High-Solids Slurry Placement for Uniform Gravel Filters
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Solution Overview
Problem
Gravel filter placement in wellbores is complex and can cause formation sand ingress, leading to reduced well productivity due to pressure drop and conductivity issues, especially in hostile environments.
Innovation Solution
A method involving a high viscosity fluid and a slurry with stability additives is used to form a viscous pill, which is displaced by a solids slurry to create a gravel filter, maintaining a packed volume fraction exceeding 0.75 and inhibiting settling, ensuring uniform deposition and improved conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gravel filter is installed by gravel packing in a wellbore, then formation sand is prevented from flowing into the wellbore and wellbore conductivity is improved, but the placement procedure becomes complex and requires several stages with moving parts in a hostile wellbore environment
Solution Approach 1:
The placement procedure is divided into distinct stages: first placing a viscous pill with high plastic viscosity, then placing a high solids content slurry that displaces the viscous pill. This segmentation allows each component to perform its specific function independently, simplifying the overall placement procedure while maintaining reliability.
Solution Approach 2:
The viscous pill is placed in advance before the high solids content slurry. This preliminary action creates a barrier that controls the placement and displacement process, ensuring that the gravel filter is formed correctly without requiring complex moving parts or multiple intervention stages.
2Ease of operation
If conventional low solids content slurries are used, then placement is simpler, but particle separation occurs and uniform distribution is compromised leading to reduced well productivity
Solution Approach 1:
The slurry is formulated with high solids content (exceeding 0.75 packed volume fraction) and appropriate viscosity characteristics. This parameter change prevents particle separation during placement while maintaining ease of operation, as the high solids content slurry flows adequately to displace the viscous pill and form a uniform gravel filter.
Solution Approach 2:
The system uses a composite approach combining a viscous pill (with high plastic viscosity greater than 100 mPa·s at 100°C) and a high solids content slurry. This composite material system ensures both ease of placement and compositional stability, preventing particle separation while maintaining uniform distribution in the gravel filter.
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 method enhances the integrity and effectiveness of gravel filters by preventing particle separation and ensuring uniform distribution, thereby reducing pressure drop and improving wellbore conductivity.
Implementation Method 1
A viscous pill is deposited at the screen. The viscous pill has a plastic viscosity greater than 100 mPa·s at 100° C.
Implementation Method 2
A second bailer deposits a slurry at the viscous pill. The slurry displaces the viscous pill from the target location.
Implementation Method 3
The slurry includes a solids mixture, a fluid, and a stability additive. The stability additive inhibits settling of the solids mixture.
Data Source
AI summary
A method includes placing, via a bailer, a slurry into a wellbore to deposit a slurry downhole. The slurry includes a solids mixture and a fluid. The method also includes terminating placement of the slurry for a period of time. A viscous pill inhibits settling of the solids mixture, and the slurry displaces the viscous pill in contact with a surface of a screen.