Analysis of present-day stresses and tectonic structures within the Main Dolomite (Ca2) for optimized oil recovery.
Project start date: 09.2015
Project end date: 06.2017
Funding: Polish Oil Mining and Gas Extraction (PGNiG)
The occurrence of systematic opened fracture sets preferentially oriented with respect to contemporary stresses results in the appearance of strong hydrocarbon drainage anisotropy within the fractured reservoir. Such conditions are favorable for reservoir exploitation by directional drilling or with the use of hydraulic fracturing stimulation. The aim of this project was to check if the selected reservoirs in Main Dolomite (Zechstein) has potential in this area, and then to reinterpret the archival data (borehole cores and geophysical data) in terms of occurrence of dominant fracture directions and horizontal stress anisotropy.Initially, we defined theoretical options for the development of systematically oriented open fractures from the 3D seismic image interpretation. These predictions were compared with observations of tectonic (and drilling-induced) structures made on drill core from several boreholes. Tectonic analyses allowed us to distinguish genetic types and density of fractures and to reconstruct the structural stratigraphy within the carbonate reservoir. We have demonstrated the importance of fracture pattern for exploitation of the analyzed reservoir and proposed recommendations as to the cases preferential for use of horizontal drilling or hydraulic fracturing.