Fine-Amplitude Structure Localization Using Correlation Coefficients Between DAS VSP Data and Surface Seismic Data at the Same Interface.

As conventional reserves of oil and gas resources continue to decrease, the target of seismic exploration is progressively shifting to the unconventional field. Fine-amplitude structure can form rich oil and gas resources under favourable conditions, which is an important unconventional reservoir. Surface seismic exploration is capable of revealing a large range of stratum structure, but its resolution is limited, and it is unable to detect fine-amplitude structures of small closure. Distributed acoustic sensing (DAS) vertical seismic profile (VSP) technology is a new, high-precision method for oil and gas resource detection, but it can only collect stratum information from a small area in the vicinity of the well. To explore the stratum structure with finer profile information, expand the identification range, and takes full advantages of these two exploration methods, this letter proposes the stratum correlation technology to calculate correlation coefficients between DAS VSP data and surface seismic data at the same interface. By analyzing the shape and variation of the correlation coefficient curves, it is possible to locate and extend the information on fine-amplitude structure with a closure of less than 12m. Stratum correlation processing can improve the accuracy of surface seismic data, clarify the existence and location of fine-amplitude structures, and extend the lateral extent of borehole DAS fine profiles.