RU154804U1 - DEVICE FOR SCANNING GRAVITY AND WAVE FIELDS - Google Patents

Abstract

An automatic gravimeter comprising a housing in which are installed: a thermostatically controlled unit with a sensor consisting of three acceleration meters made in the form of accelerometers whose sensitivity axes are located orthogonally; power batteries, computing and navigation systems, connectors for connecting external devices, communication systems and a user interface, characterized in that the base of the gravimeter is configured to change the position of the plane of the base of the gravimeter in space by changing the height of its supports with electric drives controlled by the gravimeter’s computing system according to current measurements values of accelerations and preset values of directions for automatically changing the directions of the sensitivity vector of the sensor when ska the gravitational field at the point of measurement, and also installed compass sensors made with the possibility of determining the direction and installation of the sensitivity vectors of the accelerometers of the sensor in space, and a pressure sensor configured to take into account the influence of the atmosphere on the measured values.

Description

The utility model relates to geophysical engineering, namely to devices used to measure the parameters of gravitational and wave fields.

Devices that implement the measurements described above are called gravimeters. All gravimeters have gravity acceleration sensors, devices to compensate for the effects of gravity, temperature compensators, a registration system, installation devices, isolation devices (from external effects of temperature, pressure, magnetic and electric fields).

The common disadvantages of known gravimeters include the complexity of devices and calculations, the inability to automatically scan the gravitational field with programming the scanning parameters of the gravitational field of the space under study.

The prior art block diagram of the device [1], the corresponding block diagram of modern gravimeters. The block diagram of the device contains an acceleration measuring sensor consisting of three orthogonally located accelerometers, a system for determining the direction of the horizontal axes of the sensor sensitivity in space (Compass), a system for determining the coordinates of the measuring point (GPS), a computing unit, a data storage unit, a communication system and battery power . The block diagram is designed for the use of accelerometers made according to MEMS technology, which in some parameters, in particular ease of manufacture, dimensions, reliability and cost significantly exceed the accelerometers used in modern gravimetry containing elastic compensation systems, a suspension system, strings, pendulums or electrolyte. In terms of noise, modern MEMS accelerometers reach 2-3 μGal / √Hz (in the near future 0.4 μGal / √Hz), the same parameter of the system of the modern gravimetric complex gPhoneX Micro-g LaCoste has a system noise value of 0.75 μGal / √Hz. By design, some types of MEMS accelerometers are no different from the sensors used in gravimetry, they have test mass, a suspension system, compensations and converters of moving the test mass into an electrical signal, but they have significant advantages of microelectronics technologies, and the dimensions of the test mass and suspension design provide a smaller taper of the measurement vector, which is of great importance when measuring the vector values of the gravitational field.

In the technical literature, reports periodically appear about the use of MEMS accelerometers (due to their simplicity of manufacture, reliability and low cost) to create a global system for obtaining high-precision detailed images of the Earth’s depths, on the basis of which decisions will be made about the prospects and commercial viability of newly discovered fields, as well as monitor the status of fields already in operation.

When using orthogonally located accelerometers made in accordance with MEMS technology in gravimetry, devices with an automated system for setting the angles of sensitivity vectors of sensors relative to a vertical line are not described using calculated values of accelerations and values specified by the solution of the geological problem, and to determine the value of the vector and angles of the maximum force acceleration severity [2].

Known devices for automatically setting the axis of sensitivity of the gravimeter in the vertical, used in measurements in hard-to-reach places [3], [5], or on moving objects [5]. On moving objects, gyro-stabilized platforms are mainly used for installing gravimeters in a vertical [6].

A known method and device for exhibiting in the vertical axis of the gravimeter [7]. The method consists in the fact that a series of throws of the test body is carried out at different inclinations of the gravimeter, the acceleration of gravity is determined in each throw, the minimum value of acceleration in the series of throws and the corresponding tilt of the platform are found, while the tilt is fixed to the platform, and a platform is proposed for implementing the method, accelerometers and engines.

Known telecontrolled gravimeters [8], containing a housing with a sensitive system, including a lever and suspension threads of the sensing element, a vertical sensor (for example, two-coordinate electrolytic level), a vertical meter, a telecontrol system, cable conductors. When measuring in the initial position of the sensing element at least two times, the angle of inclination of the housing with the sensitive system is additionally measured and the correction is calculated from the measurements, which is introduced into the value of the compensating force when calculating the acceleration of gravity.

The closest in technical essence to the claimed device is a method and device for determining the parameters of gravitational and wave fields [9] adopted as a prototype. In the known device, three electrolytic sensors are installed along mutually perpendicular coordinate axes to determine the angular coordinates of the object relative to the gravitational field. During field or borehole measurements, signals are recorded by a three-component block of sensors proportional to the force from the total acceleration of the gravitational and wave fields in time and the values of the gravitational field are calculated using a low-pass filter, averaging data over a period of time, taking into account corrections and errors from the angle of inclination vertical axis of the device. The device provides measurement of signals from mutually perpendicular sensitivity vectors of the three sensors of the meter and allows you to determine the parameters of the gravitational and wave fields, the angular coordinates of the object and its acceleration.

A disadvantage of the known device is the absence in the device of a measurement system and setting in the direction space of the sensitivity vectors of horizontal accelerometers (and for determining the direction of accelerations during movement), therefore, the known device is used to determine the angular coordinates of the device relative to the gravitational field. When constructing a spatial model of the gravitational field of the studied area and other measurements, it is necessary to measure and install a single direction of the sensitivity axes of horizontal sensors at all points of measurement of the values of the gravitational field. Another significant drawback of the known method and device is the lack of an automated feedback system between the calculated values of the accelerations and the angles of inclination of the sensitivity vectors of the sensors relative to the plumb line, specified by the solution of the geological problem and to determine the angles of the vector of the maximum value of the acceleration of gravity.

A common disadvantage of the known gravimeter installation devices is the impossibility of the gravimeter to scan the gravitational field with the given vectors, the work of the known installation systems is aimed only at measuring values for corrections for the angle of deviation of the vertical line in order to increase the accuracy of gravimetric measurements. Known systems do not have the technical ability to automatically scan the gravitational field by measuring the values of programmable directions of the gravitational field vectors determined by the geological task, calculated and set automatically relative to the desired coordinates or vertical line and directions of the sides in real time from the measured acceleration values along the variable vectors of the sensitivity axes devices.

EFFECT: automatic obtaining of gravitational and wave field values in the geometry of the space under study, for constructing a three-dimensional geological model from automatically measured and calculated parameters of the gravitational and wave fields.

To achieve this technical result, an automatic gravimeter is used, containing a housing in which are installed: a thermostatically controlled unit with a sensor consisting of three acceleration meters made in the form of accelerometers whose sensitivity axes are located orthogonally, power batteries, computing and navigation systems, connectors for connecting external devices , communication systems and user interface, characterized in that the base of the gravimeter is made with the possibility of changing in space the position of the pl the base of the gravimeter, by changing the height of its supports with electric drives controlled by the gravimeter computing system according to the current measurements of the acceleration value and the set direction values for automatically changing the direction of the sensor sensitivity vectors when scanning the gravitational field at the measurement point, as well as compass sensors configured to determine the direction and setting the sensitivity vectors of the accelerometer sensor in space and the pressure sensor, made with the possibility of taking into account the influence of the atmosphere on the measured values. In order to reduce the measurement time during scanning, the sensor of the device, consisting of three acceleration meters made in the form of accelerometers, whose sensitivity axes are located orthogonally, can be supplemented by acceleration meters, whose sensitivity axes are located at given angles in the planes of the sensitivity vectors of two of the orthogonally mounted acceleration meters.

Moreover, the advantages of the present utility model will be apparent to those skilled in the art from the following detailed description.

In the claimed utility model for three orthogonal accelerometers located, sensitivity vectors are automatically redirected to measure the acceleration of the gravitational field at points in the space under study according to the conditions of the geological problem. When measured at a point in space, the device measures the acceleration values from three vectors of the gravitational field: Gx, Gy, Gz. These values are recorded in the measurement file and used to calculate two angles of deviation of the measurement vectors, depending on the geological problem, which can coincide with the orthogonally located vectors of the sensitivity axes of the accelerometers.

The zenith angle for the vector of the vertical axis of measurement (angle of deviation of the vertical line) α is calculated in degrees by the formula:

α = 57.295779 × arccos (Gz / √ (Gx + Gy + Gz))

where Gx, Gy, Gz are the acceleration values measured along the axes X, Y, Z of the sensitivity vectors of orthogonally mounted acceleration sensors, in µGal (cm / s).

The azimuthal angle of inclination P (the direction in the horizontal plane of the angle of deviation of the vertical line) is calculated taking into account the desired direction of the sensitivity axes of the horizontal accelerometers and the direction of increase of the angle relative to the direction of rotation of the sensitivity axes in the horizontal plane, determined by the solution of the geological problem. The axes of the device can be installed in any direction relative to the cardinal points; for this, the value of the magnetic azimuth of the X axis, which can be checked by moving the device in space to determine the direction of the sides according to the navigation system, is measured, displayed and recorded in the device’s file and memory.

If during measurements the desired angle increment is directed counterclockwise, the zero value β coincides with the Y axis of the device (the line of measurement points for parallel profiles), and the X axis corresponds to a value of 90 ° (profile direction), then the azimuthal inclination angle β in degrees is calculated by the formulas: β = βi + 57.295779 × arctan (Gx / Gy)

where Gx, Gy are the acceleration values measured along the sensitivity axes of the orthogonally mounted acceleration sensors of the horizontal plane, X, Y vectors in µGal (cm / s);

βi - takes into account the direction (±) of the vectors Gx and Gy in the value of the azimuthal angle of inclination.

βi = 0 ° for Gx> 0; Gy> 0

βi = 180 ° for Gx> 0; Gy <0

βi = 180 ° at Gx <0; Gy <0

βi = 360 ° at Gx <0; Gy> 0

If, when scanning the gravitational field and building models, it is necessary to use the spatial orientation of the device axes relative to the cardinal points, then the values of the azimuthal angle of deviation β are calculated from 0 ° to 360 ° with increasing clockwise, the direction of the X axis is set to 0 ° of the azimuthal angle of deviation (profile direction ), and the direction of the Y axis is 90 ° (the line of measurement points for parallel profiles):

β = βi + 57.295779 × arctan (Gy / Gx)

where Gy, Gx are the acceleration values measured along the sensitivity axes of the orthogonally mounted acceleration sensors of the horizontal plane, vectors Y, X in µGal (cm / s);

βi - takes into account the direction value (±) of the vectors Gy and Gx in the value of the azimuthal angle of inclination.

βi = 0 ° for Gx> 0; Gy> 0

βi = 180 ° at Gx <0; Gy> 0

βi = 180 ° at Gx <0; Gy <0

βi = 360 ° for Gx> 0; Gy <0

If necessary, the direction of the axes and the zero value for reading the azimuthal angle can easily be changed programmatically, for this the value of the X-axis magnetic azimuth is measured, displayed and recorded in the measurement file on the device’s memory and the memory. The values of the azimuthal angle and the angle of deviation of the vertical line at the measurement point are determined by the conditions geometry of vectors for measuring acceleration values when solving a geological problem.

The system of setting scan angles controls the electric tilt of the horizontal plane of the device and automatically tilts the axes of the device (if necessary, without changing the direction of the axes along the profile or the cardinal points, or the task), using the measured values of accelerations, monitors the necessary change in the values of accelerations and angles (feedback) to the values programmed by the conditions for solving the geological problem or to determine the values and angles of the vector of maximum acceleration of gravity, or the norm and to construct a two-dimensional and three-dimensional model of the site.

For the first time, on the basis of the developed device, a simultaneous, geometrically interconnected measurement of the acceleration values of the gravitational field vectors for all points of the plot has been achieved, which allows the construction of a three-dimensional geological model of the plot from the measured values of multidirectional (horizontal and vertical) acceleration vectors and distances by solving a system of equations from interrelated values and not by calculating the derivatives of gravity from the values of the vertical vectors for reducing the field in the gravimetric matic modeling of objects in three-dimensional space.

The proposed device implements the following algorithm of work, for solving a geological problem or building a three-dimensional geological model of the site:

1. Programming the device from the interface of a personal computer before starting work on profiles: setting measurement parameters in accordance with the task and the necessary accuracy; setting coordinates of measurement points in accordance with the developed route along profiles and measurement parameters at each point; programming automatically set values of the angles of the sensitivity vectors of the sensors for measuring acceleration values in accordance with the network size and the task to be solved; setting the number of required measurements, setting diagnostic and service parameters for current messages to the operator about exceeding the deviation limits allowed by the task from the set measurement values (coordinates, azimuth, movement of supports, wind, etc.) The device interface allows the operator to carry out all programming of the device without using an external computer.

2. Transportation of the device by the operator to the points of the agreed route (points and the route are automatically checked by the device), installation on a suitable base for measurement and pressing the "Start" button. After taking measurements and checking the quality of measurements, the device gives a signal of its movement to the next point, where the measurement cycle is repeated in accordance with the task.

After installing the device at the measuring point, the sensitivity vector of the X axis is set using the built-in electronic compass.

The measurement and writing to the measurement file of coordinates, magnetic azimuth, altitude, temperature, time and pressure for the current measurement is automatically performed. By pressing the “Start” button, a cycle of all measurements is started according to the program set before work. Automatically calculates the value of the acceleration of gravity along the sensitivity axes of the sensors, calculates the zenith and azimuthal angles of the gravitational field to determine the initial installation of the device. The sensitivity vectors of horizontal sensors are determined and automatically set in a tangent plane at the measurement point, and the acceleration value is measured for a vector perpendicular to the tangent plane (normal). The device is automatically tilted (relative to the tangent plane or vertical line) to the given angles (anti-aircraft and azimuthal) to measure the value of the vectors, usually in the direction of other measurement points. The angles (and the required number of angles) of the axis tilt for measurements are set during programming depending on the location of the network points; for a square or rectangular network, azimuthal deviation angles are usually set to multiples of 90 °.

If the task is programmed, the axis tilt control system is turned on to search and measure the maximum value of the acceleration of gravity at a point along the Z axis. All measured values (accelerations and angles) and operation parameters are recorded in the device memory in a separate measurement file at a point containing unprocessed and processed calculation algorithms, the measurement results are adjusted and can be transferred to a personal computer or removable media, or read on the device interface. According to the measurement data, a two-dimensional or three-dimensional model of the site is constructed

Measurements are usually carried out according to a system of profiles laid in accordance with a geological or other task. In this case, the profiles are placed in parallel on the studied area to create a square or rectangular network. The distance between the profiles (network density) and the distance between ordinary gravimetric points along the profile are calculated based on the required accuracy and detail of the survey. When measuring at a point, the X axis is usually set in the direction of profile movement, and the Y axis is set in the plane of the measurement points on parallel profiles. Additionally, in the center of the investigated area, at the intersection of the diagonals of the area, a reference point is created to control the displacement of the instrument null point when measuring at points and to check the internal convergence of the measurements. At the reference point, one device is also installed for continuous recording of current measurement values during the operation of other devices on profiles, otherwise the technology of the work is no different from the known gravimetry.

Based on the data of the heights of the measurement points, directions, angles and distances, a geometric model of the measurement vectors of the gravitational field of the section is constructed, corresponding to the measured values of the accelerations of the gravitational field vectors. By solving the system of equations, the measurement data are converted into an array of values of unit mass volumes, from which a three-dimensional model of the density distribution of geological objects of the studied area is built.

Used sources:

1. Device and method for determining the parameters of the gravitational and wave fields, RU 2260199 C2, publ. 09/10/2005.

2. "MEMS Applications in Seismology Seismic Instrumentation Technology Symposium." Nov 11, 2009 p. 29.

3. "HP and Shell are developing a system of wireless sensors for mineral exploration and the study of the bowels of the earth," the description is located on the Internet: http://www.computerweekly.com/

4. The electromechanical drive of the gravimeter in the vertical, SU 1144070 A1.

5. Downhole gravity exploration device and method of gravity well exploration, RU 2178575 C2.

6. The method of generating a control signal for the position of the axis of sensitivity of the gravimeter mounted on the aircraft, with its remote exhibition along the plumb line, RU 2221990 C2.

7. Correction system gyro stabilizer marine gravimeter, RU 2282147 C1.

8. The method of exhibiting in a vertical laser beam a ballistic gravimeter and a gravimeter for its implementation, RU 2522116.

9. A method of measuring the acceleration of gravity by a telecontrolled gravimeter, SU 1166042.

Claims (1)

An automatic gravimeter comprising a housing in which are installed: a thermostatically controlled unit with a sensor consisting of three acceleration meters made in the form of accelerometers whose sensitivity axes are located orthogonally; power batteries, computing and navigation systems, connectors for connecting external devices, communication systems and a user interface, characterized in that the base of the gravimeter is configured to change the position of the plane of the base of the gravimeter in space by changing the height of its supports with electric drives controlled by the gravimeter’s computing system according to current measurements values of accelerations and preset values of directions for automatically changing the directions of the sensitivity vector of the sensor when ska the gravitational field at the point of measurement, and also installed compass sensors made with the possibility of determining the direction and installation of the sensitivity vectors of the accelerometers of the sensor in space, and a pressure sensor configured to take into account the influence of the atmosphere on the measured values.