Exploration. Geology and Geophysics
PROSPECTS OF DEVELOPMENT OF THE ANOMALOUS ZONES BAZHENOV FORMATION DEPOSITS OF KHANTY-MANSIYSK AUTONOMOUS OKRUG-YUGRA
Russia is one of the recognized world leaders in oil and gas, but exhaustion of traditional deposits required to seek a new resource base commensurate with the scale developed by major oil and gas provinces.
As an equivalent alternative is considered a huge potential for the world’s largest shale formation – Bazhenov Formation, which is spread along the whole Western Siberia. Sweet, in the case of the creation of new incentives for its development, Russian oil production will lead to a new level. Development of stocks look attractive because Bazhenov formation developed in areas with existing oil infrastructure, directly at the producing fields, so you can rely on lower costs.
A unique feature of the Bazhenov Formation is the high oil saturation. Moreover, it is of high quality – light, sweet crude and without other harmful impurities.
However, the lack of a clear understanding of the problems of geologists Bazhenov does not allow the government to offer transparent mechanisms to reduce the tax burden on subsoil users who are willing to carry out development only if it will be profitable. This still does not exist a unified classification of unconventional hydrocarbons and confusion of terms often creates illusions about the resource potential and production prospects. Thus, mining companies and investors planning to undertake the development of the Bazhenov Formation, faced with the enormity of uncertainties and risks.
The final opinion on the prospects and opportunities of the Bazhenov suite of commercial oil production from this horizon can be formed on the basis of analysis of log data, core analysis, well tests and geomechanical research that will eventually pick up the development of efficient technologies – a kind of “golden key”, which will allow truly discover the wealth formation.
The article focuses on the problems associated with the technology development and the development of the suite. The analysis of the geological structure, lithology and reservoir properties (FES) Bazhenov Formation in the Khanty-Mansi Autonomous District.
First Izhma Suite was selected for the South Timan in 1930 N. N. Tikhonovich in the study of oil deposits of the upper Devonian. Part of this Suite, they had included a wide range of rocks exposed on the right Bank of the r. Izhma. Later D. C. Obruchev (1958) as part of the Suite rocks have been identified the remains of testaceous fish Bothriolepis jeremejevi Rohon and Bothriolepis sp.
Detailed stratigraphic and paleontologic study of the incision retinue was made So T. I. Kouchnareva (1977), who established her Famennian age. The lower part of the Izhma suites N. N. Tihonovith she took to Ukhta the retinue of the Frasnian stage as gypsum-bearing strata. However, the name of the Suite – Izhma the upper part of the section was saved. Deposits Izhma suites in the new volume it was first compared with padonskimi layers of the Russian platform.
Lithology in Izhma the retinue are two parts: the lower part is predominantly clay, and the upper carbonate. In the study of the East wing Ukhta brachyanticline So, T. G. Obukhovska, A. C. Kuzmin (1993) attributed to the Izhma retinue only her upper carbonate part. The separation of the Izhma suites on podsvity was proposed M. N. Moskalenko with co-authors (1999) on the basis of a more careful study of organic remains and features of the lithological composition of the rocks.
P. A. Beznosov (2009) studied the fish fauna in the dolomite horizon” Izhma suites, lower podsvit transferred to the rank of a Suite called sosnogorskaya. For the upper left them rank podsvity with the same name – Izhma.
Thus, twice the changed composition of the Izhma Suite has not resulted in a change of its name. In this article it is proposed to resolve this discrepancy and the upper podsvity transferred to the rank suites by assigning her the name of the place of its location – poznanskaya.
The article is a brief review of the literature on the problem of rheniumbearing carbonaceous shale. It is given his clark, geochemical norm, values of ore anomalies, and also lists the stratigraphic levels in sections of the Riphean and Paleozoic deposits of the Bashkirsky and Uraltausky meganticlinoriums with the extensive development of black shale deposits. Further considered: 1) general features of mineralized carbonaceous strata of the western slope of the southern Urals; 2) geological structure of the most promising on W, Mo and Re Novousmanovsky square, located at the junction of the West-Uraltausky north-south fault and Burzyansky west-east fault; 3) the results of geological mapping work of predecessors in the search for molybdenum mineralization. Rare metal ore mineralization within Novousmanovsky square geologists connected with large burial intrusive body of granitoids.
We found that the abnormally high content of rare metals and rhenium are confined to quartz and feldspar-quartz veins, forming extensive areas within of carbonaceous deposits. The content of tungsten reaches 190 g/t, molybdenum – 100 g/t, rhenium – 4.6 g/t. For rhenium variation ranged from 0.6 to 4.6 g/t, averaging 18 sample – 1.74 g/t, which is within ore anomalies and 10 times greater than its clark in black shales. Since the final products of oxidation of molybdenite are easily washed away and form at the level of the groundwater zone of secondary enrichment, we can predict a sharp increase of molybdenum and rhenium with depth. Positive predictive search criterion is weak erodibility of the considered W-Mo-Re ore-magmatic system, in which only partially opened upper part. Thus, this ore mineralization may be related to the vein type and genetically linked to the burial intrusion of acidic composition, apophyses of which are marked near the top of Artlish mountain and farther south.
OIL AND GAS FIELDS IN ZHUNGEER BASIN AND THE PROBLEMS OF THEIR EXPLORATION IN THE NORTHWEST OF CHINA
Zhungeer Basin is located in the province of Xinjiang in northwest China. It has an area of 130 km2. In tectonic terms, this trap is immersed in south-eastern direction. Zhungeer Basin is made by continental deposits from the Permian to Miocene age with a total capacity of 14 thousand meters Permian source rocks, represented by high carbon clay deposits, developed in the southern part of the basin. Oil has migrated over the surfaces of disagreements and accumulated in the lenses of sandstones and conglomerates in the sediments of the Carboniferous, Upper Permian, Middle and Upper Triassic, Upper Jurassic and Miocene (C, P2, T2-3, J3, N1).
Within the Zhungeer Basin yet are identified 5 oil-bearing formations, which are dispersed in the Carboniferous and Permian sediments. Most common oil-bearing interval reaches 800-900 m. In 2008 was completed a drilling with a depth of 2010 m. When testing two-meter reservoir sandstones of Carboniferous age in the range of 605-698 m, we obtained 527 tons of oil and 1,200 m3 of gas on the nozzle 5 mm. In addition, high viscous oil also was discovered.
This paper discusses the geological and production characteristics of the main oil and gas fields of the Zhungeer basin. It was Investigated in detail the structural features, the history of the discovery and formation of hydrocarbons, dissemination and preservation of oil and gas deposits. To establish geological structures and Mesozoic thickness, which is possibly promising for oil and gas, research of the university within the state scientific and technical program “Sustainable development of natural resources and modernization of oil and gas technologies” (from 2012) and program of the China University of Petroleum “Energy program and the development of China” (from 2010) is in process.
In order to lower the risks in the processes of field development and waterflooding systems planning geologic and simulation models are built on the base of core material examinations, geophysical well logging (GWL) and seismic survey, flow well test (FWT), downhole samples. The crucial moment in simulation is the integration of all methods available of data obtaining that will allow constructing the best detailed and accurate geologic and simulation model, as the disadvantages of one method are compensated by the advantages of another and allow forming the notion of the object under study. The given article is devoted to studying causes of variety of uncertainties that arise during construction of geologic and simulation field model.
Within the work the causes of arising uncertainties have been classified according to the type of measurement (direct or indirect), the scope of research by area, the vertical resolution capacity, and according to the nature of uncertainties causes. They, in turn, are subdivided into measurement problems (equipment error and non-compliance with measurement procedures) and problems of application in modeling (interpretation problems and problems of constructing the model).
In order to reduce uncertainties we can define two possible ways. The first is minimisation of uncertainties in the frames of a separate method. The second way is the integration of all available information in a manner of reducing the uncertainty band by means of measurement’s mutual constraints, imposed on each other, i.e. the use of complex system approach to applying initial data obtained by different methods.
Instant assessment of field-geologic information and taking it into consideration when correcting geologic and simulation model allow producer to acquire practical instrument for operating and, if necessary, adjusting field development process, which includes taking into account location of the zones of remaining oil reserves the possibility for developing scenarios of enhancing reservoirs’ recovery, performing justified calculations of forecasts of production and financial risks reduction.