STUDY OF COAL EXPLORATION WELLS USING THE PULSED-NEUTRON-NEUTRON LOGGING

Abstract

Relevance of the research is defined by the necessity in optimization of coal exploration well geophysical researches by means of pulsed-neutron-neutron logging. Formulation of the problem is conditioned by modern tendencies of coal industry development and new instrumental and technical elaborations at exploration and borehole geophysics. The aim of the research is to show the opportunities and effectiveness of pulsed-neutron-neutron logging at coal exploration wells on materials of experienced-experimental works in Eastern Donbass. Object: logs of pulsed-neutron-neutron logging registered in coal exploration wells of Eastern Donbass. Methods: analysis of pulsed neutron-neutron logging logging curves for the effectiveness of using the method in a standard complex for solving problems posed by the geological service for identifying: 1) targets, i. e. coal seams with the definition of their position in the section; 2) rocks containing coal seams. Outcomes of the research. The application of pulsed-neutron-neutron logging for the study of geological sections of the coal wells was justified. The authors have studied qualitative and quantitative characteristics of thermal neutrons lifetime in rocks of the coal-bearing strata. The paper demonstrates the opportunities of the method by estimation of mark composition of coal and their ash content. The authors carried out the well logging curves matching registered at differ temporary delays and with different velocity of logging zond lifting on subject to choosing optimal conditions of geophysical work by this method. It was established that all the lithological differences including thin coal layer are unambiguously distinguished by the pulsed-neutron-neutron logging method. There authors analyzed the pulsed-neutron-neutron logging resolution on the background of well logging curves of geophysical well survey complex including the methods of electrical, radioactive, acoustical well logging and caliper. The accent was made on positive sides and drawbacks of gamma-gamma well logging with soft source. The authors suggested replace GGK-S research by pulsed-neutron-neutron logging logging in the presence of organizational and technical difficulties.

Keywords

• pulsed-neutron-neutron logging
• coal exploration well
• thermal neutron lifetime
• rational logging complex
• argillite
• aleurolite
• sandstone and limestone layers
• eastern donbass