Multi-Scale Analysis of Well Logs in Fields from USA and Venezuela

Análisis Multiescala de Registros de Pozo en Campos de EE.UU. y Venezuela

Abstract

In this study, profiles of six wells are analyzed, three located in the West Waha- Worsham Bayer fields (Texas, USA) and the other three in the Dragon Field (Venezuela), in order to identify stratigraphic boundaries and determining cyclicities associated with orbital variations in the Thirtyone and Cubagua formation, respectively. For this purpose, the Wavelet Transform, Continuous and Discrete, was used to decompose Gamma Ray (GR) and resistivity (Rt) well logs. The data were processed to obtain scalograms and to perform multi-solution analysis of the signals. The scalograms allowed for the discrimination and localization of anomalies at different scales, which were associated with stratigraphic boundaries. This served as a basis for the multiresolution analysis used to recognize sedimentary cycles attributable to Milankovitch frequencies. The identification of periodicities near the theoretical values of Milankovitch suggests the influence of these cycles on the sedimentation of the formations studied. The combination of GR logs and scalograms allowed for a detailed lateral correlation between wells and the calculation of the sedimentation rates in the fields. The results obtained allow us to conclude that the Wavelet Transform provides useful information for the characterization and quantitative division of the sedimentary cycles present in the stratigraphic units considered. This kind of analysis, of a more quantitative nature, proved to be very useful to improve the understanding of sedimentary processes and their relationship with Milankovitch cycles in both fields, suggesting its implementation for a more detailed characterization of an area of interest.