying the control mechanism compared to direct injection of pure low-salinity water.
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 mitigates the risk of formation damage during low salinity water injection by gradually adjusting the salinity of injection water, maintaining injectivity, and controlling sulfate concentrations to prevent souring or scaling, thereby ensuring stable reservoir conditions.
Implementation Method 1
A reverse osmosis (RO) array (4) to produce an RO permeate blending stream (9) and a nanofiltration (NF) array (5) to produce an NF permeate blending stream (13)
Implementation Method 2
a nanofiltration (NF) array (5) to produce an NF permeate blending stream (13)
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 an injection well that penetrates an oil-bearing layer of a reservoir; and wherein the blending system is to blend the RO permeate blending stream and the NF permeate blending stream to produce a blended injection 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 alter the composition of the blended injection water stream from an initial composition to a target composition.