When a drilling component breaks hundreds of feet down an oil well, repair on that component starts only after fishing out the part and bringing it to the surface. In the meantime, the oil rig sits idle, losing valuable drilling time and costing huge amounts of lost revenue. It is in these critical situations when huge oil companies turn to specialized oil well overshot systems.

Downhole oil well overshot systems use fishing tools, which descend a well to grip broken drilling components, extracting them for repair.

The manufacture of such fishing systems and tools is a highly competitive sector of the oil and gas industry. There are many suppliers providing such systems, so the deciding factors of which supplier wins the sale is not just on the quality of the system, but also on how quick the delivery is.

For these suppliers, a key to shortening delivery times is reducing component machining cycle times. More often than not, achieving this goal is through simple re-evaluation of individual part machining operations and incorporation of cutting tools designed for that particular part material, allowing for ramping up cutting speeds and feeds.

Seco Tools is one cutting tool company that has always taken such a materials approach in product development. It pairs advanced tooling technology with continuous support and problem solving advice, improving the machining processes for many oil well overshot system applications.

Tooling from Seco has significantly improved milling, turning, and drilling operations for oil well fishing components that typically range in size from 0.250" in diameter and 0.500" long up to 28" in diameter and as long as 110". Most workpiece materials involve various types of steels, such as 4140, 1018, 8020, and 1430. No matter what the size or material, the use of Seco tools help shorten cycle times and improve part surface finishes to levels where secondary finishing operations, such as grinding, can often be eliminated. In addition, Seco tools contribute to reducing necessary tool inventories by providing longer service life.

One of the most often improved processes resulting from Seco tooling technology is the machining of bearing races for motors used in various downhole oil well systems. These races, made of carbon steel, are carburized hardened to particular case depths, machined, then ground to achieve required surface finishes around 2Rms. Typically, total process time for these races is 1.8 hours.

However, turning the races using Seco's CBN 160 C diamond shaped inserts and CBN 060 K round geometry inserts, for example, reduces processing time by eliminating a secondary grinding operation. The inserts not only effectively turn the hardened races, but also generate 8Rms surface finishes, eliminating the need for grinding.

CBN 160 C is a fine grain, low CBN content grade that provides toughness and machining accuracy in interrupted finish machining of hard steel.

CBN 160 C encompasses the latest synthesis technology, which, together with closely controlled multi-model grain size, gives optimum product homogeneity. Together with a unique (Ti, Si) N PVD coating, it provides a PCBN grade offering long, consistent tool life, outstanding surface finish, and superb dimensional accuracies. CBN 160 C is available in insert styles, -L1 multi-corner and -LF, which are typically used when machining components such as the bearing races.

Seco's CBN 060 K grade, designed specifically for turning case hardened steels within the application area of H10 – H20, is a good example of the company's material approach to product development. The grade is the result of extensive development, relying on several entirely innovative and patented technologies.

These technologies include a multi-layer K coating, which enhances performance when cutting case hardened steels; have micron sized CPN particles distributed to optimize performance; offers a superalloy binder with TiCN hard phase; features cutting edge profiles that extend tool lifel; and have helix wiper patterns, allowing for faster cutting to reduce part machining cycle times.

With these Seco inserts, bearing race processing time drops from 1.8 hours to six minutes. Now, in the time traditionally spent setting up a race on a grinding machine, the parts can be completely finished due to of the turning process utilizing Seco tools.

During turning operations, races are in a hardness state of 58Rc, and removal of stock is about 0.005". Machining of the race's front face occurs in one pass, as well as its bore, with it then flipping for cutting of its back face.

For all its customers, Seco engineers will come in and observe machining processes, then make recommendations on how to improve them with the right tooling – often accomplishing this without any interruption to production runs. Engineers then explains exactly how a cutter will improve the process, suggesting the best speed and feeds for optimized tool performance.

Oil well downhole fishing systems involve both new and replacement parts, as well as consumable parts. One such common consumable component is a basket grapple, or catch, that looks like a jumbo toolholding ER collet. These components are either an external or an internal type, depending on what needs gripped. Grapples do the actual gripping when extracting damaged pipe sections from deep down an oil well.

Seco engineers often recommend its CNMG 543-M5 TP 2500 inserts for grapple machining, as the inserts provide increased tool life while reducing turning cycle times.

CNMG 543-M5 TP 2500 inserts are one in a group of three Seco grades that incorporate chip breaker geometries, insert grades, types, and sizes for any steel turning application. The TP 2500 grade – for general-purpose steel turning – provides a wide working window and the capability to handle high speeds as well as moderately interrupted cuts, while meeting all requirements in ISO M and K applications.

In addition to downhole fishing system grapples and motor bearing races, use of Seco's tooling is extensive in the machining of other motor components such as mandrels. There are several types of downhole oil well system motors, including those for straight hole, directional, slim hole, and coiled tubing drilling.

As a component of every drilling motor, mandrels will vary in size depending on the type of motor. Part production is in different lengths and diameters, and the use of Seco tools often reduce machining cycle times for all mandrel variations.

Mandrels, usually made of 4340 steel (36Rc to 40Rc), require multiple machined channels running along their lengths, which are evenly spaced around their circumferences. Machining one of these channels with a standard cutter normally takes at least four passes. However, Seco's Component Engineered Tooling (CET) department developed a special cutter, one that straddle mills the channels in just two passes and in half the time.

The engineers at Seco continue their materials approach to tooling and, as a result, have developed several new products for optimizing the machining of oil and gas industry components. Some of these new tool technologies are SNMG 150612-MR7 TP3500 for O.D. turning the hardband area of 36 CrNiMo4 drill collars to increase metal removal rates. Then there is R220.21-0063-R 160.5A for high feed milling safety valves from 9Cr material five to six times faster than other methods and R417.19-01.00-3 SPMX09. Additionally, there is the T25M for hole milling alloyed steel perforation tubes with high metal removal and extended tool life.

Seco Tools
Troy, MI
secotools.com/us