METHOD OF MAPPING OF ANTICLINAL DOMES IN THE TOP PART OF SEDIMENTARY COVER AND FORECASTING OF SUPERVISCOUS OILS Russian patent published in 2015 - IPC G01V11/00 G01V3/12 G01V1/00 

FIELD: measurement equipment.

SUBSTANCE: electromagnetic waves are radiated and the signals reflected from boundaries of interface of layers of the probed medium then the results of measurements are processed. The structural maps of a dome, and also temporary seismic sections of the reflected boundaries of the top part of the sedimentary cover are pre constructed, the materials of geophysical surveys of wells, core materials are studied. The lines of profiles are marked on the surface taking into account the structural maps of the dome and temporary seismic sections of the reflected boundaries of the top part of the sedimentary cover. Lines of profiles are drawn in mutually perpendicular directions through the drilled wells with passing outside the dome contour no less than by 500 m. The coordinates of extreme and critical points of lines of profiles are added into the database. The possible external disturbance are considered, the necessary corrections of coordinates of lines of profiles are added. The lines of profiles are located, the altitude and coordinate points of study are determined. Test studies are conducted in one line of profiles. The duration of record of the reflected wave of measurement of set of the electromagnetic signals registered in a reception point during the pre-set time after the radiation of electromagnetic wave as exceeding a double transit time of an electromagnetic wave to the deepest object of studies is assigned experimentally. On the basis of data on depths and supposed or in advance known values speeds of propagation of electromagnetic waves in the medium received during the analysis of geophysical surveys and core materials the fixed time during which the receiver receives the reflected signals is selected. The sampling step is selected sufficient for the detailed description of the electromagnetic reflected signal in a quantity from 10 to 20 points for the central frequency period. During field observations the radiation of electromagnetic waves from the 10 MW transmitter and reception of the reflected signal is performed consistently by three antennas at three frequencies: 50 MHz, 25 MHz and 10 MHz in the linear and logarithmic modes of record and registration with a step 4-6 m. The impulse received at the highest frequency is considered as reflecting the detailed nature of studies and high resolution, and at the lowest frequency - as the maximum depth of sounding. In the linear mode of impulse registration the reflected signal of the lower part of the section is separated and digitised. In the logarithmic mode the registration of "desensitisation" of high amplitude of a signal and amplification of low amplitude record of the top part of the section is performed. As a result of processing of field materials the temporary sections are constructed on which the wave picture displays the features of the geological structure and composition of rocks. By change of properties of dielectric permeability the boundaries of the interface of layers and the diffracting objects in the fields of electromagnetic waves pre-determined by an axis of phase synchronism of the reflected waves are separated. For visualisation the separation of the return reflection field from the set of the obtained data using the frequency and spatial filtration is used. The summation-subtraction function for radargrams, recorded in the linear and logarithmic modes by means of which the detailed partition of the lower part of a radarogram is achieved. For lithologic- stratigraphical binding of boundaries of the reflected waves the correction of high-speed characteristics of electromagnetic impulse and materials of geophysical surveys of wells and coring data is performed. From this the regularities in nature and distribution of an electromagnetic signal are identified. The objects with weak and transitional reflecting characteristics are separated. The search indicator of the deposit boundary on the temporary section is a reduction of time of passing of the boundary of the separated oil layer and increase of the signal amplitude with respect to indications out of the deposit. The maps of time electromagnetic impulse reflections are constructed, on the basis of which the stratigraphical surfaces of the reflecting horizons of the top part of the sedimentary cover are mapped. By changes of amplitude and sign of electromagnetic signal in various mediums over a deposit, at transition and outside the deposit the maps of oil saturated depths are constructed.

EFFECT: forecasting of deposits of superviscous oils.

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