Elemental geochemistry of the Upper Cretaceous reservoir and surrounding formations applied in geosteering of horizontal wells, Lebăda Field – Western Black Sea

摘要: The precise landing and steering of horizontal wells using conventional mudlogging Logging While Drilling (LWD) data is a particular challenge for the Lebăda Field, offshore Romania. use new technique elemental geochemistry analysis (or chemosteering) became an option identification Cenomanian, Turonian–Coniacian–Santonian, Campanian Eocene strata. This has enabled more accurate placement development within desired reservoir target interval. Geochemical chemostratigraphic zones C1, C2, C3 zone R that correspond to section. application result geochemical zonation performed elements ratios are sensitive depositional environment, sea level change, heavy mineral concentrations siliciclastic input namely: Sr/Ca, Zr/Th, Si/Zr Si/K. In ascending stratigraphic order, ratio thresholds Zr/Th > 11, Sr/Ca 1.1, 22 Si/K 19. C2 defined by selected indicate strong zonation. case offset wells, 85.9% confirmed proposed classification 89.4% real-time case. shows contrast with surrounding formations facilitating critical decisions during well geosteering, increasing exposure 28%. quantitative approach delivered very valuable results, providing solid foundation define correlation intervals. Simultaneously, cost method represents fraction LWD 0.15% total project cost, making it effective standard future projects.