Method for proppant suspension and suspension parameter optimization based on bubble bridge effect

A method for proppant suspension parameter optimization based on bubble bridge effect, comprising the following steps:

• Selecting a proppant and measuring its average particle size to obtain the average radius of the selected proppant;
• Hydrophobically modifying the surface of the selected proppant to obtain a hydrophobically surface-modified proppant;
• Preparing a water-based fracturing base fluid, injecting nitrogen into the base fluid, and stirring the base fluid to cause uniform bubbles to obtain a bubbly water-based fracturing base fluid;
• Selecting a basic parameter of the bubbly water-based fracturing base fluid as a proppant suspension parameter for optimization, and preparing the bubbly water-based fracturing base fluid with different values of the basic parameter;
• Measuring a Zeta potential of the bubbly water-based fracturing base fluid with different basic parameter values, and taking pictures of bubbles of each base fluid with a camera to obtain the average radius of the bubbles of each base fluid by image analysis;
• Selecting a first optimization of the base fluids according to the average radius of the proppant and the average radii of the bubbles of the base fluids, wherein the first optimization includes calculating the ratio of the average radius of the proppant to the average radii of the bubbles of the base fluid;
• wherein the base fluids with a ratio in the range of 0.5-2 are the base fluids selected at the first optimization;
• Preparing an electrolyte solution with the same pH as that of each base fluid selected at the first optimization, putting the hydrophobically surface-modified proppant into the electrolyte solution, and determining the Zeta potential of the hydrophobically surface-modified proppant in each electrolyte solution;
• On the basis of the extended DLVO theory, calculating an interaction energy between the proppant particle and the bubble after the hydrophobically surface-modified proppant is mixed with the base fluids selected at the first optimization;
• Optimally selecting the base fluids selected for a second optimization according to the interaction energy, wherein the second optimization comprises comparing the interaction energy of each base fluid, wherein the base fluids with relatively stronger hydrophobic attraction between the proppant particle and the bubble are the base fluids selected at the second optimization;
• Putting the hydrophobically surface-modified proppant into each base fluid selected at the second optimization and strring them;
• wherein under the control of the interaction energy between the hydrophobic surface of the proppant and the bubble, the proppant particles are connected and aggregated through the bubble bridge effect into proppant-bubble aggregates;
• meanwhile, taking pictures of the proppant-bubble-proppant aggregation with the camera, determining a coefficient of bonding ratio between the proppant particle and the bubble through image observation and statistical analysis, and calculating an apparent density of the proppant-bubble aggregates;
• and
• Optimally selecting the base fluids selected for the third optimization according to the apparent density of proppant-bubble aggregates, wherein the third optimization comprises sorting out proppant-bubble aggregates with an apparent density in the range of 0.91.1 g/cm3;
• wherein the base fluids corresponding to the sorted-out proppant-bubble aggregates are the base fluids selected at the third optimization;
• wherein the basic parameters of the bubbly fracturing base fluid selected at the third optimization are the optimized proppant suspension parameters.