Characterization of Dolomite Bodies in Carboniferous Host Rock, Picos de Europa, Northern Spain

Abstract

Dolomitization is a diagenetic process that can alter the rock fabric and thus affect carbonate reservoir quality. This study focuses on late diagenetic dolomite bodies in the Carboniferous host rock in Picos de Europa Province, northwest Spain. The outcrop study allows the characterization of dolomite and an evaluation of its link with sedimentary lithologies and structures. Field observations have shown that dolomite bodies of elongated geometries and varying sizes are present, with the principal length axes parallel to fault planes. The dolomite bodies have higher porosity than the limestone host rock. The geobodies are elongated in the direction of the main faults and their length/width ratio is about 2. Geobodies hosted in different formations vary significantly in dimension, implying that large dolomite bodies are favoured in zones with large fluid input and accumulation to allow for extensive chemical reaction. This study has shown that the dimension and distribution of the dolomite bodies are inherently linked to a combination of factors including the original lithology of the host limestone, pre-dolomitization diagenetic history, and structural elements. This study has also provided an understanding of the diagenetic history in the study area, as well as a dataset of dolomite body dimensions, relevant for subsurface models.