Abstract: A seal for a repeatedly switchable stepless fracturing sliding sleeve includes a C-ring, and two A-rings, two jackets and two B-rings symmetrically provided in sequence on two sides of the C-ring in an axial direction. A mounting cavity open in a direction away from the C-ring is formed in the jacket, and a U-shaped leaf spring is provided therein. The A-ring covers a supporting lip of the jacket and has a protruding portion extending into the mounting, and the A-ring is provided with a through hole allowing the mounting cavity to be in communication with an external fluid. When the whole seal is pressed forwardly or reversely by the fluid, the supporting lip can support and tightly abut on the A-ring, and the external fluid can enter the mounting cavity via the through hole and provide a pressure for a sealing lip to tightly abut on a sealing surface.

Abstract: A combined sealing member for a coiled tubing blowout preventer box includes an upper plate, a first main sealing body, a second main sealing body and a lower plate that are disposed in sequence from top to bottom and are each provided with a through hole allowing a coiled tubing to pass therethrough. The upper plate is composed of two upper plate units that are separable half-and-half. The first main sealing body is composed of two first main sealing body units that are separable half-and-half. The second main sealing body is composed of two second main sealing body units that are separable half-and-half. The lower plate is composed of two lower plate units that are separable half-and-half. The first main sealing body has a hardness greater than that of the second main sealing body and a height smaller than that of the second main sealing body.

Abstract: A slip sealing structure comprises a cylindrical sealing body comprising an upper and a lower end surfaces, wherein an outer side and an inner side of at least one end surface of the sealing body are provided with an outer metal retaining ring and an inner metal retaining ring respectively, a fabric covering layer is disposed on the at least one end surface, and the outer and inner metal retaining rings are respectively pressed against an outer and inner edges of the fabric covering layer such that the fabric covering layer provides support for the outer and inner metal retaining rings. Through the outer and inner metal retaining rings, compression resistance of the slip sealing structure can be improved, and rubber extrusion at high temperatures and high pressures can be avoided; the fabric covering layer enhances performances of compression resistance and gas explosion resistance of the slip sealing structure.

Abstract: A slip sealing structure comprises a cylindrical sealing body comprising an upper and a lower end surfaces, wherein an outer side and an inner side of at least one end surface of the sealing body are provided with an outer metal retaining ring and an inner metal retaining ring respectively, a fabric covering layer is disposed on the at least one end surface, and the outer and inner metal retaining rings are respectively pressed against an outer and inner edges of the fabric covering layer such that the fabric covering layer provides support for the outer and inner metal retaining rings. Through the outer and inner metal retaining rings, compression resistance of the slip sealing structure can be improved, and rubber extrusion at high temperatures and high pressures can be avoided; the fabric covering layer enhances performances of compression resistance and gas explosion resistance of the slip sealing structure.