Multimodal Gravel Pack for High Solid Volume Fraction
Solution Overview
Problem
Current gravel packing techniques face challenges in achieving high solid volume fractions and maintaining porosity and permeability, leading to reduced well productivity due to premature bridging and fluid leak-off issues in wellbores.
Innovation Solution
A method and system for creating a high solid fraction fluid slurry with a multimodal particle size distribution, using a degradable material and leak-off control agents to inhibit fluid loss and increase porosity and permeability by forming a bridge on the screen, which is later removed to allow for efficient fluid production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high solid volume fraction slurry is used to improve gravel pack density, then the packed volume fraction increases, but porosity and permeability decrease leading to reduced fluid flow
Solution Approach 1:
The patent applies segmentation by using a multimodal particle size distribution with at least three distinct size ranges (first, second, and third PSD modes). The larger particles (first mode) provide structural framework and porosity, while smaller particles (second and third modes) fill interstices to increase solid volume fraction. This segmented approach allows achieving high PVF (>0.75) while maintaining adequate pore spaces for fluid flow.
Solution Approach 2:
The patent implements local quality by assigning different functional roles to different particle size modes within the same pack. Larger particles (first PSD mode) are positioned to create the primary pack structure and maintain porosity, while smaller particles (second and third PSD modes) are distributed to fill voids and increase overall solid concentration. This localized functional differentiation resolves the contradiction between density and permeability.
2Reliability
If gravel packing is performed to prevent formation sand from flowing into the wellbore, then sand control is improved, but wellbore and near-wellbore conductivity decreases due to damage
Solution Approach 1:
The patent uses segmentation through multimodal particle distribution where larger particles (first PSD mode) form the primary filtration structure for sand control, while smaller particles (second and third modes) fill interstices without completely blocking pore pathways. This segmented structure maintains both sand control reliability and near-wellbore conductivity by preserving adequate flow paths.
Solution Approach 2:
The patent applies porous materials principle by designing a gravel pack with controlled porosity through multimodal particle distribution. The pack maintains sufficient pore spaces between larger particles while being densely packed with smaller particles, creating a porous structure that allows fluid flow while providing effective sand control. This resolves the contradiction between filtration efficiency and flow conductivity.
3Productivity
If a degradable material is included in the solids mixture to increase porosity after placement, then permeability is improved, but the initial pack strength may be reduced
Solution Approach 1:
The patent applies preliminary action by using larger particles (first PSD mode) to establish the primary pack structure and mechanical strength before the degradable material (second and third PSD modes) is introduced. The larger particles provide immediate structural integrity, while the smaller degradable particles gradually dissolve to enhance porosity and permeability over time, resolving the contradiction between initial strength and final permeability.
Solution Approach 2:
The patent implements composite materials by combining particles with different degradation properties in a multimodal distribution. The larger particles (first mode) provide structural framework with high strength, while smaller particles (second and third modes) include degradable materials that gradually dissolve to improve permeability. This composite structure allows simultaneous achievement of initial pack strength and enhanced long-term permeability.
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 approach enables the formation of a stable, high-solids gravel pack with increased porosity and permeability, reducing pressure drop and enhancing well productivity by preventing premature bridging and fluid loss, thereby improving the efficiency of fluid flow through the wellbore.
Implementation Method 1
the degradable material can be dissolved by changing the pH in the solids pack. For example, alumina trihydrate particles at a neutral pH are solubilized at a high as well as at a low pH
Implementation Method 2
a first PSD mode comprises solids having a volume-average median size at least three times larger than the volume-average median size of a second PSD mode such that a packed volume fraction (PVF) of the solids mixture exceeds 0.75
Implementation Method 3
circulating the slurry through a wellbore to form a pack of the solids mixture having a PVF exceeding 0.75
Data Source
AI summary
A slurry and method are disclosed for low damage gravel packing. The slurry comprises a solids mixture comprising a plurality of volume-averaged particle size distribution (PSD) modes such that a packed volume fraction (PVF) exceeds 0.75; a carrier fluid in an amount to provide a solids volume fraction (SVF) less than the PVF of the solids mixture; and a stability additive to inhibit settling of the solids mixture. The method comprises circulating the slurry into a wellbore to deposit the slurry downhole; terminating the slurry circulation for a period of time, wherein the stability additive inhibits settling of the solids mixture; and thereafter circulating the deposited slurry in contact with a surface of a screen. Stability additives disclosed include colloidal particles, hydratable polymer particles, and particles having an aspect ratio above 6.