Abstract: A wellbore sealing system includes a dart retained in a top plug and deployable through a bore defined in the top plug and through a bore defined in the bottom plug to sealingly engage float equipment abutting the bottom plug. The dart and float equipment bear wellbore pressure directly. The dart latches with the float equipment and sealing features provide bi-directional sealing.

Abstract: A centralizer sub, and system, for enhanced access to subterranean zones from the surface as used in oil and gas wellbore installations to center a pipe or casing within a wellbore or previous casing string during run-in, installation, or cementing procedures. In under-reamed applications, casing strings and centralizers pass through a smaller casing string before opening up to a larger hole where repeated compressions and decompressions of bow strings of centralizers can compromise integrity and reliability. A centralizer sub, system, and method reduces and controls insertion and running forces to preserve centralizer integrity and down-bore surfaces and equipment.

Abstract: A centralizer having asymmetrical bow springs defining a more gradual lead-in angle and a steeper retreat angle to reduce the required insertion and running forces. The centralizer comprises two end bands and a plurality of bow springs connecting the two shaped to gradually contact the surrounding hole or well casing. The bow springs are arranged such that a least two of them are asymmetric and positioned such that the apex of each is the same distance from an end band.

Abstract: Asymmetric casing centralizers are provided with varying flow resistances caused by a combination of straight vanes and spiral vanes; as a result, the casing centralizer has varying pressure drops thereacross when the casing centralizer is positioned within a preexisting structure such as, for example, a horizontal wellbore section that traverses one or more subterranean formations.

Abstract: A centralizer sub, and system for enhanced access to subterranean zones from the surf ace as used in oil and gas wellbore installations to center a pipe or casing within a wellbore or previous casing string during run-in, installation, or cementing procedures. In under-reamed applications, casing strings and centralizers pass through a smaller casing string before opening up to a larger hole where repeated compressions and decompressions of bow strings of centralizers can compromise integrity and reliability. A centralizer sub, and system reduces and controls insertion and running forces to preserve centralizer integrity and down-bore surfaces and equipment.

Abstract: A centralizer having asymmetrical bow springs defining a more gradual lead-in angle and a steeper retreat angle to reduce the required insertion and running forces. The centralizer comprises two end bands and a plurality of bow springs connecting the two shaped to gradually contact the surrounding hole or well casing. The bow springs are arranged such that a least two of them are asymmetric and positioned such that the apex of each is the same distance from an end band.

Abstract: A stage tool apparatus and components for same are described. In several exemplary embodiments, the stage tool apparatus is part of tubular string or casing positioned within a preexisting structure such as, for example, a wellbore.

Abstract: A centralizer sub, system, and method for enhanced access to subterranean zones from the surface as used in oil and gas wellbore installations to center a pipe or casing within a wellbore or previous casing string during run-in, installation, or cementing procedures. In under-reamed applications, casing strings and centralizers pass through a smaller casing string before opening up to a larger hole where repeated compressions and decompressions of bow strings of centralizers can compromise integrity and reliability. A centralizer sub, system, and method reduces and controls insertion and running forces to preserve centralizer integrity and down-bore surfaces and equipment.

Abstract: A convertible valve having a conversion element retained in a seat to convert a valve gate from bidirectional flow to unidirectional flow. The convertible valve includes a valve gate moveable between a first open position and a second closed position, a seat moveable between a first position and a second position, and a conversion element retained in the seat. The seat, in its first position, maintains the valve gate in its first open position. With the valve gate in the first open position, the convertible valve allows bi-directional fluid flow. Fluid flowing through the convertible valve creates downward force on the conversion element and the seat. Upon reaching a predetermined force, the seat moves to its second position allowing the valve gate to move to its second closed position. With the valve gate in the second closed position, the convertible valve allows only unidirectional fluid flow.

Abstract: A wellbore sealing system includes a dart retained in a top plug and deployable through a bore defined in the top plug and through a bore defined in the bottom plug to sealingly engage float equipment abutting the bottom plug. The dart and float equipment bear wellbore pressure directly. The dart latches with the float equipment and sealing features provide bi-directional sealing.

Abstract: A convertible valve having a conversion element retained in a seat to convert a valve gate from bidirectional flow to unidirectional flow. The convertible valve includes a valve gate moveable between a first open position and a second closed position, a seat moveable between a first position and a second position, and a conversion element retained in the seat. The seat, in its first position, maintains the valve gate in its first open position. With the valve gate in the first open position, the convertible valve allows bi-directional fluid flow. Fluid flowing through the convertible valve creates downward force on the conversion element and the seat. Upon reaching a predetermined force, the seat moves to its second position allowing the valve gate to move to its second closed position. With the valve gate in the second closed position, the convertible valve allows only unidirectional fluid flow.

Abstract: An easy-start centralizer having asymmetrical bow springs defining a more gradual lead-in angle and a steeper retreat angle to reduce the required insertion and running forces. The reduced-slope approach of the bow spring centralizer provides for smoother, more controlled compression and engagement of the bow springs with the casing opening or other wellbore restriction.