Gas-Trapped Proppant Agglomerates for Fracture Suspension
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Solution Overview
Problem
Conventional proppant particles settle prematurely in slickwater fracturing fluids, leading to incomplete proppant distribution along the fracture length and height, resulting in reduced fracture conductivity and permeability, especially in low-permeability reservoirs.
Innovation Solution
A wellbore fluid comprising an aqueous carrier liquid with hydrophobic particulate material and a gas that agglomerates the particles, reducing their bulk density and allowing them to be transported further into the fracture, where they form agglomerates with a lower density than the individual particles, ensuring a greater propped fracture area after closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional proppant particles are used in slickwater fracturing fluid, then the fluid has low viscosity and requires less pumping energy, but the proppant particles settle prematurely and form banks close to the wellbore
Solution Approach 1:
The invention changes the density parameter of the proppant particles by coating them with gas-trapping materials, transforming them from dense settled particles to low-density agglomerates that remain suspended in the slickwater fluid throughout fracture propagation
Solution Approach 2:
The invention creates composite proppant structures by coating conventional proppant particles with materials that trap gas bubbles, forming a composite structure that combines the mechanical strength of the original proppant with the buoyancy benefits of trapped gas, preventing premature settling
2Quantity of substance
If proppant is pumped at high concentration to ensure adequate proppant placement, then the fracture conductivity is improved, but the proppant settles more quickly due to higher particle concentration
Solution Approach 1:
The invention applies the anti-weight principle by using gas-trapped agglomerates that provide buoyant counterforce to gravity, allowing high proppant concentrations to be maintained without premature settling, as each particle is effectively counterbalanced by trapped gas bubbles
3Reliability
If thicker fracturing fluid is used to keep proppant in suspension, then the proppant distribution is improved, but the pumping energy requirement increases significantly
Solution Approach 1:
Instead of changing the fluid viscosity parameter, the invention changes the particle density parameter by coating proppant with gas-trapping materials, achieving suspension stability through particle modification rather than fluid thickening, thereby avoiding increased pumping energy requirements
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 agglomeration of proppant particles enables them to be transported deeper into the fracture, maintaining a larger propped fracture area and improving fracture conductivity, even in low-permeability reservoirs, while preventing premature settling and ensuring effective proppant placement.
Implementation Method 1
an aqueous carrier liquid with hydrophobic particulate material suspended therein
Implementation Method 2
a gas which serves to wet the surface of the particles and bind them together as agglomerates
Implementation Method 3
forming gas trapped agglomerates of proppant particles which have a bulk density which is lower than the density of the proppant particles
Implementation Method 4
Fluid is pumped under pressure into a subterranean formation, forcing portions of the formation apart and creating a thin cavity between them
Implementation Method 5
When the proppant is mixed with the fracturing fluid at the surface and pumped into the wellbore it is subjected to very high shear. The proppant-laden fluid then flows down the wellbore under conditions of lower shear
Implementation Method 6
Once the fluid enters the fracture, and as the fracture propagates and extends into the reservoir, the fluid is subjected to much less shear. Suspended solid begins to settle out
Data Source
AI summary
A wellbore fluid comprises an aqueous carrier liquid, hydrophobic particulate material suspended therein and a gas to wet the surface of the particles and bind them together as agglomerates. The hydrophobic particulate material has a specified maximum volume median particle size d50 of not more than 200 micron, and/or a minimum surface area of at least 30 m2 per liter. Agglomerates of the particles contain gas and so have a bulk density lower than the density of the particles. This reduces the rate of settling. The fluid is particularly envisaged as a slickwater fracturing fluid in which the suspended particles are proppant. The small particle size and/or substantial surface area increases the amount of gas which can be retained within agglomerates and so enhances the buoyancy of the agglomerates. The end result is that a greater proportion of a hydraulic fracture is propped open.