Análisis sismoestratigráfico y definición de litotipos a partir de interpretación sísmica 2D y registros eléctricos de pozos en la secuencia cretácica, en la zona de plataforma de la cuenca de los Llanos Orientales, Colombia.

Abstract

During the last 15 years, there was limited geological knowledge of the Llanos basin, based on the premise that the Cretaceous units only represented an economic importance in the areas close to the piedmont area, therefore, the majority of investigations in The platform area was focused on the tertiary rocks, leaving aside the possibility of studying the Guadalupe, Gacheta and Une Formations. In order to contribute to the geological knowledge of the Llanos Cretaceous sequence, a seismo-stratigraphic analysis and definition of lithotypes was developed, based on the study of electrical logs from 4 wells, geological interpretation of 10 2D seismic sections, correlation of information in time and depth, by means of synthetic seismograms and obtaining structural maps in time at the top of the interpreted formations. Three (3) lithostratigraphic formations were identified and characterized; The Une Formation, demarcating the first Cenomanian seismic sequence, is made up of a very thick succession of sandstone intervals and underlies the Gachetá Formation, this unit demarcates the second seismic sequence of the Campanian, it is made up of very thick bundles of claystones and fissile siltstones and underlies the Guadalupe Formation, this unit demarcates the third seismic sequence made up of powerful sandstone intervals. Finally, it was observed that the Cretaceous sequence is configured as a homocline with normal synthetic and antithetical faults, dipping and slightly increasing its thickness towards the west, coinciding with the depocenter of the basin.