Comparative analysis between laboratory measurement and numerical simulation to evaluate anisotropy in Coquinas from Morro do Chaves Fm. – A Brazilian pre-salt analog Lucas Oliveira, André Martins, Marco Ceia, Roseane Misságia, Herson Rocha, Natan Santarém, Jessica Moreira, Irineu Lima Neto. North Fluminense State University, Brazil (UENF/LENEP) Summary The Brazilian Pre-Salt polygon is a primary petroleum area and represents more than 60% of the national petroleum- producing; the reservoirs comprise carbonate rocks exhibiting various depositional textures and facies, such as the Coquinas, which emphasizes the magnitude of the study of those rocks. Reservoir carbonate rocks may have a complex pore structure, depositional texture, and mineralogical composition, resulting in different parameters directly affecting the elastic properties. With the development of technologies, it is possible to employ new techniques in reservoirs characterization, such as Digital Rock Physics, that attempt to supplement or replace the need for relatively slow and expensive laboratory-based measurements from consolidated rock physics models. Then, this work used estimates of elastic moduli and P- and S-waves integrating laboratory measurements and numerical simulations from the Digital Rock Physics technique to evaluate elastic anisotropy. Introduction The pre-salt plays in Brazil comprise an area that spans over three sedimentary basins: Santos, Campos, and Espírito Santo. Those reservoirs are Brazil's most productive petroleum system and placed that country among the world's top ten producers. The main microbialite facies of those pre- salt rocks consist of stromatolites, Coquinas and other rocks associated with hydrothermal origin (Mohriak, 2015). Pepin et al. (2014) reported that the coquinas from Morro do Chaves Fm., located in outcrops of Sergipe-Alagoas Basin, can be considered analogs of the pre-salt coquinas. An Example is the coquinas from Itapema Fm. in Santos Basin (Fournier et al.,2018) and Coqueiros Fm. in Campos Basin (Vasquez et al., 2019). With the current developments in imaging/computational techniques and resources, Digital Rock Physics (DRP) has been emerging as a new computational field of study, investigating and computing porous rocks' physical and fluid flow properties. The DRP objective is to supplement the traditional laboratory measurements, which are time- consuming, with faster numerical simulations that allow the parameter space to be analyzed more exhaustively. These computational developments allowed visualization and compute effective properties on these large 3D micro- computed tomography (μCT) images. Furthermore, using highly innovative, very fast, and memory-efficient numerical methods based on the Fast Fourier Transform (FFT) approaches (Kabel et al., 2015); actually, several researchers and engineers are more interested in studying effective homogenized material properties such as stiffness, strain, stress, or elastic moduli. This work aims to characterize the elastic properties of those analog rocks, combining laboratory measurements and Numerical simulations by DRP, providing insights into the velocities of P- and S-waves and the elastic anisotropy. Data Set The data set consists of Coquinas core plugs samples, 10 samples with 1.5" and 4 with 1" in diameter, from Morro do Chaves Fm., Sergipe-Alagoas Basin, Brazil. This formation symbolizes an analog of the Aptian bioclastic deposit at the Pre-salt level at Campos and Santos Basin. Coquinas from Morro do Chaves Fm. mainly comprise mollusk shells and calcite as a primary mineralogical component. However, ostracods, gastropods, and other bioclasts may also be present in the formation. The matrix contains micrite, clay, siliciclastic sand dominated by quartz (Santarém et al., 2021). Methodology To develop this work, we applied two methods to determine elastic moduli (Bulk and Shear) and seismic waves. The first method, a conventional ultrasonic transmitted test to determine P- and S-wave established by the D2845-08 standard (ASTM D2845-08, 2008), using an advanced triaxial system that includes a Rock Mechanics straining frame and P- and S-wave piezoelectric transducers (in Rock Physics Laboratory at UENF/LENEP). The setup uses a thin layer of Shear Gel as a couplant between the platens and sample of 1.5" in diameter, with a confinement pressure load of 5-8 MPa on the X-, Y- and Z-axes. The results presented of 1.5'' core samples were measured at 8MPa. After that, we use samples with a diameter less than 1.5" (2.54 cm). Moreover, because of the smaller diameter, not possible to use load pressure in these samples, using the transducers in contact with the sample on the X-, Y- and Z-direction. The apparatus is composed of a pulse generator unit (transducer Pulser - P-S1-S2 signal input), three pairs of piezoelectric transducers (transmitter-receiver): one P-wave (1.3 MHz) and two independent orthogonally polarized S-wave (900 kHz) at each vertical (Z-axis, coupled in steel platens) and lateral (X and Y-axes) positions, and an oscilloscope to detect the signal output. 10.1190/image2022-3751590.1 Page 2338 Second International Meeting for Applied Geoscience & Energy © 2022 Society of Exploration Geophysicists and the American Association of Petroleum Geologists Downloaded 08/20/22 to 3.235.223.19. Redistribution subject to SEG license or copyright; see Terms of Use at http://library.seg.org/page/policies/terms DOI:10.1190/image2022-3751590.1