Marine data acquisition node

#Techniques for marine geophysical surveying include seismic surveying and electromagnetic surveying, in which geophysical data may be collected from below the Earth's surface. Marine geophysical surveying has applications in mineral and energy exploration and production and may be used to help identify locations of hydrocarbon-bearing formations. Certain types of marine geophysical surveying, including seismic and electromagnetic surveying, may include using a survey vessel to tow an energy source at selected depths—typically above the seafloor—in a body of water. The energy source can emit energy, for example, seismic or electromagnetic energy, into the body of water that interacts with subterranean formations below the water bottom. Sensors may be used to detect changes in the energy field due to the interaction with the subterranean formation and generate response signals that can be used to infer certain properties of the subsurface formation, such as structure, mineral composition and fluid content, thereby providing information useful in the recovery of hydrocarbons.

#In conventional systems, the sensors may be located in marine data acquisition nodes positioned directly on the water bottom. However, positioning the marine data acquisition node directly on the water bottom may have disadvantages. One such disadvantage may be that the acquired geophysical data may be affected by local variations of resistivity and/or acoustic impedance. For example, stones, bottom structures, and/or varying bathymetry may cause local variations of resistivity and/or acoustic impedance. Another disadvantage that may arise for marine data acquisition nodes positioned directly on the seafloor may be the housing containing the electrodes used for recording an electromagnetic field. The housing and electrodes may protrude from the marine data acquisition node and may bend, for example, due to unsuitable positioning of the marine data acquisition node, which may produce errors in the acquired geophysical data. Yet, another disadvantage that may arise for marine data acquisition nodes positioned directly on the seafloor may be that an acquisition node may get stuck in a bottom structure and/or among stones, which may affect the measured geophysical data.

#These drawings illustrate certain aspects of systems and methods of the present disclosure and should not be used to limit or define the systems and methods.

#FIG. 1 is a schematic illustration of a marine data acquisition node anchored to the water bottom, in accordance with example embodiments.

#FIGS. 2A-2C are schematic illustrations of a marine data acquisition node utilizing multiple weights, in accordance with example embodiments.

#This disclosure is related generally to the field of marine geophysical surveying. Marine geophysical surveying may include, for example, seismic and/or electromagnetic surveying, among others, in which geophysical data may be collected regarding subsurface formations.

#In some embodiments, a marine data acquisition node may be provided that comprises a base and a geophysical sensor coupled to the base. In accordance with example embodiments, the base of the marine data acquisition node may be positioned near the bottom of a body of water, such as, for example, a water bottom. However, the base of the marine data acquisition node may not be positioned directly on the water bottom. In contrast to some currently used approaches in which the marine data acquisition node may be positioned directly on the water bottom, the base of the marine data acquisition node may have a buoyancy such that the base may float a certain distance above the water bottom. By way of example, embodiments may further include a weight coupled to a line of a certain length. Without limitation, the line may couple the weight to the base. In operation, the weight may be positioned on the bottom of the body of water such that the base of the marine data acquisition node floats a certain distance above the water bottom.

#Although the following discussion relates to a first marine data acquisition node 100, it should be understood that it also equally applies to a second marine data acquisition node 200, as the first marine data acquisition node 100 is substantially identical to the second marine data acquisition node 200 of the present disclosure. Further, marine data acquisition nodes in addition to second marine data acquisition node 200 may also be substantially identical to first and second marine data acquisition nodes 100, 200. In some embodiments, marine data acquisition node 100 may be used with a dissimilar marine data acquisition node.