The Geo-Solition Component in the Forecasting and Mapping of Oil and Gas Deposits.

by Alena Lipyavko | Oct 04, 2013

Oil&Gas Eurasia, July –August 7-8, 2011


Forecasting and mapping of migration and areas of development of hydrocarbon deposits is impossible without the application of the geo-soltion concept. This allows to complement studies of the physics of migration of disseminated, gaseous, and liquid substances, opens new ways and approaches to prospecting, exploring, and developing oil- and gas fields. The article covers an example of active degassing and geo-solition activity in Western Siberia

Internal geodynamics is closely linked to the sedimentational processes of development of sedimentary sequences, distribution of sand and clay, post-sedimentation processes of local geotectonics and fluid dynamics up to the present. The study of the sources and zones of active geodynamics and fluid dynamics provides the most valuable information on the nature of a hydrocarbon reservoir in general. Many years of geological, geophysical and geochemical studies, the study of the modern geodynamics of oil- and gas fields in special geodynamic test sites localized in areas with different geological structures have demonstrated the integrity of the fluid systems that form hydrocarbon fields and how closely they are related to the deep faults and degassing of the deep layers of the Earth [1].

Association of accumulations of hydrocarbons with the most active deep faults is defined. The dynamics of these faults manifest in high gradient modern vertical and horizontal earth surface movements and changes in geophysical fields in time. The migration of fluid systems in deep horizons of the sedimentary cover and near its surface is established through geochemical studies.

The association of highly permeable rock with modern seismic instability zones is evident. The geometry of manifestation of these processes in space is localized and subvertical rather than linear and flat [1]. Modern deep geodynamic and fluid dynamic processes determine the source generation of hydrocarbons and create oil and gas deposits with a significant diversity of forms and phase relationships.

The information about the geological and hydrodynamic properties of the West Siberia oil and gas basin and location of fields accumulated to date allows to consider Earth degassing processes to be accountable for the formation of hydrocarbon deposits [1].

The geo-solition concept [1] has almost all the required mechanisms and explanations needed both for the sources of oil and gas generation of separate components, oil in general, and for the possible routes of migration of hydrocarbons in the areas of these sources. The physical nature of a geodynamic study is such that mainly temporary local lows of the gravity field, as well as intensive thermal and electromagnetic fields, are generated above the central sources of the destruction zones. Sedimentation conditions are formed in this interval at the interface of the Earth crust and atmosphere. Geodynamic processes in the internal geosphere impact not only tectonic events, but also the character of the distribution of sedimentary material during sedimentation.

The manifestation of geodynamic processes, including neotectonics, determined by the processes of geo-solition degassing of the Earth and fluid dynamic processes is associated with the so-called rock destruction zones (dynamically stressed areas, decompaction zones, loose rock areas, etc.). Such subvertical geological objects as subvertical destruction zones [1], subvertical geological bodies, dynamically stressed zones, etc. with different structures but similar properties are mapped in the majority of the oil and gas areas of Western Siberia, Russia, and globe as a whole.

In magnetic and gravity fields, the mosaic structure of such geodynamic sources of emission of energy is manifested quite clearly in continents and in oceans, including all oceanic ridges. Localized areas with a high or low concentration of discrete small-sized positive and negative anomalies prevail in these mosaic patterns. The axial parts of such geological objects, sources of active geodynamic processes and fluid and gas transfer shaped as subvertical pipes, manifest as small-sized geophysical anomalies in almost all geophysical fields, including the results of seismic explorations, gravimetry surveys, magnetic surveys, resistivity surveys, and even in radiometry, thermal and geochemical surveys. The main reason for grouping together all types of geophysical fields in local areas coinciding with an axial zone of similar source is their vortex structure [1].

The most destructed rock areas are the most “attractive” for the exit of geodynamic energy and fluid streams. These zones are manifested in all geophysical and geochemical fields, forming mineral deposits of almost all types. Due to the migration of mobile components in permeable zones, such manifestations of modern geodynamic processes, which are often called disjunctive tectonic structures, are manifested not only in physical, but also in geochemical fields, which creates a basis for the identification of high-potential areas established through structural geophysical methods.

The concept of geo-solition degassing explains also the method of gas pipes used for the identification of vertical hydrocarbon migration zones [3], as well as the differentiation of conductive and sealing faults. According to the definition [2, 3], the presence or absence of gas pipes, their shape, length and source in relation to hydrocarbon traps allows to classify those faults in terms of productivity and potential. Based on the geo-solition concept, the presence of an active geodynamic source in the vicinity and the destruction zones caused by it (usually a subvertical destruction zone) is pre-requisite for the formation of gas pipes. The degree of destruction of the covers in the area of the source will determine the preservation of the deposits, while the vertical expression of the source of the destruction will determine the possible vertical amplitude of the oil- and gas-bearing zone. The presence of gas pipes and VAMP–structures is considered in the literature [2, 3] as an attribute of oil and gas basins with active fluid and dynamic processes, while the types of gas seepage recorded according to seismic exploration data allow to judge the processes of generation or destruction of hydrocarbon deposits, as well as the productivity of hydrocarbon traps. This corresponds to the principles of the geo-solition concept of Earth degassing [1].

In the last ten years, gas pipes and VAMP structures reflecting in-depth degassing and fluid migration processes have been mapped in the northern and arctic parts of Western Siberia using 3D seismic data on the majority of the fields across the entire depth of the seismic record. Traces of natural and hydraulic rock fracturing were found in Cenoman and the Upper Cretaceous - Paleogene sediments. Traces of a mud volcano have been described in the north.

The multi-layered Van-Yoganskoye field (up to 50 productive formations) in Western Siberia is a good example. Fragments of time sections with coherence attributes (Fig. 1, Fig.2) are provided. Subvertical routes of fluid and gas migration are determined by the highly fractured sources, decompactions; i.e. destruction of rock. The high degree of geodynamic activity caused by internal geo-solition Earth degassing processes facilitated the formation of a unique, multilayered oil and gas condensate field with a large, vertical amplitude of the oil and gas interval (1900 meters) from the Cenomanian formation to the Tyumen suite with a reserves density of over 20 MM t/km2. Such a multilayered character of many fields in Western Siberia is determined by the conditions of their formation in the result of subvertical migration of hydrocarbons and filling of fractured and pore traps.

The association of the anomalies identified based on the results of seismic surveys, gas, chemical and thermal surveys with one of the unique fields confirms the high oil and gas field discovery potential, as well as the high potential of development and improvement of exploration and mapping technologies.

The relevance of geodynamics processes, Earth degassing, the role of fluid systems in the formation and transformation of the Earth’s crust, localization of solid, liquid and gaseous minerals find wide application in modern academic and practical studies. For this reason, new requirements for deposit forecasting and exploration methods are instituted. The required technology for the exploration of such fields is based on the application of 3D seismic exploration in combination with the high-precision methods of gravimetry, magnetic survey, and gas and thermal surveys.

Reference

1. R.M. Bembel, V.M. Megerya. S.R. Bembel. Geo-solitons: functional system of Earth, concept of exploration and development of hydrocarbon fields. – Tyumen: Vektor Buk, 2003. - 344 pp.

2. Aminzadeh, F. and Connoly, D. Hydrocarbon Phase Detection and Ather Application of Chimney Technology. AAPG Int. Conference, Cancun, 2004.

3. Heggland, R., Hydrocarbon Migration and Accumulation Above Salt Domes—Risking of Prospects by the use of Gas Chimney, Processing of 24-th Annual GCSSEPM Foundation Bob F. Perkins Research Conference, “Salt-Sediment Interaction and Hydrocarbon Prospectivity: Concepts, Application, and case Studies for the 21st Century”, Desember 5-8, 2004, Houston, Texas. 2004.