A downhole tool for cleaning and sealing a wellbore includes a wash tool configured at a downhole end of the downhole tool to generate pulses of a first fluid at a first frequency and a first pressure for washing a target interval of a wellbore. The downhole tool further includes a plugging tool configured uphole or downhole from the wash tool to generate pulses of a second fluid at a second frequency and a second pressure for depositing a sealing plug at the target interval of the wellbore. The second fluid has a higher viscosity than the first fluid, the second frequency is lower than the first frequency, and the second pressure is higher than the first pressure.

A wiper plug can be used in wellbore operations. The wiper plug can include a fishing neck located at a rear portion of the plug. The fishing neck can be a male or female fishing neck. A corresponding male or female fishing tool can be used to retrieve the wiper plug from a tubing string. The wiper plug can include a nose that can land on a landing tool or a female fishing neck of another wiper plug. The wiper plug can be introduced into the tubing string before or after a cement composition. The wiper plug can include a rupture disk that allows an operator at a wellhead to observe a pressure change to indicate the location of the wiper plug and fluid within the tubing string.

A system and method for a composite cement retainer. A composite cement retainer has various components. When these various components comprise composite where feasible, or a drillable metal, the retainer can be easily placed and quickly drilled if necessary.

A running tool sets and cements a liner in a borehole. While the tool’s bypass section is closed, a plug deployed to the tool diverts hydraulic pressure to set a liner hanger in the borehole. The setting plug is unseated, and the bypass section is switched opened by deploying another plug to an opening seat and shifting a control sleeve open relative to a bypass port. While the tool’s packoff remains sealed in the hanger, cement pumped out the bypass port is bullheaded into a lap of the liner and borehole. When cementing is complete, the bypass section is switched closed by deploying another plug to a closing seat and shifting the control sleeve closed relative to the bypass port. The bypass section is then placed in a flow-through condition where fluid communication is reestablished through the tool to the liner by allowing fluid to flow past the plugs in the tool.

A method of cementing a casing in a wellbore extending from an Earth's surface into a subsurface includes providing a tube having a bi-frustoconical shape. The bi-frustoconical shape is defined by an upper tube part having an inverted frustoconical shape, a lower tube part having a frustoconical shape, and a waist intermediate between the upper tube part and the lower tube part. The tube is positioned in an annulus formed between the casing and a wall of the wellbore from a surface opening of the annulus. The tube is urged in a direction down the annulus and along the casing until the tube lands on a collar radially projecting from an outer surface of the casing into the annulus.

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 fail-safe method to cement a section of casing string to a formation is provided. The method includes providing the casing string in a wellbore, the casing string comprising a stage tool, a packer, and a sensor. The packer is located vertically below the stage tool and vertically above the sensor on the casing string. The method further includes pumping cement down the casing string and up an annulus to an expected height, the expected height being a vertical distance above the sensor, and detecting a presence or absence of cement with the sensor. If the sensor detects the presence of cement, the stage tool is kept closed and the packer is kept deflated. If the sensor detects the absence of cement, the stage tool is opened and the packer is inflated.

An apparatus for flowing and mixing cement within a subterranean formation includes a housing, a flow control device, and baffles. The housing is configured to contain a cement additive. The housing includes a first end and a second end. The first end is configured to couple to a cement retainer. The flow control device is disposed at the second end of the housing. The baffles are disposed within the housing.

Aspects of the disclosure relate to stage collars and related methods of operation thereof for stage cementing operations. In one implementation, a stage collar for stage cementing operations includes a barrel, and an activation sleeve disposed at least partially in the barrel. The activation sleeve includes first fluid openings. The stage collar includes an activation ring that includes an activation seat. The stage collar includes a first set of shear fasteners coupling the activation ring to the activation sleeve, and a second set of shear fasteners coupling the activation sleeve to the barrel. The stage collar includes a setting piston, and a closing sleeve disposed at least partially in the barrel. The closing sleeve includes second fluid openings. The stage collar includes a third set of shear fasteners coupling the closing sleeve to the barrel.

A plug launching system includes a main body and a plug canister disposed within the main body. The plug canister includes a liner, a first rotational assembly disposed about the liner, wherein the first rotational assembly is configured to support a first plug disposed within the liner and selectively enable fluid flow from an annulus between the main body and the plug canister to a central passage of the liner, and a second rotational assembly disposed about the liner, wherein the second rotational assembly is configured to support a second plug disposed within the liner and selectively enable fluid flow from the annulus between the main body and the plug canister to the central passage of the liner, wherein the first and second rotational assemblies are configured to be actuated independently from one another.