Wang, X.Y., He, Z.H., Li, Y., Zhang, G., Zhang, H., Chen, J., Li, M., Wang’ Y. and Yang, Z.C., 2019. Application effects of swath 3D geometry in the foothill regions of western China. Journal of Seismic Exploration, 28: 347-361. Abundant oil and gas resources have been discovered in last decade in the foothill regions of western China, which implies a great potential for oil and gas reservoir in these areas. However, the ‘double-complex’ seismo-geological features of complex near-surface and complex subsurface result in a low signal to noise ratio (SNR) of seismic data, restricting further breakthroughs in these areas. In practice, wide-line 2D and high-density 3D are widely employed techniques in the foothill regions of western China. It has been found that wide-line 2D geometry can improve the signal to noise ratio (SNR) of seismic data effectively, but the imaging accuracy is relatively lower than conventional 3D. “Two-wide One-high” is a technology that stands for wide azimuth, wide frequency bandwidth, high-density 3D seismic exploration, which could record more complete field information, fewer alias and more low frequency signals. Featured by high-density seismic acquisition, “Two-wide One-high” has achieved significant improvements in data quality, and many cases have been carried out in different regions of China in last decade. High-density 3D geometry characterized by small bin size, high fold number and wide azimuthhas significantly improved the SNR and imaging quality of seismic data in these areas, which improve success rate of exploratory drilling. However, investment in high-density 3D in mountain areas is still not economical since the amount is large and the risk is high. Particularly, in the downturn of oil & gas industry, technology and economy must be considered as a whole. A reasonable geometry for seismic acquisition should balance the cost and risk while obtainingdesired SNR and accuracy. In this paper, a novel acquisition geometry named the swath 3D technique has been proposed. With wide application of the proposed swath 3D seismic acquisition technology, acquisition cost and exploration risk have been reduced, meanwhile the SNR of seismic data has been effectively improved and the seismic imaging results havebeen also significantly enhanced.