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2.5.2 Preparations of models of a layer and a choice of formulas of physical and chemical compositions

Extraction of residual stocks of oil from obvodnennyh layers after zavodnenija represents a challenge in which decision important value is played by physical and chemical methods of influence on productive layers.

One of perspective methods bases on application of return emulsions [45,46]. The significant contribution to experimental researches of properties of return emulsions, working out of their compositions for use as chisel solutions at opening of productive layers were brought by domestic scientists: L.K.Muhin, K.L Minhajrov, M.I.Lipkes, N.M.Kasyanov, Century And Tolkunov, I.B Heifetz, R.A.Habibullin, N.I.Rylov, B.V.Kaspersky, A.V.Kazmin. I.S.Krivonosova, N.A.Kartashova, D.F.Matveeva's works and other authors, the beginning is necessary to application of return emulsions for the purpose of an intensification of an oil recovery and petroreturn increase.

In the petrosated, non-uniform layers on permeability at difficult distribution of streamlines in an oil displacement process when there are significant changes of gradients of pressure, hold-up spots [58] can be formed. Thereupon researches, including experimental, influences of various factors on petroreturn are actual at replacement by water nenjutonovskoj oil. Represents the big interest definition of factor of petroreturn of a layer with the paraffinaceous oil, developed by a method zavodnenija.

Taking into account features of movement of paraffinaceous oil and its thermodynamic characteristics following variants of deposition of particles of paraffin in a layer pore space are possible:

- Occurrence and growth of paraffin formations directly on walls porovyh channels;

- Adherence of particles of paraffin to breed grains;

- kolmatatsionnye effects and the subsequent filling porovogo volume paraffin particles at a filtration of oil [59].

At studying of processes replacement of oil by water and other invading fluids on the laboratory installations which results could be transferred immediately on a real layer, is necessary to consider all factors defining values of factors of replacement and coverage of a layer by influence by invading fluid. In homogeneous porous mediums the coverage factor depends on geometry of a layer and physical and chemical properties of liquids.

The factor of completeness of extraction can depend on variety of characteristics: rates of displacement, interfacial tension on phase boundaries, a difference of their density, structure of a pore space, wetting angle of a solid phase, the maintenance and properties of combined water, and also chemical composition of oil and liquids superseding it or gas. By researches of last years it is positioned, that on completeness of extraction of stocks of oil make essential impact structurally-mechanical characteristic abnormal neftej [60,61], displayed at small gradients of sheet pressure.

In the existing theory of modelling [62,63,64] the dimensionless parametres considering influence only of first three factors are offered. For the account of structural features of a pore space and its moistening characteristic it is recommended to use in experimental researches real porous mediums. However use of real samples of petrocontaining breed as models to a porous medium in laboratory experiences is connected with the big difficulties. Real rocks comprise various impurities which as jointing materials, at infusion of the sample or are taken out from a pore space, or, will dissolve.

Along with pore space structural changes the moistening characteristic of a solid phase changes also.

Because of an insufficient level of scrutiny of quantitative characteristics which would allow to consider influence of chemical composition of oil and displacing fluid, in the modelling theory in general there is no the corresponding parametre of similarity. It is connected by that many properties of oil which, as a rule, are displayed simultaneously make on a displacement process of oil from a porous medium and on final factor of replacement of oil water essential impact. Significant influence on replacement factor viscosity of oil, the maintenance in it of surface-active components render, quantity of gas in solution, interfacial tension on border oil - displacing fluid, structurally-mechanical properties of oil, etc.

In works of Century of M Ljutina and other researchers it is shown, these are the experimental data received at research of a filtration of distillates of oil, cannot be propagated to all real oil. Basic difference of system oil - water from system distillate - water consists in formation neftjami on border with water tverdoobraznyh the films which physical properties considerably influence laws of replacement.

In works SH.K Gimatudinova decrease in filtration characteristics of breeds is noticed at movement in them the devolatilised oil. As a result of oxidation and change of composition of some connections and cooling there are components, unusual natural neftjam. Under S.K.Gimatudinova's recommendations experiments on replacement should be made with natural neftjami, haranivshimisja short time at temperatures not more low 18С, or rekombinirovannymi oil models.

According to I.L.Marhasina's researches it is shown, that introduction in oil of solvents (kerosene, in petroleum aether small amounts) result ins to increase in adsorption of asphaltenes. The additive of petroleum aether to oil with the smaller has the big influence on adsorption

62 maintenance of asphaltenes. Obviously, adsorption of breed of various quantity of asphaltenes results not only to gidrofobizatsii breeds, but also in change structurally-mechanical characteristics neftej. Strengthening of adsorption of asphaltenes can lead to retardation of a displacement process of oil and if it is accompanied gidrofobizatsiej surfaces porovyh channels to reduction of factor of replacement. Proceeding from I.L.Marhasin's researches comes to conclusion that for reception of authentic results it is necessary to use only sheet and as a last resort devolatilised without contact to air oil.

By researches of some authors it is positioned [59,60,65,66], that oil of many deposits possess anomalies of viscosity, and it makes essential impact on straining actions and petroreturn. Factor of final petroreturn on deposits nenjutonovskih neftej more than twice less the than corresponding factor for neftej, not displaying anomaly of viscosity. On displacement processs such neftej from a porous medium essential influence renders a gradient of pressure of replacement. It is besides, shown, that with reduction of a permeability coefficient of breed filtration characteristics abnormal neftej worsen.

The resulted short review of works of various authors shows, that the best means of reproduction in experiences of physical and chemical properties neftej is use of hallmarks of the sheet oil lifted from chinks with preservation of its natural properties. Thus, however, carrying out of researches extremely becomes complicated necessity of use of instrumentation of high pressure. Therefore the overwhelming part of experiences is made at atmospheric pressure. In atmospheric conditions prefer to use in experiments the devolatilised oil with addition of various solvents.

Thus, if straining actions and replacement are made at gradients of pressure, smaller a limiting gradient of pressure

63 destructions of structures of oil it is impossible to use oil models. Application of models of oil is admissible only when it is in advance known, that in the conditions of experiments structurally-mechanical characteristic neftej are not displayed.

Numerous laboratory researches of replacement of oil by water were made practically from the very beginning of working out of deposit Uzen. So in work [69] influence of cooling of a collector and fallout of crystals of paraffin was investigated on natural samples of breed at zakachke waters in a layer on displacement efficiency of oil. In work [69] cores are analysed and 1942 definitions are made.

It is positioned that if between an initial petrosaturation and permeability there is a direct dependence, in a wide range of permeability average values of a residual petrosaturation practically identical - 25,5 %. At carrying out of these and sets of other works, were put the problems which are meeting the requirements of current time, namely - wax precipitations and ASPO on displacement efficiency of oil by water in sheet conditions.

Lately deposit workings out much has changed. Properties of oil and collectors have worsened, centre obvodnennost to an extracted liquid became more than 80 %. Today other problems, namely - studying both on trade data, and by laboratory experiments of mechanisms of extraction of residual oil after long zavodnenija are actual.

Results of experimental researches on replacement of the petroleum crude selected from a chink of 2352 XIII horizon, are more low resulted by model of sheet water at temperature 60С [73].

Tasks in view assumed: - revealing of influence of wettability of rocks on character of replacement; - an establishment of degree of influence of inturgescence of clay components of a collector on permeability; - definition of factor of replacement of oil by water.

For the decision of tasks in view two series of experiments on the laboratory installation which schema is resulted on fig. 2.3 have been made. In the first series of experiences the cleared and screened quartz sand for formation of bulk model of a collector was used. For achievement of the set parametres of porosity and permeability sand ground certain time for a ball grinder and then filled model of a layer in length 63 see also internal section 3,09см. Model in vacuo sated with water with sheet properties and defined a permeability coefficient. Then after endurance within 15-20 hours at ambient temperature repeatedly defined a permeability coefficient on water and porosity. Then in model zakachivalas under pressure 2,0 MPa the petroleum crude selected from a chink 2352, for combined water creation. In the second experience used model of sheet oil with addition in heptane petroleum crude.

Warmed up to 60С oil, was pumped over through model which was nagreta to the same temperature. After the termination of a yield of water oil prorolling proceeded to 1,5-2 porovyh volumes. The model was maintained in rest within 15-20 hours. Then oil was superseded by water at 60С before the termination of its escaping of model. Thus, the replacement factor was defined.

Both in the first and in the second experiences after endurance of water-saturated model permeability coefficients did not change, probably, owing to absence of a clay component in breed. In both experiences the displacement process of oil water occurred under the piston schema. At the moment of the approach of front of replacement to escaping of model oil receipt was practically stopped. Further zakachka some water in 1,5-2 volumes of pores and at the raised rate of displacement did not result in to increase in factors of replacement. So at replacement of petroleum crude the replacement factor has appeared equal 50 % while at replacement of oil with heptane viscosity on 15 %) it there is less replacement factor was equal

65

48 %. On fig. 2.7 the graph of change of factor of replacement of petroleum crude and oil model (petroleum crude from скв.2352 XIII horizon with addition of heptane before achievement of viscosity of sheet oil) water, depending on relative zakachki waters in model are resulted.

0,6

О*!! 1

0 1 2 3 4 5 6

The relative saved up volume zakachki, VMK/Vnop

Fig. 2.7. Change of factors of replacement of petroleum crude and model of oil water from bulk model from quartz sand, depending on volume zakachannoj waters

Apparently from drawing of a drawing of replacement of petroleum crude and model of oil water with a sheet mineralization are identical. Replacement factors grow linearly and reach the maximum size at zakachke in model 0,4 of volume of pores of water. Neither an experiment stop at 48 o'clock, nor increase

3 3

Speeds zakachki waters about 80 sm/hour to 200 sm/hour have not affected behaviour of factors of replacement. Also has not affected zakachka otorochki a return emulsion on the basis of petroleum crude from a chink of 2352 XIII horizon in volume of pores of 0,2 volumes.

Character of a displacement process occurred under the piston schema - from

Models there was only an oil and at the moment of the approach of front of replacement

Oil practically was replaced at once with water.

As quartz sand possesses mainly hydrophilic

Properties in the second series of experiences used not ekstragirovannyj

66

The core selected from a chink of 6602 XIII horizon. It ground to the necessary parametres. After saturation of model by water with a sheet mineralization have defined a permeability coefficient. Then model have left alone for 2 days at ambient temperature. Have iterated zakachku waters at 60С, and after stabilisation of indexes have again defined a permeability coefficient which has appeared in 2 times less.

1,3

"1,2

I '

| 0,9

$ 0,8

1 0,7 about

? 0,6 0,5 0,4

Change of permeability of bulk model of a layer on water depending on dwell time at 20С

\

. 1 35

40

50

45

10 15 20 25 30 time, hour

Fig. 2.8. Dependence of permeability of bulk model of a layer from ground not ekstragirovannogo a core from dwell time

It is well visible on fig. 2.8 where dependence of a permeability coefficient on dwell time is resulted. Permeability coefficient falling testifies, most likely, to influence of inturgescence of clay making model of a collector on filtratsionno-capacitor properties.

At replacement of oil by water the first droplet of water has occurbed practically right after selection of a small amount of oil at the very beginning of the process beginning that answers known representations about distribution of water and oil in a pore space at hydrophobic character of wettability. On fig. 2.9 graphs of change of indexes of selection of oil and water depending on relative zakachki waters are presented.

The period amplitude of fluctuations the greatest. Water and oil occurbed on a model yield serially drops that testifies, probably, about movement of these phases in collector model on own channels. Zakachka waters it is equal to the saved up selection of a liquid.

Relative zakachka the waters, equal to the saved up selection of a liquid carried to volume of pores, d.e.

мш+шт Factor vgtesnenichja. %-Q - Volume obvodnennost idkosti, %-about - the Saved up selection of a liquid from model (zakachka waters), smz d oil Selection in a unit vremni, smz/minute

Fig. 2.9. Change of indexes of replacement depending on relative zakachki waters in model

Despite fluctuations of selection of oil and obvodnennosti, it is possible

To observe "stabilisation regiments" as on the curve obvodnennosti at level

80 %, and otbooa oil at level of 20 sm3/mines which begin with

Relative za'achki waters approximately with 0,4 also proceed to 1,5 volumes

Pores. Then obvodnennost to 100 %, and oil selection linearly increases

Accordingly falls to zero. It is possible to evolve 3 periods of change

Replacement factor at the first stage of experiment. During the first

The period which lasts from the beginning zakachki to value of the relative

zakachki 0,52, the replacement factor increased linearly to value

0,291, i.e. rate of increase has made 0,56. During the second period, when

obvodnennost fluctuated about value of 80 %, i.e. during the shelf period

68

Stabilisation, rate of its increase has essentially dropped. So at zakachke waters with 0,52 to 1,73 volumes of pores the replacement factor has increased with 29,1 to 0,451, rate of increase has made 0,13. During the third period at zakachke waters about 1,73 volumes of pores to 2,1 factor of replacement has grown with 0,451 to 0,48. Rate of growth has made 0,078.

After endurance of model at ambient temperature within 48 hours zakachka waters it has been iterated with a speed of 80 sm/hour, but the model left water with oil signs. Then have increased speed zakachki to a 200sm3/hour that has led to additional selection of oil in volume of 5 sm3. Thus the factor of replacement of oil water has increased by 5 % and has reached 53 %. On fig. 2.9 the graph of dependence of factor of replacement from relative zakachki waters is resulted. On this graph three periods of change of factor of replacement of oil at the first stage of experiment and jump are displayed at transferring from speed zakachki waters about 80 sm3/hour to 200 sm3/hour.

80 sm3/hour

200 sm3/hour

0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5 6

The relative saved up volume zakachki waters, V-;, K/Vri [) |)

Fig. 2.10. Change of factor of replacement of oil by water from model of a layer depending on volume zakachannoj waters

Thus, the made experiments on replacement of petroleum crude by water from bulk models of a collector allow to consider that:

At replacement of oil by water from the bulk model prepared from quartz sand, oil is taken during the anhydrous period, i.e. replacement occurs under the "piston" schema. At the approach of front of replacement to a yield of model oil practically is replaced at once cha water. The factor of replacement of oil water grows linearly as on a yield there is no water.

At replacement of oil by water from the bulk model prepared from not ekstragirovannogo of a milled core, the anhydrous period short and practically all oil is taken simultaneously with water, to tell in serially portions more truly.

Hence, it is possible to assume, that oil and water dvizhutsja separately on the channels. In due course water occupies channels on which oil moved. And the displacement process occurs during three periods. During the first period which lasts from the beginning zakachki to value relative zakachki 0,52, the replacement factor increased linearly to value 0,291, i.e. rate of increase has made 0,56. During the second period when obvodnennost fluctuated about value of 80 %, i.e. during the period of a shelf of stabilisation, rate of its increase has essentially dropped. So at zakachke waters with 0,52 to 1,73 volumes of pores the replacement factor has increased with 29,1 to 0,451, rate of increase has made 0,13. During the third period at zakachke waters about 1,73 volumes of pores to 2,1 factor of replacement has grown with 0,451 to 0,48. Rate of growth has made 0,078.

Features of a displacement process of oil water from bulk model of a collector from not ekstragirovannogo a core in comparison with replacement from the model prepared from quartz sand, allow to assume about display of properties partially gidrofobizovannogo a collector.

Display signs partially gidrofobizovannogo a collector are:

- The short anhydrous period of a yield of oil from model,

- Fluctuations obvodnennosti and an oil recovery especially in an incipient state of replacement,

- Formation of "stabilisation shelves" on curves obvodnennosti and selection of oil,

Increase of factor of replacement of oil by water occurs to different rate in growth obvodnennosti, during the period of a shelf of stabilisation obvodnennosti and in growth obvodnennosti to limiting value,

Jump of factor of replacement at increase in speed zakachki waters in model.

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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

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