CHARACTERISTICS OF THE GEOLOGICAL STRUCTURE AND PROSPECTS OF THE OIL AND GAS POTENTIAL OF THE LEDOVYI LICENSE AREA OF THE BARENTS SEA ACCORDING TO 3D SEISMIC SURVEY
Unique Leningradsky and Rusanovsky gascondensate fields in the Barrem-Cenomanian layer are discovered in the Kara Sea. Non-industrial accumulations of oil and gas have been discovered in the Lower Cretaceous sediments of the western part of the Barents Sea shelf. However, the structure and oil and gas potential of the Lower Cretaceous sediments of the Barents-Kara shelf remain unexplored. Based on the seismic-stratigraphic and cyclostratigraphic analysis, a regional geological model of the Lower Cretaceous deposits of the Barents-Kara shelf was created, the distribution area and the main stages of the accumulation of clinoforms were identified. As a result of a detailed analysis of the morphology of clinoform bodies, paleogeographic conditions were restored in the Early Cretaceous and a forecast of the distribution of sandy reservoirs was given
The article presents a brief overview of the views on the stratification of the section of the neocomian deposits. As a basis for geological modeling, instead of formation units, seismic facies complexes were taken, including reservoirs in the coastal shallow-water zone, in a relatively deep-water zone - isochronous clinoform formations of the achimov strata. Within the researched territory, the characteristic of the established oil and gas potential of the complex is presented, on the basis of 3D seismic survey, perspective objects are identified, and their seismogeological characteristics are given.
Relevance of the work. The paper considers challenging problems related with outlining of intervals with oil and gas presence in the mature Khylly field by use of latest 3D seismic survey techniques in order to gain larger crude resources base. The purpose of this research is to discover the most promising intervals of target horizons with relatively high reservoir properties outlined by 3D seismic data. The subjects of research are 3D seismic survey data, downhole seismic survey – Vertical Seismic Profiling (VSP) and well logging diagrams. The object of research is the Khylly deposit. The paper describes in brief geological and geophysical characteristics, stratigraphic and lithological features of rocks making the section. It is noted that despite repeated surveys by use of various geological and geophysical techniques, the field setting is not thoroughly studied and it has been covered by 3D seismic survey in 2012. Research results. 3D seismic survey applied across Khylly area is resulted in drawing of 4 structural maps for III and I horizons of Productive Series (PS), Akchagyl and Lower Absheron suites. Taking into account the relevance of structural planes of various stratigraphic levels and III horizon of PS being one of the major reference horizons the paper gives description of structural map drawn for this horizon. The detailed velocity model is designed based on VSP data with wide use of velocity analysis data. It has been made clear that Khylly area has block structure and each block has been described in detail. Based on acquired data it has been recommended to drill exploratory well R-1. Conclusion. Processing and interpretation of seismic data are aimed at solving some geological problems; the main task was to obtain results that ensure the study of the geological structure in the seismic survey area, including tracing of seismic horizons, faults and outlining the areas and section intervals which may be of interest due to possible oil and gas presence. VSP data acquired in well 2012 and velocity analysis made it possible to design velocity model of the section under the study, with the use of which the temporary 3D cube was transformed into a depth cube. The quality of seismic data is good and made it possible to solve the tasks set for this research.
Background. In terms of oil and gas, the territory of the Chezhen depression has been studied insufficiently compared to the neighbouring same-range depressions. These depressions complicate the first-order Jiyang depression, geographically coinciding with the largest Shengli hydrocarbon field. In recent years, much geological and geophysical information about the oil geologyof the Chezhen depression has been accumulated, which allows its prospecting oil and gas potential to be assessed.Aim. To reveal regular features of the geological structure and location of oil deposits in the Chezhen depression in order to support the prospecting and exploration work within the Chezhen block of the Shengli field.Materials and methods. A comprehensive analysis of literature data and collected materials was conducted. A historical and geodynamic study of the evolution of the studied area according to literature data was carried out, along with an analysis of the most recent geological and geophysical information and exploration data based on the materials of the “Shengli AKOO Sinopek” oil company. The analysis was based on the data from 52 drilling wells and the results of seismic surveys performed in the central part of the Chezhen depression.Results. Specific features of the block geological structure of the area under study were established, which formed under the repeated influence of large-scale horizontal tectonic movements occurring at different periods of geological history. The role of the most recent fault system in the modern spatial distribution of oil deposits was determined.Conclusions. Our studies demonstrate a great prospecting potential of the Chezhen depression territory, where the discovery of new industrial oil deposits can be expected.
Conditions of formation and forecast of natural reservoirs in clinoform complex of the Lower Cretaceous of the Barents-Kara shelf