Purpose. The paper concerns additional geological appraisal and identification of extra localization criteria of cupriferous mineralization of a stratiform type. The research is intended to define physical and geological factors influencing sandstone distribution within the north-end of Zhezkazgan synclinal in the Central Kazakhstan. Methods. A complex analysis of geological and mineralogical, geophysical, and geochemical data was carried out relying upon the information obtained from deep-hole wells. Modern methods to process and interpret the field data were applied. The analysis involved lithological dismemberment of the productive Taskuduk suite as well as determination of sulfide mine-ralization zone boundaries. Findings. The research has shown that the productive levels reach down to 1500-m depth. The data interpretation has helped specify the geological structure and develop a model of ore-promising bodies of cupriferous sandstones at great depth. The applied complex data analysis has increased potential to prospect new loci of productive cupriferous sandstone deposits of Zhezkazgan type. Originality. The research has contributed significantly to understanding of the physical and geological factors influencing the copper ore distribution in deep layers. New physical and geological criteria, determining deep copper mineralization localization, have been identified which were not considered by earlier similar studies. Practical implications. The obtained new data as well as the developed methods are important while deep drilling planning and implementing to identify promising copper mineralization sites. The findings may be used to optimize exploration within the north-end of Zhezkazgan synclinal, and other districts having analogous geological conditions.

This article presents the results obtained from a high-resolution wide-azimuthal 3D seismic reflection method used for the prediction and detailed exploration of complex ore targets in the Zhezkazgan ore district of Central Kazakhstan. We demonstrate the ability of modern seismic data processing and interpretation systems to identify underground mine objects associated with stratiform copper sandstones and improve geological models. The 3D seismic imaging tools, along with the implementation of a modern seismic processing sequence, allow for the clarification of geological structures in the studied area. The target stratigraphic horizons, large faults, and microtectonic disturbances (small faults and cracks) are clearly delineated in the seismic volumes. The use of seismic attribute analyses on geological data is tested to identify ore horizons and deposits with volumetric predictions of copper mineralization. Recommendations for further exploration drilling were developed, and five new wells were drilled. Copper mineralization was confirmed in all recommended wells. We carried out a marketing review in Kazakhstan and uncovered an increased interest among subsoil use companies in 3D seismic exploration technology to investigate existing mining objects of different genetic types. These results demonstrate the expediency of 3D seismic exploration aimed at identifying ore targets.

The features of uranium mining on Kazakhstan’s enterprises have been examined, and uranium deposits located in the Syrdarya and Shu-Sarysu depressions have been described. Actual and projected data on the development of technological blocks in areas with complex geological structures have been analyzed and compared. Core samples were collected and, using X-ray diffraction analysis, quantitative and qualitative characteristics as well as mineral compositions of ores from various productive horizons of uranium deposits in the Syrdarya and Shu-Sarysu depressions were comparatively analyzed. It was determined that the ores in the Syrdarya depression are relatively homogeneous compared to those in the Shu-Sarysu depression, although in some places, clay minerals and gypsum are present, which hinder the uranium leaching processes. In the ores of the Shu-Sarysu depression, clay minerals that impede the uranium leaching processes are present in certain areas. Microscopic analysis of core material samples using a LEICA DM 2500 P microscope revealed particle sizes and shapes, as well as their distribution within the structure of host rocks in the productive horizon. Using X-ray diffraction analysis, mineral compositions of sediment-forming components during uranium well mining in the considered productive horizons were determined and comparatively analyzed. It was established that in the geotechnological wells of the Syrdarya depression, sediments of predominantly chemical origin, such as gypsum, are formed. However, in the geotechnological wells of the Shu-Sarysu depression, sediments of mechanical origin, consisting predominantly of quartz particles and clay minerals, are formed. Based on the obtained data, a method for intensifying underground uranium leaching in complex geological conditions has been developed, which involves dissolving sediment formations and increasing the oxidative–reductive potential of the leaching solution. The proposed and experimentally substantiated universal methodology for enhancing uranium well production involves the dissolution and prevention of precipitation using hydrofluoric acid solutions, as well as the oxidation of uranium dioxide with hydrogen peroxide.

The article deals with the results of dynamic interpretation of 3D CDPM seismic data in combination with logging data. The authors were faced with the task of comparing the results of pre-stack seismic inversion and neural learning technology in the conditions of the Arykty gas condensate field. The reason for this was the low seismic knowledge of the studied area, the fairly good predicted prospects for oil and gas content in the region, and the need to study the criteria for selecting a particular dynamic interpretation procedure. In this regard, an attempt was made to consider the structure and oil and gas content of the Arykty gas condensate field from the point of view of a comparative analysis between pre-stack inversion, which is currently actively used in the geological exploration industry within the framework of a standard interpretation graph, and neural machine learning. Justification for the relevance of the studies performed is availability of new wells and updated logging data, the ability to update and to compare the results of synchronous pre-stack inversion, and the ability to test neural learning algorithms. The conducted studies make it possible to identify criteria for the preferential use of machine learning in the conditions of the Arykty field, to take a fresh look at the features of the internal structure of the rocks that make up the productive part of the section, and to demonstrate physically the advantages of machine learning results in comparison with pre-stack seismic inversion.

Purpose. Purpose is to generalize and analyze the currently accumulated geological and physical as well as field data to study productive strata of Prorva group of oil-and-gas occurrence of the Southern deposits of the Caspian Depression in Kazakhstan. Methodology. Deep Triassic rock systems were studied thoroughly relying upon the explained new data by seismic data together with logging and field information using current processing and interpretative systems according to the newly drilled deep wells within the unexplored northwest part of the structure. Findings. The specified geological model of the field has been obtained. Twenty-one estimation targets have been singled out in the Jurassic-Trias structures; three new oil-and-gas-bearing formations have been identified as part of the Lower Cretaceous share of a productive stratum within the Valanginian level. According to geophysical analysis, Western Prorva and S. Nurzhanov deposits are the unified system with the oil-water contact level. Originality. Selection of the recommended location of the new wells is based upon specificity of the innovative scientific and technical approaches while studying regularities of facies substitution of reservoir rocks with enclosing systems of each productive stratum; and studying permeability and porosity of the reservoir rocks as well as fluids saturating them. Practical value. The obtained data have become the basis to assess the remaining carbohydrate reserves, and identify new opportunities increasing the reserves within the Western area of S. Nurzhanov deposit; moreover, they raise a question on the expediency to develop the Unified Project of the field mining.

New+Geology +https://doi.org/10.33271/nvngu/2024-2 +/jdownloads/pdf/2024/2/02_2024_Contents-en-GB.pdf