STATISTICAL ANALYSIS OF DIPMETER LOGS FROM EXPLORATION WELLS IN THE DRAVA DEPRESSION, NORTHERN CROATIA

摘要

Stratal dip and azimuth data from dipmeter logs recorded at wells in the western Drava Depression (northern Croatia) were analysed in order to assist with subsurface structural interpretations. The dipmeter data came from the Miocene Moslavacka gora, Ivanic-Grad and Kiostar Ivanic Formations at wells Virovitica-3, Rezovacke Krcevine-1 istok, Rezovacke Krcevine-2 and Oresac-I, located near the town ofVirovitica. In contrast to conventional dipmeter interpretations in which dip patterns are represented by "colour trends" (e.g. red represents increasing dip with depth), statistical methods of analysis were used in this study, and consisted of the interpretation of regression curves of dip and azimuth variations with depth. Interpretation of the dipmeter data in this way assisted with the structural interpretation of this folded and faulted part of the Drava Depression. Also discussed are techniques for the selection of typical regression curves which can help in the identification of lithologically similar intervals based on stratal dip and azimuth data. A total of six such curves can be used for structural and depositional interpretation of such intervals.