Thixotropic Cement Composition for Lost Circulation Control
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Solution Overview
Problem
Existing compositions fail to effectively address fluid loss and rapid strength development in wellbores penetrating subterranean formations, particularly in lost circulation zones.
Innovation Solution
A thixotropic cement composition comprising a cementitious material, maltodextrin, and an aqueous fluid, which maintains low viscosity under shear and develops gel strength when static, thereby reducing fluid loss and enhancing compressive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a drilling fluid is circulated in the wellbore to service the well, then the wellbore can be drilled and hydrocarbons can be recovered, but the drilling fluid is lost to the subterranean formation through lost circulation zones
Solution Approach 1:
The patent applies parameter changes by modifying the rheological properties of the cement composition through the addition of specific additives (e.g., hydrophilic-hydrophobic balanced additives, viscosifiers) to achieve thixotropic behavior. This allows the fluid to maintain low viscosity during pumping (for efficient placement) and develop high viscosity/gel strength when static (to prevent fluid loss), directly resolving the contradiction between productivity and substance loss.
Solution Approach 2:
The patent implements dynamics by creating a composition with time-dependent and shear-dependent viscosity characteristics. The thixotropic cement composition dynamically adjusts its rheological properties: it remains fluid and pumpable during circulation but develops gel strength and prevents fluid loss when static in the lost circulation zone, thereby addressing both productivity and fluid loss prevention.
2Loss of substance
If a composition is introduced to control fluid loss, then fluid loss into the formation is reduced, but the composition must achieve rapid compressive strength development to enable continued operations
Solution Approach 1:
The patent applies preliminary action by incorporating additives that pre-condition the cement composition to rapidly develop gel strength and compressive strength upon placement. The hydrophilic-hydrophobic balanced additives and other components are pre-formulated to initiate quick setting and strength development, reducing the time loss while maintaining fluid loss control.
Solution Approach 2:
The patent uses composite materials by combining cementitious materials with multiple additives (hydrophilic-hydrophobic balanced additives, viscosifiers, accelerators) to create a thixotropic cement composition that simultaneously achieves fluid loss control and rapid compressive strength development, resolving the contradiction between substance loss control and time loss.
3Ease of operation
If a thixotropic composition is used to maintain low viscosity under shear, then the composition can be pumped effectively, but it must quickly develop gel strength when static to prevent fluid loss
Solution Approach 1:
The patent applies dynamics by formulating a thixotropic composition that dynamically transitions between pumpable (low viscosity under shear) and gel-strength developing (high viscosity when static) states. This dynamic rheological behavior ensures ease of operation during pumping while providing reliability for fluid loss prevention when the composition is stationary in the lost circulation zone.
Solution Approach 2:
The patent uses parameter changes by modifying the rheological parameters of the composition through additives that enable thixotropy. The composition's viscosity parameter changes based on shear rate and time: low viscosity under shear for pumpability, and high viscosity/gel strength when static for reliable fluid loss prevention.
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 thixotropic cement composition effectively reduces fluid loss into subterranean formations by sealing lost circulation zones and achieves rapid compressive strength development, enabling continued drilling operations.
Implementation Method 1
the composition should ideally be thixotropic, which can maintain a low viscosity while under shear
Implementation Method 2
when allowed to remain static, the wellbore servicing fluid should develop gel strength quickly
Implementation Method 3
Rapid development of compressive strength is also desired after placement into the lost circulation zone
Data Source
AI summary
Disclosed herein is a method of servicing a wellbore penetrating a subterranean formation with a thixotropic cement composition. The thixotropic cement composition comprises a cementitious material, maltodextrin, and an aqueous fluid, has a 10-minute gel strength of from about 30 lbf/100 ft2 to about 300 lbf/100 ft2, and can be used to reduce lost circulation in the wellbore. By incorporating maltodextrin into the thixotropic cement composition as disclosed herein, the thixotropic cement composition can have a similar 10-minute gel strength and an increased thickening time when compared to a reference composition.