The effective application of gamma-gamma density logging in the dissection of a geologic section is largely determined by the correct choice of the distance between the source and detector of radioactive radiation (probe length), the integration constant and the speed of the logging tool.
The distribution of gamma quanta along the directions of motion is one of the main characteristics of gamma fields. Data on the angular distribution of gamma rays are used in the design of probe devices, selection of optimal geometric conditions and methodological techniques of measurements in nuclear geophysical methods of studying rocks.
Along with the development and improvement of traditional methods of pressure determination, based on the study of elastic deformation values of rocks, various physical methods are increasingly used, including gamma methods of determining the density of rocks.
In order to exclude the influence of borehole diameter on the results of density γ-γ logging, special clamping 2π-probes are used. In small diameter wells (36—50 mm) it is difficult to use clamping probes. Symmetrical 4π-probes are widely used for such boreholes. However, the presence of an intermediate zone (air, water, drilling mud) between the probe and the borehole walls leads to a significant dependence of the 4π-probe readings on the borehole diameter. When the borehole diameter is constant, this dependence can be taken into account when benchmarking the probes. Violation of the identical conditions of reference and measurement when the borehole diameter is changed leads to differences between the measured Rism and true Rism values of density.
Estimating the strength properties of a rock mass by radiating the physical and mechanical properties of rock samples is inefficient due to the influence of scale factor. Both geologic and mining engineering features of the deposits influence rock stability. It is necessary to study rock properties directly in the massif. In this respect, the U-method of measuring the density of rocks in natural occurrence has great possibilities, since the density of rocks in the massif is either functionally or correlatively related to other physical and mechanical properties of rocks.
The development of the theory and practice of the γ-method requires the study of the depth of studies in specific conditions. Depth depends mainly on the type of the γ-radiation source, the density of the medium, the size of the probe (measuring unit) and its design, the position of the probe relative to the surface of the medium under study (the presence of the intermediate medium and its properties). Experimental study of depth studies mainly refers to the method of scattered γ-radiation ...