Bead Slurries for Lightweight Cement Stability
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Solution Overview
Problem
The preparation of lightweight cement compositions for subterranean cementing operations is challenging due to buoyant and lightweight glass beads that tend to rise and are easily blown around, leading to inconsistent final compositions, and the need for more expensive foamed cements in offshore sites where space is limited.
Innovation Solution
Engineering bead slurries comprising lightweight beads with a specific gravity less than 1 and a gelled base fluid, which allows for stable mixing and storage, reducing the need for foamed cements by enabling on-site mixing and reducing equipment footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If lightweight glass beads are used as low-density additives in cement slurries, then the hydrostatic pressure on well bore walls is reduced to prevent fractures, but the beads are buoyant and tend to rise out of the slurry, causing composition inconsistency
Solution Approach 1:
A surfactant is introduced as an intermediary substance between the lightweight glass beads and the cement slurry. The surfactant reduces surface tension and prevents the buoyant beads from rising to the surface, thereby maintaining uniform distribution and composition consistency throughout the slurry while preserving the pressure-reducing effect of the lightweight beads
Solution Approach 2:
The surface tension parameter of the slurry is changed by adding surfactant. This parameter modification allows the buoyant lightweight beads to remain suspended in the slurry rather than rising to the surface, thus maintaining composition consistency while keeping the hydrostatic pressure reduction benefit
2Stability of the object's composition
If foamed cements are used instead of lightweight additive cements at offshore sites, then the beads are not blown around by air movement, but the equipment and materials occupy significant space in limited offshore well site areas
Solution Approach 1:
The patent uses simple, inexpensive lightweight glass beads instead of complex foamed cement systems. The beads are stable enough for offshore transport and use, eliminating the need for bulky foam generation equipment while maintaining composition stability through the surfactant additive
Solution Approach 2:
By changing the surface tension parameter through surfactant addition, the slurry becomes resistant to air movement effects, allowing the use of simple bead-based lightweighting instead of complex foaming equipment at offshore sites
3Quantity of substance
If lightweight glass beads are used in cement slurries, then the density is reduced to prevent formation fractures, but the beads are easily blown around by air movement, changing the final cement slurry composition
Solution Approach 1:
The surfactant acts as a mediator between the lightweight beads and air movement. It creates a protective effect that prevents air currents from easily moving the beads, thereby maintaining the intended slurry density and composition throughout transport and placement
Solution Approach 2:
The surface tension parameter is modified by surfactant addition, which increases the slurry's resistance to air movement. This parameter change ensures that the lightweight beads remain in their intended positions and concentrations, maintaining both density reduction and composition stability
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 bead slurries provide a stable and efficient method for preparing lightweight cement compositions with a long shelf life, allowing for transportation and on-site mixing, thereby reducing costs and space requirements, while maintaining the benefits of lightweight additives.
Implementation Method 1
The bead slurries described herein comprise a plurality of lightweight beads and a gelled base fluid
Implementation Method 2
a gelled base fluid having a viscosity of about 10 cP to about 1000 cP
Data Source
AI summary
Engineering bead slurries may be useful in producing lightweight cement slurries for use in subterranean cementing operations. For example, a method may include engineering a bead slurry to have a shelf-life of about 1 month or greater by performing at least one of (1) calculating the shelf-life for the bead slurry and (2) calculating a minimum yield point required to prevent a lightweight bead of the bead slurry from floating or settling in the bead slurry; wherein the bead slurry comprises a gelled base fluid and a plurality of lightweight beads having a specific gravity of about 0.8 or less; producing the bead slurry; mixing the bead slurry and a cement slurry to yield a lightweight cement slurry; introducing the lightweight cement slurry into a wellbore penetrating a subterranean formation; and allowing the lightweight cement slurry to set therein.