Hydrophobic Silt Control Screen for Unconsolidated Gas Reservoirs
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Solution Overview
Problem
Unconsolidated siltstone gas reservoirs face issues with water and silt infiltration leading to blockages, reducing gas well production due to multiphase flow, hydration expansion, and migration of fine silt and clay particles, which existing water control and gas recovery methods fail to adequately address.
Innovation Solution
A ternary water control and gas recovery method involving a silt control screen pipe with hydrophobic modification, hydrophobic gravel packing, and injection of a wetting agent aqueous solution to prevent water and silt infiltration, reversing hydrophilicity to hydrophobicity and reducing capillary driving forces, thereby controlling silt and water migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water control measures are implemented in unconsolidated siltstone gas reservoirs, then water infiltration is reduced, but gas well production decreases due to blockage by silt and clay particles
Solution Approach 1:
The patent introduces a ternary composite material consisting of hydrophobic modified silt control screen, hydrophobic gravel packing material, and hydrophobic modified seepage channel surface as intermediary layers between the water-bearing formation and the wellbore. These intermediary layers selectively block water while allowing gas to pass through, thereby reducing water infiltration without significantly impacting gas well production
Solution Approach 2:
The patent changes the wettability parameter of the screen pipe, gravel packing material, and seepage channel surface from hydrophilic to hydrophobic through chemical modification. This parameter change enables the materials to repel water while maintaining gas permeability, effectively reducing water infiltration without causing silt and clay particle blockage
2Object-generated harmful factors
If silt control measures are implemented, then silt blockage is reduced, but hydration expansion of clay minerals increases, causing further blockage
Solution Approach 1:
The hydrophobic gravel packing material serves as an intermediary filtration layer that captures silt particles while preventing water from reaching the clay minerals in the formation. This intermediary layer reduces silt blockage in the wellbore while preventing water-induced hydration expansion of clay minerals
Solution Approach 2:
The patent applies preliminary anti-action by pre-treating the screen pipe and gravel packing material with hydrophobic modifiers before installation. This preliminary treatment creates a water-repelling barrier that prevents water from causing hydration expansion of clay minerals, thereby preventing further blockage before it can occur
3Object-affected harmful factors
If hydrophobic modification is applied to increase capillary resistance, then water blocking improves, but gas seepage permeability may be reduced
Solution Approach 1:
The patent applies local quality by selectively modifying only the surface properties of the screen pipe and gravel packing material to be hydrophobic, while maintaining the bulk material properties that provide gas permeability. The hydrophobic modification is localized to the surface, creating water-blocking capability without significantly impacting gas seepage through the material structure
Solution Approach 2:
The patent utilizes porous hydrophobic gravel packing material that maintains open pore structures for gas flow while the hydrophobic surface treatment creates capillary resistance to water. The porous structure allows gas to pass through freely while the hydrophobic surfaces prevent water from entering and blocking the pores
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 effectively increases capillary resistance, prevents silt and water blockages, and enhances gas recovery by maintaining permeability and stability in the gas reservoir, ensuring stable and increased production.
Implementation Method 1
increase capillary resistance to slow down or prevent the bottom water ridge and the edge water fingering
Implementation Method 2
running a silt control screen pipe manufactured by an interface hydrophobic modification into a wellbore
Implementation Method 3
injecting a wetting agent aqueous solution into the stratum, performing a hydrophobic modification on the gas reservoir seepage channel surface
Implementation Method 4
injecting a wetting agent aqueous solution into the stratum
Implementation Method 5
filling a surface hydrophobic modified gravel into the annular space between the silt control screen pipe and the wellbore to form a hydrophobic gravel packing layer
Implementation Method 6
reduce hydration expansion and hydration dispersion of clay after the gas reservoir is flooded
Implementation Method 7
reduce hydration expansion and hydration dispersion of clay after the gas reservoir is flooded
Data Source
AI summary
A ternary water control and gas recovery method suitable for an unconsolidated siltstone gas reservoir is provided. It includes the following steps: first, running a silt control screen pipe manufactured by an interface hydrophobic modification into a wellbore to realize wellbore water control and silt control; second, filling a surface hydrophobic modified gravel in an annular space between the silt control screen pipe and the wellbore to form a hydrophobic gravel packing layer for water control and silt control; third, injecting a wetting agent aqueous solution into a stratum, and performing a hydrophobic modification on a gas reservoir seepage channel surface to realize in-situ waterblocking and silt migration of the unconsolidated siltstone gas reservoir, and then closing a well for a preset time before exploitation.