A cementing tool and a method for cementing a casing string using the cementing tool is provided. The cementing tool comprises threaded top and bottom openings for attaching to a casing string, a plurality of ports, and a plurality of shear plugs shaped to fit within the ports. In the method, a casing string comprising the cementing tool is run into a well and the cementing process of the casing string is initiated. When the casing shoe of the casing string becomes plugged, the cementing tool is activated without removing the casing string from the well. Activation of the cementing tool releases pressure trapped in the cementing tool, thereby releasing the shear plugs from the ports and opening the ports to create alternative passages for the cement to complete the cementing process.

A wiper plug is used in an operation to cement tubing in a borehole. The wiper plug is pumped down the tubing to separate an advancing fluid from a following fluid of the cementing operation, and an internal pressure chamber is maintained in a throughbore of the wiper plug between uphole and downhole barriers. The wiper plug eventually lands in the tubing, and the uphole barrier is removed by applying a first predetermined pressure against the uphole barrier. Removal of the uphole barrier is facilitated by the known and controlled internal pressure of the plug's chamber. The downhole barrier is also removed so that flow is permitted through the throughbore of the wiper plug. To perform a tubing pressure test, the downhole barrier can be removed due to pressure, and the chamber may have a temporary valve to hold applied pressure to a test level. Alternatively, the downhole barrier can hold the applied pressure. The temporary valve and the downhole barrier can then be self-removing in response to a stimulus.

A wiper plug is used in an operation to cement tubing in a borehole. The wiper plug is pumped down the tubing to separate an advancing fluid from a following fluid of the cementing operation, and an internal pressure chamber is maintained in a throughbore of the wiper plug between uphole and downhole barriers. The wiper plug eventually lands in the tubing, and the uphole barrier is removed by applying a first predetermined pressure against the uphole barrier. Removal of the uphole barrier is facilitated by the known and controlled internal pressure of the plug's chamber. The downhole barrier is also removed so that flow is permitted through the throughbore of the wiper plug. To perform a tubing pressure test, the downhole barrier can be removed due to pressure, and the chamber may have a temporary valve to hold applied pressure to a test level. Alternatively, the downhole barrier can hold the applied pressure. The temporary valve and the downhole barrier can then be self-removing in response to a stimulus.

Provided are wiper plugs with removable cores and methods of using the wiper plugs with removable cores. An example wiper plug with a removable core comprises a molded body, a wiper, a cavity through the interior of the molded body, a support disposed in the cavity, and the removable core disposed in the cavity. An example method of use comprises removing the core of the wiper plug without drilling through the wiper plug, and leaving the remainder of the wiper plug in the wellbore.

Provided are wiper plugs with removable cores and methods of using the wiper plugs with removable cores. An example wiper plug with a removable core comprises a molded body, a wiper, a cavity through the interior of the molded body, a support disposed in the cavity, and the removable core disposed in the cavity. An example method of use comprises removing the core of the wiper plug without drilling through the wiper plug, and leaving the remainder of the wiper plug in the wellbore.

A method of treating a subterranean formation can include: introducing a first fluid into a wellbore penetrating the subterranean formation; introducing a second fluid into the wellbore after introduction of the first fluid, wherein the second fluid comprises: a base fluid comprising water; a viscosifier; and a stabilizer, and wherein the second fluid has a rheological 3-rpm dial reading to 300-rpm dial reading ratio in the range of 1:1 to 1:3; and introducing a third fluid into the wellbore after introduction of the second fluid, wherein the second fluid inhibits or prevents the first fluid from mixing with the third fluid. The second fluid can be a liquid plug that substantially inhibits or prevents the first fluid from mixing with the third fluid. The first fluid can be a drilling mud or spacer fluid. The third fluid can be a spacer fluid or a cement composition.

A stage cementing tool includes a housing configured to couple to a casing and having a central bore therethrough, a first plurality of ports arranged on a radial surface of the housing and configured to fluidly connect the central bore and an annulus of a wellbore, a second plurality of ports arranged on the radial surface of the housing uphole of the first plurality of ports and configured to fluidly connect the central bore and the annulus of the wellbore, an expandable element coupled to the housing between the first plurality of ports and the second plurality of ports, and a sleeve. The sleeve is moveable from a first position on the housing to a second position on the housing to fluidly disconnect the central bore and the annulus through the first plurality of ports and fluidly connect the central bore and the annulus through the second plurality of ports.

A stage cementing tool includes a housing configured to couple to a casing and having a central bore therethrough, a first plurality of ports arranged on a radial surface of the housing and configured to fluidly connect the central bore and an annulus of a wellbore, a second plurality of ports arranged on the radial surface of the housing uphole of the first plurality of ports and configured to fluidly connect the central bore and the annulus of the wellbore, an expandable element coupled to the housing between the first plurality of ports and the second plurality of ports, and a sleeve. The sleeve is moveable from a first position on the housing to a second position on the housing to fluidly disconnect the central bore and the annulus through the first plurality of ports and fluidly connect the central bore and the annulus through the second plurality of ports.

A system for controlling surge pressure and deployed into a wellbore drilled using a managed pressure drilling technique includes auto-fill float equipment allowing flow into a liner casing string, a drillpipe diverter providing a flow path between a drillpipe landing string and an annulus, and a drillpipe flow restrictor selectively blocking the flow path from the top of the drillpipe landing string while allowing fluid to be displaced up the liner casing string and into the annulus. The drillpipe flow restrictor and the drillpipe diverter are convertible to provide a flow path from the wellbore through the auto-fill float equipment to a top surface while blocking flow through the diverter into the annulus. The auto-fill float equipment is convertible to block the flow path from the wellbore into the liner casing string, while allowing fluid to flow from the liner casing string into the wellbore.

A system for controlling surge pressure and deployed into a wellbore drilled using a managed pressure drilling technique includes auto-fill float equipment allowing flow into a liner casing string, a drillpipe diverter providing a flow path between a drillpipe landing string and an annulus, and a drillpipe flow restrictor selectively blocking the flow path from the top of the drillpipe landing string while allowing fluid to be displaced up the liner casing string and into the annulus. The drillpipe flow restrictor and the drillpipe diverter are convertible to provide a flow path from the wellbore through the auto-fill float equipment to a top surface while blocking flow through the diverter into the annulus. The auto-fill float equipment is convertible to block the flow path from the wellbore into the liner casing string, while allowing fluid to flow from the liner casing string into the wellbore.