Thixotropic Lost Circulation Composition for Stable Wellbore Sealing
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Solution Overview
Problem
Conventional methods for preventing fluid loss in subterranean formations, particularly in lost circulation zones (LCZs), are ineffective due to the breakdown of viscous masses under fluid pressure, leading to reestablishment of fluid flow channels, which hampers wellbore servicing operations.
Innovation Solution
A composition comprising a base fluid, a thixotropic viscosifier, and a gellable material is introduced into LCZs, with a shear force applied to decrease viscosity for flow, followed by a reduction in shear force to allow the composition to set, forming a non-flowable gel that plugs the zone, thereby preventing fluid loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a viscous mass is introduced into the lost circulation zone to prevent fluid loss, then fluid loss is reduced, but the viscous mass breaks down under fluid pressure allowing reestablishment of fluid flow channels
Solution Approach 1:
The patent applies parameter changes by utilizing thixotropic behavior, where the composition's viscosity changes based on shear rate. At high shear rates during pumping, viscosity decreases for easy flow. Upon placement in the LCZ, shear rate drops and viscosity increases to form a stable plug. This dynamic parameter change allows the composition to maintain stability under varying pressure conditions without breaking down.
Solution Approach 2:
The composition exhibits dynamic rheological properties through thixotropy, transitioning from a low-viscosity state during injection to a high-viscosity gel state upon placement. This dynamic behavior enables the material to adapt to different operational phases: flowing easily during pumping then stabilizing as a rigid plug in the lost circulation zone, thereby maintaining reliability without breakdown.
2Ease of operation
If a viscous composition is pumped into the wellbore to seal the lost circulation zone, then fluid loss is prevented, but the composition must remain flowable during pumping and then set to prevent breakdown
Solution Approach 1:
The thixotropic composition dynamically adjusts its viscosity based on shear conditions. During pumping operations, high shear rates maintain low viscosity for easy flow and pumpability. Upon placement in the LCZ, the shear rate decreases and the composition transitions to a high-viscosity gel state, ensuring seal integrity and preventing breakdown under static or low-flow conditions.
Solution Approach 2:
The composition utilizes parameter changes in viscosity as a function of shear rate. The thixotropic properties allow the material to be pumped at low viscosity (high shear) then set at high viscosity (low shear), resolving the contradiction between ease of operation during injection and reliability of the seal after placement.
3Ease of operation
If the composition viscosity is decreased by applying shear force to enable flow into the lost circulation zone, then the composition can be pumped, but reducing shear force allows the composition to set and form a stable plug
Solution Approach 1:
The thixotropic composition dynamically responds to shear force application. During pumping, applied shear force maintains low viscosity for flowability. Upon placement in the LCZ, shear force is reduced or eliminated, allowing the composition to transition to a high-viscosity gel state with enhanced stability, forming a reliable plug without requiring additional setting agents or complex mechanisms.
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 solution effectively seals lost circulation zones, reducing fluid loss and maintaining isolation of the formation, allowing for more efficient wellbore servicing operations by forming a stable, non-flowable gel that withstands fluid pressure.
Implementation Method 1
a thixotropic viscosifier
Implementation Method 2
a gellable composition and a bridging material
Data Source
AI summary
A method of servicing a wellbore in a subterranean formation comprising placing a first stream comprising a dilute solution of a metal acrylate into a lost circulation zone in the subterranean formation; placing a second stream comprising an activator into the lost circulation zone; and forming a lost circulation material upon contacting of the metal acrylate and the activator, wherein the lost circulation material forms in from about 0 to about 60 minutes. A method of servicing a wellbore in a subterranean formation comprising placing a composition comprising a dilute solution of a cross-linkable material and an encapsulated activator into a lost circulation zone in the subterranean formation; and allowing the composition to set.