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To interpret carbonate heterogeneities and understand the correlation between these rock features and their petrophysical parameters, an integrated dataset formed by thin section, core sample description, image log, and nuclear magnetic resonance analysis were used. This interactive approach enables the comparison of depositional and acoustic image log facies and their permo-porous behaviors. The advantage of the proposed integration lies in the ability to expand the interpretation of depositional facies to the entire imaged well interval. The results highlight the occurrence of six depositional facies, four ultrasonic image log facies, and two intervals with different permo-porous behavior present at Macabu Formation (Aptian, Campos Basin). Based on core sample and thin section analysis, three in situ carbonates were described: F1 – shrubstones, F2 - spherulitic grainstone-wackstone and hybrid forms, F3 - stevensitic claystone with spherulites, and others like transported facies: F4 - intraclastic grainstone-rudstone, F5 - laminated Detrital packstone-grainstone, and F6 - laminated dolomudstone. According to ultrasonic signal amplitude and structural patterns, such as descriptive criteria, the ultrasonic image log facies characterization resulted in: UIF1 - bright-heterogeneous, UIF2 - dark laminated, UIF3 - bright massive, and UIF4 - dark dendritic. The NMR well log analysis helped us divide the formation into two main zones, the first with good reservoir behavior and the other with poor behavior. This approach resulted in the correlation between facies and reservoir quality, indicating those with better fluid flow potential, in which facies F1, F2, F4, and UIF4 showed the best results. Finally, the integration between the different facies analysis demonstrated that several lithofacies may have the same appearance in the acoustic image, leading them to integrate the same ultrasonic image facie, this occurs due to their similarity in roughness. • Airborne geophysical data applied to map mafic dike. • We have produced a new map of mafic dikes across the Borborema Province, NE Brazil. • Several new dikes are identified in the Borborema Province using magnetic and structural criteria. • New 1388 mafic dike are identified by magnetic anomalies. • The areal extension of mafic dikes is at least 6.8 × 106 km2. • NE trend of Rio Ceará-Mirim Dike Swarm is better characterized. [ABSTRACT FROM AUTHOR]

Natural open fractures have been reported in the Barra Velha Formation (BVE) in the pre-salt lacustrine carbonate reservoirs in the Santos Basin offshore Brazil. These fractures contribute to excess permeability i.e., well test permeability is significantly larger than core permeability or log derived permeability, and they are therefore important for the fluid flow in the reservoirs during production and injection. In this paper we summarize the characteristics of natural open fractures in acoustic borehole image logs (BHI) in 19 wells from the BVE reservoirs and discuss their distribution, occurrences and formation. The data quality is overall good and consistent so that results can be compared between wells. The P21 fracture intensity, which is fracture trace length per area (bore hole wall) was used, instead of Terzaghi corrected P10 fracture intensity which do not distinguish between minor and major fractures. Mean P21 fracture density shows a variation of 2 orders of magnitude between interpreted wells. Data binning was used in the analysis of P21 fracture intensity vs petrophysical parameters to reduce the effect of sampling volume being much smaller than the representative elementary volume (REV) of the fracture pattern. P21 fracture intensity shows a positive correlation with silica content, which varies in the carbonates, whereas the porosity is less important for fracture intensity. The occurrence of fractures is also associated with vug-fraction estimated from the acoustic BHIs. Fractures are also frequent in fault damage zones, above and below cavities. The main orientation of the fractures is NNW-SSE, that is in the same direction as the dominating fault trend, and this indicates a structural control on fracture formation. Natural open fractures are rare in high porosity rocks with a shrubby or grainy texture, and also in intervals with a conglomeratic appearance in the BHI image logs. • We characterise fractures and discuss their formation using acoustic BHI logs from pre-salt carbonates in the Santos Basin. • Fracture density correlate with silica content, are frequent in fault damage zones and are associated with presence of vugs. • The dominant fracture orientation is NNW-SSE i.e., in the same direction as the main fault trend in the area. [ABSTRACT FROM AUTHOR]

Assessing the geometry, flow dynamics and, petrophysical properties, of a carbonate reservoir has been a key task for a long time, but the challenges presented by these highly heterogeneous rocks seem endless. Geophysical well logs have been, over this time, a very important tool in this type of evaluation. The applications of logs, in the evaluation of the geological formations, range from the estimation of lithology, porosity, permeability and mechanical properties. Commonly, logs are classified as basic or special. The basic logs, used in this work, are the gamma ray, resistivity, density, neutron and sonic. The special ones, utilized in the study, are the acoustic image and the photoelectric logs. From the analysis of the basic logs, the lithologies were identified, the reservoir was delimited and zoned, the fluids and the contact between them were identified and, petrophysical properties, as porosity and water saturation, were estimated. The total porosity was estimated using the empirical relationships from density, neutron and, sonic logs. The identification of the porosity type, such as fractures, vugs etc., although, was determined from the acoustic image borehole wall, as well as different geological structures, such as lithological contacts, inclined layers, natural and induced fractures, besides the identification of caves. The photoelectric log helped to identify the different lithologies, which were compared with those derived from the basic logs. Thus, the main objective of this work was the joint use of the basic and specialized logs, in the characterization of a carbonate reservoir in the Campos Basin, using real data from the post - salt layer. In the end, the advantages and disadvantages, in the usage of these tools, were indicated, as considerably as the applications and care with the occurrence of no geological structures. The joint use of the data and, the adopted methodology proved effective in the characterization of this reservoir. • Basic logs estimated lithologies, boundaries, fluids, porosity and, the water saturation. • The geological structures that produce them were detailed by the acoustic images. • Photoelectrical log was used to assist in the determination of the lithology. • Uncertainties will only be reduced in conjunction with other available data wellbore data. • Amplitude acoustic images were much more efficient than the transit time images. [ABSTRACT FROM AUTHOR]