This is an internal catch tool and is used when an external catch tool is not practical. Most spears used today are releasable type spears, however, there are a few Bulldog or non-releasables still around.
There are two types of releasable spears available: the slip type and the grapple type. The grapple type spear has a full circle catch. This means the grapple is in full contact with the inside circumference of the fish. This gives a better bite in the fish and also lessens the chance of distorting the fish when extreme pull or torque is applied to the fish.
Some slip type spears have a full circle catch also. This is possible by having the slips mounted on a hanger or cage; other slip type spears have slip segments mounted on a hanger or cage. Still other slip type spears have slip segments mounted in the body with space between them. They have three slips evenly spaced around the outside circumference of the spear body. Some slip type spears have six segments with the next three mounted below and offsetting the top three. This distributes the force over a more equal area. Shucking them down and turning ¼ round to the right release most slip type spears.
Shucking or Shucking down means to jar down on a spear or overshot until you break the bite on the fish and put the slips or grapple in a released or neutral position.
The Bowen spear is the most popular spear in the field. It is a grapple type spear and is available in most any area of the oil field. It is very simple construction and has very few parts. Since this is the spear that is used mostly, we will discuss it more thoroughly.
The Bowen spear body has large spiral threads that accommodate the large spiral threads on the inside of the grapple. Remove the bottom nut and screw the grapple onto the spear body until it is in place. The large spiral threads of each part then form a cone effect that is called the draw. When the spear is raised, the draw moves into the smaller area of the grapple and expands it against the wall of the fish. These large spiral threads should be cleaned and lubricated before putting the grapple on the spear body. On the outside of the grapple are small spiral threads that grip or bite into the fish. These threads are called Wickers. The spear is released by driving it downward and moving the large part of the draw into the larger opening of the opposing draw. This will relax the grapple and permit it to contract. This is referred to as shucking the spear. When the spear is shucked, hold a neutral weight and rotate one complete round to the right. The spear should be released.
There are two types of Bowen spears: the Flush type and the Shoulder type. The Flush type is the same O.D. of the full length of the spear body. The box connection in the top of the spear is small enough to go in the I.D. of the fish.
The Shoulder type has a larger O.D. connection than the spear body; therefore, creating a shoulder at the top of the spear body. The shoulder type spear is stronger because of the larger tool joint connection. There is a stop ring or bumper ring that is optional. It has a box and pin connection usually with the same connection as the spear, with a large O.D. flange around it. Bumper or stop rings are available in most any size O.D. you’ll need. When this is screwed into the top of the spear, it forms a shoulder that will stop on the top of the fish; therefore, limiting the depth you could run the spear in the fish. Spears are available with different shank lengths. The shank is the distance between the top of the grapple and the top of the spear body. If you run a shoulder type spear to get the strength of a larger connection, and wanted to catch deeper in the fish, then you would need a long shank spear. Extensions are also available. The extension is run on top of the spear body of a flush type spear to get deeper in the fish. If you plan to jar with a spear, then you will have to have a stop or bumper ring to stop on top of the fish, so you can apply weight down to reset or cock the jars. This can also be done with a shoulder type spear.
Packoffs are available for the spear. It is an assembly that screws on the bottom of the spear. It is called a spear packoff assembly. It is made up of a three-part body called the mandrel, a steel ring called the thimble, and a rubber cup called the packing element. The packing element is run with the open side down. When pressure is applied through the spear, the element will expand against the fish and form a packoff.
The spear should always have a minimum of ten thousands pounds strain up on the spear before attempting to put torque into the fish.
The spear should never be dressed in the shop to send on a job. The grapple is very easy to break and the weight of the spear body could easily break it if dropped or jarred around while hauling.
The spear grapple has a recommended gap that is stamped in the tang on top of the grapple. This should always be checked before running it in the hole. Some supervisors tape the grapple in the catch position before running it in the hole. This cannot be relied upon, so always put the grapple in the fish and with a neutral weight. Turn the spear to the left one round; to be sure the grapple is all the way in the catch position.
The Bowen spear has been modified recently and it is not necessary to tape or tie the grapple in the catch position (if you are using one of the newer types). If you are using one of the older types, then some caution should be taken.
Caution should also be used when catching casing at the surface with a spear. Sometimes the casing will be thin where the Kelly has rotated in one position in the casing, and it is possible to split the casing when you pull on the spear. If this happens, the spear could release suddenly, creating some danger to personnel and equipment.
Always think the job out from beginning to end before a hazardous situation surprises you.