With the innovation of extended-reach and directional drilling, running casing and liner strings has become increasingly difficult. Not much has been done to address the challenges, which include ledges and obstructions, washouts, swelling shale, bridging, high doglegs, difficult well profiles, fill on bottom, and well collapse. To overcome the challenges, a new product line was developed as a way to facilitate casing operations, especially for long horizontal strings, production strings, and intermediate casing strings.

The technology can rotate independently from the casing when encountering obstructions and hanging. The rotation is performed by reciprocating the casing through 3- to 5-ft strokes that cause the tool shoe to act as a bit and ream. It drills off the obstruction and guides the casing string through ledges, tight swollen sections, and doglegs, allowing effective removal of fill and debris from below the casing/liner shoe to land at the intended total depth (TD).

The technology comprises two main components: the tool body, which is made similar to the casing grade being run, and the internal mechanism, which is made from industrial-grade aluminum alloy for the mandrels and bronze components for the bit, both of which lend strength and durability to the tool while facilitating a smooth clean drillout with a standard polycrystalline-diamond-compact (PDC) bit.

The tool provides rotation at the end of the casing string by reciprocating the casing string rather than by rotating the string at surface. It uses a very small amount of hydraulic pressure, provided by the mud pump, to enable the removal of fill by penetrating through it and circulating it out. Also, it provides deflection of the casing shoe to bypass ledges.

The tool has a fixed helical mandrel connecting to the casing string, so the lower tool body is able to rotate.

Only 21 psi of internal hydraulic pressure is needed to extend the lower tool body along the mandrel into an open position. By applying this pressure, the mechanism at the lower assembly of the tool rotates and extends into an open position. By setting weight on the tool, the lower assembly moves up along the mandrel, causing right-hand rotation on the lower assembly by lowering the casing string.

The tool is effectively torque neutral, causing no torsional torque transmitted up the casing string.

PDC-Bit-Drillable Version. The tool (Fig. 1) comes in a PDC-bit-drillable version for the surface- and intermediate-casing strings, with a short aluminum mandrel to reduce drillout time. The internals are made from industrial-grade aluminum alloy and bronze components, both of which lend strength and durability to the tool while facilitating smooth clean drillouts without damage to the PDC drillout bit.

The operator does not need to make a special bit trip for drilling out the tool. The drilling bottomhole assembly will be used for that, and drilling will continue into the formation after the float equipment and tool are drilled out.

PDC-Bit-Drillable Short Version. A short version of the basic tool is available (Fig. 2) to address specific applications and deal with ledges and doglegs in wells that require cost-­effective solutions. This version is PDC-bit-­drillable and uses a 1-ft stroke to provide three-quarters of a revolution, which is enough to orient an eccentric bit away from the ledge or obstruction to find the open hole and guide the casing.

Nondrillable Steel Version. The nondrillable version (Fig. 3) was designed to provide a mechanical solution to address obstacles that interfere with getting the production-casing string to bottom. The tool is designed to provide maximum revolutions to facilitate reaming, agitating of fill and debris, and deflection off ledges, obstructions, and washouts. 

Nondrillable Auto-Set Steel Version. This version (Fig. 4) was developed to assist in running casing and liners in applications where hydraulic pressure cannot be induced to the bit or where circulation through the casing is impossible. With a high-tensile-spring design, the tool is reset to the open position by reducing weight on bit rather than with hydraulic pressure. The tool can be sealed to prevent the production of sand, cuttings, and paraffin through it during the run and during production.

Wellbore-Cleanout Tool. The cleanout tool (Fig. 5) features a design similar to that of the basic tool but is designed specifically to clean out produced sands and paraffin from producing wells. It can be equipped to clean hole from 4½- to 9⅝-in. inner diameter. When used on a service rig, reciprocation of the tubing along with pump pressure actuates the tool, providing a mechanical solution to clean out production-hampering debris. When used with coiled tubing, the tool uses the increased hydraulic pressure to auger its way through the obstruction and the coil is run in to close and reset the tool. This technique is used to minimize reciprocation.

Bronze Casing-Pilot Bit. This tool is a PDC-bit-drillable bit made completely out of bronze, with tungsten ­carbide cutting faces and tungsten carbide buttons to minimize the wear on the bit. With a 2-in.2 flow area, it includes a locking mechanism to prevent the bit’s rotation when drilling it out. The tool was designed to be the best all-around bit, suitable for reaming and bridge removal regardless of geology. The profile of the tool is a long taper, allowing for deflection off ledges, washouts, and doglegs.

Bronze Eccentric Bit. This eccentric bit (Fig. 1) is a heavy-duty bronze drillable bit with a long eccentric profile. It is equipped with stabilizers and a cutting face, and it provides 360° reaming capability, with tungsten carbide cutting faces and tungsten ­carbide buttons to resist wear. The long eccentric profile of the bit seeks out open hole through rotation provided by the basic tool.

Bronze Bridge-Breaker Bit. This tool is all-bronze construction, which makes it completely drillable, and is outfitted with tungsten carbide buttons to resist wear and is tungsten carbide clustered to increase its cutting and agitation power. Designed primarily for coal seams and swelling shales, the outer row of cutters is designed to cut the exposed shales and coal into large pieces, which are then broken down further by a row of inside cutters for easy removal by circulation.

Bull-Nose-Profile Bit. This tool (Fig. 3) was designed with a rounded bull-nose profile. The bit has four stabilizers tipped with tungsten carbide, which deflect off ledges, washouts, and doglegs and facilitate reaming and agitation. The bit is available in steel for nondrillable applications.

Aluminum Eccentric Bit. This tool has an eccentric nose profile to facilitate sliding (Fig. 2). It is made of aluminum composite, so it is completely PDC-bit-drillable. The eccentric bit is a cost-effective solution for situations involving extreme washouts, ledges, and doglegs. Through rotation, the long eccentric nose of the bit is aligned toward the open hole, acting as a guide to find the open hole.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 172144, “Rotation by Reciprocation Casing-Landing Technology,” by R. Gosselin and T. Montgomery, Longhorn Casing Tools; A. Muriby, SPE, and Moataz Yussef, Wildcat Oilfield Services; and S. Karrani and A. Khamis, Abu Dhabi Marine Operating Company, prepared for the 2014 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 10–13 November. The paper has not been peer reviewed.

The Journal of Petroleum Technology, the Society of Petroleum Engineers’ flagship magazine, presents authoritative briefs and features on technology advancements in exploration and production, oil and gas industry issues, and news about SPE and its members.

ISSN: 1944-978X (Online) ISSN: 0149-2136 (Print)