Pumpable Geopolymer Cement for HPHT Well Sealing
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Solution Overview
Problem
Current oil and gas well cements, particularly Ordinary Portland Cement (OPC), face challenges in maintaining strength under high-temperature high-pressure (HPHT) conditions and generate significant carbon dioxide emissions, while geopolymer cements lack pumpable rheological properties suitable for various well conditions.
Innovation Solution
A pumpable geopolymer cement composition is developed, comprising an aluminosilicate source material, an alkaline solution with specific weight ratios, and additives such as weighting agents, lightweight materials, defoamers, and retarders, which can be tailored to accommodate a range of downhole conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Ordinary Portland Cement (OPC) is used for well cementing, then the cement can provide initial strength and sealing, but it loses strength under high-temperature high-pressure (HPHT) conditions and generates significant carbon dioxide emissions
Solution Approach 1:
The patent changes the chemical composition parameters by using geopolymer cement with specific ratios of aluminosilicate source material (60-80 wt%), alkaline activator (10-30 wt%), and silicate material (5-20 wt%). This compositional parameter change enables the cement to maintain strength under HPHT conditions while reducing CO2 emissions compared to traditional OPC
Solution Approach 2:
The patent creates a composite geopolymer cement system combining aluminosilicate source material, alkaline activator, and silicate material. This composite approach leverages the synergistic effects of different materials to achieve both strength retention under HPHT conditions and environmental benefits
2Object-generated harmful factors
If geopolymer cement is used to reduce carbon dioxide emissions and improve HPHT strength, then environmental impact is reduced and strength is improved, but the cement lacks pumpable rheological properties suitable for various well conditions
Solution Approach 1:
The patent adjusts rheological parameters by optimizing the water-to-binder ratio, alkaline activator concentration, and silicate material content. These parameter changes modify the viscosity and flow characteristics of the geopolymer cement, making it pumpable while maintaining environmental benefits and strength properties
Solution Approach 2:
The patent introduces silicate material as an intermediary component that modifies the rheological behavior of the geopolymer cement. This intermediary substance acts as a flow modifier, enabling pumpability without compromising the environmental performance or mechanical strength of the cement
3Strength
If geopolymer cement formulation is optimized for specific well conditions, then performance under those conditions is improved, but the formulation complexity increases and adaptability to various well conditions decreases
Solution Approach 1:
The patent creates a universal base formulation of geopolymer cement with optimized proportions of aluminosilicate source material, alkaline activator, and silicate material that can serve multiple well conditions. This multi-functional formulation can be adapted to different temperatures, pressures, and well depths through minor adjustments, maintaining both strength and versatility
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 composition remains pumpable with controlled viscosity and can accommodate varying well conditions, offering improved strength and reduced environmental impact compared to OPC, while maintaining effective sealing and integrity.
Implementation Method 1
Geopolymer cements are a low calcium, alkali-activated aluminosilicate cement which is obtained through geopolymerization (i.e. the reaction of aluminosilicates with an aqueous alkaline solution to provide a new class of inorganic binder)
Implementation Method 2
the geopolymer cements developed so far do not show a useful rheological properties that would allow it to be pumpable
Implementation Method 3
the composition may further comprise a weighting agent selected from one or more of the group consisting of barium sulfate, iron oxide, manganese tetroxide, where the weighting agent is present in an amount of from 30 to 75 wt % relative to the total weight of aluminosilicate source material
Implementation Method 4
the composition may further comprise one or more of a defoamer (e.g. a polydimethylsilicone)
Implementation Method 5
the composition may further comprise a retarder material at a concentration of from 0.001 kg/L to 0.3 kg/L relative to the total volume of the composition
Data Source
AI summary
This invention relates to an adaptable Geopolymer cement composition for application in oil and gas wells having a wide range of downhole temperatures. The base Geopolymer cement composition has an acceptable rheology of below 200 cP and can be tailored by the inclusion of various chemicals to control properties such as thickening time over a wide range of temperatures and densities. The disclosed Geopolymer cement composition is pumpable, mixable and stable. The composition can also be adapted to have expandable and swellable properties.