- Industry: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
- Company Profile:
A downhole tool used in conjunction with a jar to store energy that is suddenly released when the jar is activated. The energy provides an impact force that operates associated downhole tools or, in a contingency role, helps release a tool string that has become stuck. Depending on the operating mode, the energy in tension or compression can be stored by means of a mechanical spring or a compressible fluid such as nitrogen gas. Accelerators should be selected on the basis of their compatibility with the jar to be used.
Industry:Oil & gas
A downhole tool typically used with motors or assemblies that restrict the allowable fluid-circulation rates. When operated, the circulation sub allows a higher circulation rate to be established by opening a path to the annulus in the top section of the tool string. This is especially useful in applications such as drilling in slim-diameter wells, where a higher circulation rate may be necessary to effect good cuttings transport and hole cleaning before the string is retrieved.
Industry:Oil & gas
A downhole tool that is located and set to isolate the lower part of the wellbore. Bridge plugs may be permanent or retrievable, enabling the lower wellbore to be permanently sealed from production or temporarily isolated from a treatment conducted on an upper zone.
Industry:Oil & gas
A downhole tool that is designed to part under controlled conditions. A release joint enables part of the tool string to be left in the wellbore while the running string is retrieved.
Industry:Oil & gas
A downhole tool that is designed to enable communication between the tubing internal diameter and the annulus, typically for reverse circulation purposes, although conventional circulation often can also be undertaken. The valve design may be simple, enabling circulation without the ability to reset the tool until it is retrieved to surface, or be of a more complex design allowing several cycles between open and closed positions.
Industry:Oil & gas
A downhole tool similar in function to a casing scraper. A junk pusher is run to ensure an unobstructed wellbore before setting a packer or similar fullbore device.
Industry:Oil & gas
A downhole tool run on wireline to sever tubing at a predetermined point when the tubing string becomes stuck. When activated, the chemical cutter use a small explosive charge to forcefully direct high-pressure jets of highly corrosive material in a circumferential pattern against the tubular wall. The nearly instantaneous massive corrosion of the surrounding tubing wall creates a relatively even cut with minimal distortion of the tubing, aiding subsequent fishing operations.
Industry:Oil & gas
A downhole tool routinely used in fishing operations to prepare the top and outside surface of a fish, generally to allow an overshot or similar fishing tool to engage cleanly on the fish. In some cases, the outer portion of a fish may be milled out to allow the body and remaining debris to be pushed to the bottom of the wellbore.
Industry:Oil & gas
A downhole tool or logging device used to detect and track (log) casing or tubing collars across a zone of interest, typically for correlation purposes. Most collar locators detect the magnetic anomaly created by the mass of the steel collar and transmit a signal to surface-display and depth correlation equipment.
Industry:Oil & gas
A downhole tool on which downhole gauges or instruments that are to be temporarily left in the wellbore are attached. The instrument hanger is run into the wellbore on slickline and set in a completion nipple at the required depth.
Industry:Oil & gas
