Risk analisys of self-induced hydraulic fracture growth in vertical plane

UDK: 622.276.66.004.58
DOI: 10.24887/0028-2448-2019-6-50-53
Key words: hydraulic fracturing, self-induced fracture, cell-based pseudo-3D model, stress intensity factor, crack growth resistance, water breakthrough, waterflooding, hydrodynamic studies of wells, self-induced fracture height
Authors: A.R. Davletova (RN-BashNIPIneft LLC, RF, Ufa), A.I. Fedorov (RN-BashNIPIneft LLC, RF, Ufa), G.A. Shchutsky (RN-Yuganskneftegas LLC, RF, Nefteyugansk)

Reservoir flooding is one of the basic methods of oil production in low-permeable fields. At the same time, a natural efficiency decrease of flooding method leads to increasing the water injection pressure. One of the side effects there is so-called self-induced fracture growth on injection wells that can be accompanied by a breakthrough of fractures in the producing wells operation zone. The fracture breakthrough in its turn entails the emergence of problems associated with premature products watering. Another negative effect of increased pressure is the growth of fractures in the vertical direction. Breakout of self-induces fractures in vertical direction is a serious problem, especially for the fields on a late stage of development (brownfields) or the fields with several objects of development. There are a number of negative consequences due to the lack of control of fracture growth in vertical. For example, breakout of self-induces fractures into the above-and underlying layers leads to water pumping out of the target layer, in the other words it leads to increasing the volume of ineffective injection in comparison to volume used in hydrodynamic models. The volume of ineffective injection can exceed 50%. The self-induced fracture growth in the vertical direction can also lead to the formation of high pressure zones in the adjacent layers. This, in turn, can lead to problems of drilling wells through such intervals or problems with completion of wells using hydraulic fracturing operations, if the high pressure zone is not taken into account in their design.

It is clear that we need to have an essential tool for the fracture geometry prediction to improve the efficiency of water-flooding technology using hydraulic fracture as a completion and to analyze appropriate conditions of water injection. In this paper, we present an approach that allows us to perform a quick estimation of self-induced fracture height. The approach is based on a simplified pseudo 3D cell fracture model with the fracture growth determined by a local criterion at the fracture ends.


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