A method for temporary isolation of a well interval is proposed, the method comprising: pumping a first slurry into the well, the slurry comprising a viscous carrier fluid, degradable particulates, and degradable fibers, until a first filter cake is formed; and pumping a second slurry into the well, the slurry comprising a viscous carrier fluid, non-degradable particulates, and degradable fibers, until a second filter cake is formed. The first and the second slurries are not mixed when pumped into the well. To ensure optimum interval isolation, the ratio of the volume of the first slurry to the volume of the second slurry should be in the range 1:5 to 2:1.

A method for hydraulic refracturing within an interval with several hydraulic fractures and a non-damaging well killing method are also proposed.

The technical result is manifested in no formation damage and degradation of the sealing layer formed.

A multistage cementing assembly is used for cementing casing in a borehole. A subsurface tool on the casing holds a subsurface plug therein using a temporary retainer. The subsurface plug is located in a subsurface location below one or more stage tools or cementing collars on the casing. First stage cement passing down the casing can pass through a passage of the subsurface plug to flow out of a float valve. A wiper plug passed through the casing behind the cement is then engaged with the subsurface plug. Pressure buildup can release the two plugs as a unit from the temporary retainer. Before reaching the float valve, a deformable ring on the subsurface plug can engage in a locator ring on the casing to indicate the plug unit's location during operations. Eventually, additional stages can be cemented using the one or more stage tools uphole on the casing.

A hydraulic port collar includes a housing having one or more housing ports. The hydraulic port collar includes a port collar bore disposed within the housing forming an inner surface of the housing. The hydraulic port collar includes a sliding sleeve disposed within the port collar bore. The sliding sleeve has a sliding sleeve inner surface and a sliding sleeve outer surface. The hydraulic port collar includes a dissolvable or fragmentable landing seat radially aligned with and abutting the sliding sleeve inner surface.

A cementing system and method for selectively providing bottom-up cementing and top-down cementing of a liner during a single downhole trip are provided. The cementing system has three configurations. A first configuration of the tool allows fluid flow through a central flowbore of the cementing tool, a liner hanger setting tool below the cementing tool, and the liner. A second configuration of the tool routes fluid from the central flowbore of the cementing tool to an annulus surrounding the liner hanger setting tool and the liner. A third configuration of the tool reestablishes flow through the central flowbore of the cementing tool and enables a dropped ball to reach the liner hanger setting tool.

Systems and methods for thru-tubing completion including a sub-surface completion unit (SCU) system including a SCU wireless transceiver for communicating with a surface control system of a well by way of wireless communication with a down-hole wireless transceiver disposed in a wellbore of the well, one or more SCU anchoring seals having an un-deployed position (enabling the SCU to pass through production tubing disposed in the wellbore of the well) and a deployed position (to seal against a wall of the target zone of the open-hole portion of the wellbore to provide zonal isolation between adjacent regions in the wellbore) and one or more SCU centralizers having an un-deployed position (enabling the SCU to pass through the production tubing disposed in the wellbore of the well) and a deployed position (to position the SCU in the target zone of the open-hole portion of the wellbore).

The present disclosure relates to multiple stage operations, and more particularly to systems and methods for performing second stage cementing operations with a stage tool. A stage tool comprises: a mandrel; an opening seat; a closing seat; a plurality of ports; a closing sleeve; and a packer element, wherein the opening seat is attached to an interior surface of the mandrel, wherein the closing seat is attached to the interior surface of the mandrel, wherein the plurality of ports is configured to allow fluid communication between the interior surface of the mandrel and an exterior surface of the mandrel, wherein the closing sleeve is disposed on the exterior surface of the mandrel and coupled to the closing seat, wherein the packer element is disposed on the exterior surface of the mandrel.

A stage tool comprises a body with a tubular wall, defining an outer surface and an inner surface. Fluid ports, such as cement circulation ports, extend through the tubular wall. The stage tool further comprises a primary closing sleeve. The primary closing sleeve may be movable along the outer surface of the tubular wall for closing the ports when the treatment of the wellbore stage ends. A secondary closing sleeve may be movable along the inner surface of the tubular wall for closing the port in case of failure of the primary closing sleeve or for redundancy. The primary closing sleeve may be actuated by an internal member joined to the primary closing sleeve by a crosslink and movable on the inner surface. The internal member and the secondary closing sleeve may move along different surfaces on the internal wall to avoid interference.

A rupture disc assembly and a float tool incorporating the rupture disc assembly is disclosed. The rupture disc assembly may include a rupture disc assembly comprising a rupture disc, an upper tubular portion and a lower tubular portion, and a securing mechanism for holding the rupture disc between the upper and lower tubular portions. A float tool for creating a buoyant chamber in a casing string may include the rupture disc assembly and a sealing device for sealing the lower end of the casing string, the buoyant, sealed chamber may be created there between. In operation, applied fluid pressure causes the rupture disc to move downward. The rupture disc may be shattered by contact with a surface on the lower tubular portion. Full casing internal diameter may be restored in the region where the rupture disc formerly sealed the casing.

A plug for use in a cementing operation in a borehole includes a tail segment and a nose segment separate from the tail segment. The plug also includes a coupler configured to couple the tail segment to the nose segment, in which the tail segment is movable with respect to the nose segment.

A rupture disc assembly and a float tool incorporating the rupture disc assembly is disclosed. The rupture disc assembly may include a rupture disc assembly comprising a rupture disc, an upper tubular portion and a lower tubular portion, and a securing mechanism for holding the rupture disc between the upper and lower tubular portions. A float tool for creating a buoyant chamber in a casing string may include the rupture disc assembly and a sealing device for sealing the lower end of the casing string, the buoyant, sealed chamber may be created there between. In operation, applied fluid pressure causes the rupture disc to move downward. The rupture disc may be shattered by contact with a surface on the lower tubular portion. Full casing internal diameter may be restored in the region where the rupture disc formerly sealed the casing.