The effect of full-azimuth local angle domain (LAD) imaging on the study of terrigenous and carbonate reservoirs under complex in-situ conditions at an eastern Siberian field

The EarthStudy 360 full-azimuth local angle domain (LAD) imaging and analysis technology, developed by Paradigm, appeared on the geophysical services market in 2012. GazpromNeft NTC, a high-tech company that strives to incorporate the most advanced systems into its operations, did not let this opportunity pass by. A pilot project to test LAD imaging was undertaken in 2014. The study’s most significant findings were anisotropy intensity and direction determinations in terrigenous and carbonate reservoirs, and improved acoustic impedance convergence calculated on a combination of advanced technology results and GIS data. In 2015 GazpromNeft NTC used the technology to assess 3D full-azimuth angle domain survey data in an Eastern Siberian field. Historically, Eastern Siberia has been one of the most difficult areas for seismic studies attempting to prospect for and predict reservoir properties. Complex relief and subsurface velocity heterogeneity in both vertical and lateral directions creates problems for seismic survey operations and for seismic data processing. The greatest challenges occur in depth processing, where specific complexities hinder the development of a depth/velocity model, beginning with near-surface formations and the top portion of the geologic profile. Local lithological variations in the lateral direction, accompanied by the surface exposure of rocks of various ages and lithological characteristics (from carbonates to clays, salt-bearing strata, and sometimes trapped intrusions) make it necessary to develop complex velocity models and apply full-azimuth depth surveys which traditional approaches and migrations, based on the Kirchhoff integral, cannot provide. Cambrian, Jurassic and Quaternary rocks with P-wave velocities of 5000-5500 m/s, 3000-3500 m/s, and 900-1200 m/s, respectively, are exposed at the surface of the survey area.