The technology of selective constraints in water production with the use of the reagent SBF

Material "SBF", used in the form of a suspension in oil for injection in a porous medium leads to a strong hydrophobic collector, which increases the permeability of the reservoir oil. 

Material "SBF" has a strong water - and kislotoustoichivam, is fixed on a porous terrigenous collectors. 

When you fix the "SBF" in the producing wells with a concentration of from 1.0% or higher, the suspension has cementing properties, limiting the inflow of water from washed interlayers, while not impeding the flow of oil, leading to increased production capabilities of the reservoir, well productivity and reduce water production. 

Technology is used in low-permeability reservoirs from 10MD to 500мД to eliminate the in-situ flow and isolation of the produced water. 

THE USE OF THE MATERIAL IN SBF NEFTEGAZODOBYVAYUSCHEE INDUSTRY


"SBF" is a trademark of chemically modified silicas (SiO2) with a discrete particle size of 0.005-0.1 µm. The basis of it are produced by special technology of aeroforce, which by chemical modification become hydrophobic, hydrophilic or devilinia properties with high surface energy. These materials have a large range of applications in various industries, but the greatest use is in Russia, they are found in the oil and gas industry. 
In the result of laboratory tests of the filtration characteristics of natural and artificial cores of SBF-treated material was made following conclusions: 

The absolute permeability of the porous medium has a very significant impact on the effectiveness of suspensions of SBF.
The use of suspensions of SBF as a reagent to reduce the proportion of water in the produced products become technologically unacceptable for reservoirs with permeability greater than 2 µm2, in this case prevails filtration of water. 
In the range of permeabilities from 0.15 to 2 µm2 SBF reduces the water production while reducing the production of fluid. 
For reservoirs with permeability less than 0.15 µm2 treated with the suspension of SBF, the reduction of water content will occur with increasing flow rates. 
Injection of a suspension of the hydrophobic sample of SBF at low concentrations leads to a significant increase of permeability and decrease of neftprominvest porous media. 
The following figure (2) shows the diagram of dependence of relative permeability from water saturation quartz Sandstone for water (blue curve) and oil (black curve). These curves are typical curves of Vitkova and Basseta which is virtually the entire theory of fluid flows. On the basis of numerous experiments it was established that the treatment of the hydrophobic core of SBF there is a significant increase (1) relative permeabilities in the water.

The observed effect of water repellent porous space PZP due to the following reasons: 
The surface wettability of the pore channels loosely bound water in non-draining or poorly drained sites intervals and zones of the reservoir, is determined by the Laplace equation: 

i.e. capillary pressure holding water in the pore channels, is determined by the surface tension (σ) and edge angle (θ) (slide 3). As a result of porizatsii surface, the angle selective wetting becomes more than 900, with the result that cos θ becomes a negative value, i.e. decrease in capillary pressure leads to easier displacement of loosely bound water. In addition, tobitatsu clay particles present in the reservoir, reduces the thickness of the hydration shells, thereby increasing the effective sizes of the pore channels. 

Efficiency of application of the inverse emulsions on the basis of the material "SBF" with the aim of limiting water production and increase oil production producing wells NGDU "jalilneft"

As you know, when the displacement of oil by water due to pronitsaemosti heterogeneity occurs advanced water filtration for high-permeability layers, which leads to premature flooding of producing wells, and partial or complete exclusion from the processes of development of oil-saturated interlayers lower the permeability because of the increase in them the filtration resistances. 
For water shutoff and leveling of displacement front in the oil industry is widely used injected into the reservoir aqueous solutions of polymers, gel-forming and precipitation mixes, cement mortar and other compositions. One of the most effective compositions to create a screen for the aquifer is the reverse water-oil emulsion type water in oil, stabilized by surface-active substance (surfactant). The efficacy of these emulsions is related to several factors. Getting in the first place, washed high-permeability parts of the reservoir, invert emulsion thickens and is structured under stirring with her, dramatically decreasing the permeability of rocks in the water. On the other hand, this emulsion is easily diluted with oil and clogs the oil channels of the reservoir. Invert emulsion fluids has found wide application in the works to limit water production in producing wells, to align the profiles of pick-up and redistribution of filtration flows in injection wells. 
Known water-in-oil reverse emulsion on the basis of refined petroleum products (fuel oil, bitumen, paraffin wax compositions, etc.). 
The disadvantages of such emulsifiers include their low stability. More stable reverse emulsions are obtained by using ionogenic and nonionic emulsifiers, such as "emortal", "sulfonol", "catamin A", "neonol", etc. All currently known compounds reverse water-in-oil emulsions in the petroleum industry for waterproofing work, stabiliziruemost liquid (soluble in water or oil phase) surfactant. 
In INNOYL, OOO developed solid finely dispersed emulsifier on the basis of chemically modified silica (Aerosil, white carbon, etc.), called "SBF".

As can be seen from the figure, when changing the ratio of water:oil from 1/1 to 4/1, the viscosity of the emulsion increases by an order, acquiring the consistency of vaseline. As the hydrocarbon phase can be used oil or its fractions, such as diesel fuel, nefras, wide fraction of light hydrocarbons (NGL), hexane, and others. 

For injection inverse emulsion in the well, the composition and the volume required is selected depending on geologic characteristics of the reservoir and wells. 
Separately prepared aqueous phase and the desired density of the hydrocarbon phase (oil) with required amount of powder emulsifier- "SBF". Further, both phases are mixed until a homogeneous emulsion and injected into the reservoir. As squeezing the fluid is oil. 
The use of powder emulsifier "SBF", having the properties of a solid nonionic surfactant, allows to obtain a stable and inexpensive reverse emulsion.

The advantages of this solid surfactant than with liquid, include:

  • long duration insulating action of the emulsion compared to emulsions based on surfactant liquid;
  • lower machining cost due to low consumption of hydrocarbon phase and an emulsifier;
  • less consumption of surfactant ("SBF").

When choosing the objects of field tests must meet the following geotechnical requirements, ensuring correct terms of performance of works:

The technology can be used on all types of reservoirs with permeability of 0.01 to 1.0 µm2..
Reservoir temperature up to 1300C.
Effective thickness is not less than 1.5-2m.
Production wells water cut - 50-99 %.
The flow rate of the fluid production well of at least 10,0m3/day.
Pick-up of producing wells from 80 to 400 m3/day.
Well technically correct, in the absence of annular flow.
Mineralization of water to make the invert emulsion is changed in the range of 1050...1300kg/m3 and depends on the composition of formation waters.
For injection of emulsions used standard equipment and technical means used in workover: 
To obtain an inverse emulsion of a hydrocarbon suspension "SBF" is mixed in the hydrocarbon and aqueous phase in ratio from 1/2 to 1/4. 
The obtained emulsion is injected into the reservoir at the rate of 2,0...3,0 m3 1m opened perforated effective capacity of the reservoir. As the dispersed phase is mineralized water as the dispersion medium is oil, and as an emulsifier - material "SBF". 
The concentration of material "SBF" in the oil phase to create the invert emulsion is chosen in accordance with table 1.

 

 
Water cut, %
 
Permeability, MD
0-60
60-70
70-80
80-98
Reaction time, hours.
 
Concentration, kg per 1m3 emulsion
 
50-200
4,0-6,0
4,5-6,0
5,5-7,0
6,0-7,5
24
200-500
5,0-6,5
5,5-7,0
5,5-7,0
6,5-8,0
24
500
5,5-6,5
6,0-7,0
6,5-7,5
7,5-10,0
24

 

After pumping the total volume of the emulsion produced by the displacement of its oil in the volume equal to the volume of emulsion and volume of the internal space of the tubing. 
In NGDU "jalilneft" in the period of 1999-2000. seven wells in East Sulewski, Alkeevsky (pashysky horizon) and Deposits number 31 (the beaver) was carried out processing PZP reverse emulsions on the basis of SBF. Quick collection feature on the horizon according to the presented in table.2.

Collection feature layers

 

Horizon
Permeability,
мD
Viscosity,
GPa
Temperature
reservoir, °С
Gas. factor,
М3/Т
Dismemberment,
shares of the units.
Pashiyskiy
0.375
4.5
40
63
3
Bobrik
0.967
29.5
25
13.4
1.3

 

The basic water content of the treated wells was 88-99,2%, oil production rate, respectively, of 0.3-9.5 t/day (table 3). 
The amount of material selected in accordance with the Regulations INNOYL, OOO depending on the thickness of the perforated layer. 
In General, 1.01.2001 till processed further selected wells 4381,5 tons of oil. The wells that were processed in October 1999, the effect is observed for 16 months. In Fig. 2 shows data on the changes in oil production, the percentage of water content and fluid rate of well No. 5353 NGDU "jalilneft" after the processing of the reverse water-oil emulsion on the basis of "SBF". It is seen that the well, which gave up handling 9.5 t/day of oil for years had a stable oil production of 16-18T/day. Water cut decreased from 97 to 85-87%, and liquid flow with 260м3/day decreased more than 2 times and stably for a long time kept at 100-120m3/day. Dynamics of indicators it is obvious that the effect will continue. 
As can be seen from table 3 water cut on average for the six wells decreased by 14% , varying from 6% to 56% (well No. 11477), and production rate for this well for five months after treatment is kept almost stable in 19 times above the base. 
At well No. 1244 performance indicators have become somewhat lower. Thus, the success of the technology was 86%. 
Of course, on such a small sample of wells is difficult to conduct geological analysis of the effectiveness of the technology and to talk about the criteria of applicability of the method. However, the undisputed fact that the effect, and quite noticeable in the wells of NGDU "jalilneft", takes place.

Baseline and average efficiency technologies in the wells

 

wells, field
Treatment date key
Debit
liquid,
t/day
Debit
oil,
t/day
(change
Debitа)
Watering,
%
(change
watering)
number
spe-
nt
material, kg
The average
additional
mining oil,
tons
28190
The reservoir 31
15.09.1999
18.4
2.1
(1.5)
94
(-17.5)
60
43.9
15860
The reservoir 31
23.09.1999
17.7
20.5
(0.84)
88
(-6.25)
66
25.0
15848
The reservoir 31
04.10.1999
15.2
0.3
(0.85)
98.4
(-9.9)
50
19.5
5353
Alkeevsky
18.10.1999
258.5
9.5
(4.5)
97
(-7.8)
90
133.3
1267
Vost-Sulewska
23.03.2000
84.3
0.7
(0.50)
99.2
(-0.9)
60
16.2
1244
Vost-Sulewska
06.04.2000
25.5
0.8
(-0.2)
96.7
(2)
60
-7.3
11477
Alkeevsky
25.07.2000
31.8
0.3
(7.2)
99.2
(-55.7)
20
173

 

With some confidence we can say that the use of inverse emulsions on the basis of "SBF" help reduce selection associated water and increase the productivity of wells on oil, while reducing the flow rate of the fluid. This fact is well-tracked by the example of SLE. n 11477 (table. 4) and other wells.

(Alkeevsky square pashysky horizon)

 

Mode before processing
Mode after processing
Date
measuring
Additional
Debit
oil,
The cha-
nge of
wat-
er content,
Additional
mining
oil,
 
Relative
effect
(Qд/Qмес),
share units
Debit,
t/day
%
Water
 
Debit,
t/day
%
Water
 
 
t/day
%
 
 
Oil
Liquid
 
Oil
Liquid
 
 
 
 
 
 
 
 
 
5.2
10.0
55.5
August
4.9
-43.7
42
0.95
 
 
 
6.9
11.4
48
September
6.6
-51.2
185
1.0
0.3
31.8
99.2
7.6
11.2
41.9
October
7.3
-57.3
226
1.0
 
 
 
9.1
11.9
34.4
November
8.8
-64.8
176
0.97
 
 
 
11.6
16
37.6
December
11.3
-61.6
238
0.97
 
 
 
 
 
 
 
 
Total:
866
 

 

In addition, from table.4 largest relative effect, which is 0.9-1, it is seen that production from the well in the whole months are mainly obtained through the applied technology. 
Only 7 wells were spent 406 kg "SBF". This means that for 1 kg of material gain of 10.8 tons of oil. 
Given the processing costs of one well, the cost of the purchase and delivery of the reagent and the cost of additional oil production, the average economic effect per year of treatment is 18572$, and the economic effect on 1тонну additionally selected oil – 14.1$.

Conclusions:

1. In NGDU "jalilneft" since September 1999. on 1.01.2001 till six treated wells received in addition 4381,5 tons of oil.

2. The use of inverse emulsions on the basis of "SBF" has allowed the average for the six wells to reduce obvodnennogo by 14% and increase oil production 1.5 times. ( A single result for well No. 11477 we are considered to be random.).

3. Tentatively we can say that collectors pecheskago horizon, characterized by a lower viscosity oil and a higher roughness compared to the bobrikovsky effectiveness of the technology in the average above.

 
 
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