Abstract: The present invention discloses a supercritical CO2 thickener for shale gas reservoir based on hollow mesoporous silica nanoparticles and a preparation method thereof, and relates to the technical field of oil and gas field development. The preparation method of the thickener includes: reacting a monomer consisting of fluoroacrylate, styrene and vinyl acetate in a molar ratio of 3-5:1-2:1-2 with 2%-5% of a total weight of hollow mesoporous silica nanoparticles with carbon-carbon double bonds under the action of an initiator to obtain the thickener. The preparation method of the present invention does not involve the addition of organic solvents during the reaction process and thus does not cause harm to the human body. The thickener of the present invention has good CO2 viscosity-increasing effect and good sand carrying performance, and can effectively improve the fracturing effect.

Abstract: A displacement system designed for robust heterogeneous oil reservoirs and its application within the oil exploitation field. System comprises a polymer-enhanced foam plugging agent and an active polymer flooding agent. Plugging agent consists of 0.12% bio-polysaccharide polymer diutan gum foam stabilizer and 0.4% ?-olefin sulfonate foaming agent by mass. The active polymer flooding agent is formulated through free radical polymerization, with components comprising a total monomer concentration of 27.5%, wherein monomer A to monomer B ratio is 7.5:2.5, monomer C constitutes 5.5% of the total monomer concentration, and water comprises the remaining. Monomer A is acrylamide, monomer B is 2-acrylamide-2-methyl propane sulfonic acid, and monomer C is a quaternary ammonium salt type active monomer. Demonstrated through parallel core displacement experiments, this displacement system exhibits effective displacement in heterogeneous oil reservoirs with a permeability gradation of 30 at 65° C.

Abstract: The present invention discloses a method for preparing a low-density proppant by taking oil-based mud wastes as raw materials. The method includes following steps: S1, determining content of oils, silicon oxide, alumina and water in the oil-based mud wastes; S2, adding a viscosity modifier, a framework material and a pore-forming agent into oil-based mud wastes so as to obtain mixed slurry; S3, performing ball milling on mixed slurry to form powder, granulating and drying the powder, and forming a proppant pellet billet; S4, performing dehydrogenation pre-sintering on the pellet billet, and performing carbide reaction pre-sintering; and S5, performing final sintering in a natural gas protective atmosphere, thereby obtaining the low-density proppant that takes silicon carbide as the framework material. In the present invention, the low-density proppant is prepared by taking the oil-based mud wastes produced in a drilling process as the raw materials, thereby recycling the oil-based mud wastes.