Summary Based on the results of numerous seismic surveys conducted on the areas and deposits of the Dnipro-Donetsk depression, an appropriate strategy for detecting hydrocarbon traps in this region has been determined. This takes into account modern requirements for exploration and prospecting of gas and oil deposits. They consist in determining the probable zones of accumulation of hydrocarbons based on the analysis of the structural model. At the same time, the use of direct hydrocarbon indicators to predict structural, lithological or combined traps is also a necessary element in solving this problem. It has been shown that an effective approach to detecting hydrocarbon traps in this region is attribute analysis using seismic attributes such as seismic signal envelope, acoustic impedance or relative acoustic impedance. In most practically important cases, the analysis of the distribution of values of these attributes was sufficient to solve geological problems. At the same time, an example of extracting additional useful information on the spatial distribution of hydrocarbon traps from volumetric seismic images obtained from seismograms of common sources with a limited range of seismic angle inclinations is given. To analyze the distributions of seismic attribute values it is recommended to use geobody technology of geological bodies extracting as the most effective when using volumetric seismic data. Depending on the type of seismic attributes involved in the analysis, the distributions of different properties of rocks are determined, in particular the zone of increased porosity or the presence of hydrocarbons. Analysis with the simultaneous use of several seismic attributes allows to directly identify hydrocarbon-rich geological bodies with high porosity and the like. The paper presents examples of detection of hydrocarbon traps in the areas and deposits of the Dnipro-Donetsk depression, which are confirmed by drilled wells. Generalizations are made on the distribution of promising areas for the presence of hydrocarbons on the northern side of the Dnipro-Donetsk depression and the ratio of this distribution with the identified structural elements of the geological environment.
ПРОГНОЗУВАННЯ ЗОН ПІДВИЩЕНОЇ ПОРИСТОСТІ У ГЛИНИСТИХ ПОРОДАХ СХОДУ УКРАЇНИ (Рекомендовано членом редакційної колегії канд-м геол.наук, ст.наук.співроб.І.М.Безродною
Summary The modern approach to prospecting and exploration of gas and oil traps within the northern side of the Dnieper-Donetsk depression is considered. The results of volumetric seismic surveys performed in this region indicate a decrease in the efficiency of traditional technologies for predicting hydrocarbon traps, which are based on the analysis of structural and tectonic models. In some cases, the use of only the structural factor does not give positive results. This is due in part to the absence of major structural traps. Accordingly the development of such deposits may not achieve the desired profitability. The scheme of location of geological bodies and structures promising for the presence of hydrocarbons is given, from which the next results follow. A significant part of the structures that are conventionally considered promising are characterized by a low probability of hydrocarbons. The practice of drilling wells on such structures confirms this conclusion. It is concluded that the increase in the efficiency of prospecting, exploration and development of gas and oil deposits in this region is related to the use of direct indicators of hydrocarbons. The efficiency of application of different sets of seismic attributes is analyzed. The most appropriate way to interactively analyze the volume distributions of seismic attribute values has been defined. Examples of detection of hydrocarbon traps and determination of their physical properties, which are confirmed by drilling wells, are given. Keywords: seismic image, seismic inversion, multi-attribute classification, direct hydrocarbon indicators.
The possibilities of allocation of geological bodies with certain physical and filtration-capacitive properties on the basis of classification by a set of seismic attributes are considered. This classification is based on the use of computer technology with parallel computing on graphic processors. High-speed parallel computing provides the ability to interactively classify and get results in real-time. At the same time, application of graphic processors allows to realize technologies of interactive classification not only on computing clusters, but also on personal computers. Geological efficiency of technologies of interactive classification is shown. Their application allows to detect geological bodies with certain physical properties on the basis of computer analysis of three-dimensional arrays of seismic data, in particular seismic images and arrays of seismic attributes. It is important to note that computer technologies of the interactive classification of three-dimensional seismic data not only provide a high speed of determination of the spatial position and properties of geological bodies, but also allow to realize the fundamental possibility of such a definition. Traditional approaches to the identification and classification of geological bodies are based on a sequential analysis of sections of three-dimensional seismic data. In this case, the solution of the problem of the identification and classification of geological bodies often encounter the fundamental problems due to the complexity of the visual assessment of three-dimensional geological objects based on the analysis of the sequence of two-dimensional sections of the arrays of seismic data. The authors propose a convenient approach to systematizing methods of interactive classification of geological bodies by one and several seismic attributes. The known technologies of bright spots and AVO are considered as elements of a sequence of methods of interactive classification using different numbers of seismic attributes. According to the results of 3-D seismic survey carried out on the areas of the east of Ukraine, the classification of geological bodies using one and two seismic attributes was performed. Some objects with perspectives concerning presence of hydrocarbon were found and analyzed. The conclusion of classification expediency using several parameters is done. It creates preconditions for realization of more perfect and versatile approaches to the detection of geological bodies with given physical properties.
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.
Summary The new approach for clay rock differentiation using porosity value is proposed. This approach is based on the correlation coefficient values analysis for acoustic impedance and shaliness. The correlation between acoustic impedance and shaliness is absent for shale and shaliness rocks with small values of porosity. For rocks with porous shale the correlation coefficient between acoustic impedance and shalines can be higher than correlation coefficient between acoustic impedance and porosity. In this case the shale fraction of rocks is a carrier of porosity. This fraction controls distribution of acoustic impedance values at the physical level. The prognosis of the clay rocks zones with increased porosity was done. For solution of this task the 3D seismic data is used. The total area of investigations is about 200 square kilometers. The geophysical data obtained from three wells at the investigation area are used as well. Constructed model of rocks physical property coincides with drilling and testing data in these wells. Geological section of this area is characterized by high amount of clay rocks and small amount of sandy layers. These sandy layers have not industrial flow rate of hydrocarbons.
Based on the results of numerous seismic surveys conducted on the areas and deposits of the northern side of the Dnieper-Donetsk depression, an appropriate strategy for detecting hydrocarbon traps in this region has been determined. This takes into account modern requirements for exploration and prospecting of gas and oil deposits. They consist in determining the probable zones of accumulation of hydrocarbons based on the analysis of the structural-tectonic model. At the same time, the use of direct hydrocarbon indicators to predict structural, lithological or combined traps is also a necessary element in solving this problem. It has been shown that an effective approach to detecting hydrocarbon traps in this region is attribute analysis using seismic attributes such as seismic signal envelope, acoustic impedance or relative acoustic impedance. In most practically important cases, the analysis of the distribution of values of these attributes was sufficient to solve geological problems. At the same time, an example of extracting additional useful information on the spatial distribution of hydrocarbon traps from volumetric seismic images obtained from seismograms of common sources with a limited range of seismic angle inclinations is given. To analyze the distributions of seismic attribute values it is recommended to use geobody technology as the most effective one when using volumetric seismic data. Depending on the combination of seismic attributes involved in the analysis, the distributions of different properties of rocks are determined, in particular the zone of increased porosity or the presence of hydrocarbons. Analysis with the simultaneous use of several seismic attributes allows to directly identify hydrocarbon-rich geological bodies with high porosity and the like. The paper presents examples of detection of hydrocarbon traps in the areas and deposits of the northern side of the Dnieper-Donetsk depression, which are confirmed by drilled wells. An example of providing recommendations for wells drilling using the distributions of values of different seismic attributes is given. Generalizations are made on the distribution of promising areas for the presence of hydrocarbons on the northern side of the Dnieper-Donetsk depression and the ratio of this distribution with the identified structural elements of the geological environment.
The aim of this work to study the integration of modern geological and geophysical methods for identifying stratigraphic traps. Permian deposits of the Dnieper-Donets depression were selected for the analysis. These deposits are characterized by inconsistency of productive horizons and the sandstone bodies formation. Direct indicators of the hydrocarbons, various characteristics of the seismic wave field, lithological classification and analysis of the reservoir properties of rocks were used. The available literature data on the oil and gas development and production from the Permian deposits and geophysical data were used for a comprehensive analysis. Geophysical data was presented by well logging data and seismic data. consolidated geological section across the Dnieper-Donets depression was constructed by geophysical data. The geological section gave information about the modern occurrence of the Permian sediments. Seismic surveys was used for attribute analysis. Attribute analysis give us zones with possible hydrocarbon contents and improved reservoir properties. This method shows the role of seismic studies in determining the lithology and oil and gas content of the studied strata. The combination of lithology, seismic data and information about paleodepositional environment allowed us to identificate unconventional hydrocarbon traps.
Summary Possibilities of multi-attribute analysis of seismic data for prediction of hydrocarbon prospective zones are shown. The conclusion is made about the expediency of using geobody technology for multi-attribute classification of geological bodies. The results of forecasting of perspective hydrocarbon zones using one and two seismic attributes are compared. Practically important results are presented for the identification of hydrocarbon-promising zones associated with structural and non-structural oil and gas traps. The results of the forecasting of oil and gas zones were obtained for deposits in the Dnieper-Donetsk basin.
