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The precise landing and steering of horizontal wells using conventional mudlogging and Logging While Drilling (LWD) data is a particular challenge for the Lebăda Field, offshore Romania. The use of a new technique of elemental geochemistry analysis (or chemosteering) became an option for the identification of Cenomanian, Turonian–Coniacian–Santonian, Campanian and Eocene strata. This has enabled more accurate placement of the horizontal development wells within the desired reservoir target interval. Geochemical data enabled the identification of chemostratigraphic zones C1, C2, C3 and zone R that correspond to the reservoir section. The application is a result of the geochemical zonation performed using elements and ratios that are sensitive to depositional environment, sea level change, heavy mineral concentrations and siliciclastic input namely: Sr/Ca, Zr/Th, Si/Zr and Si/K. In ascending stratigraphic order, the ratio thresholds of zone C3 are Zr/Th > 11, Sr/Ca > 1.1, Si/Zr < 22 and Si/K < 19, while zone R corresponds to 5.5 < Zr/Th < 11, Sr/Ca < 1.1, Si/Zr > 22 and Si/K > 19. C2 zone is defined by Zr/Th < 5.5, Sr/Ca > 1.1, Si/Zr < 22 and Si/K < 19 and C1 zone is characterized by Si/Zr > 22 and Si/K > 19. The selected geochemical ratios indicate a strong geochemical zonation. In the case of offset wells, 85.9% of the data confirmed the proposed classification and 89.4% for the real-time application case. The zone R shows a strong contrast with the surrounding formations facilitating critical decisions during well placement and geosteering, increasing the reservoir exposure by 28%. The quantitative approach delivered very valuable results, providing a solid foundation to define correlation and well landing intervals. Simultaneously, the cost of the method represents a fraction of the LWD cost and 0.15% of the total project cost, making it very cost effective and a standard approach for future projects.

The present paper is focused on the mineralogical analysis of soils from two apple orchards (Fălticeni and Sârca) from the North-Eastern region of Romania, geologically located on the Moldavian Platform. 20 samples have been analysed from both areas (11 from Fălticeni and 9 from Sârca), through SEM-EDS and XRD (powder method). The main minerals which were identified are quartz, feldspar, illite and partially calcite. As secondary minerals and trace minerals, chlorite, smectite, glauconite, kaolinite, pyrite, apatite and oligoclase were also identified. Generally, the most abundant mineral is quartz and while for the Sârca area illite is present in notable quantities, in the samples taken from Fălticeni, calcite was identified as a main mineral alongside quartz. The main factor which controls the distribution of minerals within the soils from the two orchards is the geological substratum. The results, correlated with the geochemistry of the soils reveal differences between the soils from the two areas, in matters of their ability to bond certain microelements, especially those with a notable toxic potential, as a function of their mineralogical composition. The principal components' analysis suggests that the distribution of microelements is controlled by the presence of clay minerals, oxides and amorphous material, while Cu points towards an anthropic origin due to agricultural practices. [ABSTRACT FROM AUTHOR]

The Totea-Vladimir structure belongs to the Getic Depression, which was formed at the beginning of the Lower Miocene in the South Carpathians foredeep. In terms of hydrocarbon accumulations, the Sarmatian and Burdigalian formations are of major trade interest. In this context, several technical problems were encountered at the entry of the drilling bits into the Burdigalian formations due to certain abnormal pressures, although their possible occurrence has been monitored in the geologist's cabin. The method used by the geologist was generically named "the Corrected dc-exponent", and it pointed out the entry of the drilling bits into the overpressured Burdigalian formations, but it failed to establish the correct value of the recorded pressures; therefore, the necessary measures to avoid the kicks were not taken in advance. Consequently, in the present paper, to correctly establish both the entry into overpressured areas as well as the value of their pressure, it was used the method proposed by Bourgoyne and Young (1974) which, applied to "H" well, it rightly indicated the magnitude of the pressure at the entry of the drilling bit into the Burdigalian formations. Regarding the causes of the pressure deviations in the Burdigalian formations opened by the "H" well, this paper shows that their presence is closely related to the tectonic events that have controlled the completion of the Totea-Vladimir structure architecture during the Sarmatian period. [ABSTRACT FROM AUTHOR]