Abstract: A method for monitoring production mineral reservoirs, the method comprising: permanently installing a geophone in a borehole; generating a first set of seismic waves; receiving a first set of seismic data with the geophone; recording the first set of data of said receiving a first set of seismic data; generating a second set of seismic waves after sufficient time has passed for conditions in the reservoir to have changed from the generating a first set of seismic waves; receiving a second set of seismic data with the geophone; and recording the second set of seismic data of said receiving a second set of seismic data. A method for installing instruments below the surface of the earth, the method comprising: drilling a borehole with a drill apparatus; inserting an instrument in the borehole; and permanently fixing the instrument in the borehole.

Abstract: A system comprising: a mooring bridle, wherein the mooring bridle is installed below the wave zone of the sea and wherein the bridle is attached to a first vessel; and vessel lines which attach a second vessel to the mooring bridle. A line comprising: an anchor which is attached to the sea floor; an anchor line comprising an upper end and a lower end wherein the lower end is connected to the anchor; an anchor line buoy which is attached to the upper end of the anchor line; and a vessel line comprising an upper end and a lower end wherein the lower end attaches to the buoy and the upper end attaches to the vessel.

Abstract: A method for monitoring production mineral reservoirs, the method comprising: permanently installing a geophone in a borehole; generating a first set of seismic waves; receiving a first set of seismic data with the geophone; recording the first set of data of said receiving a first set of seismic data; generating a second set of seismic waves after sufficient time has passed for conditions in the reservoir to have changed from the generating a first set of seismic waves; receiving a second set of seismic data with the geophone; and recording the second set of seismic data of said receiving a second set of seismic data. A method for installing instruments below the surface of the earth, the method comprising: drilling a borehole with a drill apparatus; inserting an instrument in the borehole; and permanently fixing the instrument in the borehole.

Abstract: Methods, systems, and towing bridles, are provided to increase spread width, streamer separation, and number in marine seismic data acquisition. The invention is applicable for towing seismic equipment behind a marine seismic data equipment handling vessel along a data acquisition path, the system comprising: a deflector attached to a deflector line; an equipment handling vessel attached to the deflector; a deflector line pulling vessel attached to the deflector line; and the marine seismic data equipment attached to the deflector line.

Abstract: A method for monitoring production mineral reservoirs, the method comprising: permanently installing a geophone in a borehole; generating a first set of seismic waves; receiving a first set of seismic data with the geophone; recording the first set of data of said receiving a first set of seismic data; generating a second set of seismic waves after sufficient time has passed for conditions in the reservoir to have changed from the generating a first set of seismic waves; receiving a second set of seismic data with the geophone; and recording the second set of seismic data of said receiving a second set of seismic data. A method for installing instruments below the surface of the earth, the method comprising: drilling a borehole with a drill apparatus; inserting an instrument in the borehole; and permanently fixing the instrument in the borehole.

Abstract: Acoustic transmitter in particular for use in offshore seismic explorations, having sound-emitting surfaces (1, 2) being adapted to be subjected to vibrational movement by means of a drive unit (21) through at least one push element (22A, 22B) and two plate-like end pieces (3, 4) which are connected to the sound-emitting surfaces. The sound-emitting surfaces are formed by two curved plate members (1, 2) being of comparable width and heigth dimensions. The end pieces (3, 4) have a generally rectangular shape with a first pair of opposing side edges connected (5, 6, 7, 8) to end portions of the plate members (1, 2). Another pair of side edges on each end piece (3, 4) as well as side edges of the plate members engage two side plates (9, 10) which at either side closes the acoustic transmitter, preferably in a tightly enclosing manner.

Abstract: Flextensional acoustic source with sound-emitting surfaces (1, 2, 3, 4) adapted to be excited into vibrational movement, and for use in seismic exploration at sea. The source comprises a drive unit (21) being through the intermediary of at least one push element (22A, 22B) adapted to impose vibrational movement to the sound-emitting surfaces. Between at least one push element (22A, 22B) and the associated sound-emitting surface(s) (1, 2, 3, 4) there is provided a non-linear spring element (27, 28) the spring constant of which is controllable. Two oppositely acting push elements (22A, 22B) are arranged in axial alignment and preferably centrally in the source, and in addition thereto there are provided at least two tension elements (39, 40) with associated controllable, non-linear spring elements (35, 36, 37, 38) and being coupled to the sound-emitting surfaces (1, 2, 3, 4).

Abstract: A ship of a displacement type with a pointed bow and a transom stern, a longitudinal length of L, and defining a base plane and a design waterline plane, the ship comprising: approximately sinusoidal waterlines; a surface extending from the transom stern at the design waterline plane to the base plane at about L/2 and defining an angle between: the base plane and an oblique plane, the oblique plane being defined by: a line at the intersection of the transom stern and the design waterline plane and a point located on the surface at about 0.2 L from the transom stern, and a first propeller which is attached to the ship so that the hull wake through the first propeller is less than 0.50.

Abstract: A ship comprising: approximately sinusoidal waterlines; and a surface extending from the transom stern at the design waterline plane to the base plane at about L/3 from the bow and defining an angle between the base plane and an oblique plane, the oblique plane being defined by: a line at the intersection of the transom stern and the design waterline plane and a point located on the surface at about 0.2 L from the transom stern; and a turret along the middle line plane.

Abstract: A process comprising: organizing the top of the risers; organizing the bottom of the risers; and twisting the risers to impose tension in the risers. A system comprising: an organizer of the top of the risers; an organizer of the bottom of the risers; and a twister the risers to impose tension in the risers.

Abstract: Acoustic source assembly for offshore seismic exploration, comprising at least one active vibration transducer (1) adapted to be excited by a sweep signal within a desired frequency range. At least one further and passive vibration transducer (2,3) is positioned at such small spacing (B) between the transducers that interaction therebetween provides for a relative enhancement of the frequency response of the whole source assembly at low frequencies.

Abstract: A depth control apparatus for seismic streamers, comprising a central unit adapted for inserted mounting in the streamer substantially in axial alignment with the streamer, a housing which can rotate about the central unit and carries at least one control wing being angularly adjustable about a transverse axis adapted to be substantially horizontal in operative position, and an electric motor for adjusting the angle of the control wing about the transverse axis. The motor is located in the central unit and is adapted to have its current supply through the streamer. The control wing is so arranged on the housing that the transverse axis in operative position runs underneath the central unit. A transmission mechanism for the angular adjustment of the control wing by means of the motor, comprises a slide member which can be moved in the axial direction of the central unit and preferably surrounds the central unit.

Abstract: Apparatus for towing a surface buoy or float, in particular a reference position buoy (1), from a marine seismic streamer (4) being adapted during operation to be immersed in the sea. The towing takes place by a means of a length of cable or the like (5A,5B) being attached to a section of the streamer and to the surface buoy respectively. At an intermediate portion of the length of cable (5A,5B) there is provided a weight or deflector device (2) being adapted during towing to impose an angular deviation of the length of cable so that the direction thereof downwards (5A) and upwards (5b) from the weight or deflector device (2), forms a mutual angle (Vb) differing significantly from 180.degree.. The point of attachment (3) at the streamer is located at an active section (4) thereof.