Natural Gas Industry B (Dec 2021)
Key technologies for complex surface seismic acquisition in the Sichuan Basin and their application effect
Abstract
The earth surface in the Sichuan Basin and its periphery is geologically complex, which causes low signal-to-noise ratio of seismic data, poor imaging quality of seismic profiles and great difficulty in data acquisition. In order to ensure high-quality operation of the seismic survey project in the complex surface of the Sichuan Basin, researchers have been working continuously to solve the bottleneck problems in the seismic acquisition technology for complex surface in recent years. In addition, the upgrading of acquisition technology and operation capacity is promoted effectively by means of technical innovation, and a series of key technologies for seismic acquisition are developed. And the following application results of this series of technologies are obtained. First, the optimization design technology of the geometry based on wave equation forward modeling and actual data, combined with prestack migration imaging can show the influence of different acquisition schemes on the prestack imaging effect of complex targets more directly, which makes the seismic acquisition scheme more economic and effective. Second, by extracting landform risks and surface obstacle information intelligently, combined with field fine reconnaissance, landform risk identification and hierarchical evaluation and indoors intelligent optimization of well-shot physical point deployment are conducted, and thus the GIS+ intelligent deployment technology of shot point in complex surface is formed, which effectively reduces the risks of operation. Third, the cavity excitation technology which reduces the initial pressure of explosive pulse and extends the explosive action time of explosives can increase the conversion rate of rock excitation energy into effective elastic wave energy and the reflected energy and improve the quality of seismic single shot data. Fourth, combination of the automatic evaluation technology for field seismic data acquired in mountainous regions and the KL-GMLiveQC1.0 software can improve the evaluation efficiency, reduce the evaluation cost and ensure the high-quality acquisition of seismic data in complex surface. In conclusion, this series of key seismic acquisition technologies greatly improve the signal-to-noise ratio and resolution of seismic data, lay a foundation for fine reservoir prediction, and ensure the continuous important breakthrough of three-dimensional natural gas exploration and development in the gas fields of marine carbonate rock, shale gas, volcanic rock and shallow tight sandstone gas in the Sichuan Basin.
