New approaches to equilibrium initialization of the BlackOil model and free water level evaluation

UDK: 622.276.1/.4.001.57
DOI: 10.24887/0028-2448-2018-6-70-75
Key words: equilibrium initialization, initial saturation cubes, Leverett J-function, pseudo-J-function, free water level, oil-water contact, transition zone
Authors: E.O. Sazonov (Bashneft-Dobycha LLC, RF, Ufa), A.N. Nugaeva (Bashneft-Dobycha LLC, RF, Ufa), A.N. Chervyakova (BashNIPIneft LLC, RF, Ufa)

The paper presents a new technique that allows to obtain cubes of saturation that do not contradict the physics of equilibrium initialization and corresponding to the results of the well logs interpretation, the value of the historical water-cut for each well, well testing. One of the sections of the work is devoted to a new approach for equilibrium initialization of the BlackOil model and free water level evaluation. Other section of the article presents a comparative analysis of the proposed and regular approaches to initialization, highlights the pros, cons of both methods and accepted assumptions. Since the initial data have different degrees of reliability and often contradict each other, then, for the correct account of them in the model, in the section "basic definitions, designations and assumptions of the proposed method", a rating of types of well studies in order of increasing the error in the free water level evaluation is proposed.

Also in the work the influence of the product of the surface tension between oil and water phases and the cosine of the boundary wetting angle under reservoir conditions on the size of the capillary impregnation zone, and, accordingly, on the reserves, is investigated. The value of this product is generally unknown and is an uncertainty parameter. Therefore, the paper proposes two options for its evaluation - by calculating the residuals of the starting water-cut and the cumulative values on the hydrodynamic model on the one hand, and on the other - an operational assessment of the variation of pairs and the values of the free water level.


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