Three-dimensional geophysical characterization of the La Rambla and Zafra de Z´ancara anticlines (Loranca Basin, Central Spain)
C. Ayala, F.M. Rubio, C. Rey-Moral, M.I. Reguera and C. Biete
Journal name: Geophysical Prospecting
Issue: Vol 67, No 3, March 2019 pp. 580 - 594
Info: Article, PDF ( 15.57Mb )
The Zafra de Z´ancara anticline (also known as the El Hito anticline), located in the Loranca Cenozoic Basin (part of the Tagus Basin, Central Spain), had been studied by several oil companies during the late 1960s and early 1970s. In 2009, within the ‘Plan for selection and characterization of suitable structures of CO2 geological storage’, this anticline was selected as a potential CO2 storage site. A preliminary three-dimensional geological model, based on five geological cross sections that were constrained with the interpretation of the available seismic profiles (that are rather old and do not have very good quality), was created. With the aim of improving the geological knowledge of the Zafra de Z´ancara anticline and helping to investigate the suitability of a nearby anticline, namely La Rambla, as another structural closure that might make it a possible CO2 storage site, a local gravity survey (1 station every km2) was carried out in the area, seven new geological cross sections, based on these existing seismic profiles and field geology, were build, and a new three-dimensional geological model that included both anticlines, improved through three-dimensional stochastic gravity inversion, was constructed. The densities needed for the geological formations of the model come from the analysis of rock samples, logging data from El Hito-1 drillhole and petrophysical information from Instituto Geol ´ ogico y Minero de Espa ˜ na database. The inversion has improved the knowledge about the geometry of the anticlines’ traps and seals as well as the geometry of the basement relief and the structural relationship between basement and cover.