- Settore: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
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A sonic tool with a longer transmitter-to-receiver spacing (generally 10 to 15 ft) than a standard sonic tool. The rock near the borehole is sometimes altered by drilling fluids, stress relief, or both, causing a thin zone whose velocity is lower than that of the true formation. With standard spacings, the wave traveling through the altered zone may arrive first at the receiver, since this zone is closer to both transmitter and receiver. The increased spacing permits the wave traveling through the true formation to arrive first and be measured. The depth of investigation varies with slowness and transmitter-receiver spacing but is of the order of 2 to 3 ft. An increased transmitter-to-receiver spacing also allows better separation of waveforms relating to different acoustic waves, such as compressional, shear and Stoneley arrivals.
Industry:Oil & gas
A solids-free liquid used to "complete" an oil or gas well. This fluid is placed in the well to facilitate final operations prior to initiation of production, such as setting screens production liners, packers, downhole valves or shooting perforations into the producing zone. The fluid is meant to control a well should downhole hardware fail, without damaging the producing formation or completion components. Completion fluids are typically brines (chlorides, bromides and formates), but in theory could be any fluid of proper density and flow characteristics. The fluid should be chemically compatible with the reservoir formation and fluids, and is typically filtered to a high degree to avoid introducing solids to the near-wellbore area. Seldom is a regular drilling fluid suitable for completion operations due to its solids content, pH and ionic composition. Drill-in fluids can, in some cases, be suitable for both purposes.
Industry:Oil & gas
A solid plug used as an isolation device in piping systems, conduits or wellbore tubulars.
Industry:Oil & gas
A small-diameter tubing string run inside the production tubing of a well as a remedial treatment to resolve liquid-loading problems. As the reservoir pressure in a gas well depletes, there may be insufficient velocity to transport all liquids from the wellbore. In time these liquids accumulate and impair production. Installing a velocity string reduces the flow area and increases the flow velocity to enable liquids to be carried from the wellbore. Velocity strings are commonly run using coiled tubing as a velocity string conduit. Safe live-well working and rapid mobilization enable coiled tubing velocity strings to provide a cost effective solution to liquid loading in gas wells.
Industry:Oil & gas
A small-diameter hydraulic line used to operate downhole completion equipment such as the surface controlled subsurface safety valve (SCSSV). Most systems operated by control line operate on a fail-safe basis. In this mode, the control line remains pressurized at all times. Any leak or failure results in loss of control line pressure, acting to close the safety valve and render the well safe.
Industry:Oil & gas
A small-diameter conduit that is run alongside production tubulars to enable injection of inhibitors or similar treatments during production. Conditions such as high hydrogen sulfide (H<sub>2</sub>S) concentrations or severe scale deposition can be counteracted by injection of treatment chemicals and inhibitors during production.
Industry:Oil & gas
A small vessel in a pipeline to receive water and heavy hydrocarbons that drop out of a gas stream. Drips are normally installed in the lower points of flow lines and must be blown periodically to remove liquids.
Industry:Oil & gas
A small, radioactive plastic sphere that is insoluble and used to make a tracer-loss measurement. The bead is designed to have the same density as the injection fluid so that it travels with the fluid when it is placed in the flow stream of an injection well. However, the bead does not enter the formation. It remains on the rock face in openhole, or within the perforation channel in cased hole, where it can be detected by a gamma ray log. A high radioactivity opposite a perforation indicates a large number of beads and hence a high injectivity. The technique was used mainly in the 1960s and 1970s.
Industry:Oil & gas
A small tank with accurate volume markings used to measure flow into or out of a well. Treatments that require accurate volume tracking of fluids, such as squeeze cementing, generally use a gauge tank to measure fluid volumes.
Industry:Oil & gas
A small sensor, part of a production logging tool, which determines the type of fluid in its vicinity as it moves up and down a production well. Typically there are four or more sensors, or probes, held on arms to measure the four quadrants of the well cross-section. The probes may be electrical, to distinguish hydrocarbon from water; optical, mainly to distinguish gas from liquid, but also oil from water; or dielectric, mainly to distinguish water from hydrocarbon, but also, with less resolution, oil from gas. They can detect bubbles that are larger than about 1 mm diameter. Their response is essentially digital, indicating either one fluid or the other, so that the percentage of time that they see a fluid is a direct measure of its holdup. The rate of change between the two fluids is known as the bubble count. <br><br>The results can be averaged to give the mean holdup and bubble count, or converted into an image, showing the holdup or bubble count at different locations across the well at different depths. The image is particularly useful in highly deviated or horizontal wells where different flow regimes may be found in different quadrants.
Industry:Oil & gas
