Key Problems and Techniques of Geophysical Exploration in Underground Salt Cavern for Compressed Air Energy Storage

[Introduction] The world′s first 300 MW compressed air energy storage (CAES) power station is in Yingcheng City, Hubei Province, China. The station uses the existing underground salt cavern which is the best of its tight sealing and high capacity as gas storage, The parameters of the underground salt cavern, such as the underground salt cavity volume, shape, and depth, are crucial for the construction feasibility of the CAES power station. [Method] Based on the Yingcheng CAES power station project practice, this paper analyzed and summarized the many key problems and processing techniques of the high precision 3D seismic geophysical exploration methods in detecting deep salt cavity shapes. [Result] For the purpose of proving the occurrence characteristics of existing underground salt cavity, the 3D seismic geophysical exploration observation system shall be designed to meet the high resolution requirements, and the CDP gridding shall have an accuracy of at least 5 m×5 m, in order to make sure the fold number of the target area is more than 30 times. It is indispensable to improve the salt cavern 3D seismic data quality by conducting static correction and pre-stack denoising. Consistency processing technique is used and accurate velocity field is constructed according to different excitation and receiving conditions to realize precise depth homing. We find the track integral attribute, reflection strength attribute and sweetness attribute have an obvious advantage in identifying salt cavern space distribution, while edge detection attribute has a strong indication on cavity border depiction and connectivity. [Conclusion] Through research on key techniques of data processing and interpretation in geophysical exploration, the salt cavity parameters such as volume, shape, and depth are clearly detected to provide detailed and reliable data support for the salt cavern project. Research on the key problems and techniques of the 3D seismic geophysical exploration for the salt cavern can provide reference to the construction of large-scale CAES power stations of underground salt cavern type.