Lost Circulation Composition for Removable Low-Pressure Well Sealing
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Solution Overview
Problem
Existing lost circulation materials (LCMs) used in low-pressure well interventions face challenges such as difficulty in forming a temporary seal, maintaining the seal during the intervention, and removing the material post-intervention, particularly due to temperature-dependent properties and sensitivity to osmotic pressure and shear degradation, limiting their effectiveness in reducing fluid loss in low-pressure formations.
Innovation Solution
A composition comprising hydrated superabsorbent polymers (SAPs) mixed with chemically-digestible fibers and a salt-tolerant osmotic barrier polymer, optionally combined with colloidal gas aphrons (CGAs), is pumped into the well to form a seal, which can be removed by reducing well pressure or using oxidizing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LCM materials are used in low-pressure well interventions, then fluid loss reduction is attempted, but the materials fail to form a durable seal due to temperature-dependent properties and osmotic pressure sensitivity
Solution Approach 1:
The patent employs a multi-component composition where each material responds to different parameters: SAPs respond to osmotic pressure by swelling, chemically-digestible fibers provide structural framework, and low-melt plastics respond to temperature by softening. This coordinated parameter response creates a durable seal that adapts to downhole conditions rather than relying on a single material's stability
Solution Approach 2:
The invention combines three distinct materials (SAPs, chemically-digestible fibers, and low-melt plastics) into a composite LCM composition. Each component contributes different properties: SAPs provide osmotic-driven swelling for seal formation, fibers provide structural integrity, and low-melt plastics provide temperature-responsive flow closure. The composite effect creates a seal that is more reliable than any single material could achieve alone
2Reliability
If LCM materials are deployed to seal perforations in low-pressure formations, then fluid loss is reduced, but the materials become difficult to remove after intervention
Solution Approach 1:
The patent designs the LCM composition to respond to parameter changes in opposite directions during deployment and removal: during deployment, SAPs swell and low-melt plastics soften to form a seal; during removal, the same materials shrink and harden when exposed to different temperature and osmotic pressure conditions, enabling easy retrieval
Solution Approach 2:
The LCM composition is designed with dynamic properties that allow it to change state based on environmental conditions. The materials transition from a deployable suspension to a sealed mass, and can be reversed back to a removable state, providing flexibility for both seal formation and post-intervention cleanup
3Productivity
If gas-liquid mixtures are used to reduce hydrostatic pressure for circulation, then circulation is maintained in low-pressure wells, but the mixtures lack sufficient rheological properties to carry debris effectively
Solution Approach 1:
The patent combines multiple LCM materials that collectively provide both the low density needed for circulation in low-pressure wells and the rheological properties needed for debris transport. The chemically-digestible fibers and SAP particles provide viscosity and suspension capability, while the overall composition remains less dense than conventional drilling fluids
Solution Approach 2:
The LCM composition serves multiple functions simultaneously: it acts as a lost circulation material to seal perforations, a drilling fluid to maintain circulation in low-pressure formations, and a debris carrier to transport cuttings and scale to the surface. This multi-functionality eliminates the need for separate gas-liquid mixtures and LCM treatments
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 effectively reduces fluid loss by forming a durable seal that withstands low formation pressures and can be easily removed, enhancing well intervention efficiency and reducing equipment damage.
Implementation Method 1
particles of a hydrated superabsorbent polymer (SAP)
Implementation Method 2
particles of a hydrated superabsorbent polymer (SAP)
Implementation Method 3
chemically-digestible fiber
Implementation Method 4
colloidal gas aphrons (CGAs)
Implementation Method 5
removal of the composition by degrading the polymer with an oxidizing agent
Data Source
AI summary
A composition for lost circulation material (LCM) usable in subsurface well intervention includes particles of a hydrated superabsorbent polymer (SAP) mixed with a chemically-digestible fiber and an aqueous solution of a salt tolerant osmotic barrier polymer. A method for stopping fluid loss from a well into a formation penetrated by the well includes pumping a selected volume of the composition into the well until the selected volume is adjacent to the formation.