Accurate dynamic gravity measurement method and apparatus
AssigneeMicro-g LaCoste, Inc.
InventorsTimothy M. Niebauer, Christopher J. M. Nind
Life of this patent
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Abstract
Gravity information for a gravity survey is obtained by using an array of relative gravimeters whose relative gravity measurement signals have been calibrated by using an absolute gravimeter to approximate absolute gravity measurements. The absolute gravimeter is moved periodically to the location of each relative gravimeter to measure absolute gravity. The absolute and relative gravity measurements for each relative gravimeter form an error signal which is used to calibrate each relative gravimeter.
Claims23
A method of obtaining gravity information having an accuracy comparable to absolute gravity information by using an array of relative gravimeters to obtain gravity information for determining characteristics of a subsurface structure located beneath the surface of the earth, comprising:
- positioning each of the relative gravimeters in the array at predetermined stationary locations at the surface of the earth;
- moving an absolute gravimeter to each of the predetermined locations of each of the relative gravimeters;
- making absolute gravity measurements using the absolute gravimeter and making relative gravity measurements using the relative gravimeter, while the absolute gravimeter is positioned at the predetermined position of each relative gravimeter;
- processing the absolute and relative gravity measurements obtained when the absolute gravimeter is at the position of each relative gravimeter to determine an error value for each relative gravimeter;
- and
- applying the error value to alter subsequent relative gravity measurements supplied by each relative gravimeter into calibrated relative gravity measurements which closely approximate absolute gravity at the predetermined location of each relative gravimeter in the array.
Apparatus for use in obtaining gravity information, comprising:
- an array of relative gravimeters located at predetermined stationary locations at the surface of the earth, each relative gravimeter measuring gravity at the predetermined location and supplying a relative gravity measurement signal corresponding to the gravity measured at the predetermined location;
- an absolute gravimeter which is movable to the predetermined location of each relative gravimeter, the absolute gravimeter measuring gravity at the predetermined location of the relative gravimeter and supplying an absolute gravity measurement signal corresponding to the gravity measured at the predetermined location of the relative gravimeter;
- and
- data processing equipment connected to the absolute and relative gravimeters to receive the absolute and relative gravity measurement signals, the data processing equipment processing the absolute and relative gravity measurement signals for each relative gravimeter of the array to determine an error value applicable to each relative gravimeter of the array, the error value related to the difference between the relative and absolute gravity measurement signals at each relative gravimeter, the data processing equipment thereafter applying the error value to alter subsequent relative gravity measurement signals supplied by each relative gravimeter into calibrated relative gravity measurement signals, each calibrated relative gravity measurement signal approximating the absolute gravity at the predetermined location of each relative gravimeter at the time that the subsequent relative gravity measurement is supplied by each relative gravimeter, the data processing equipment supplying the calibrated relative gravity signals as the gravity information.
Dependencies are inferred from the claim text.