Geophysical research: article

Аnnotation: The article deals with the issues of automation for processing and interpreting of well logging data using prompt fission neutron method for direct determination of uranium content in ores of reservoir-infiltration (sandstone) type deposits. Infiltration deposits of uranium are located in watered weakly lithified sedimentary rocks and are operated using in situ leaching technology. A distinctive feature of deposits of this type is the variability of the coefficient of radioactive equilibrium between uranium and the products of its radioactive decay. Gamma-ray logging, which is widely used to assess uranium reserves in the bowels, allows measuring only the integral level of gamma radiation from rocks, most of which is generated by radium and its decay products. Being an indirect method, gamma ray logging can significantly overestimate or underestimate the actual uranium content in conditions of natural or man-made disturbance of radioactive equilibrium between uranium, radium and radon, which are characteristic of infiltration deposits and method of their development. Prompt fission neutron logging is one of the modifications of impulse neutron-neutron logging methods, based on the registration of prompt neutrons that occur during the fission of the nuclei of uranium atoms under the influence of thermal neutrons, which are formed in the medium as a result of deceleration of fast neutrons injected into this medium from a pulsed neutron generator. In this case, the flux density of prompt fission neutrons is proportional to the content of uranium in rocks, which makes it possible to directly determine the uranium content regardless of radioactive equilibrium state. The high demand for prompt fission neutron logging in the process of exploration and development of infiltration-type uranium deposits contributes to the constant development of hardware and methodological complexes for its implementation. The latest Russian equipment AINK-49 that implements the method of ura-nium direct determination of uranium at the modern level includes a two-probe design of the downhole tool. A thermal neutron detector has been added to the prompt neutron detector, which makes it possible to perform a fairly accurate assessment of the ore moisture in natural occurrence conditions and, as a result, significantly increase the accuracy of uranium content determining. Successful trial operation of new equipment at existing exploration and uranium mining enterprises and the transition to its wide industrial use set the task of developing software and mathematical support for the automated interpretation of the received data. The article describes a number of methodological, mathematical and algorithmic techniques that make it possible to automate the existing methodology for prompt fission neutron logging data interpretation and soft-ware developed by the authors for automated processing and interpretation of logging materials obtained using the AINK-49 hardware and methodical complex.