Downhole acoustic scanner
FIELD: physics, acoustics.
SUBSTANCE: invention relates to geophysical well survey using an acoustic method based on reflected waves. The electronic unit of the device is further equipped with a Flash memory card, a telemetry channel, a gamma logging channel and a continuous tiltmeter, and the probing part of the device is divided into "dry" and oil-filled compartments and is further equipped with a sensor for measuring ultrasound speed in a liquid, mounted on the outer side of the housing. The oil-filled compartment accommodates an ultrasonic sensor, a contactless collector and a contactless line pulse former. The ultrasonic sensor with elements of the collector and the line pulse former are rotated by a contactless rotary electric drive.
EFFECT: invention improves measurement accuracy and improves reliability of the device.
SUBSTANCE: method includes calculating a Fourier spectrum from waveforms of external earthquakes detected by two seismic stations, wherein one of the stations, which is close to the earthquake hypocentre, is called the input station and the other, which is located at the point of estimating tension in the earth environment, is called the output station; calculating the quasi-amplitude-frequency characteristic of the earth environment at the location of the output station, as well as two criteria therefrom: integral and fractional-integral; deducing an imminent earthquake from observing a sharp decrease in the values of the integral criterion and a sharp increase in the values of the fractional-integral criterion; predicting the local magnitude of the imminent earthquake from the maximum value of the fractional-integral criterion, wherein the local magnitude is predicted using a calibration curve of local magnitudes of earthquakes plotted in advance for a specific pair of stations from values of the fractional-integral criterion.
EFFECT: short-term prediction of the local magnitude of an earthquake.
2 dwg, 1 tbl
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.
FIELD: physics, computer engineering.
SUBSTANCE: present invention relates to designing systems and methods of processing seismic data. The disclosed group of inventions includes computer-implemented methods of processing seismic data, systems for processing seismic data and computer-readable data media storing commands which, upon execution by a processor, carry out steps in any one of the methods. Methods and means of preprocessing data before interpreting seismic data include converting voxel connectivity, reducing seismic reflections, suppressing voxels and determining voxel density. Voxel connectivity is used to facilitate removal of insignificant data.
EFFECT: reduced seismic response of a given reflecting horizon in a beam lobe, such as a main lobe, by reducing seismic reflections, as well as highlighting and amplifying lithologic boundaries to facilitate interpretation by a person and a computer through voxel suppression.
55 cl, 30 dwg
SUBSTANCE: method includes successive operations for acquiring and preparing data by a common-depth-point method, seismic logging, vertical seismic profiling, acoustic logging, gamma-ray density logging and verifying the quality of said data, and obtaining reference values of interval velocities; obtaining an initial hodograph and calculating a synthetic seismogram; performing quality control and inputting a constant time adjustment for landing on the upper reference horizon of the lithologic and stratigraphic system; recalculating the synthetic seismogram and performing quality control again; calculating and inputting an adjustment for landing on the lower reference horizon of the lithologic and stratigraphic system; recalculating the synthetic seismogram and performing quality control; transferring the point of the obtained hodograph to the nearest acoustically weak boundaries; recalculating the synthetic seismogram, followed by quality control and obtaining an apriori hodograph.
EFFECT: high reliability and accuracy of alignment of horizons of a time section and geologic marks of a well.
11 cl, 2 dwg
FIELD: physics, hydrophysics.
SUBSTANCE: method for parametric reception of hydrophysical and geophysical waves in a marine environment is characterised by that, in addition to scanning the environment with low frequency hydroacoustic signals, it also includes infra-low frequency pumping of the sea bottom along the direction of parametric antennae which radiate from the centre of the investigated water area; furthermore, a receiving hydroacoustic transducer is formed from two vertically spaced apart receivers, mounted on a mobile carrier which moves on the boundary of the investigated water area, wherein the low frequency hydroacoustic signals are generated by two vertically spaced apart forward-scattering parametric antennae, wherein during movement on the perimeter of the water body, the direction of the maximum manifestation of the measured information waves is determined; further, the receiving unit is moved in the said directions towards the location of the radiating transducers with a constant velocity minimally possible for the carrier or with given stoppage intervals, wherein the method also includes measuring and specifying the location of sources of the maximum manifestation of information waves, the length thereof and space-time characteristics thereof, and based thereon, identifying the measured waves, identification thereof as water hydrophysical or bottom geophysical, e.g., hydrocarbon or seismic ones; furthermore, upon detecting geophysical waves and selection of spectral characteristics thereof, the latter are compared with generalised reference spectra and the identity of the measured information waves to specific types of hydrocarbon accumulations is determined or are identified as earthquake precursors.
EFFECT: invention reduces the time and equipment costs on investigating a water area with search purposes for hydrocarbon deposits and enabling detection of seismic disturbances of the medium of earthquake precursors.
7 cl, 10 dwg
SUBSTANCE: in compliance with claimed process, several pairs of "amplifier-time selector" circuits are additionally used for received acoustic signal. Said circuits are controlled by generated control signals, their magnitude for further circuits depending upon duration of previous "amplifier-time selector" circuit power surges. Quantity of circuits is selected proceeding from preset SNR defined by analytical relationship. The latter comprises such parameters as useful signal, input noise signal, signal of noise from time selector power surges, amplifier gain factor, time selector circuit rejection factor and quantity of pairs of "amplifier-time selector" circuits.
EFFECT: higher validity of control.
FIELD: physics; geophysics.
SUBSTANCE: invention relates to geology and can be used to predict development zones of secondary fracture-type reservoirs in a sedimentary section. The method involves detecting reflected seismic waves associated with a selected system of deposits; performing lithologic-petrophysical investigation of rock samples to determine the most probable genesis of secondary reservoirs; selecting lithotypes on which secondary fracture-type reservoirs are formed; drilling a well in anticline structures and determining the depth of occurrence of fold hinges, morphologic parameters of the structures, including maximum seam contortion, width, length, area and intensity of folding; using downhole logging results to determine secondary porosity; measuring formation pressure in test intervals; establishing a critical value of secondary porosity Kpvtcr; establishing a multidimensional correlation relationship of the secondary porosity Kpvt=f(i, gradp, J, Kpob, H), where i is the maximum seam contortion; gradp is the gradient of formation pressure; J=i/S is folding intensity; S is the surface area of the structure; Kpob is the overall porosity; H is the depth of occurrence of fold hinge; performing detailed field seismic survey on unstudied areas of the territory with a dense seismic grid through not more than 100 m; processing field seismic materials; detecting presence of anticline structures and deep faults; constructing seismic-geologic profiles along and across the detected structures; determining the depth of occurrence of vfold hinges and morphologic parameters of the structures; using the established relationship Kpob=f(H) to determine overall porosity at the depth of occurrence of the bedrock on newly detected structures; determining the predicted gradient of formation pressure; using the established multidimensional correlation relationship of secondary porosity Kpvt=f(i, gradp, J, Kpob, H) to predict the value of Kpvt; comparing Kpvt with the lower limit of Kpvtcr for the "reservoir-nonreservoir" boundary, which is then used to predict the probability of development of secondary fracture-type reservoirs, the expediency of drilling on said structures and the well drilling procedure. If Kpvt/Kpvtcr>1.2, it is expedient to drill on a profile of three dependent wells; if Kpvt/Kpvtcr=(0.7-1.2), drilling only one well in the crest of the structure is expedient.
EFFECT: high efficiency of prediction.
1 dwg, 5 tbl
SUBSTANCE: group of inventions refers to method and device for control and correction of time settings used in a distributed nodal seismic receiving system. So a wireless seismic data recording unit is fitted by a wireless receiver providing access to the common external time standard shared by the variety of seismic data recording units in a seismic system. The receiver is made able of replicating the local version of the external time reference point with which an analog-to-digital converter of a seismic sensor is synchronised. The receiver is made able of replicating the local version of the common external time standard to put time marks on local events of the node. The receiver can be switched into nonoperating mode with low power consumption for the time periods when the seismic data recording unit continues to record the seismic data, thus battery supplied power is preserved. The system implements the method for local clock correction basing on the intermittent access to the common external time standard. The method provides for the correction of local time at the clock with the help of a voltage controlled clock generator to consider the time errors caused by the environment conditions. Additionally the invention provides for more reliable method to correct drift of the local clock.
EFFECT: minimisation of power consumption, improved accuracy of data acquisition.
33 cl, 7 dwg
FIELD: physics; geophysics.
SUBSTANCE: invention relates to devices for seismic exploration of hydrocarbon deposits on the water area of the arctic shelf. The mobile self-contained underwater seismic-hydroacoustic station for exploration of hydrocarbons on the water area of the arctic shelf has a hard, streamlined housing, a power plant, a motor, a gyroscope, a distance measuring device, an echo sounder, a depth sensor, a hydroacoustic beacon signal locator, buoyancy control means and an on-board computer with a program device for controlling movement of the station from one point on the sea to another, hovering, sinking to the bottom, raising from the bottom to a given depth and onto the sea surface.
EFFECT: designing a mobile underwater self-contained seismic-hydroacoustic station for exploration of hydrocarbons, capable of independently moving according to a given program to investigated points on the sea, hovering over said points, sinking to the bottom and raising from the bottom to a given depth while simultaneously reducing self-generated seismic-hydroacoustic noise.
SUBSTANCE: method involves excitation of elastic vibrations by a vibration source in a well crossing hydraulic fracturing cracks, recording at receiving points at least in one neighbouring well of resonant vibrations emitted with a hydraulic fracturing crack system at excitation in drilling fluid of elastic vibrations, and determination of parameters of the crack system as per resonant vibrations occurring in the cracks. Excitation of vibrations in the well and their recording is performed before and after hydraulic fracturing. Besides, for each fixed source-receiver pair there formed is a difference seismic record of the records received before and after hydraulic fracturing; signals emitted by the crack system are separated on the difference seismic record, and parameters of cracks are determined as per the above signals.
EFFECT: improving reliable determination of spatial orientation of a hydraulic fracturing crack system and its dimensions.
FIELD: seismic prospecting.
SUBSTANCE: method can be applied at prospecting of oil and gas pools as in sedimentary and in metamorphic and crystal rocks. Seismic waves induced by seismic standard source close to surface are registered. Wave fields are formed from expected objects of reflection, diffraction and dissipation and parameters of processing are chosen in such a manner to provide better selection of modeled objects on the error background. Received parameters are used for processing real data and selecting real objects. Shapes of objects of dissipation are presented in form of maps and sectional views.
EFFECT: increased level of valid signal.
FIELD: electro-seismic prospecting.
SUBSTANCE: signal of source are subject to correlation with reference signals chosen to minimize side lobes of correlation function. To form fragment of prolonged source signal having minimal side lobes of correlation function sequence of which is specified by binary code, the circuit with frequency of 60GHz is used. Preferable binary codes are based on complimentary Golay pair and sequences of shift registers with maximal length.
EFFECT: improved efficiency.
21 cl, 8 dwg
FIELD: seismic prospecting.
SUBSTANCE: method comprises recording seismic vibrations of the Earth in a given range, generating and recording additional seismic vibrations, extracting information signal, which is a signal from the productive pool, analyzing the spectra of the data obtained, and determining presence or absence of hydrocarbons and position of productive hydrocarbon pools.
EFFECT: enhanced accuracy and reliability of prospecting.
19 cl, 4 dwg
FIELD: seismic prospecting.
SUBSTANCE: method can be used for searching non-uniformities. While conducting seismic prospecting the radiated wave receivers and transmitters are located outside inspected rock mass at two adjacent faces of tested volume of rock at the squares having radius equal or 5 times longer than wavelength in tested volume of rocks. Tested mass is a divided to cubic unit having heights of faces no longer than Ѕ wavelength of radiated wave specified by depth of testing. Rock mass is subject to radiographic test at two orthogonal directions. Radiated waves are focused into center of any cubic unit and waves at receivers are subject to co-phase summation from center of any cubic unit for any radiation of seismic waves. Energy of waves from any center is measured. Volumetric image of local diffracting object in rock mass is achieved from maximal values of energy from any center. When getting local volumetric image of object the calculations are repeated for speed values increasing subsequently depending on speed achieved during seismic well logging. Speed values at which centers of image of object coincide are assumed to be truthful and position of object received at that speed is assumed to be truthful as well. Image of object is put to coincidence from two directions for separate cross-sections. That image is assumed as truthful. Units are put together from which units the energy has maximal value at two images.
EFFECT: improved precision of determination and shape of diffracting object.
FIELD: seismic reconnaissance.
SUBSTANCE: intervals with ramp gradients of speed of spreading of fluctuations are picked out in a geological section. Parameters of interferential system of excitation are determined for these intervals of the section. The parameters include linear dimensions of the base of a group of oscillators, the distance between oscillators and their number, frequency structure and duration of sweep. Oscillators are located at fixed distances one from another. Elastic vibrations of the group of oscillators are excited in series. Elastic vibrations received for each interval of the section at fixed number of oscillators of elastic vibrations are registered. At completion of the full cycle of observations at one placing of oscillators the group of oscillators is moved one step further. This step is equal to the distance between oscillators and the cycle of observation is repeated fulfilling observations in accordance of the whole profile with the duration of recording exceeding intervals of registration of waves from the base of processing intervals. Groups of seismograms are made and compiled. Summary seismograms of elastic vibrations are formed. On the basis of received results makeshift sections are built.
EFFECT: increases effectiveness.
FIELD: seismic prospecting.
SUBSTANCE: method can be used when prospecting oil and gas fields. Method is based upon forming of random wave field (microseism) on the base of microseisms received during seismic prospecting works at profile and area observations. Wave field is formed by creating series of time fields composed by totality of routes being equally distant from explosion site for areas, which are free of recording of regular waves, and summary time fields composed by seismograms of multiple overlapping integrated by the same point of reception. Received wave fields are subject filter filtration and spectral analysis. Parts of abnormal values of low-frequency component and specific energy of the component in total random wave field is determined. Gradients of spectra are determined and maps of those parameters distributed along the area are built. If drilled holes are available, correlation links of c calculated parameters are found and those data is used in complex interpretation of seismic prospecting works of materials or for expert evaluation and specification of given before drilling recommendations for search or survey holes.
EFFECT: simplified technology.
FIELD: the invention refers to the field of seismic research and may be used at studying seismic field of natural or artificial origin.
SUBSTANCE: notified mode of seismic monitoring, in the algorithm of which an operation of calculating energy of seismic waves is additionally introduced with following registration of calculation results in the point of measuring for some beforehand installed interval of time chosen in dependence of frequency band of registered signals and prolongation of fading of a seismic wave to the background level at impulse impact. For carrying-out this function an additional energy calculating block is introduced in the field seismic registering equipment.
EFFECT: increases efficiency of transmission of seismic data to the collecting and processing post and increases duration of work of field registering apparatus in autonomous regime.
3 cl, 5 dwg
FIELD: the invention refers to geophysical methods of researching of oil wells and designed for evaluation of dominant saturation of a collector with oil or water.
SUBSTANCE: measurements of natural geo acoustic signals are determined along the axle of a well cased with a column in three or more given ranges of frequencies. The value of the terms ratio of amplitudes of signals registered in each given frequency range is determined in relation to the amplitude of the signal registered in the range of the least frequencies. The character of saturation of the plast-collectors is determined is evaluated according to an established value of relation of the amplitudes of signals registered in ranges of frequencies to the signals of the low-frequency range, equal 0,8. The exceeding of this value indicates on the dominant saturation of the plast-collector with oil.
EFFECT: increases efficiency of determination of the character of saturation of collectors in wells cased with tubes.
SUBSTANCE: in accordance to the method, dispersive curve of micro-seismic waves is determined preliminarily. Wave lengths λ are determined as well as frequency spectrum of micro-seismic signal on basis of analysis of apparent speeds, wherein it consists of Raleigh waves. Seismic indicators are positioned across researched territory in such a way, that distance between them was not more than half the shortest length of Raleigh wave. Then, amplitude difference of measuring channels of seismic indicators is determined within frequencies band of micro-seismic signal. Micro-seismic signal is registered by no less than two seismic stations, one of which is mounted in stationary manner in the central portion of researched territory, and the rest are moving across researched territory. Accumulation of power spectrum of micro-seismic signal is performed in each measurement point during time, enough to reach stationary spectrum. Spatial variations spectrum of micro-seismic signal is connected for each measurements point. Maps of amplitude variations of micro-seismic signal are built for each spectrum frequency of spatial variations. Alignment of each received map is performed to appropriate depth H.
EFFECT: increased depth capacity of exploration seismology with simultaneous increase in trustworthiness of results.
FIELD: the invention refers to seismic prospecting precisely to modes of carrying seismic prospecting works with application of non-explosive surface sources.
SUBSTANCE: the mode includes separation of a geological cut on depth floors, computation for each floor and location on the terrain of a system of reception of seismic signals distinguishing between themselves with a pitch of receiving channels, excitation of waves by sources, reception and registration of the wave field. New in it is that according to the results of computation a system of reception of seismic signals is picked up. The system is tuned on the depth floor rendering the outmost distorting influence on the wave field of the depth floors lying below and the receiving channels in this system and the sources are located on the terrain with an identical pitch. At that the excitation of waves is made at least by two seances . In one of them the excitation of waves is made by all sources simultaneously and in the other seance the excitation of waves is made successively with each source.
EFFECT: increases efficiency and accuracy of prospecting works.