STUDY OF REGULARITIES OF DISTRIBUTION OF FILTERING PROPERTIES WITHIN COMPLEXLY CONSTRUCTED CARBONATE RESERVOIRS

Abstract

The relevance. Currently, significant volumes of oil are produced during the development of deposits confined to carbonate reservoirs. The presence of various types of voids within such deposits is a factor complicating development of reserves. Studying the features of the geological structure and patterns of development of oil deposits in carbonate reservoirs is a priority task, the solution of which will allow making informed decisions on the management of such assets. One of the main issues, extremely poorly covered in the scientific literature, is the study of the vertical and horizontal components of the permeability of a carbonate reservoir and their distribution within the reservoir. The main aim of the study is to investigate the regularities of the spatial distribution of the vertical and horizontal permeability of the reservoir within the carbonate reef reservoir and their impact on the inflow and production of oil reserves. Object: a complex carbonate reef reservoir – an object of development of one of the oil fields in the north of the Perm Kray. The methods: geological field and hydrodynamic research, methods of mathematical modeling. The results. A specially performed interpretation of hydrodynamic studies of wells operating a carbonate reservoir of one of the fields in the Perm Kray made it possible to obtain information on the values of the reservoir permeability, taking into account its components, as well as to establish the fact of abnormally high values for some wells. For a comprehensive account of the likelihood of increased reservoir permeability within the reservoir under consideration, taking into account the vertical and horizontal components, a special parameter Рcomp is proposed. This criterion makes it possible to reasonably differentiate the layer within the reservoir into conditionally high and low permeability. A diagram of a complex indicator distribution over the area of the deposit was built, on the basis of which the zones with increased reservoir permeability and specificity in the implementation of developing reserves were identified within the deposit. The performed differentiation of reservoirs made it possible to reasonably approach the problem of research and modeling of fluid inflow. Multidimensional mathematical models have been developed that allow not only predicting liquid flow rates with a high degree of reliability, but establishing as well the inflow patterns individually for the selected reservoir zones. Thus, it was found that in the zone of increased permeability, the flow corresponds to a three-dimensional spherical radial model, and the flow rate of the fluid is influenced by both the horizontal and vertical components of the reservoir permeability. In zones of conventionally reduced permeability, filtration corresponds to a two-dimensional flat-radial model, the value of fluid flow rate, in addition to other geological and technological indicators, is influenced only by the horizontal component of permeability.

Keywords

• anisotropy of permeability
• vertical permeability
• reservoir fracture
• fluid inflow
• development of oil reserves
• geological field data
• carbonate reservoir