<<
>>

1.1.2 Is capillary-jammed residual oil

In the washed out sites of developed layers it is possible to evolve following principal views of residual oil of micro-level [11]: is capillary-jammed, adsorbed, film, IT of deadlock pores and mikroneodnorodnostej.

According to this classification it is possible to speak about corresponding saturations. At real developed layers there are, as a rule, some kinds of residual oil which in aggregate form bulk volume of residual oil of developed layers. At the same time studying of separate components and structure of residual oil of developed layers is necessary in connection with a problem of identification of a condition of residual oil at designing of methods of increase in petroreturn.

This kind of residual oil is formed in mainly hydrophilic plumose environment in separately taken pores, knots of pores, or in several pores simultaneously in the form of the isolated microdrops of-globules. Two schemas of formation of the is capillary-jammed oil routinely use: globule formation in one separately taken pore and globule formation in porovom a doublet. In case of the former the oil globule arises at the expense of an overclamping in a place of narrowing of a pore. At replacement of oil from the hydrophilic environment water on micropores and on pore walls makes through forward, overtaking receding oil. In a place of narrowing of a pore the overclamping of a lace of oil which is narrowed in process of ingress of water is formed until the drop will not come off an oil great bulk. After that to push a globule in pore space narrowing, it is necessary to change the globule form, having spent on it significant energy (in a condition of stationary balance the drop takes the form, corresponding to a minimum of superficial energy). At usual zavodnenii the hydrodynamic pressure of invading water developed at length of a globule, is extremely small in comparison with capillary forces.

The effect of breakoff of a drop of a non-wetting liquid at capillary lift of a moistening liquid has been positioned in nineteenth century ZHamenom which investigated water capillary ascent in a capillary of variable section [17,18].

Issledovaniz effects of a jamming in individual pores a little informatively as 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, basic of which are:

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;

Applied gradients of pressure and gravity.

In process of growth of hydrodynamic difference of pressure, last since some critical value, starts to affect on local displacement processs.

Existing representations about the is capillary-jammed oil in zavodnennyh collectors are connected, first of all, with character of display of capillary and hydrodynamic forces in process zavodnenija on mikro - and makro level [12,1,15, etc.].

Depending on character of display of capillary forces various mechanisms of formation are possible: the is capillary-jammed residual oil. Character of display of capillary forces in the washed out part of a layer is defined by a mode of replacement of oil in transition zones. At small gradients of flowing pressure character of distribution of phases in a displacement process is completely defined by capillary forces.

Under the influence of capillary difference of pressure the moistening phase is implanted in micropores in which the maximum difference of capillary tension develops.

The non-wetting phase remains in macropores, in places of expansion of pores and partially in sorbirovannom a kind on a solid phase surface. It is possible to consider modes of replacement and formation of residual oil purely capillary. Primary advance of meniscuses on micropores causes presence of significant volumes of a non-wetting phase in large pores. At sharp expansions porovyh channels spontaneous movement of a meniscus stops and the effect of reversion of meniscuses takes place - capillary pressure drop becomes directed aside more moistening phase. The above-stated mechanism of a capillary jamming says that is capillary-jammed THEY is formed in mainly hydrophilic or partially gidrofobizovannyh collectors. Influence of difficult type of wettability on a capillary jamming is a little studied now [12,19].

At small gradients of flowing pressure speed of advance mechiskov under the influence of hydrodynamic difference in some part of pores appears less travelling speeds of meniscuses under the influence of capillary difference. Thereof there is an advancing capillary desaturation from pores with small diameter. It result ins to outbreak of a moistening phase on micropores and a jamming of significant volumes of a non-wetting phase in pores of the big diameter. At the same time in some part of the largest pores of hydrodynamic difference of pressure it appears enough for pushing through of the jammed phase and its involving in the general filtration stream. Such mode of replacement and formation of the jammed phase is is capillary-pressure head.

At pure a capillary control of replacement the factors connected with a gradient of pressure and influence of a gravity, do not play a role. The basic role at a capillary jamming is played by structure of a pore space,

. ? *

Is superficial-molecular and interphase properties. As the volume of micropores is much less than volume of large pores at pure a capillary control it is natural to expect the greatest possible values jammed IT.

Traditionally influence of conditions of replacement can be characterised the relation of capillary difference pressure Ark to hydrodynamic Arg [3,8]. This parity defines also size is capillary-jammed ONN. Generally there are two critical values of relation Ar J Ar of At first critical value Ar J Ar g purely capillary

The replacement mode passes in is capillary-pressure head. At the second the is capillary-pressure head mode of replacement passes in the automodelling.

It is traditional for the description of dynamics of a capillary jamming, since Moore's works and the Large village [9], use model of pores in the form of capillary pair.

In this model the positive stream arises only in a narrow capillary, that is water will imbide in a narrow pore, and oil will be caught in larger. Though the general stream a positive, general gradient of pressure on a pore containing an interface oil/water, strongly negative, that grows out of that at the front zavodnenija capillary forces much more exceed hydrodynamic (vjazkostnye).

From the described mechanism follows, that the capillary jamming should not be sensitive to the relation vjazkostej oil and water. Is capillary-jammed ONN is the relation of volume of a large pore to total amount of two pores and always more than 50 %. For example, if the radius of a large pore in 3 times exceeds radius of a small pore, 80 % of oil are jammed.

Now dynamic effects on various models of pores are in details analysed. However effects of a jamming are not limited to separate pores or pairs pores. Actually, separate pores, as a rule, have, at least, one more additional path for a filtration at minor alterations of conditions of a jamming. Such

17

In the image, difficult systems of the is capillary-jammed residual oil can be formed. The structure is capillary-jammed IT in details was studied by I.Chatzisom, N.Morrou, X. Limom, N.Uordlou, M.Makkellarom, B.Vajnhardtom, 3. Hajnemanom [7,20,21] and other foreign researchers. I.Chatzisom, etc. [5,6,7] had been carried out researches of structure ONN both on micromodels, and on real sandstones.

The researches made on physical micromodels with various porometricheskoj by the characteristic, have shown, that oil is caught, mainly in rather large pores connected by the big throats, and also at the expense of tearing up of crosspieces in norovyh bodies.

For studying of structure of residual oil in B.Vajnhardt's natural porous mediums [21 3. Hajnemann [22], I.Chatzis [5-7], etc. experiments on zavodneniju made the samples sated with monomers; after replacement the monomer which has remained in a core polimerizovalsja, the porous medium skeleton was leached, and the selected hardened globules of polymer are exposed to studying.

Microscopic studying of the hardened globules of this has shown to "residual oil", that distribution of forms of drops of oil in the models made of glass balls and from sandstone Vegea, laboratory modelling being the basic object, it has appeared to similarly three types of the structures meeting in micromodels: to singlets, doublets and triplets.

The important line of distribution of globules on the size is that 50 % of the sizes of globules get to a range from 30 to 120 microns. These sizes corresponded to the pore sizes measured on electronic microphotos of sandstone Vegea and polymeric mould pieces of a porous medium of this breed. On a full photo mikro to graphic pore-size distribution in sandstone Vegea, 80 % of the general porovogo volume consist of pores from 30 to 120 microns.

Influence of conditions of replacement on structure of the is capillary-jammed oil is caused by features of local replacement of oil water. At increase in pumping rate of water local distinctions in peripheral speed of passage of interfaces through a heterogeneous microstructure of a porous medium raise. As a result, languages obvodnenija are formed the significant size and larger oil globules are jammed. On the other hand, with growth of a gradient of pressure operating on a jammed globule the probability of its division into smaller globules increases.

To achieve mobility of the jammed oil it is possible also in other ways, for example, at the expense of decrease in operating local capillary tension by means of use of PEAHENS or at the expense of increase of viscosity of invading fluid. Some methods of increase in petroreturn of layers are based on action of these factors [14,23].

Research of changes of the jammed residual oil have shown, that to growth of number of capillary attraction there are qualitative and quantitative changes is capillary-jammed IT. This process goes until the majority of oil globules will not turn to singlets. It occurs at some critical value of number of capillary attraction then the shattered globules of the jammed oil get mobility and start to leave system.

In real collectors on conditions of achievement of mobility is capillary-jammed IT the big influence is rendered by pore space structure. The jammed oil globule in a pore in radius gp gets mobility in case the local hydrodynamic difference Arg operating on a globule, will exceed the local capillary

Difference

L 2сг

Where D - an index of structural complexity, the factor depending on values of coming and receding contact angles. For factor D some expressions connecting it with values of contact angles and with structure of a pore space in diameter of a pore and an overclamping, are received by their sizes, other structural characteristics. Influence of structure of a pore space on mobility of residual oil is the most evident has shown F.Dullen [24]. As factor D it used parametre

Чг-4

Where g "- input radius in a pore.

Using in quality value of radius of an input in a pore of value of diameter, corresponding to a bend point on the curve mercury porometrii, and values of radius of a pore defining according to microphotos, Dullen has established close correlation connection between degree dovytesnenija residual oil and parametre of complexity of geometry of pores under the fixed conditions of replacement.

<< | >>
A source: Kozhabergenov Murat Mokanovich. Substantiation of effective technologies doizvlechenija residual oil from obvodnennyh layers on an example of XIII horizon of deposit Uzen: Dis.... A Cand.Tech.Sci.: 25.00.17. - M: RGB, 2006. 2006

More on topic 1.1.2 Is capillary-jammed residual oil:

  1. 1.1.6 Residual oil at unstable replacement
  2. 1.1.4 Film residual oil
  3. 1.1 Kinds of residual oil in zavodnennyh layers
  4. 1.2 Quantitative distribution of residual oil on the deposit area
  5. 1.1.5 Residual oil in deadlock pores and micronon-uniform zones
  6. 1.1.3 Adsorbed residual oil
  7. 1.3 Distribution of residual oil of water in emptiness of hydrophilic and hydrophobic collectors
  8. 2.7 Bases of technology doizvlechenija residual oil from obvodnennyh chinks
  9. 2.6. Laboratory researches of possibility doizvlechenija micro-residual oil after zavodnenija for conditions of layers of XIII horizon of deposit Uzen
  10. CHAPTER 1 MODERN REPRESENTATIONS ABOUT RESIDUAL OIL In DEPOSITS AFTER THEM ZAVODNENIJA
  11. Kozhabergenov Murat Mokanovich. the Substantiation of effective technologies doizvlechenija residual oil from obvodnennyh layers on an example of XIII horizon of deposit Uzen: Dis.... A Cand.Tech.Sci.: 25.00.17. - M: RGB,, 2006 2006