publication_number US 9234415 B2 abstract 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 d 50 of not more than 200 micron and or a minimum surface area of at least 30 m 2 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 application_number US 86817710 A description there are several procedures for hydrophobic modification of materials such as sand which have hydroxyl groups at their surface before modification sand of the required particle size was washed by mixing with ethanol at ambient temperature then filtering washing with deionised water and drying overnight at 80 u00b0 c quantities of this pre washed sand were hydrophobically modified 75 gm pre washed sand was added to a mixture of 200 ml toluene 4 ml organo silane and 2 ml triethylamine in a 500 ml round bottomed flask the mixture was refluxed under.