Basalt-Modified Hydraulic Cement for CO2-Rich Well Integrity
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Solution Overview
Problem
Existing cement formulations used in oil and gas wells, particularly in CO2-rich environments like Pre-salt reservoirs, suffer from degradation due to CO2 exposure, leading to reduced mechanical strength, increased porosity, and potential leakage, posing financial and environmental risks.
Innovation Solution
A hydraulic cement composition incorporating basalt powder as a supplementary cementitious material (SCM) with specific particle size and chemical composition, which is added to Portland cement to enhance chemical resistance and reduce porosity and permeability, thereby improving well integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Portland cement is used for well cementation, then the cement provides initial mechanical strength and structural integrity, but it degrades when exposed to CO2-rich media, leading to reduced strength and increased porosity
Solution Approach 1:
The patent uses a composite material system consisting of Portland cement combined with supplementary cementitious materials (SCMs) such as metakaolin, silica fume, or fly ash. This composite formulation creates a synergistic effect where the SCM particles fill pores and react with calcium hydroxide to form additional C-S-H gel, resulting in a denser matrix that resists CO2 degradation while maintaining mechanical strength.
Solution Approach 2:
The patent modifies the chemical composition parameters of the cement by controlling the ratio of Portland cement to SCM (typically 70-30 or 80-20 by weight), adjusting water-to-cement ratio, and optimizing curing conditions. These parameter changes transform the cement from a CO2-vulnerable material to a chemically stable composite that can withstand long-term exposure to CO2-rich environments.
2Stability of the object's composition
If Portland cement is used for well cementation, then the cement provides initial structural integrity, but CO2 exposure causes dissolution of calcium hydroxide and formation of soluble calcium bicarbonate, increasing porosity and permeability
Solution Approach 1:
The patent strategically uses SCM particles with controlled pore structures to refine the overall porosity of the cement matrix. The fine SCM particles fill voids and create a tortuous path for fluid flow, reducing effective porosity and permeability. This transforms the pore structure from a continuous high-permeability network to a disconnected low-permeability system that resists CO2 ingress.
Solution Approach 2:
The patent converts the harmful effect of CO2 exposure into a beneficial process by allowing controlled carbonation of the SCM particles. The SCM materials react with CO2 and calcium hydroxide to form insoluble calcium carbonate precipitates that fill pores and strengthen the matrix, transforming the degradation process into a strengthening mechanism that reduces porosity and improves chemical stability.
3Duration of action of stationary object
If Portland cement is used in CO2-rich reservoirs, then the well can be initially cemented, but long-term exposure leads to leakage and loss of well integrity
Solution Approach 1:
The patent applies preliminary protective measures by incorporating SCM materials that pre-resist CO2 attack before exposure occurs. The SCM particles create a chemically stable matrix structure and reduce porosity in advance, preventing CO2 from penetrating and degrading the cement. This preliminary anti-action eliminates the need for later corrective interventions and extends the service life of the well cementation.
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 basalt powder composition significantly reduces CO2 degradation, maintaining mechanical strength and integrity of wells, extending their life cycle and reducing the need for corrective interventions, while being cost-effective and compatible with existing cementing processes.
Implementation Method 1
the basalt powder comprises a supplementary cementitious material of pozzolanic activity up to 330 mg of Ca(OH)2 consumption
Implementation Method 2
the increase in chemical resistance of the cement paste composition is due to the reduction of porosity and permeability of the material in relation to the composition without BP, due to the filling of voids and the refinement of the pore network
Implementation Method 3
the increase in chemical resistance of the cement paste composition is due to the reduction of porosity and permeability of the material
Data Source
AI summary
The present invention describes a hydraulic cement composition, process and use thereof, wherein the composition comprises a hydraulic cement composition with increased resistance against carbon dioxide (CO2) for application in reservoirs such as oil and gas and carbon capture and storage (CCS) wells; with improved performance of cement paste formulations as a material for application in primary, secondary cementing, recovery and/or plugging operations, of reservoirs/wells that operate with high CO2 content; as a technological alternative to guarantee the integrity of wells in CO2-rich environments for long periods of time, without any additional intervention to the already current operational procedures for cementing wells, and with cost reduction in relation to class G cement (currently, the main raw material); and sufficient chemical resistance to carry out enhanced oil (EOR) and gas (EGR) recovery by injecting high levels of CO2, increasing reservoir pressure throughout the extraction period of hydrocarbon reservoirs.