A system (100) for monitoring a field (20) under a body of water, wherein the system (100) comprises a reference station (112) and a plurality of permanent seafloor sensors (120, 121). Each permanent seafloor sensor (120, 121) is fixed relative to a seafloor (2) on or at the field (20). The seafloor sensor (120, 121) further has a nearby survey station (111) sufficiently distant to ensure that a movable sensor (122) visiting the nearby survey station (111) does not disturb measurements from the permanent seafloor sensor (120). The distance is sufficiently close to ensure that the offset (Δp, Δg) from a value provided by the permanent seafloor sensor (120) is constant or can be modelled, e.g. to account for changes in the pressure/depth relation due to changes in water density. Each seafloor sensor is associated with a unique drift function d(t) at least comprising a drift rate (a). Thus, each permanent seafloor (120, 121) sensor provide an output that is corrected for drift at any time between calibration surveys. The system may be used for permanent monitoring of a seafloor.

A system (100) for monitoring a field (20) under a body of water, wherein the system (100) comprises a reference station (112) and a plurality of permanent seafloor sensors (120, 121). Each permanent seafloor sensor (120, 121) is fixed relative to a seafloor (2) on or at the field (20). The seafloor sensor (120, 121) further has a nearby survey station (111) sufficiently distant to ensure that a movable sensor (122) visiting the nearby survey station (111) does not disturb measurements from the permanent seafloor sensor (120). The distance is sufficiently close to ensure that the offset (Δp, Δg) from a value provided by the permanent seafloor sensor (120) is constant or can be modelled, e.g. to account for changes in the pressure/depth relation due to changes in water density. Each seafloor sensor is associated with a unique drift function d(t) at least comprising a drift rate (a). Thus, each permanent seafloor (120, 121) sensor provide an output that is corrected for drift at any time between calibration surveys. The system may be used for permanent monitoring of a seafloor.

A method for determining a location of a proppant in a subterranean formation includes obtaining a first set of data in a wellbore using a downhole tool. The proppant is pumped into the wellbore after the first set of data is obtained. The proppant is pumped while or after the subterranean formation is fractured. A second set of data is obtained in the wellbore using the downhole tool after the proppant is pumped into the wellbore. The first set of data and the second set of data include a gravitational field measurement. The first and second sets of data are compared, and in response to the comparison, the location of the proppant in the subterranean formation is determined.

A method for determining a location of a proppant in a subterranean formation includes obtaining a first set of data in a wellbore using a downhole tool. The proppant is pumped into the wellbore after the first set of data is obtained. The proppant is pumped while or after the subterranean formation is fractured. A second set of data is obtained in the wellbore using the downhole tool after the proppant is pumped into the wellbore. The first set of data and the second set of data include a gravitational field measurement. The first and second sets of data are compared, and in response to the comparison, the location of the proppant in the subterranean formation is determined.

A system and a method which determines the mass of a ship moving in water, comprising at least two gravitational field strength sensor units that are stationary relative to the ship at a known distance from each other, and an analytical unit which determines the mass of the ship based of measurement signals acquired by the at least two GFS sensor units.

A system and a method which determines the mass of a ship moving in water, comprising at least two gravitational field strength sensor units that are stationary relative to the ship at a known distance from each other, and an analytical unit which determines the mass of the ship based of measurement signals acquired by the at least two GFS sensor units.

The present invention discloses a method and system for processing gravity and magnetic data in geological resource exploration. The method includes: acquiring first (i) potential field data and (ii) gradient data of an observation surface, performing upward continuation of the acquired data using a wave-number domain conversion method to obtain second and third gradient data and second potential field data, and determining third potential field data using a fourth-order explicit scheme Milne method according to the first, second, and third gradient data, and the second potential field data; calculating fourth gradient data using an ISVD method according to the third potential field data; and correcting the third potential field data using a fourth-order implicit scheme Simpson method according to the fourth gradient data, the first potential field data, and the first and second gradient data to obtain corrected third potential field data.

The present invention discloses a method and system for processing gravity and magnetic data in geological resource exploration. The method includes: acquiring first (i) potential field data and (ii) gradient data of an observation surface, performing upward continuation of the acquired data using a wave-number domain conversion method to obtain second and third gradient data and second potential field data, and determining third potential field data using a fourth-order explicit scheme Milne method according to the first, second, and third gradient data, and the second potential field data; calculating fourth gradient data using an ISVD method according to the third potential field data; and correcting the third potential field data using a fourth-order implicit scheme Simpson method according to the fourth gradient data, the first potential field data, and the first and second gradient data to obtain corrected third potential field data.

The present disclosure discloses a submarine position detection method based on extreme points of gravity gradients. A space rectangular coordinate system is established by taking a centroid of the middle cylindrical portion as a coordinate origin, a direction pointing to a bow is taken as a forward direction of the X axis, a direction pointing to a port is taken as a forward direction of the Y direction, and a vertical upward direction is taken as a forward direction of the Z axis. The detection method includes steps of: determining a horizontal position of a submarine, i.e., coordinates (X, Y), according to a position of a central extreme point and a central position between extreme points of non-diagonal components of a gradient tensor; and determining a functional relation between a depth and the extreme points of gravity gradients by using the submarine model.

A method including: storing, in a computer memory, geophysical data obtained from a survey of a subsurface region; and extracting, with a computer, a subsurface physical property model by processing the geophysical data with one or more convolutional neural networks, which are trained to relate the geophysical data to at least one subsurface physical property consistent with geological prior information.