Zone of influence

A sample is representative of a neighborhood measured by the range of correlation. For example, a soil sample could represent a circular area in the field centered at the sample site with a radius less than or equal to the zone of influence. This has always been intuitively obvious to the environmental scientist but now can be described statistically. The zone of influence is defined by the theoretical semi-variogram and is easily estimated from an empirical semi-variogram. 

The zone of influence of a horizontal well can be calculated either by the rectangular or elliptical approach. The rectangular approach assumes the radius of influence is constant along the length of the well and is equal to the extent of the... 

The elliptical approach assumes that the zone of influence is elliptical (Ae) with the well end points constituting the face of the ellipse, and the minor semiaxis equal to the radius of influence. The area of drainage (Ae) is... 

A third approach was developed by Aller (1980a, b) who studied solute fluxes in near-shore marine sediments showing seasonal variation. In this approach, the geometry of the burrow-sediment system is allowed for explicitly and transport in the sediment between the burrows is described with appropriate diffusion equations. It is assumed that the burrows are oriented normal to the sediment surface and distributed uniformly or randomly in the horizontal plane (Figure 2.11). Thereby a cylindrical zone of influence is ascribed to each burrow with a radius... 

The rhizosphere is the three-dimensional zone of influence that a root exerts on the surrounding soil. Its iiuier boundary is the rhizoplane, which is the two-dimensional root surface. The rhizosphere penetrates a variable distance into the soil as determined by the biological, chemical, and physical soil characteristics. The thickness or volume of the rhizosphere for a particular element or compound depends on the source-sink strength of the root, the source-sink strength of the soil, and the diffusion rate (van Bodegom et al., 2001a). 

Fast moving neutrons emitted from a radioactive source (usually Radium-Berrylium or Americium-Beryllium) upon collision with a particle having mass nearly equal to its own, like hydrogen atom in the soil, release their energy and gets thermalized or slowed down. The thermalized neutrons are detected by a detector and recorded on a scalar. Usually BFg gas is used as detector of slowed down neutrons. Increased thermalization indicates higher water content of the soil. The zone of influence is normally about 15-20 cm arormd the detector. 

The productivity q oil of the injection well 159 itself rose 1.5 times. The relatively limited oil productivity increase of well 159 itself can be explained by the fact that the oil in its zone of influence has been drained already during prior production. However, the productivity of fluids of well 159 remained high as before it was also true of the other steam injection wells. Productivity increases due to drop in oil viscosity are indicated by counterclockwise shifts of straight line plots from their original position 1 to positions 2 and 3 in the direction of the yield axis (see Figs. 41-44). 

Studies by Roark would indicate short zones of influence in the longitudinal direction (quick decay) and a much broader area of influence in the circumferential direction (slow decay, larger attenuation). This would also seem to... 

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