In my last column, I wrote about the need to pull casing from the ground. Maybe you drilled a dry hole, or need to remove bent pipe or set a well screen by the telescoping method. I previously talked about two methods for casing not too tight in the ground: the slotted pulling head and pipe pulling jars. For casing driven down deep and really tight in the ground, we may want to use one of two other methods.
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Here, I focus on the first: a very popular tool called a casing spear (or, sometimes, trip spear). You can lower this tool to any position inside the casing and teeth expand to grip that inside. You need to use long-stroke jars just above the trip spear with a drill stem and rope socket above the jars. The stroke of these jars needs to be longer than the stroke on the machine, and the operator would generally set the stroke at its shortest length. Small water well rigs have a short stroke of about 18 inches, so we would need to select jars made for a stroke of at least 24 inches or, preferably, 30 inches. The reason for this is that the casing spear is adjusted at the surface to slide down inside the pipe.
When reaching the point where jarring will be used, the driller pulls up on the tool string and the pulling slips engage the pipe. After some light, almost tap-like strokes on the jars, you can apply full power to them and the teeth will dig into the pipe and grip it, moving it toward the surface. To release this tool, you stop jarring and apply a few downward blows. That causes a spring in the spear to retract the jaws, and you can then pull the tool and the string itself to the surface &#; either because pullback finished or a section of casing needs removal. Avoid pulling from the same point in the casing every time you use the spear, as this might elongate the casing and ruin it.
Another reason for the long-stroke jars with a stroke of a fair amount longer than the stroke of the machine stems from downward force on the spear. Too much force can trip it, and then it has to be pulled from the casing and reset. This resetting is one of the disadvantages of this tool. I never owned a trip spear but I did borrow one on occasion, even rented one from a tool company. I found setting the jaws difficult &#; in fact, almost tricky. This setting adjusts how large of diameter of pipe the trip spear will engage. If set too light, it will not engage the pipe and be ineffective. If set too heavy, the spear will not disengage, complicating the driller&#;s problem. At least one manufacturer I know of advertises that their trip spear easily adjusts for different casing weights. I believe they have notches on the setting ring, a part of the spear. Other manufacturers use wood blocks to hold the jaws closed and they are quite tricky.
The big advantage of a trip spear comes from placement. You can lower it to the lowest part of the casing before engaging it. This is where the casing is tightest and the upward blow most effective. Casing has a springiness in it so that a blow at the top &#; as I wrote about last time &#; has affect than a blow near the bottom.
Another point about setting the machine to use the trip spear: If it has an adjustable stroke, set it in the fishing or pulling position with a fast rise and a slow drop. This is just the opposite of the drilling stroke. On a machine without this adjustment feature, the driller should select the shortest stroke possible. Under extreme conditions, he might go to medium stroke (with suitable fishing jars) but it is best to use the short stroke.
Most cable tools are pretty rough, tough and simple. They don&#;t have moving parts and, with properly set up joints, work very well. Not so for the casing spear. I find these spears difficult to use. If you use one, follow the manufacturer&#;s instructions to the letter. For example, one basic requirement is that the tapered &#;ways&#; that the jaws slide on need to be very clean and nicely lubricated.
Manufacturers make trip-type casing spears to pull 3-inch ID pipe all the way up to 16-inch OD casing, which covers just about all the water wells drilled in the United States and abroad.
This wraps up my thoughts on casing spears. Next time, I&#;ll get into yet another method to pull casing from the ground: the casing ring, a tool whose use and, indeed, selection is not simple.
As I write this very late July, we continue to have a rather nice summer in southern Michigan. We have had warm and slightly hot weather, but not terrible heat and high humidity. I know some of you in other parts of the country have had just terrible heat, and I feel for you. I also understand that drought is too prevalent in other areas. We have had enough rain to keep my infamous lawn green, although the buckhorn keeps coming back. Nearby corn and soybean fields look good and, if the weather holds, I think the farmers will have a good year. Until next time, work hard, work safe, enjoy life and remember pulling casing is just part of the job.
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The Releasing Spear Fishing Tools are used in drilling to internally engage and to retrieve all sizes of tubing, drill pipe, and casing as opposed to overshots that catch on the outside. It is designed to assure positive internal engagement with the fish and is ruggedly built to withstand severe jarring (Drilling Jars) and pulling strains without distorting the fish.
Usually, a spear is not the first choice, as the spear will have a smaller internal bore than an overshot which limits the running of some tools and instruments through it for cutting (Mechanical Cutter), free-pointing (FPI Tool), and in some cases, backing-off.
Spears, however, are popular for use in pulling casing liners, picking up parted or stuck casing (pipe sticking), or fishing any pipe that has become enlarged when parted due to explosive shots, fatigue, or splintering.
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The most popular spears in use today are built on the same principles as overshots with a tapered helix on the mandrel and a matching surface on the inside of the grapple. The slip or gripping surface is on the outside surface of the spear so that it will catch and grip the inside of the pipe that is being fished. Due to the design with the small-bore in the mandrel, spears are usually very strong.
The spear is run inside the fish and positioned. The slips are released by the action of the J-slot by using left-hand torque, moving the drill string down a short distance, and then picking it back up slowly. This action releases the slips so they can slide up over a taper on the body of the spear as the spear is moved uphole. The slips move outward engaging the inner wall of the fish.
In order to release a spear, it is rotated to the right. If the grapple is frozen to the mandrel, it may be necessary to bump down to free or &#;shuck&#; the grapple. Usually, a bumper sub is run just above the spear and this can be used to effectively jar down (Mechanical Jar &#; Hydraulic Jar) and free the grapple.
The spear is a very versatile tool, in that it can be run in the string above an internal cutting tool if desired or in combination with other tools. Milling tools (Milling In Drilling Operations Guidelines For Oil & Gas) may be run below the spear to open up the pipe so that the spear can enter and catch the fish.
When running the spear, verify that the grapple is the correct size for the pipe to be caught. Refer to the Bowen instruction manual catching range table. For example, a grapple to catch 9.625&#; by 47 to 58# casing will have a nominal catch range of 8.597&#; with a minimum of 8.534&#; and a maximum of 8.755&#;.
It is essential that the spear is properly assembled. Be sure to check the gap of the spear grapple, which is marked on the tang. Tape the grapple in the catch position prior to running into the hole. You should always install a spear pack-off when you are performing fishing operations in an open hole. A packer assembly may be run on the bottom of the spear to pack off. A bumper jar is also required to aid in releasing the spear.
There are many types of releasing spears, but the most popular ones are:
Running the spear into the fish, causing the grapple to be pushed up, operates the Bowen Itco releasing spear. The grapple gets tighter as it goes into the fish. When the spear is picked up, the grapple is pulled down on the tapers of the spear. The harder the spear is pulled, the tighter the grapple will bite. Below is the running procedure for such type:
The Bowen Full Circle Releasing Spear is a good tool to use for ensuring positive internal engagement over a long section of a fish. The design of the full circle slips and the effect of the tapers of the body on the slips cause the expansion strain to be distributed evenly over a long vertical section and virtually over the entire inner circumference of the fish. Below are the procedures for running the such tool:
The Houston Engineers Releasing Spear consists of:
All of the components of the Houston Engineers Releasing Spear are locked together and cannot unscrew in the hole. However, even after high torque loads in either direction, this spear can be disassembled by hand for field maintenance. Full bore is maintained in all sizes to facilitate the use of wireline equipment. Only one part, the slip, is exposed to extreme wear. Below are the procedures for running the such tool:
A typical spear assembly when fishing 9 5/8&#; casing would be: 9 5/8&#; Spear c/w Cup and Stop Ring, 8&#; Bumper Sub, 8&#; Fishing Jar, 6 x 8&#; Drill Collars, 8&#; Fishing Accelerator, 2 x 8&#; Drill Collars, 15 HWDP.
When fishing casing and other thin-walled tubulars then an internal catch spear and grapple is the tool to be used. The spear is made up of an inner mandrel which is cut on a tapered helix. The grapple then screws onto the mandrel and will move up and down the helix as the string is rotated.
Two types of grapple are available. The one-piece grapple is sized to catch small to medium-sized tubing and casing whereas the segment type grapple is designed for larger bore casing and conductor. Grapples are supplied for a nominal size of casing or tubing and will be stamped with the weight range they can catch. Right-hand rotation will move the grapple to the bottom of the mandrel which is the release position. Conversely left hand rotation will move the grapple to the top of the mandrel which is the catch position.
An elastomer cup is normally run on the mandrel to allow for circulating through the fish. Above the mandrel, a fishing spear stop or ring tool is positioned to provide a &#;NoGo&#; on the top of the casing.
The best practice to use when running a spear is:
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