An evaluation of the application of indirect methods of pore pressure gradient prediction in well projects of the Sergipe-Alagoas Basin

Abstract

In the current oil scenario, the exploration of layered oil at great depths is becoming increasingly frequent. Thus, a more complete study of geopressure is necessary, since it is responsible for maintaining the stability of wells. When predicting geopressures, indirect methods are usually used, which consist of empirical correlations that have been calibrated for a certain area. This work’s main objective was to make a comparative and technical analysis of the pore pressures predicted in the Sergipe-Alagoas Basin, using calibrated empirical correlations for the Gulf of Mexico. In the calculation of the pore pressure gradients, data from two wells, X and Y, provided by company Z were used. The results obtained using the indirect methods were compared with the data from formation tests that were performed in the wells during drilling. The results showed that, for well X, the predicted values were conclusive and coherent, as the mean relative errors of the pore pressure gradients ranged from 2.52% to 11.38%, and these values are close to the data measured in the training. As for well Y, the predicted results were representative only in the interval in which the pore gradient measured in the formation test had a normal value.