Low Salinity Waterflood Ion Diffusion Calculation

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Solution Overview

Problem

The effectiveness of low salinity waterflooding in hydrocarbon-bearing reservoirs with interbedded permeable and impermeable layers is reduced due to ion diffusion from high salinity connate water in shale layers into the injected low salinity water, leading to increased salinity and reduced oil recovery.

Innovation Solution

A computer-implemented method to configure operating conditions for desalination and fluid injection equipment by deriving an ion diffusion distance value and comparing it to the thickness of permeable layers, generating an indication of the effectiveness of the low salinity waterflood, and optimizing equipment settings to maximize oil recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If low salinity water is injected into the reservoir, then oil displacement efficiency is improved, but ion diffusion from shale layers increases salinity of injection water reducing effectiveness

Engineering Contradiction:

Improveoil recoveryVSAvoidion diffusion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by calculating the ion diffusion distance before the low salinity waterflood operation. The system determines whether the permeable layer thickness is sufficient to prevent harmful ion diffusion from adjacent shale layers, and only then proceeds with the low salinity water injection to ensure oil recovery effectiveness.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies preliminary anti-action by establishing criteria to prevent ion diffusion harm before it occurs. The system evaluates the relationship between permeable layer thickness and ion diffusion distance, and only permits low salinity water injection when the layer thickness exceeds the diffusion distance, thereby preventing salinity contamination before it can reduce oil recovery effectiveness.

Inventive Principle:

Principle #9Preliminary anti-action

2Productivity

If low salinity water is used for waterflooding, then displacement of oil from reservoir is improved, but limited availability of low salinity water constrains operation

Engineering Contradiction:

Improveoil recoveryVSAvoidlow salinity water availability

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent applies preliminary action by performing a feasibility assessment before initiating the low salinity waterflood. The system calculates ion diffusion distance and compares it with permeable layer thickness to determine whether the reservoir geometry will protect against ion contamination, ensuring that limited low salinity water resources are only used when conditions favor successful oil recovery.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If low salinity waterflood is performed without evaluating ion diffusion, then operation is simplified, but effectiveness is reduced due to increased salinity from shale layer diffusion

Engineering Contradiction:

Improveoperational simplicityVSAvoidoil recovery effectiveness

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent replaces complex physical experimentation and field testing with a computational model that calculates ion diffusion distance using Fick's law. This substitution allows the system to evaluate reservoir suitability for low salinity waterflood through mathematical calculations rather than physical trials, maintaining operational simplicity while ensuring effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach allows for efficient planning and operation of low salinity waterfloods, ensuring effective use of limited low salinity water and optimizing well placement, thereby enhancing oil recovery by minimizing ion diffusion impacts.

Implementation Method 1

ion diffusion from high salinity connate water in shale layers into the injected low salinity water

Methodology Applied

Scientific EffectIon diffusion: Diffusion

Data Source

PatentUS9982521B2Method for injecting low salinity water

Publication Date: 2018.05.29 BP EXPLORATION OPERATING CO LTD

AI summary

A computer-implemented method for configuring operating conditions for at least one of desalination equipment and fluid injection equipment to be used in a low salinity waterflood on a hydrocarbon-bearing reservoir is provided. The reservoir is penetrable by an injection well and a production well. The method comprises deriving an ion diffusion distance value from: a diffusion coefficient indicative of a rate of diffusion of ions through relatively permeable layers of the reservoir when the low salinity water is present therein; and a residence time value indicative of the time required for the low salinity water to pass from the injection well to the production well through the reservoir; comparing the thickness of the relatively permeable layers to the derived ion diffusion distance value; generating an indication of the effectiveness of performing a low salinity waterflood; and configuring said operating conditions based on the indication of the effectiveness.