Perpustakaan Digital ITB

This study evaluates selected empirical Unconfined Compressive Strength (UCS) correlations for Chicontepec sandstone and applies the results to sand onset screening. The scope is limited to a screening level evaluation using a published benchmark core dataset. The main objective is to assess how UCS correlation selection affects critical drawdown pressure, drawdown margin, and sanding tendency interpretation under limited geomechanical and production data. The workflow consists of literature mapping, dataset preparation, unit standardization, empirical UCS calculation, error evaluation, UCS scenario classification, and shear failure-based screening using the Yi Valkó Russell model. The evaluated correlations use porosity, acoustic transit time, Young’s modulus, and median grain diameter as input parameters. Laboratory UCS data from Core Samples A, B, and C are used as benchmark references. Representative UCS scenarios are defined as laboratory average reference, lower bound, mid bound, and upper bound, then evaluated under assumed bottom hole flowing pressure cases of 20% and 30% of reservoir pressure. The laboratory UCS values for Samples A, B, and C are 80.68 MPa, 71.72 MPa, and 73.95 MPa, with an average of 75.45 MPa. McNally gives the closest average UCS estimate at 74.12 MPa, while Erfourth gives the lowest sample based mean absolute percentage error of 11.23%. McNally is selected as the lower bound scenario, Silva/Rabe ???? ? ???? ? ???????? as the upper bound scenario, and the mid bound scenario is calculated as 78.91 MPa. The Yi Valkó Russell screening results show negative critical bottom hole flowing pressure for all UCS scenarios. These values are not interpreted as operating pressures but indicate that the calculated shear failure threshold lies outside the physical Pwf range. Therefore, the critical drawdown required to initiate shear failure is higher than the drawdown limit that can be reached within the physical Pwf range. For both bottom hole flowing pressure cases, all scenarios remain below threshold, indicating a very low sanding tendency within the evaluated screening conditions. This study provides an integrated workflow that connects empirical UCS correlation evaluation with sand onset screening for a heterogeneous sandstone dataset. The main contribution is showing that UCS correlation selection should not rely only on numerical error, but also on input basis, geological relevance, rock fabric, and the engineering impact of each correlation on critical drawdown interpretation.