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.