Fishing tools

Due to the different nature of junk a wide variety of fishing tools are employed. 

Causes and Prevention 1114. Fishing Tools 1115. Free Point 1124. 

Logging cable and wireline can part due to the logging tool becoming stuck. Such cable and wireline can be removed by special fishing tools. 

There are basically three categories of fishing tools. These are (1) those used to define the geometry and orientations of the fish or junk in the borehole, (2) those used to recover tubular items (fish), and (3) those used to recover miscellaneous items (junk). 

There are two subcategories of tubular fishing tools those that can attach to the inside of the tubular fish and those that can attach to the outside of the tubular fish. 

Figure 4-,356 shows an example of a complex spear fishing tool. Once the spear is inside the fish, rotation to the left will place the grapple in the engaging position. Upward pull will wedge the grapple in the fish. The fishing tool can be released if it becomes necessary to come out of the hole. Bump downward... 

Figure 4-355. Inside fishing tool, tap. (Courtesy Bowen Tools, Inc.)...

Outside Fishing Tools. Outside fishing tools must pass over the outside of the fish before attaching themselves. The simplest of the outside fishing tools is the die collar, which is shown in Figure 4-357 with lipped guide. This is a short tubular that has case-hardened coarse threads cut in the inner surface of the tool. Such a tool is used to recover tubular items. 

Bottom hole assemblies and certain types of downhole equipment (e.g. logging tools, MWD tools) cost several US 100,000. Some logging tools will have radioactive sources which may need to be recovered or isolated for safety and legal reasons. However, prior to commencing fishing operations, a cost - benefit assessment will have to be made to establish that the time and equipment attributable to the fishing job is justified by the value of the fish or the cost of sidetracking the hole. 

Theory and Equipment. Many diseases of the human body can be identified by visual appearance. Tumors in the upper gastrointestinal (GI) tract, for example, possess a characteristic salmon pink color (3). The presence of such a color can be an indication of disease. Endoscopy is the medical imaging tool used to detect such colors in the inside of hoUow internal organs such as the rectum, urethra, urinary bladder, stomach, colon, etc. An endoscope is the instmment used to perform endoscopy. Endoscopic imaging involves the production of a tme color picture of the inside of the human body using lenses and either hoUow pipes, a fiber optic bundle, or a smaU CCD camera. AU three use a large field-of-view, sometimes referred to as a fish eye, lens to aUow a 180° field of view. 

Another way (Anadrill) is to use removable sources. Figure 4-285 shows the sources being installed in the tool at surface. The two sources, neutrons and gammas, are mounted on the same flexible shaft. They are moved from the shield to the sub without being exposed. Furthermore, if the BHA becomes stuck, they can be fished out with an overshot that connects to the fishing head on top of the neutron source. 

The tools used to define the geometry and orientation of the fish or junk in the borehole vary from sophisticated downhole televiewers to very simple impression blocks such as that shown in Figure 4-354. The impression block has a soft lead insert in the lower end of its steel housing. The impression block is made up to the end of the fishing drillstring and is lowered to the top of the fish (or junk). A small amount of weight is placed on the impression block, which... 

Ajar is a device for providing an impact load to the fish when the fish cannot be retrieved by normal string and derrick forces. There are purely mechanical jars and hydraulic Jars (see the section titled Drilling Bits and Downhole Tools for details on drilling Jars). In a fishing operation the Jar is usually placed... 

There are items other than tubulars that must be fished from boreholes. These are drill bit parts, pieces of downhole tools left in the borehole and hand tools accidentally dropped in the borehole. Nearly all of these items cannot be drilled by a normal rock bit. Such items are called junk. 

Milling Tool. The milling tool is a common device used for fishing junk. The milling tool is used to grind the junk into small pieces so that the pieces can be circulated to the surface or removed in a junk basket. Figure 4-364 shows the various milling tools that can be used to drill up junk in the bottom of the... 

There exist many fundamental and philosophical truths in the universe. Among these is the notion that the value of an item is determined by its inherent characteristics and its surrounding environment. For example, a fishing pole near the sea is a useful tool, but when relocated to the desert its usefulness decreases. 

Any analysis of risk should recognize these distinctions in all of their essential features. A typical approach to acute risk separates the stochastic nature of discrete causal events from the deterministic consequences which are treated using engineering methods such as mathematical models. Another tool if risk analysis is a risk profile that graphs the probability of occurrence versus the severity of the consequences (e.g., probability, of a fish dying or probability of a person contracting liver cancer either as a result of exposure to a specified environmental contaminant). In a way, this profile shows the functional relationship between the probabilistic and the deterministic parts of the problem by showing probability versus consequences. 

FUN Tool. Depending on the complexity of the scenario, the 2FUN Tool calculates the concentration in soil, water, vegetables (leaf and root), cereals, fruits, animal products (milk and beef), and fish. 

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