Stratigraphy examines the origin, sequence, structure, fossils and lithology, age of rocks, age of formations and layers of the earth's crust. Stratigraphic studies are not only based on knowing the sequence of sedimentary layers in different geological times in order to understand the history of earth events and the evolution of organisms, but also examines the lateral changes of facies in different places. In other words, stratigraphy examines the determination of changes in the earth's layers and their relative age, which is based on the following three principles: 1- The principle of stacking of layers: In this case, the layers may have changed due to tectonic factors, in this condition, the science of stratigraphy is related to the science of structural geology. 2- The principle of continuity in a certain sedimentary layer in terms of petrological properties: in this case, stratigraphy is related to petrology. 3- The principle of similitude in the paleontology of strata: in this case, palaeontology is considered the basis of the science of stratigraphy.

Paleontological data,  particularly derived from microfossils such as foraminifera, are crucial in biostratigraphy, paleoenvironmental reconstructions, and hydrocarbon exploration. Fossils provide high-resolution chronostratigraphic markers and act as sensitive proxies for depositional environments, recording changes in paleoceanographic conditions and diagenetic processes in sedimentary basins, which are essential factors in identifying potential petroleum systems.  The mineralogical composition of bioclasts -calcite, aragonite, or phosphate-makes them sensitive to taphonomic alteration and diagenetic changes such temperature, pressure, and pore fluid chemistry, serving as indirect indicators of subsurface thermal maturity and potential hydrocarbon generation zones. 

The quality of reservoir rocks often correlates with the taphonomy and morphometry of the microfossils present in the deposits. By example, large benthic foraminifera, characterized by coarse, perforated, robust, well-calcified test, are commonly associated with high-energy, high-porosity, and high-permeability facies, shallow marine environments, and, consequently, good reservoir quality. On the other hand, fine-grained assemblages dominated by small, fragile or agglutinated tests, densely packed may indicate tight, low-energy, low-porosity, and low-permeability zones, often reflecting distal or deeper depositional settings. 

Furthermore, advances in geochemical and isotopic proxies (δ¹³C, δ¹⁸O, Sr/Ca) from foraminiferal tests provide improved resolution in paleoenvironmental interpretations, including kay parameters as salinity, productivity, thermal gradients, and others, refining sequence stratigraphy and reservoir prediction models. In summary, integrating morphogroup analysis, taphonomic signatures, and geochemical data offers a powerful, multidimensional approach to refining the stratigraphic framework, guiding drilling strategies, and improving the characterization of heterogeneities in oil reservoirs, particularly in complex depositional settings such as mixed siliciclastic-carbonate systems. 

Geoscientists perform a central role in strategic phases of hydrocarbon exploration and development, acting as surface interpreters based on an integrated analysis of sedimentological, stratigraphic, structural, and geophysical data. The success of the exploratory campaigns is directly related to the geological knowledge applied during the delineation of prospective targets and the location of the initial exploration well, as well as to the planning and optimization of the delineation, influencing drilling success rates and reducing exploratory risk and cost. 

This paper explores the scientific responsibilities of geologists in hydrocarbon prospecting, emphasizing the importance of integration of biostratigraphy, basin modeling, and reservoir characterization. Likewise, technological advances such as machine learning, seismic inversion and high-resolution stratigraphy are redefining how geologists contribute to reserve estimation and field development strategies. 

Considering the global energy contexts with the current energy transition landscape, where exploration efficiency, environmental responsibility, and resource maximization are essential, geologists assume an even more strategic role in enabling data-driven, low-carbon exploration models. The presence of geologists throughout the drilling process-exploratory, appraisal, and development phases-not only ensures optimal well placement but also enables real-time decision-making critical to operational and economic success.