Produced Water pH Control Using CO2 to Prevent CaCO3 Scaling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The challenge of calcium carbonate (CaCO3) scaling in oilfield produced water during reinjection or disposal is addressed, as traditional scale inhibitors are stripped from the water as it traverses porous formations, leading to reduced well injectivity and the need for frequent stimulation treatments with potential environmental impacts.

Innovation Solution

Incorporating carbon dioxide (CO2) injection into produced water based on real-time thermodynamic data to neutralize scaling risks, using a system that adjusts CO2 injection amounts based on well and reservoir characteristics to maintain effective scaling control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If continuous injection of threshold scale inhibitor is used to prevent calcium carbonate scale formation, then scale prevention is improved, but the inhibitor is gradually removed by reservoir rock leading to under-protection or unprotected water from scale formation

Engineering Contradiction:

Improvescale prevention effectivenessVSAvoidinhibitor removal by reservoir rock

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent changes the chemical parameter of scale control by using CO2 injection to adjust pH and carbonate equilibrium, replacing traditional scale inhibitors. This transforms the scale prevention mechanism from chemical inhibition to thermodynamic control, preventing scale formation through pH management rather than inhibitor molecules

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

CO2 acts as an intermediary substance that mediates between the produced water and scale formation. By injecting CO2, the system creates a intermediate chemical environment (acidification) that prevents calcium carbonate precipitation without requiring continuous inhibitor addition

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If produced water is injected underground for disposal or reinjection, then water disposal is improved, but calcium carbonate scaling occurs especially within carbonate reservoirs affecting well injectivity

Engineering Contradiction:

Improvewater disposal efficiencyVSAvoidwell injectivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by injecting CO2 into produced water before injection to pre-adjust the chemical conditions. This preliminary acidification prevents scale formation from occurring during the injection process, maintaining well injectivity throughout the disposal operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

CO2 injection creates a preliminary anti-action against scale formation by acidifying the water and shifting carbonate equilibrium. This preemptive chemical adjustment counteracts the scaling tendency before calcium carbonate can precipitate in the wellbore or reservoir

Inventive Principle:

Principle #9Preliminary anti-action

3Object-affected harmful factors

If scale control is managed to avoid scale formation, then technical challenges are reduced, but frequent stimulation treatments are needed with potential environmental effects

Engineering Contradiction:

Improvescale formationVSAvoidenvironmental effects from stimulation treatments

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of CO2 (acidification) into a beneficial scale prevention mechanism. By deliberately acidifying the produced water with CO2, the system transforms a potentially harmful substance into a useful tool for controlling carbonate scaling and preventing well injectivity problems

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 optimizes scaling control by minimizing the use of toxic chemicals, reduces environmental risks, and minimizes the need for well stimulation treatments, ensuring safe and efficient disposal of oilfield produced water.

Implementation Method 1

triggering, by the one or more processors, an injection of the amount of the carbon dioxide in the produced water stream to neutralize the scaling risk

Methodology Applied

Scientific EffectCarbon dioxide dissolution and acidification:

Implementation Method 2

determining, by the one or more processors, by using the thermodynamic data, a supersaturation degree of the produced water stream to be disposed in the well

Methodology Applied

Scientific EffectSupersaturation: Supersaturation

Data Source

PatentUS12497885B1Scale control in oilfield produced waters

Publication Date: 2025.12.16 SAUDI ARABIAN OIL CO

AI summary

Systems and methods include scale control in oilfield produced waters. Thermodynamic data indicative of surface conditions and subterranean conditions of a subterranean region including a well is received, from probes. An acidity of a produced water stream to be disposed in the well is received from a pH meter. A supersaturation degree of the produced water stream to be disposed in the well is determined, by using the thermodynamic data. An amount of carbon dioxide to be injected in the produced water stream to neutralize a scaling risk is determined, by the one or more processors, by using the supersaturation degree and the acidity. An injection of the amount of the carbon dioxide in the produced water stream is triggered to neutralize the scaling risk.