Vol. 330 No. 9 (2019)

DOI https://doi.org/10.18799/24131830/2019/9/2276

INFORMATIVITY OF GEOMETRIC ATTRIBUTES FOR PREDICTING RESERVOIR FRACTURES ON THE EXAMPLE OF HYDROCARBONS DEPOSIT IN TOMSK REGION

In recent years, due to depletion of traditional hydrocarbon reservoirs, interest in, the permeability of which is mainly due to the degree of their fracturing collectors, has significantly increased. Prospects for mapping fractured zones are associated with seismic exploration. In essence, it is the only ground geophysical method that allows obtaining a detailed three-dimensional image of the geological environment. However, the possibilities of seismic exploration are limited by its resolution and the structure of the reservoir intervals. Based on the results of our earlier comparative analysis of the latest techniques and technological methods for studying fractured cavernous reservoirs, the main methods for analyzing seismic data in the sequence in which they are presented in the surveys, were tested. They are ranked by breadth of use and proven effectiveness. By decreasing efficiency, methods for studying fracturing are as follows: 1. Azimuthal analysis of anisotropy with obtaining an effective model of azimuthal anisotropy; 2. Analysis of geometric attributes; 3. Special technologies of migration transformations (duplex migration, etc.); 4. Isolation of the field of scattered waves from a seismic record. Since the seismic survey carried out at the site is standard (not wide-azimuthal, not multi-azimuthal, not multiwave), only methods for analyzing geometric attributes were available to us to study fracturing from the list of the above methods. It should be noted that in this case the prediction of fracturing could be limited by the allocation of zones of fracturing (qualitative analysis). The aim: study of the possibilities of seismic attribute for prediction and identification of tectonic disturbances and fracture enhancement zones. Objects: rocks with a complex structure, intense cavernosity and fracturing reservoirs, due to which tectonic dislocations were formed in the sedimentary cover. Methodology. Some volumetric seismic attributes, such as attributes of coherency and curvature (and its various variants), chaos were calculated. The results were visualized in the Schlumberger Petrel® software interface using available 3D CDP (Total Depth Point Method) seismic data to investigate potential structural and stratigraphic controls and highlight areas with fracture intensity within the study area. Similarly, surface attributes were taken on the horizon in order to create attribute maps and obtain a complete understanding of targets and features to highlight areas of intense crack development. Results. Geometric attributes were analyzed to highlight fracture enhancement zones; seismic attribute calibration based on well data (core) was also considered.

Keywords:

Cavern-pore type reservoirs, fracture type, fracture-porous-cavern type, seismic attributes, geometric attributes, coherency, curvature, chaos, Ant-Tracking

Authors:

Alexander N. Orekhov

Marc Martial Amani Mangoua