- Industry: Oil & gas
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A distance that characterizes the ability of a logging measurement to resolve changes in the formation perpendicular to the tool. Alternatively, the term refers to the smallest distance for which a significant change can be detected. The resolution is a feature of the radial response, which is often summarized by a geometrical or pseudogeometrical factor. A measurement with good or high radial resolution will have a sharp peak in the radial differential geometric factor at some distance from the tool.
Industry:Oil & gas
A distance that characterizes how far a logging tool measures into the formation from the face of the tool or the borehole wall. The depth of investigation summarizes the radial response of the measurement in one or more directions. For nuclear and resistivity measurements, the depth of investigation should be associated with the percentage of signal received from within that depth, typically either 50% or 90%. Most quoted depths of investigation assume a homogeneous formation with certain properties, such as a given resistivity or fluid content. The depths of investigation can vary considerably in inhomogeneous conditions, and at different values of the properties concerned. They should be considered only a qualitative guide to tool response. <br><br>For other measurements, the depth of investigation is either well-defined by the tool physics (in the case of nuclear magnetic resonance), or else can be given only approximately, an accurate value being too dependent on formation properties (in the case of acoustic and electromagnetic propagation). <br><br>The term is used for all measurements but is most appropriate for azimuthally focused devices such as nuclear logs. For azimuthally symmetric devices such as resistivity logs, the term radius of investigation is more appropriate.
Industry:Oil & gas
A distance that characterizes how far a logging tool measures into the formation from the axis of the tool or borehole. The term is similar to depth of investigation, but is more appropriate for certain azimuthally symmetric measurements, mainly resistivity. <br><br>The radius of investigation summarizes the radial response of the measurement in one or more distances, and should be associated with the percentage of signal received from within that depth, typically either 50% or 90%. Most quoted depths of investigation assume a homogeneous formation with certain properties, such as a given resistivity or fluid content. The radius of investigation can vary considerably in inhomogeneous conditions, and at different values of the properties concerned. It should be considered only a qualitative guide to tool response.
Industry:Oil & gas
A distance that characterizes how far a logging tool measures into the formation from the axis of the tool or borehole. The term is similar to depth of investigation but is appropriate only for azimuthally symmetric measurements such as resistivity.
Industry:Oil & gas
A dimensionless factor calculated to determine the production efficiency of a well by comparing actual conditions with theoretical or ideal conditions. A positive skin value indicates some damage or influences that are impairing well productivity. A negative skin value indicates enhanced productivity, typically resulting from stimulation.
Industry:Oil & gas
A discontinuous parabola kernel that is used in contouring areal density of data points in a crossplot. The kernel function can take many other forms, such as triangular, rectangular or Gaussian. The function determines the shape of the bump or cluster of data under scrutiny. This technology is often used in cluster analysis and statistical graphic techniques.
Industry:Oil & gas
A difference in vertical and horizontal resistivity within a formation and at the scale of the resistivity measurement. Although there are several possible types of anisotropy, the term usually is used when the electrical properties are the same in all horizontal directions, but different in the vertical direction. For horizontal beds, this type of anisotropy is more fully known as transverse isotropy with a vertical axis of symmetry (TIV). The term may also refer to a difference in resistivities measured parallel and perpendicular to bedding.
Industry:Oil & gas
A dimension in Euclidian space. Euclidian dimensions are all orthogonal to each other (at right angles to each other) and refer to physical space with X, Y and Z components.
Industry:Oil & gas
A diagram noting the major profiles and dimensions of tools and equipment run into a wellbore. A fishing diagram should be prepared for every tool operation, enabling contingency plans to be implemented efficiently if the tool string becomes stuck or lost.
Industry:Oil & gas
A diagram that displays multivariate data. A good choice of glyph design can aid the recognition of complex similarities or distinctions in a set of data. A well-known example of an oilfield glyph is the Stiff diagram, which shows the patterns of cations and anions in fluids. <br><br>Reference:<br><br>Stiff HA Jr: 鈥淭he Interpretation of Chemical Water Analysis by Means of Patterns,鈥?Journal of Petroleum Technology 3, no. 10 (1951): 15-16.
Industry:Oil & gas
