RU2527996C1 - Composition for shutoff of water influx to oil producers - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: composition for isolation of water influx to oil producers includes amides of fatty acids and fresh water. At that as amides of the fatty acids the composition contains 40-50 wt % of ethanolamides of fatty acids with 12-18 carbon atoms, among which there are additional 10-20 wt % of secondary atoms and 10-20 wt % of polyatomic alcohols.

EFFECT: improving efficiency of water shutoff treatment in producers due to use of homogenous composition with selective action towards water-saturated sites of terrigenous and carbonate reservoirs.

1 ex, 1 tbl, 4 dwg

Description

The invention relates to the oil industry, in particular to compositions used to isolate the influx of water into producing oil wells.

A known composition for isolating the influx of formation water into the well and a method for its production (see AS USSR No. 872734, class E21B 43/32, publ. Bull. No. 38 dated 10/15/1981). The composition contains an aqueous solution of fatty acid diethanolamide with 10-16 carbon atoms and a dispersed phase - paraffin, which is emulsified in molten form in an aqueous emulsifier solution heated above the melting point of paraffin, followed by natural cooling of the resulting direct emulsion until the dispersed phase solidifies.

When pumping the specified water-paraffin composition into the well, the porous medium becomes saturated not only with water, but also with the released paraffin, which reduces the phase permeability. However, when using this composition to isolate the influx of formation water into the well during injection of the resulting paraffin slurry into the formation, blockage of the bottomhole zone with filtered paraffin will occur, followed by the formation of a paraffin crust and pressure increase. As a result, due to insufficient depth of penetration of the paraffin phase into the bottomhole zone, the required work efficiency will not be achieved.

A known method of limiting water inflow and oil-water emulsion used in the method (see AS No. 726305, class E21B 33/138, publ. Bull. No. 13 from 04/05/1980), including the injection into the reservoir of a hydrophilic oil-water emulsion, containing an aqueous solution of diethanolamide fatty acids with 10-16 carbon atoms and a dispersed phase - oil.

The disadvantage of this method is the watering of wells in a short period of time due to insufficient viscosity released during the decay of the oil emulsion.

Closest to the proposed invention is a method of limiting water inflow into production wells (see patent RU No. 2221130, ЕВВ 33/138, published January 10, 2004) containing an aqueous solution of fatty acid diethanolamide with 10-16 carbon atoms and paraffin as dispersed phase.

The specified method can be taken as a prototype.

The disadvantage of the prototype is the low selectivity and phase instability of the insulating composition, which ultimately affects the effectiveness of limiting water inflow.

The technical result of the claimed invention is to increase the efficiency of waterproofing works in producing wells through the use of a homogeneous composition of selective action to water-saturated areas of terrigenous and carbonate reservoirs.

The technical result is solved due to the fact that the composition includes amides of fatty acids and fresh water.

New is that the composition as fatty acid amides contains ethanolamides of fatty acids with 12-18 carbon atoms, which additionally includes secondary and polyhydric alcohols in the following ratio of components, wt.%:

Ethanolamides of fatty acids 40 ... 50.

Secondary alcohol 10 ... 20.

Polyols 10 ... 20.

Fresh water is the rest.

The composition is environmentally friendly and can be prepared in the form of a concentrate and brought, before use, to its presentation with fresh water. As raw materials for production can be used:

Paraffins produced by JSC Khimprom (Volgograd);

Olefins produced by OAO Nizhnekamskneftekhim (Nizhnekamsk);

Ethanolamines produced by Kazanorgsintez OJSC (Kazan) or Sintez-OKA LLC (Dzerzhinsk);

Ethanolamides of synthetic fatty acids produced by NPO Tathimprodukt CJSC (Kazan);

Isopropanol produced by Synthesis OJSC (Dzerzhinsk);

Isobutanol, produced by Butyl Alcohol Plant CJSC Sibur-Khimprom (Perm);

Mono-, di-, triethylene glycols produced by OAO Nizhnekamskneftekhim (Nizhnekamsk) or OAO Kazanorgsintez (Kazan).

The selective action mechanism of the claimed composition is based on the selective formation of a clogging insulating screen in contact with formation water. In oil saturated intervals, when in contact with oil, the composition does not form an insulating material. Thus, the composition itself “finds” in the formation a zone of formation water inflow into the well and blocks it.

The effectiveness of the composition is achieved by selective isolation of the waterlogged intervals of the oil reservoir, blocking of the water-saturated (waterlogged, washed) intervals of the reservoir and maintaining the permeability of the oil-saturated, while injecting the reagent throughout the entire thickness of the perforated reservoir both in vertical, inclined, and in wells with horizontal bores.

The combination of distinctive features of the claimed composition leads to an increase in hydrodynamic resistance in the zones of the formation washed by water flooding and allows you to create the necessary depressions to extract oil from less permeable layers.

To confirm the effectiveness of the composition, studies were conducted on four models of the oil reservoir with the parameters presented in the table.

In laboratory conditions, the properties of the claimed composition were studied on single reservoir models with residual oil saturation, representing a metal tube 330 mm long and 33 mm in diameter, filled with ground rock. To create relict water saturation, the models were saturated with formation water under vacuum. To create the initial oil saturation, formation water from the pore space was replaced by oil. The displacement was carried out until the filtration characteristics were completely stabilized at the outlet of the porous medium. When creating residual oil saturation, the models were connected to the pressure vessel and oil was displaced from the pore space of the model with formation water. Oil displacement was carried out until the water cut at the output of the model. All stages of the experiment were carried out at a temperature of 26 ° C.

After creating the residual oil saturation in the pore space of the oil reservoir model, in accordance with the statement of the problem in the experiment, a composition of 10% of the pore volume of the model was introduced from the reverse side. The composition contains palmitic acid N- (2-hydroxyethyl) amide (40%), isopropanol (20%), ethylene glycol (20%) and water (20%). After the introduction of the reagent, the displacement of oil by formation water in the initial direction was continued. When conducting experiments in models No. 3 and No. 4, the reagent was pressed into the porous medium with formation water in the amount of 10% of the pore volume of the model.

Four experiments were carried out:

Model No. 1 carbonate was saturated with formation water and oil, selected from a well operating carbonate deposits.

Terrigenous model No. 2 was saturated with formation water and oil taken from a well operating carbonate deposits.

Model No. 3 carbonate was saturated with formation water and oil taken from a well operating terrigenous deposits.

Terrigenous model No. 4 was saturated with formation water and oil taken from a well operating terrigenous deposits.

According to the experimentally obtained graphs, Figs. 1-4 show a change in the permeability of formation models by water when oil is displaced by formation water, reagent is introduced and further formation water is filtered in the direction of displacement.

When analyzing the presented table and graphs in figures 1-4, we see a decrease in the permeability of the models from 1.85 times (model No. 4) to almost complete filter attenuation (model No. 3).

More stable results were obtained when modeling using produced water and oil taken from a well operating carbonate deposits (models No. 1, 2), the decrease in water permeability was 6.6-6.8 times.

Thus, laboratory studies have shown that the proposed reagent leads to a decrease in water permeability of the reservoir model.

Concrete example

The proposed composition was used to limit the influx of water into the production well No. 1380 of the Dachnoye field of OAO IDELOIL. Well 1380 operates the Verey horizon of middle carbon with a water cut of 95%. After pumping 5 m ^{3 of the} composition into the reservoir, the water cut decreased to 6.7%, while the oil production rate increased by 2 times. The effect of increasing oil production and reducing water cut in the well lasts from March 2011 to the present.

The composition is simple and technologically advanced, it is highly effective for enhancing oil recovery in flooded formations both in vertical, deviated, and in wells with horizontal shafts, including are in a late stage of development.

Parameters of oil reservoir models Before reagent input After entering the reagent and pumping with water Mod number V _then (cm ³ ) k _abs (μm ² ) k _water (μm ² ) S _n (%) k _nave (μm ² ) S _ost (%) k _{water.ost n / n} , (μm ² ) The volume of reagent / sale (shares V _then ) S _ost.con (%) k _water.con (μm ² ) Residual Filter Resistance one 26.54 0.561 0.22 60,2 0.44 39.8 0.04 0.1 21.25 0.006 6,667 2 21.72 0.922 0.47 96.6 0.28 5.23 0,048 0.1 13.3 0.007 6,857 3 23.92 0.634 0.21 81.9 0.04 51.5 0.01 0,1 / 0,1 48.21 0,0002 more than 100 four 22.76 1,293 0.61 47.5 0.08 42.1 0,048 0,1 / 0,1 28.24 0,026 1.85

where V _then - the pore volume of the oil reservoir model, cm ³ ;

k _abs - absolute permeability (gas), μm ² ;

k _water — model water permeability, initial, μm ² ;

S _n - maximum (initial) oil saturation (pore volume of the model occupied by oil),%;

k _nef - oil permeability of the model, μm ² ;

S _ost - oil saturation of the model after displacement by water (in% of the initial oil saturation),%;

k _{water.ost.n / n} - the permeability of the model with residual oil saturation in water, μm ² ;

S _ost.con - oil saturation of the model after exposure to the reagent and further displacement with water (in% of the initial oil saturation),%;

k _vod.kon - permeability of the model after exposure to the reagent and further displacement with water, microns.

Claims (1)

Composition for isolating the influx of water into producing oil wells, including fatty acid amides and fresh water, characterized in that the composition contains fatty acid ethanolamides with 12-18 carbon atoms, which additionally includes secondary and polyhydric alcohols in the following ratio components, wt.%:
Ethanolamides of fatty acids 40-50.
Secondary alcohol 10-20.
Polyols 10-20.
Fresh water is the rest.

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