Job description:

When developing carbonate reservoirs, the zones of intense fracturing are the most promising from the point of view of extraction. The key tool for determining the zones of wells is the discrete fracture model (DFN), which describes the fracture distribution in digital form.

In this paper, the approach to constructing the DFN model consisted in developing the concept of fracture formation, digitizing it in the downhole space based on microimaging studies and distributing properties across the modeled volume (Fig. 1.).

Fig. 1. Diagram of the process of modeling discrete fractures

The proposed concept of fracturing was based on the fact that the formation of cracks in the deposit is associated with the formation of a folded structure of the target horizons. As a result of the formation of this structure, fracturing zones were formed under the influence of tectonic collision and deformation of formations (Fig. 2.). In accordance with the developed concept, zones of high fracture intensity were identified near the axes of folds of the main deformation formations, which correlates with the results of borehole microimaging studies.

Fig. 2. Diagram of the conceptual fracture model.

To obtain inflows, it is necessary that the fracturing is represented by a system of open cracks. A 3D geomechanical model was built to identify areas with open fracturing.

Combining geological, DFN, and geomechanical modeling allowed us to identify areas of the best filtration and capacitance properties of the reservoir.

Fig. 3. The scheme of the process of complex modeling of carbonate reservoirs.

The productivity of previously drilled wells fully corresponds to the results of complex modeling. 

As a result, recommendations were issued on the placement of wells in areas with potentially maximum flow rates.

Result:

Based on the recommendations issued, 2 appraisal wells were drilled, which produced industrial inflows. The obtained models were also used to determine the grid of production drilling in the field.