HISTORY OF THE DECADE OF GEOLOGICAL KNOWLEDGE POPULARIZATION BY THE PUBLIC ORGANIZATION UKRAINIAN ASSOCIATION OF GEOLOGISTS

The article reveals the chronology of events lasting ten years from 2010 to 2020, which are devoted to the geological industry promotion. The Public Organization Ukrainian Association of Geologists fulfils its mission and supports scientific activities, promotes the professional consolidation of scientists and specialists working in geology and related fields; boosts the prestige of professions related to the exploration and use of mineral resources, the geological environment protection.

DISCOVERY OF NEW KIMBERLITE FIELDS ON THE SOUTHERN SLOPE OF THE LEONE-LIBERIAN SHIELD (Sierra Leone)

During 2017–2018 not far from Sewafeh town, Kono province (Republic of Sierra Leone), we identified a number of previously unknown manifestations of kimberlite magmatism in the form of a system of individual veins localized at the contact of the migmatite basement and Archean ultrabasic massifs, or in the immediate vicinity of ultramafic massifs, which is part of the rocks of the greenstone belt. The optimal sequence of conducting remote sensing studies, such as interpretation of space images of various resolution, neotectonic and geomorphological analysis, SRTM modeling, and then field geological and geophysical research have facilitated this discovery. According to drilling data, kimberlites in different spots of their occurrence (Punduru 1 area) are represented by subvolcanic phlogopite-olivine (with perovskite), and olivine varieties, as well as veins of numerous intensely metasomatic altered kimberlite breccias (Yomby area). Veins of subvolcanic kimberlites are concentrated in the contact part with ultramafic massifs of magmatic and lava (metakomatiite xenoliths) genesis. Kimberlites are the youngest vein formations in the area, crossing even vein pegmatites, the generation of which was provoked by the intrusion of ultramafic rocks in the basement migmatites (Cederholm effect). Kimberlites are present in the section of wells in the form of separate veins of complex morphology and thickness from a few centimeters to 45 cm. In well P1-2 at a depth of 92 m, these are represented by micro porphyry kimberlites of the basaltoid type with microlithic groundmass, altered by secondary metasomatic processes. Porphyry inclusions are represented by pseudomorphs of carbonate-serpentine composition after olivine and rare phlogopite flakes. Olivine crystals of the second-generation act as micro porphyry inclusions. The rock matrix is carbonate. Carbonate is represented by finely crystalline calcite, or replaced by dolomite. In addition to olivine, the groundmass contains relics or pseudomorphs after phlogopite, as well as magnetite, perovskite (it can be replaced by magnetite), secondary apatite. The kimberlites of the Bambawo area are represented by sub-volcanic porphyry basaltoid kimberlites, autolithic kimberlites and kimberlite xenotuff breccias.

APPLICATION OF DIRECT HYDROCARBON INDICATORS FOR OIL AND GAS PROSPECTING IN THE DNIPRO-DONETS DEPRESSION

Based on the results of numerous seismic studies carried out in the areas and fields of the Dnipro-Donets depression, the strategy to identify hydrocarbon traps in this region has been developed taking into account modern requirements for prospecting and exploration of gas and oil fields. The studies are designed to determine the favorable zones of hydrocarbon accumulations based on the analysis of the structural-tectonic model. A necessary element for solving such a problem is to aaply direct indicators of hydrocarbons to predict traps of the structural, lithological or combined type. It was determined that an effective approach to identify hydrocarbon traps in the region is attribute analysis employing seismic attributes such as seismic envelope, acoustic impedance or relative acoustic impedance. In most cases of practical importance, the analysis of the distribution of the values of these attributes turned out to be sufficient for performing the geological tasks. It is given an example of extracting additional useful information on the spatial distribution of hydrocarbon traps from volumetric images obtained from seismograms of common sources with a limited range of ray angles inclinations. To analyze the distributions of seismic attribute values, it is recommended to use the Geobody technology for detecting geological bodies as the most effective when using volumetric seismic data. The distributions of various properties of rocks, including zones of increased porosity or zones of presence of hydrocarbons are determined depending on the types of seismic attributes used in the analysis,. The use of several seismic attributes makes it possible to identify geological bodies saturated with hydrocarbons with increased porosity and the like. The paper provides examples of hydrocarbon traps recognition in the areas and fields of the Dnipro-Donets depression practically proved by wells. A generalization on the distribution of promising hydrocarbon areas on the Northern flank of the Dnipro-Donets depression and the relationship of this distribution with the identified structural elements of the geological subsoil is made.

PROBLEMS OF DEVELOPMENT OF THE NATIONAL PETROLEUM INDUSTRY

Development of the country’s economy, industrial and economic infrastructure is impossible without the use of oil and gas, as well as their products. Ukraine does not fully meet its own needs for fuel and energy resources. An important role in the solving of this issue belongs to geophysical research methods, their integrated complex and the types of geological and geophysical researches. In many cases, the materials of geophysical research methods are the main ones with respect to the geological documentation of wells that were drilled for the search and exploration of productive reservoirs. Domestic oil and gas service companies need government support to increase quality of geological and geophysical services, updating the equipment fleet, and ground equipment, introducing modern technologies to enable the development of equal competition with foreign companies both in the domestic and global markets.

DRILLING OF COMPLEXES WITH HYDRAULIC TRANSPORT OF A CORE FOR INCREASE OF EFFICIENCY OF GEOLOGICAL EXPLORATION WORKS

On the basis of an in-depth analysis of domestic achievements and the results of experimental and methodological works and practice the expediency of widespread use of improved technical means and technologies for drilling geological exploration wells with complexes counterflush coring (CCD) till the depth of 300 m upon sedimentary strata is substantiated. During the exploration of brown coal deposits and titanium placers, which convincingly confirm the high efficiency of CCD with appropriate modifi cations of equipment, technology and testing methods for specific productive horizons and host rocks. The best results of industrial application of CCD were obtained during the exploration of the Paromivske ilmenite placer deposit (2016). High technical and economic indicators of completion of work in difficult socio-economic and geological and technical conditions were achieved thanks to CCD application. The main argument in favor of CCD is undoubtedly proven by ultra-high productivity with a significant reduction in cost and improved quality of the work. The operational geological informational content of the method allows timely adjustments and responsibly choose the most optimal flexible schemes and methods of geological research. Due to the significantly reduced timing of drilling operations, field research can be carried out shorter at the most favorable climatic conditions and seasons of agricultural activity. The mobile circulation system excludes the construction of earthen sedimentation tanks, which signifi cantly reduces the size of disturbed soils, their contamination and prevents the loss of flushing fluid. The peculiarities of the technology and organization of work promote close cooperation, mutual control and understanding of technical, geological, geophysical and other personnel serving and actively mobilize for high-quality and highly efficient performance of geological tasks. A reduction of heavy operations in the technological process significantly improves the working conditions for the service personnel, increases the production culture, and contributes to the attractiveness of the drilling profession. Ukraine has sufficient production facilities (at Kiev Drilling Equipment Plant, Dnepropetrovsk Drilling Equipment Plant, Discovery - Drilling Equipment. Ukraine LLC, etc.), which are capable of providing geological exploration companies with modern CCD. The main reasons that hinder the development of modern highly efficient geological exploration technologies are recognized and the optimal ways to solve the problem of widespread introduction of CCD are featured.

CORRELATION OF THE SILURIAN SEQUENCE OF THE 25-KOTYUZHINY STRUCTURAL WELL WITH THE DNIESTER REFERENCE SECTION OF THE SILURIAN IN THE VOLYN-PODILLYA PLATE

The paper is devoted to lithostratigraphic and biostratigraphic subdivision of the Silurian deposits of 358 m total thickness in the 25-Kotyuzhiny structural well and its comparison with the stratotypic Dniester section of the Silurian system in accordance with Legend to the geological map of Ukraine, the Volyn-Podolsky series of 1: 200 000 scale, consistent with the latest modernization of Silurian stratigraphic charts. The described section is a parastratotype for Silurian litho-stratons of the Kovel-Khotyn structural and facies zone and a reference one for Silurian deposits in the central part of this zone. The Silurian in the 25-Kotyuzhiny well is represented by the lower (Llandoverian and Wenlockian stages) and upper (Ludlovian and Przhidolian stages) series. According to the lithological-facies composition and sedimetantaion conditions during Silurian times, there are 3 major completed stages of sedimentation as transgressive-regressive cycles, corresponding to the the Yarugian, Malinovetsian and Rukshinian series, which are quite clearly subdivided into 10 suites and 12 sub-suites. In correlation with the Dniester reference section, litho-stratons of the Silurian are characterized mainly by carbonate and clay-carbonate composition, relative stable thickness and facies pattren, diversity of fauna with a predominance of shallow benthic forms. The well is characterized by bituninous manifestations indicating hydrocarbon potential of the area and its prospectivity for shale gas accumualtions in the formations of the upper Silurian in particular.

POWERFUL GEOPHYSICAL INDUSTRY AS THE BASIS OF ENERGY INDEPENDENCE OF UKRAINE

In the oil and gas industry, the geophysics bears the most knowledge-intensive and high-tech activity. The results of geophysical studies underlie the search, exploration and development of oil and gas fields. It is impossible to effectively drill, operate and repair wells without it. Success in the development of technology and technology in geophysics depends on the level of academic and industrial science, the effectiveness of the education system, and the intellectual training of personnel. The paper provides a historical insight into the era of geophysical research from the beginning of the last century to the present day. The current state and prospects of further development of the geophysical industry as the basis of Ukraine’s energy independence are analyzed. The main reasons for the negative state of affairs in Ukrainian geophysics are as follows: loss of professionalism, lack of high-quality basic education, lack of funding and short-sighted decision-making.

APPARATUS-METHODICAL COMPLEXES TO DETERMINE PETROPHYSICAL PARAMETERS OF HYDROCARBON RESERVOIRS WHILE DRILLING AND IN CASED BOREHOLES

The results of the development of apparatus-methodical complexes for the topical trends of geophysical borehole research, namely logging while drilling and wireline logging in cased boreholes, are presented. The complexes are based on the use of radioactive logging methods, which are effective in the presence of steel pipes in the borehole (integral gamma-ray logging, neutron-neutron logging, neutron-gamma logging and density logging). Combined tools for logging while drilling (LWD-KPRK-48, diameter 48 mm) and wireline logging in cased wells (WL-KPRK-42, diameter 42 mm) have been developed. The grading characteristics of the tools for typical logging conditions were obtained. The main elements of interpreting-methodological support have been developed to determining the petrophysical parameters of oil and gas reservoirs: shaliness, density, porosity, type of saturation, etc. The borehole tests have demostrated high information capacity and efficiency of developed complexes.

INVERSION OF GRAVITY DATA USING A GENETIC ALGORITHM

The genetic algorithm for the selection of gravitational sources is considered. In the basis of the approach, the principle of selection of genes from fathers and mutations was laid down, which was adapted to form geological structures. For a two-dimensional grid model, the designation of apparent density in the blocks is selected by a choice of models of two (parental) variants, in which gravitational initial and calculated anomalies coincide better. In the quality of the object function is used a middle gradient norm of gravity fields. Generation of new models for effective density in blocks is released randomly. Theoretical models were built up for one body with one and two values of apparent densities. The theoretical sections with four layers were considered. The fitting of the model was carried out under the condition that the value of the effective density was known or a certain range was set. Each block was rectangular in shape with a square section in the plane of the gravity data profile and a limited lateral elongation. Comparison of the output and calculated anomalies of the gravitational acceleration was carried out using the average norm and the percentage error. The absence of jumps in the objective function graph ensured that an accurate model was determined. The correct geometry of a body with a homogeneous apparent density was determined at a fixed value of the effective density for four layers. The model with two values of density had some errors in determining the geometry of the bodies. The genetic algorithm, based on an evolutionary approach to certain physical parameters of blocks, performs the fitting of a gravity model rather quickly and effectively. The main factors affecting the accuracy of geometry are apparent density data. The implemented approach allows one to estimate the cross section by the grid distribution of the effective density. The development is applied for a two-dimensional interpretation of the gravity anomaly over an oil and gas field. The resulting interpretation of the shape of the anticlinal structure is consistent with geological data.

THE MAGIC OF AGATE

The article examines the magical properties of agate, a striped modification of chalcedony. Images of several agates from the author’s personal collection are shown. Memories of the author’s adventures related to the search for agates are given. Images of agates on postage stamps are featureded, as well as numerous books about agates. A virtual collection of agates from different continents of our planet is shown.