Olive Waste Cementitious Blend for Carbonation Resistance
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Solution Overview
Problem
Current wellbore cements used in geologic carbon sequestration projects are prone to carbonation-induced degradation, leading to reduced compressive strength and increased permeability, which compromises the integrity of the cement sheath and reservoir formations.
Innovation Solution
A carbonation-resistant cementitious blend comprising 30-40% silica flour, 0.4-2% expandable agent, 0.5-1.0% dispersion agent, 0.5-1.0% fluid loss additive, 1×10−8-1×10−6% defoamer, and 0.01-0.75% olive waste, which forms a concrete with enhanced tensile and compressive strength and reduced permeability when exposed to CO2-rich environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oil well cement is used, then the cement can be easily manufactured and applied, but it suffers from carbonation-induced degradation leading to reduced compressive strength and increased permeability
Solution Approach 1:
The patent uses a composite material system consisting of Portland cement combined with pozzolanic materials (fly ash, silica flour, natural pozzolan) and supplementary cementitious materials (ground granulated blast-furnace slag, olive waste). This composite approach creates a synergistic effect where the pozzolanic materials react with calcium hydroxide to form additional C-S-H gel, reducing portlandite content and improving carbonation resistance while maintaining workability and strength development.
Solution Approach 2:
The patent modifies the chemical composition parameters of the cement blend by controlling the ratios of different pozzolanic materials and supplementary cementitious materials. Specifically, it optimizes the Ca/Si ratio reduction through controlled pozzolanic reaction, adjusts the water-to-cement ratio to balance workability and strength, and modifies the portlandite content to enhance carbonation resistance while maintaining manufacturing feasibility.
2Reliability
If pozzolanic materials are added to decrease Ca/Si ratio and portlandite content, then carbonation resistance improves, but the liquidity of the cement deteriorates
Solution Approach 1:
The patent applies local quality by using a multi-component pozzolanic system where different materials serve different functions. Fly ash provides spherical particles that improve liquidity, silica flour contributes to early strength and low Ca/Si ratio reduction, and natural pozzolan provides additional pozzolanic reactivity. This localized functional assignment to different components maintains overall liquidity while achieving carbonation resistance.
Solution Approach 2:
The patent changes the physical and chemical parameters of the cement blend by optimizing the particle size distribution, specific surface area, and chemical composition of the pozzolanic materials. It controls the water-to-cement ratio and uses chemical admixtures to adjust liquidity parameters while maintaining the pozzolanic reaction efficiency and carbonation resistance properties.
3Reliability
If excessive concentrations of pozzolanic additives are used, then carbonation resistance increases, but microcracks form inside the cement matrix
Solution Approach 1:
The patent optimizes the concentration parameters of pozzolanic materials to fall within specific ranges (10-40% fly ash, 5-20% silica flour, 5-20% natural pozzolan) rather than using excessive amounts. It controls the water-to-cement ratio and curing conditions to ensure proper hydration and minimize microcrack formation. The patent also uses chemical admixtures to maintain workability and reduce shrinkage, thereby preserving matrix integrity while achieving adequate carbonation resistance.
Solution Approach 2:
The patent applies partial action by using moderate concentrations of pozzolanic materials (not excessive amounts) to achieve the required level of carbonation resistance. It uses a balanced combination of multiple pozzolanic materials rather than relying on high doses of a single additive, thereby achieving the desired effect while minimizing adverse effects such as microcrack formation and liquidity loss.
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 blend maintains 90-99% of the tensile strength and 92.5-99.9% of the compressive strength of the corresponding concrete without olive waste after exposure to CO2-saturated brine, while reducing permeability by 65-90%, thereby enhancing the durability and integrity of the cement sheath.
Implementation Method 1
the addition of pozzolanic materials and supplementary cementitious materials... decrease the cement's hydration products of high pH and high Ca/Si content to prevent formation of portlandite
Implementation Method 2
silica flour present in an amount of 30 to 40% by weight of cement... the integrity of the cement sheath and the durability of the cement is considerably reduced by the cement carbonation-induced degradation
Implementation Method 3
an expandable agent present in an amount of 0.4 to 2% BWOC... decrease the cement matrix permeability
Data Source
AI summary
A carbonation-resistant cementitious blend containing cement, an expandable agent present, a dispersion agent, a fluid loss additive, a defoamer, and an olive waste. Concrete samples made therefrom and methods of producing such concrete samples are also specified. The addition of olive waste provides enhanced durability (carbonation resistance) and maintains mechanical strength (e.g. compressive strength, tensile strength) after exposure to CO2 and/or brine. The resulting concretes are suitable cementing material for oil and gas wells as well as wellbores for geologic carbon sequestration.