# 1.1.6 Residual oil at unstable replacement

By working out of the oil layers containing oil with viscosity of invading water several times exceeding viscosity, there are phenomena of instability of the replacement, result ining to formation of water "fingers" of significant extent.

Numerous experiments show, that at replacement at first the flat border has undressed becomes covered by a ripple, and after a while one of fingers grows faster, than next, contains their growth and, at last, fills all space.The layer part, ' not occupied with fingers, represents the neosufficed volume of the pores which relation to total amount of pores can be characterised as a practical residual petrosaturation at astable replacement [36].

This practical IT will be defined essentially by geometrical characteristics of a stream. So, at identical intensity paptse formations, the residual petrosaturation of outbreak will depend on system of arrangement of chinks, distance between them, geological heterogeneity of a layer in whole and other geometrical characteristics.

As for the most widespread hydrophilic granuljarnogo type of a collector the basic on volume basis komponentoj residual oil (8090 % and more) are the is capillary-jammed residual oil, we will understand as residual oil the is capillary-jammed residual oil.

In real porous mediums the capillary jamming of oil in process zavodnenija is connected with action of a considerable quantity of factors and the phenomena subdivided into two groups; 1) Geologo-Fshichesky

- Geometry in a pore space;

Is superficial-molecular properties of system breed / sating fluids, such as wettability, ion exchange, adsorption;

Interphase properties, such as interfacial tension, distinctions in density, the relation vjazkostej phases

2) Technological

Applied gradients of pressure;

Type and properties of working substance;

System of placement of extracting and forcing chinks.

By working out of modes and technologies of extraction and doizvlechenija it is important to residual oil to study influence as the first so the second groups of factors.

Let's consider influence of technology factors. From the point of view of the technology, most simply controlled at zavodnenii the factor is the gradient of pressure depending on system of arrangement of chinks, type of chinks of rates of forcing of selection of a liquid, etc.

On existing representations final factor of petroextraction KIN is defined under following formula КИН=Квыт-Кохв (A.P.Krylov),

Where Kvyt - replacement factor, Kohv - coverage factor.

Where Knn - factor of an initial petrosaturation, Кн0 - factor of a residual petrosaturation.

For definition of change of final factor of petroreturn at various specific density of a grid of chinks various dependences are used. We will consider these formulas:

KHH=KebM-eas = (l-l/l - eas (V.N.ShChelkachev),

Where Kvyt - replacement factor = const, and - proportionality factor between change of size of pattern arrangement of chinks (S) and factor of coverage of a layer.

КИН^А-BS (A.P.Krylov).

KMH = (l~KJKJ - (l-aS) (V.D.Lysenko, E.D.Muharsky).

Consequence of these formulas is independence Kvyt of pattern arrangement of chinks, grid influence is displayed through change K^hv, as was the definition basis separately replacement factor in laboratory conditions according to the branch standard (OST 39-195-86).

In too time N.N.Mihajlova and A.V.Dzhemesjuka's laboratory and analytical researches, etc. have shown, that the factor of a residual petrosaturation is not to constants, and depends on capillary attraction number.

The capillary attraction number is entered for quantitative expression of a parity hydrodynamic and capillary forces and can be presented in a kind.

Ncl=kJHip \(aL),

Where к0 - permeability, Ar - pressure drop on testing length L, about - interfacial energy on border water/oil.

## More on topic 1.1.6 Residual oil at unstable replacement:

- 1.1.4 Film residual oil
- 1.1.2 Is capillary-jammed residual oil
- 1.1 Kinds of residual oil in zavodnennyh layers
- 1.2 Quantitative distribution of residual oil on the deposit area
- 1.3 Distribution of residual oil of water in emptiness of hydrophilic and hydrophobic collectors
- 1.1.3 Adsorbed residual oil
- 2.7 Bases of technology doizvlechenija residual oil from obvodnennyh chinks
- 1.1.5 Residual oil in deadlock pores and micronon-uniform zones
- 2.6. Laboratory researches of possibility doizvlechenija micro-residual oil after zavodnenija for conditions of layers of XIII horizon of deposit Uzen
**CHAPTER 1 MODERN REPRESENTATIONS ABOUT RESIDUAL OIL In DEPOSITS AFTER THEM ZAVODNENIJA**