A system and method for fine seismic exploration of natural gas hydrate

Abstract

The invention relates to an accurate seismic exploration system and method for natural gas hydrate. The exploration system comprises a geophysical prospecting ship, a towing cable, a control module and at least two seismic sources, wherein the towing cable at least consists one long cable and a plurality of short cables; the main frequency of each seismic source is the same; the short cables are distributed on two sides of the long cable or distributed on one side of the long cable, wherein the length of the long cable is greater than the length of each short cable; the control module comprises seismic collection modules, a clock module and a time service module, wherein the amount of the seismic collection modules is matched with the amount of seismic sources and towing cables; the time service module outputs a time signal to the clock module; the clock module and the seismic collection modules control the motivation moment of each seismic source and the recording moment and recordingduration of the corresponding towing cable; and while the seismic source is stimulated each time, each towing cable simultaneously collects seismic data stimulated by each seismic source. By use of the system, the exploration system consisting of the long cable and the short cables is adopted to obtain high-resolution seismic collection data with an extra small surface element so as to be favorable for the accurate exploration of the natural gas hydrate of a core area.

Description

technical field [0001] The invention relates to the technical field of natural gas hydrate exploration, in particular to a natural gas hydrate fine seismic exploration system and method. Background technique [0002] Natural gas hydrate (referred to as hydrate) is an important energy source. Before the hydrate is exploited, it is necessary to carry out geological exploration of the hydrate. However, the conventional high-resolution streamer multi-channel seismic exploration technology (main frequency 65Hz, surface Yuan 50*6.25m) can no longer meet the high requirements of the current hydrate exploration situation in terms of hydrate resolution, boundary delineation, inversion, and content estimation, and new technologies are urgently needed to support it. [0003] Existing hydrate seismic exploration technologies mainly include: multi-channel 2D / 3D towed seismic, single-channel seismic and foreign P-cable technology. Great success, but due to the constraints of cable spacin...

AI Technical Summary

Problems solved by technology

[0002] Natural gas hydrate (referred to as hydrate) is an important energy source. Before the hydrate is exploited, it is necessary to carry out geological exploration of the hydrate. However, the conventional high-resolution streamer multi-channel seismic exploration technology (main frequency 65Hz, surface Yuan 50*6.25m) can no longer meet the high requirements of the current hydrate exploration situation in terms of hydrate resolution, boundary delineation, inversion, and content estimation, and new technologies are urgently needed to support

[0003] Existing hydrate seismic exploration technologies mainly include: multi-channel 2D / 3D towed seismic, single-channel seismic and foreign P-cable technology. Great success, but due to the constraints of cable spacing and field construction, there are problems such as low main frequency (about 65Hz) and large bins (50*6.25m), which are difficult to meet the needs of fine evaluation of hydrate reservoirs in the future. The single-channel seismic exploration technology cannot obtain the velocity structure and is not conducive to noise suppression. The P cable is designed and produced by the American Geometrics company. Since 2005, several tests have been carried out successively, and the details of the hydrate BSR and fluid channels are very clearly described (mainly Frequency 90-130Hz), but still can not get the velocity structure