Optimization of the high-speed injection for horizontal well hydraulic fracturing in terms of Vingayahinskii section of Bazhen formation

UDK: 622.276.66

DOI: 10.24887/0028-2448-2017-4-90-95

Key words: unconventional reservoir, elasto-plastic model, stress state, strain, hydraulic fractures, Bazhenov formation

Authors: D.D. Bek, A.I. Akhtyamova, A.V. Myasnikov, V.P. Stanin (Skolkovo Institute of Science and Technology, RF, Moscow), Yu.P. Stefanov (A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of RAS, RF, Novosibirsk), D.V. Alchibaev (Gazpromneft NTC LLC, RF, Saint-Petersburg)

The results of optimization of high-speed pumping during hydraulic fracturing (HF) fr om horizontal wells in formations of the Bazhenov formation are presented. The authors regarded the influence of two of seven major factors characterizing features of stress-strain and filtration properties of these formations – strength characteristics of rocks including influences of a micro-jointing and mineralogical structure; and stratigraphically determined alternation of zones of brittle and ductile failure is considered. Also, the dependence of the solution on the mode of injection and on the initial stress distribution was considered. The elasto-plastic model specified for geomaterials was used. It is initialized by the technique developed on the base of the core tests carried out for one of the wells of the Vyngayakhinskoye field.

Optimization of the modes of injecting was performed on the basis of the concept of the pseudo-stationary condition of pumping realized at the termination of injecting into the well on the fixed volume of a fluid of the hydraulic fracturing and differing from stationary in ignorance of long relaxation dynamic effects of settling of the coordinated stress-strain state in layer and the well. Choosing of criterion function for optimization is not obvious in the conditions of manifestation of plastically caused effects of failure and is discussed in the details.

Optimization was preceded by the creation of a tornado charts for determination of the influence of uncertainty of elastic and strength parameters for the main rocks presented in all formations of a cross section

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