Davis-Lynch Casing Equipment

Davis-Lynch™ Non-Weld Type “NW” centralizers are designed to exceed the performance requirements of API Specification 10D for both starting and restoring forces.

The Non-Welded Turbolizer is a centralizer with metal fins installed on the bows to help induce turbulence in the cement slurry during pumping operations. Like the spring bows, the fins are made of heat-treated alloy steel. This makes them flexible, which minimizes damage while moving downhole. The Davis-Lynch Turbolizer incorporates the same nonwelded end collar to springbow interlocking adjoinment as the Davis-Lynch centralizer. Turbolizers are available in the same sizes and bow heights as centralizers. As with the Davis-Lynch centralizer, turbolizers can be manufactured with a builtin stop device. These items are available on special order.

Other design features of the Type “NW” Centralizer include:

• Bow springs made of alloy steel which are heat treated and tempered to a hardness of 42-44 Rc ensures proper and consistent spring characteristics.
• End collar hinges that are folded to the inside. This minimizes the collar stretch that tends to occur when centralizers encounter tapers common to some pipe connections.
• A reinforcing rib stamped into the end collar. This strengthens it to ensure maintenance of its round configuration during transport.
• Several different spring bow heights that are available to accommodate most any casing-to-hole configuration.
• Centralizers with built-in stop devices as well as those for unusual sizes available on request.

The Semi-Rigid Centralizer features a unique bow design that allows each centralizer two contact points with the borehole while having low starting and running forces, but very high restoring or centering forces. It is also a non-weld variety and features a bow with dual curves giving the bow an “S” shape. It simultaneously provides features found desirable in both bow-spring and rigid centralizers. Davis-Lynch Semi-Rigid Type “SR” centralizers are designed to exceed the performance requirements of API Specification 10D for both starting and restoring forces.

• As the bow OD is typically very close to hole size, the centralizer has very low starting and drag forces.
• The double profile of the bow results in much higher restoring forces than conventional bow-springs.
• Bows are made from alloy steel, heat-treated and tempered.
• Utilizes Davis-Lynch patented interlocking bow attachment to end collars.
• Can be run in highly-deviated and horizontal wellbores.
• Can be run over casing connections or stop collars.
• Can be supplied with built-in stop device if requested.
• Bows still provide some flex that allow the centralizer to compress through tight spots and severe doglegs unlike a conventional rigid centralizer.
• Can be provided with turbolizer fins to help induce turbulence in the cement slurry during pumping operations.

This Forum product features the patented interlocking adjoinment between the end collars and bow springs that is widely used though out Davis-Lynch™ centralizers due to its effectiveness.

Coupling this feature with stamped sheet steel or stamped and welded bow springs results in a low drag, rigid unit that is sought after by today’s operators.

Not only does the Rigid bow centralizer deliver low drag, it also delivers optimum concentricity for cementing operations, and it can be used in cased hole as well as open hole applications with the same results.

These centralizers are offered in a wide assortment of bow sizes to accommodate most casing-to-hole configurations. They can also be configured using a new type of bow that is stamped and does not require welding to become rigid. These bows are fixed to the end collar in the same patented non-welded fashion.

The Forum One Piece Bow Spring Centralizer is nonweld uni-body bow-type centralizer. These Centralizers are made from a single piece of alloy steel tube that is precision-cut with a laser to form the end collars and bow springs as one unitary body. The bows are then expanded to the desired outside diameter with advanced tooling. Finally, the entire unit is heat treated to maximize the restoring force of the bows as well as provide strength to the whole unit. Optionally it can be coated with various coatings to provide friction reduction, corrosion prevention or protection for hanger seal areas.

• The strongest bow-type centralizer available today.
• Manufactured from tubular steel with closer tolerances that allow for running in tighter annular spaces (close-tolerance wellbores).
• More stand-off than solid-body centralizers in conventional and bi-center wellbores (where the open-hole ID drilled below a casing string is larger than the casing ID).
• As the bow OD is typically the same or only slightly larger than the wellbore ID, drag forces are considerably lower than conventional bow-type centralizers, yet restoring forces are higher.
• Greater flow-by area than most bow-type or solidbody centralizers.
• Easily coated with low-friction polymers to reduce friction factor in extending reach horizontal casing installations, or to prevent erosion due to plating of expensive casing alloys when installed in a corrosive environment. Also coatings can prevent damage to sensitive areas such as hanger seal ID’s, etc.
• Radially curved bows decrease friction and reduce the chance of drag or damage when passing through milled-casing windows.
• Set screws can be integrated into the lower end collar to provide anchoring without the need for a separate stop collar.

Similar to our Slip-on Close-Tolerance Bow Spring Centralizer, however, this version has a fast-rising bow spring to allow running a set-screw stop collar inside the centralizer.

• Set-screw stop collar is run internally so that the centralizer may be pulled into and out of the wellbore for lower starting/drag forces.
• Allows rotation of the casing.
• Can be optionally run between stop collars.
• Bows are welded flush with end collar to provide maximum strength with minimum clearance.
• Bows are made of alloy steel and are heat-treated and tempered to a hardness that ensures proper and consistent spring characteristics.

In applications for running casing in close-tolerance wellbores or slim holes, Forum offers a special bow spring centralizer for these requirements. To provide optimum performance in close-tolerance wellbores, these centralizers feature low starting forces and high restoring forces. These centralizers consist of a solid type end collar for slipping over the pin end of the casing joint.

• Available with set screws in the lower end collar for an integrated stop device (standard), so that no separate stop collar is necessary. The end collar with set screws should be run down (toward the bottom of the hole) so that the centralizer is pulled into the wellbore to optimize starting/drag forces.
• Can be optionally run between stop collars for applications that require rotating casing.
• Bows are welded flush with end collar to provide maximum strength with minimum clearance.
• Bows are made of alloy steel and are heat-treated and tempered to a hardness of 42-44 Rc ensuring proper and consistent spring characteristics.
• Typical applications include 5” casing in 6” hole, 7-5/8” casing in 8-1/2” hole, and 9-5/8” casing inside 10-5/8” hole.
• Recommended set screw torque is 20-25 ft-lbs.

Benefits

• Used in close tolerance and under-reamed wellbore applications
• Suited for use in horizontal, tortuous well paths, and passing through tight restrictions.
• Can pass safely through tight clearance Sub- Sea equipment such as Well Heads, Connectors, and Landing Seats.