- Settore: Oil & gas
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The amount by which a log measurement must be adjusted in order to remove the contribution of the borehole. Although most log measurements are designed to pick up a minimum of signal from the borehole, some contribution usually remains. This contribution may be removed by software or by manual entry into correction charts. In resistivity logging, the correction replaces the borehole with a resistivity equal to that of the formation. In nuclear logging, the correction adjusts the reading to that which would be found in a standard condition, such as an 8-in. (20-cm) borehole filled with fresh water.
Industry:Oil & gas
Distortions in the reservoir response due to wellbore storage. The characteristic trends are an early unit slope trend with pressure change and the derivative overlain on the log-log plot, followed by a "hump" in the pressure derivative that gradually disappears as reservoir trends become recognizable. Complex behavior in the wellbore, such as wellbore phase distribution, can result in a more complex transient trend. A crucial part of the transient analysis is to distinguish the effects of wellbore storage from the interpretable reservoir response.
Industry:Oil & gas
Display ranges chosen for the density and neutron porosity logs such that the two curves will overlay at all porosity values providing the matrix is pure calcite and the pores are filled with fresh water. The most common overlay spans two tracks, with the density reading from 1. 95 to 2. 95 g/cm<sup>3</sup>, and the neutron in limestone porosity units from 0. 45 to ?0. 15 vol/vol.
Industry:Oil & gas
The adjustments that must be made to log measurements to bring them back to the standard conditions for which the tool has been characterized. Different measurements require different corrections. For example resistivity measurements usually require correction for the borehole, invasion and shoulder beds, and may also be corrected for apparent dip, anisotropy and surrounding beds in horizontal wells. Density measurements require correction only for borehole size, while neutron porosity measurements require corrections for temperature, pressure and a large number of borehole and formation parameters. Not all corrections are significant in all cases. Corrections can be calculated manually, using charts, or applied through software. Conventionally, corrections are applied sequentially, as for example first borehole then invasion. In some situations, such as the combination of deep invasion and high apparent dip on a resistivity measurement, the corrections are too interdependent for sequential application to be accurate. The solution is iterative forward modeling.
Industry:Oil & gas
The action of forcing a pipe or tubular into a well against wellbore pressure. Well-intervention techniques in live wells, such as coiled tubing and snubbing, use equipment designed to apply the necessary forces while supporting the tubing and safely containing wellbore pressure and fluids.
Industry:Oil & gas
The act of producing a model of a reservoir. The model could include any of the geological, fluid or other characteristics of the reservoir.
Industry:Oil & gas
The additional loss in amplitude of an electromagnetic wave emitted by an electromagnetic propagation or dielectric propagation measurement compared to that of a plane wave. The spreading loss depends on the geometry of the transmitter-receiver array and also on the dielectric properties of the formation. The same effect also causes a small correction to the propagation time.
Industry:Oil & gas
The act of passing the mud around a piece of equipment, such as passing mud returns around the shale shaker screens or going around a hydrocyclone device. From a mud-engineering viewpoint, this can be a bad practice because it can allow drill solids to degrade and accumulate as fines to the degree that they might cause mud problems.
Industry:Oil & gas
The act of modeling a reservoir using knowledge of the facies that make up the reservoir and the depositional environments that the facies represent. The depositional characteristics will suggest rules concerning the geometries of the facies and the possible relationships between facies, especially where the facies have been related to each other within a stratigraphic sequence or a cyclothem. Facies modeling is often an important component of geostatistical reservoir characterization and facilitates construction of superior reservoir models for complex reservoirs.
Industry:Oil & gas
One of a number of possible distributions that may occur when the results of events are plotted. Boltzmann distributions were originally described from theoretical consideration on the probable interactions of molecules. It has been used in simulation of annealing and can be used for studying perturbations in geostatistical models.
Industry:Oil & gas
