Basis of borehole radiometric defectoscopy for rocks. Part II. Physical modeling

Conclusions We have shown that the distance between cracks can be determined from the distance between the maxima of radiometric logs. With a reduction in probe base there is an increase in the absolute maximum of the anomaly I_γmax with a simultaneous reduction in its width. The width of the maximum I_γmax of the anomaly equals the sum of the probe base and crack opening lengths. Physical and mathematical modeling demonstrates the identical qualitative dependence of recorded γ-radiation on crack parameters. However, in arranging problems of mathematical modeling it is necessary to carry out a laboratory experiment previously with the aim of eliminating unmonitored parameters. The possibility has been demonstrated of using hypotheses 1–4, which lie at the base of a theory for borehole geophysical defectoscopy, for interpreting gamma-gamma ray logging data. Institute of Mining, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Fiziko-tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 35–40, September–October, 1990.