- Industry: Oil & gas
- Number of terms: 8814
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In electromagnetic methods, to measure the variation of a property versus depth, including electrical, electromagnetic and magnetotelluric properties. Probing differs from profiling in that the goal of probing is to provide a record of vertical changes, whereas profiling documents lateral variations.
Industry:Oil & gas
In chemical flooding, a fluid stage, normally water thickened with a polymer, pumped between the micellar or alkaline chemical solution and the final water injection. <br><br>Mobility buffers are prepared with polyacrylamides or polysaccharides and are frequently employed in micellar-polymer flooding operations because they improve sweep efficiency, which increases oil production. The high viscosity of the mobility buffer aids in the displacement of chemicals into the reservoir and also minimizes the channeling of the final water injection into the chemical solution or into the resulting oil bank.
Industry:Oil & gas
In a sucker-rod pump, one complete round of the polished rod (surface stroke). On each stroke, a fixed volume of liquid is lifted. This volume is related to the cross-sectional area of the pump and the length of the stroke. <br><br>The stroke length at the subsurface sucker-rod pump usually differs from the surface stroke because of the stretching in the upstroke and the rebounding in the downstroke.
Industry:Oil & gas
In an intergranular rock, the small pore space at the point where two grains meet, which connects two larger pore volumes. The number, size and distribution of the pore throats control many of the resistivity, flow and capillary-pressure characteristics of the rock.
Industry:Oil & gas
In a subsurface sucker-rod pump, the valve that closes the barrel chamber allowing the trapped fluid to be lifted in the upstroke of the pump. This valve is similar in configuration to the standing valve.
Industry:Oil & gas
In a spinner flowmeter, the theoretical minimum fluid velocity required to initiate spinner rotation, assuming the spinner response is linear. In this sense, it is synonymous with threshold velocity. However, it is sometimes taken to mean the fluid velocity at which a significant amount of flow begins to leak past a basket flowmeter, sufficient to cause the response to be nonlinear.
Industry:Oil & gas
In a spinner flowmeter, the theoretical minimum fluid velocity required to initiate spinner rotation, assuming the spinner response is linear. The actual fluid velocity required to start spinner rotation is slightly higher because of additional viscous and mechanical effects. The threshold velocity is determined by extrapolating the spinner response at higher fluid velocities, where it is known to be nearly linear, back to the value that exists when spinner rotation is zero.
Industry:Oil & gas
In a separator, a series of inclined parallel plates or tubes to promote coalescence, or merging, of the foam bubbles liberated from the liquid.
Industry:Oil & gas
In a nuclear magnetic resonance measurement, the use of a gradual rather than a sharp cutoff to distinguish between bound water and free water. A sharp cutoff at, for example T<sub>2</sub> = 33 ms in sandstones, is normally used to distinguish free water (all T<sub>2</sub>s above 33 ms) from bound water (all T<sub>2</sub>s below 33ms). In a water-filled rock, in the fast diffusion limit, T<sub>2</sub> is directly related to pore size. The distinction between bound and free water is based on the assumption that all free water resides in large pores, and all bound water in small pores. However, in rocks with large pores, a significant volume of bound water exists on the surface of the grains around a large pore. Being part of a large pore, it gives a long T<sub>2</sub> and will be incorrectly counted as free water. One solution is the tapered cutoff, in which the bound water is the sum of all the T<sub>2</sub> below a minimum, for example 5 ms, and is then a progressively smaller fraction of the volume at T<sub>2</sub>s up to a maximum, for example 500 ms. All signal above 500 ms represents free water. The form of the taper is usually empirical, but is based on some model of pore shape, such as a bundle of tubes. <br><br>See Kleinberg RL and Boyd A: 'Tapered Cutoffs for Magnetic Resonance Bound Water Volume' paper SPE 38737, presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, October 5-8, 1997.
Industry:Oil & gas
In a nuclear magnetic resonance measurement, the loss of coherent energy by hydrogen atoms as they interact with each other in bulk fluids. Bulk relaxation in fluids is caused primarily by fluctuating local magnetic fields arising from the random tumbling motion of neighboring molecules. Local field fluctuations may be high, but the fast movement of molecules tends to average these out. Thus the bulk relaxation depends strongly on the rate of movement and is affected by temperature and viscosity. <br><br>In water-wet rocks, hydrocarbons do not touch the pore walls and are not affected by surface relaxation. Thus the T<sub>1</sub> and T<sub>2</sub> of hydrocarbons are the result only of bulk and diffusion relaxation. This is an important feature of NMR logging. Based on this feature, direct hydrocarbon-typing techniques have been developed for the detection and characterization of hydrocarbons.
Industry:Oil & gas
