Abstract: A seismic node (1) for an ocean bottom seismic survey comprising: At least one seismic sensor capsule (2), a seafloor casing (6) comprising a lower surface configured to make contact with a seabed. The seismic sensor capsule (2) comprises first engagement means; the seafloor casing (6) comprises second engagement means (10). The first and second (10) engagement means are adapted to releasable engage with each other whereby the seismic sensor capsule (2) is releasably fastened to the seafloor casing (6). The seismic sensor capsule (2) is adapted to be removed from the seafloor casing (6) after a certain time T. The seafloor casing (6) is configured to be left permanently on the seabed.

Abstract: An apparatus and methods for loading and unloading of sensor capsules (9) into or out of seismic node casings (5) forming part of a seismic cable (19) to be deployed or retrieved by a vessel (18), the apparatus comprises: a trolley (3) with room for at least one sensor capsule (9), the trolley (3) is moveable back and forth in a direction essentially corresponding to the longitudinal direction (24, 25) of the seismic cable (19); a support structure (12) for the trolley (3); a latching mechanism (7) for latching the trolley (3) to a node casing (5), and at least one inserting/withdrawing mechanism (8, 11) for inserting and withdrawing the sensor capsules (9) into or out of the node casing (5).

Abstract: An apparatus and methods for loading and unloading of sensor capsules (9) into or out of seismic node casings (5) forming part of a seismic cable (19) to be deployed or retrieved by a vessel (18), the apparatus comprises: a trolley (3) with room for at least one sensor capsule (9), the trolley (3) is moveable back and forth in a direction essentially corresponding to the longitudinal direction (24, 25) of the seismic cable (19); a support structure (12) for the trolley (3); a latching mechanism (7) for latching the trolley (3) to a node casing (5), and at least one inserting/withdrawing mechanism (8, 11) for inserting and withdrawing the sensor capsules (9) into or out of the node casing (5).

Abstract: An ocean bottom seismic cable recording apparatus comprising a plurality of seismic node casings (1), said node casings being separated from each other by separate stress member sections (2), each stress member section having acoustic decoupling arrangements (3) at each end connecting to said seismic node casings (1), and where each seismic node casing comprising an autonomous sensor capsule (5) for sensing and recording seismic data, and wherein the autonomous sensor capsule (5) is removable from said seismic node casing (1), and wherein each seismic node casing (1) further comprising an inner compartment (4) accommodating the autonomous sensor capsule (5).

Abstract: An ocean bottom seismic cable recording apparatus comprising a plurality of seismic node casings (1), said node casings being separated from each other by separate stress member sections (2), each stress member section having acoustic decoupling arrangements (3) at each end connecting to said seismic node casings (1), and where each seismic node casing comprising an autonomous sensor capsule (5) for sensing and recording seismic data, and wherein the autonomous sensor capsule (5) is removable from said seismic node casing (1), and wherein each seismic node casing (1) further comprising an inner compartment (4) accommodating the autonomous sensor capsule (5).

Abstract: A method for simultaneous collection of seismic data of shallow and deep targets, in which two seismic streamers are towed at different water depths (1 and 2 in FIG. 2), and only one acoustic source of seismic signals is used. The seismic data recorded by the different streamers are mixed in a subsequent processing step, seismic data being weighted before being mixed by a weight which is made dependent on the recorded two-way travel time for the respective streamers, so that data from one or several streamers located at the least water depth receive a weight which decreases with travel time, whereas data from a corresponding number of streamers of greater depths receive a weight which increases with travel time.