A cement wiper plug for deployment in casing with an inner radius has a central axis, a leading end, and a trailing end opposite the leading end. The wiper plug includes an elongate body. In addition, the wiper plug includes a first plurality of axially adjacent annular fins mounted to the body. Each fin extends radially outward from the body and each fin extends circumferentially about the body. The first plurality of fins includes a first fin and a second fin axially adjacent the first fin. The second fin is axially positioned between the first fin and the trailing end. The first fin and the second fin are configured to contact each other in the casing. The second fin is configured to bias the first fin radially outward and axially forward toward the leading end.

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.

An improved method and apparatus for dropping a ball, plug or dart during oil and gas well operations (e.g., cementing operations) employs a specially configured tool body assembly having valving members (e.g., safety or kelly values) and valving members holding plugs, balls, or darts to be dropped. In one embodiment, the ball(s), dart(s) or plug(s) are contained in a sliding sleeve that shifts position responsive to valve rotation. An optional indicator indicates to a user or operator that a ball or plug has passed a selected one of the valving members. A transmitter (or transceiver) provides an ability to generate a wireless signal that is received by receivers (or transceivers) on the tool body assembly. Each receiver (or transceiver) controls an electrical actuator that engages a valving member or the indicator. Wireless signals can be used to open or close a valve or to reset a tripped indicator.

Methods and apparatus are provided for cementing a liner. In one embodiment, the method includes releasing a dart behind a cement; landing the dart in an activation seat; increasing pressure to activate a liner hanger; further increasing pressure to release the dart from the activation seat; landing the dart in a plug; and increasing pressure to release the dart and the plug. In one embodiment, releasing the dart from the activation seat comprises deforming the dart.

A top latch-in plug includes a housing having a bore; and a transitionable seal, wherein: the transitionable seal seals the bore of the housing when in a first configuration, the transitionable seal unseals the bore when in a second configuration, and the transitionable seal is triggerable to transition from the first configuration to the second configuration. A casing floatation system includes a casing having a pre-load collar and a landing collar; and a lower bottom latch-in plug comprising: a catch mechanism compatible with the pre-load collar; and a landing mechanism compatible with the landing collar.

An apparatus and method are disclosed for wet shoe applications in cementing tubing in a wellbore. A wet shoe tool has a seat and an insert in a flow bore of the tool. A first wiper plug is deployed down the tubing at least behind the cement and seats on the insert, which can then be moved in the flow bore to a bypass position allowing for fluid flow through the tool to produce a wet shoe track. A second plug is deployed down the tubing behind the second plug and seats on the seat in the flow bore of the tool. The seated second plug isolates applied pressure from passing downhole end of the tool so the integrity of the tubing can be tested. The second plug is self-removable (e.g., dissolvable) in the tool to reestablish fluid communication through the flow bore of the tool.

The position of a droppable object (e.g., a cementing plug or drillpipe dart) in a cased wellbore may be determined in real time during a cementing operation. A pressure data acquisition system is installed at a wellsite and a pressure transducer is installed at the wellhead. As the droppable object travels through casing it encounters regions with a positive or a negative change of inner cross-sectional dimension. The droppable object generates a pressure pulse as it passes through the regions. The pressure pulse and associated reflections are detected by the pressure transducer, and the signals are processed mathematically to determine the current position of the droppable object.

An apparatus and method are disclosed for wet shoe applications in cementing tubing in a wellbore. A wet shoe tool has a seat and an insert in a flow bore of the tool. A first wiper plug is deployed down the tubing at least behind the cement and seats on the insert, which can then be moved in the flow bore to a bypass position allowing for fluid flow through the tool to produce a wet shoe track. A second plug is deployed down the tubing behind the second plug and seats on the seat in the flow bore of the tool. The seated second plug isolates applied pressure from passing downhole end of the tool so the integrity of the tubing can be tested. The second plug is self-removable (e.g., dissolvable) in the tool to reestablish fluid communication through the flow bore of the tool.

A method may include: providing a spacer fluid comprising water and an agglomerated zeolite catalyst; and displacing a drilling fluid in a wellbore using the spacer fluid.

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.