RU2274739C1 - Oil field development method - Google Patents

Abstract

FIELD: oil production industry, particularly secondary and tertiary methods for oil recovery increase from oil formations by applying bioreagent and bactericide action to formation.

SUBSTANCE: method involves injecting excessive active silt passing through secondary sumps of biological disposal plant through injection wells; injecting aqueous bactericide solution in 6-12 months after active silt injection and producing oil through production well. Above active silt treated with polydimethyldiallilammonium chloride is used as nutrient substrate with concentration of 400-400 mg/dm and having main substance in amount of 38-40 mass%.

EFFECT: increased efficiency of formation treatment due to successive bioreagent and bactericide action and increased conformance.

1 ex, 4 tbl

Description

The invention relates to the oil industry and can be used in oil production by microbiological methods and chemical reagents.

A known method of displacing oil from the reservoir by a composition based on excess activated sludge (IAI) - waste biological treatment plants (BF) after secondary settling tanks [US Pat. RF №1755615, class E 21 B 43/22, 1996].

A disadvantage of the known solution is the low biochemical activity due to the lack of nutrient substrates, which leads to a short-term effect on the formation with the formation of biofouling and clogging of pores and cracks in the reservoir in the immediate vicinity of the bottomhole zone of the wells and a decrease in efficiency from bio-exposure.

The closest in technical essence and the achieved effect is a method of developing an oil field [US Pat. RF №2150580, class E 21 In 43/22, 2000], which consists in pumping excess activated sludge into injection wells and then pumping aqueous solutions of a mixture of dioxibenzenes after 3-12 months. Aqueous solutions of a mixture of dioxibenzenes contribute to the destruction of biofouling and uncorking pores and fractures of the reservoir due to the dispersion of accumulated bio-formations and increase the coverage of the formation by water flooding.

The disadvantage of this method is the low biochemical activity of the composition due to the lack of nutrient substrates for microorganisms of excess activated sludge with the formation of small amounts of bio-formations, clogging medium-permeable zones, which leads to a short-term increase in oil recovery.

The aim of the invention is to increase the biochemical activity of the composition and increase the coverage of the formation by water flooding.

The specified goal and technical result is achieved by the fact that the method of developing an oil field, including the injection of excess activated sludge through a secondary well after secondary clarifiers of biological treatment plants and sequentially after 6-12 months of an aqueous solution of bactericide and oil production through a producing well, according to the invention, activated sludge is pumped treated with polydimethyldiallylammonium chloride, and LET-11c is injected as a bactericide.

Polydimethyldiallylammonium chloride is a water-soluble cationic polyelectrolyte grade VPK-402, manufactured according to TU 2227-184-00203312-98 and is a high molecular weight compound of a linear cyclic structure. VPK-402 is highly soluble in water, including wastewater, as well as lower alcohols, solutions of acids and alkalis. It is non-combustible, low-toxic, does not have an unpleasant odor, is used as a flocculant-coagulant to intensify the processes of biochemical wastewater treatment, treatment of antibiotic solutions in the medical industry, in the process of dehydration of wastewater, etc. VPK-402 polymer was used with a mass fraction of the main substance of 38-40%, a viscosity of 2.35 mm ² / s, a mass fraction of sodium chloride of 9.9%, and a pH of 6.9.

The bactericide LPE-11v is produced according to TU 6-01-1012949-08-89 in the form of a liquid from yellowish-orange to burgundy with a mass content of the main substance of at least 50%, pH 6-8, pour point minus 15 ° С, it not combustible, non-explosive. By the degree of exposure to the body, LPE-11v belongs to the 3rd hazard class - substances that are moderately hazardous, according to GOST 121.007-76.

The composition is prepared by mixing aqueous solutions of 0.5-2.0% concentration of IAI with aqueous solutions of the polymer VPK-402.

Example. Prepare aqueous solutions of polydimethyldiallylammonium chloride (1 ml contains 10.0 mg VPK-402 polymer) and in an amount of 3.5 ml (based on 300-400 mg VPK-402 per 1 dm ³ , the optimal dose is 350 mg / dm ³ ) in a Lisenko cylinder or in a graduated cylinder of 100 ml, then 96.5 ml of a solution of excess activated sludge are introduced into these cylinders and the mixture is thoroughly mixed.

As a control (prototype), 100 ml of excess activated sludge is introduced into the same cylinder. Then, at certain intervals, the volume occupied by the settled excess activated sludge is noted. All other operations are carried out as described. The general results of laboratory studies of the positive effect of the polymer VPK-402 on PAI are given in table. 12.

Table 1 Examples The volume of the mixture, ml Settling time, min IAI VPK-402 0 fifteen thirty 45 60 120 one 96.5 3,5 100.0 45.0 40,0 39.0 38,0 38,0 2 96.5 3,5 100.0 46.0 40,0 40,0 40,0 40,0 3 96.5 3,5 100.0 44.0 40,0 39.0 38,0 38,0 four 96.5 3,5 100.0 45.0 39.0 39.0 39.0 39.0 Avg. 96.5 3,5 100.0 45.0 39.7 93.2 38.7 38,0 Control (prototype) one 100.0 - 100.0 96.0 92.0 91.0 90.0 89.0 2 100.0 - 100.0 97.0 93.0 92.0 90.0 89.0 3 100.0 - 100.0 96.0 93.0 91.0 90.0 90.0 Avg. 100.0 - 100.0 96.3 92.7 91.3 90.0 89.3 table 2 Examples The volume of IAI, ml VPK-402,
mg Amount of displaced fluid in 20 days, ml COD, mg O ₂ / dm ³ at the beginning of the experiment after 20
day % COD decay one 590.0 206.5 265.0 1,020.0 107.0 89.5 2 590.0 206.5 260,0 1010,0 - - 3 590.0 206.5 255.0 1023.1 109,4 87.5 Avg. 590.0 206.5 260,0 1018,0 108,2 88.5 Control (prototype) one 590.0 - 40,0 293.0 166.0 43,4 2 590.0 - 39.0 291.8 170.0 41.7 Avg. 590.0 - 39.5 292.4 168.0 42.5

From the data table. 2 shows that the addition of VPK-402 polymer at a concentration of 350 mg / l (optimal concentration) in the IAI contributes to an increase in the biochemical activity of the composition (the amount of displaced liquid due to gas generation is several times higher in the experiment than in the control (according to the prototype) and oxidative the ability of the IAI microorganisms (% decomposition of organic substances after 20 days in the control is only 42.5, and in the experiment (according to the proposed 88.5). In addition, the VPK-402 polymer stimulates the processes of deep decomposition of organic substances: COD in control 292, 4 m O ₂ / l, after 20 -168 days, and in the experiment 1018.0 and 108.2, respectively, which is of no small importance in reservoir conditions.

In the table. 3 shows the results of laboratory studies of the filtration characteristics of the proposed method. The study of the effectiveness of the method was carried out on an oil-saturated quartz-sand bulk model of the reservoir. The saturation of the model was carried out by the isoviscous model of oil from the Romashkinskoye field (density 875 kg / m, viscosity 22 MPa * s, the content of purified kerosene - 17.6%). Then, oil was displaced from the reservoir model by mineralized (density 1105 kg / m) water of the Romashkinskoye field until the water cut at the output of the model and stabilization of the pressure drop were stabilized. The model has an oil permeability of 2.10 μm ² with residual water. After that, excess activated sludge with VPK-402 polymer was pumped into the model (based on 350 mg / l of polymer with a mass fraction of the main substance of 38-40%) in an amount of 0.5 pore volume with rims of fresh water (0.2 pore volume ) The model was thermostated at 25 ° C for 21 days and then mineralized water was again pumped into it and after a 0.2% solution of LPE-11v in an amount of 0.1 pore volume.

From the data in Table 3 it can be seen that the injection of the IAI of the polymer into the model is accompanied by a sharp increase in pressure drop, the resistance factor of the reservoir model after injection of the IAI with the polymer increased by 22 times compared to the initial value, the permeability of the model decreased from 2.10 μm ² to 0.596 μm ² due to selective clogging with a bioreagent.

After injection of LET-11 in 0.1 pore volume (0.2% solution), the permeability of the model is gradually restored. Excess activated sludge treated with VPK-402 polymer at the above concentration is called IAIP-1 bioreagent. The use of the IAIP-1 bioreagent is regulated by TU 38-039-1274989-97 and the sanitary and epidemiological conclusion No. 2. BC.01.01.245. P.001428.12.02 of December 9, 2002

In field conditions, the method is as follows. Excess activated sludge after secondary settling tanks of biological treatment facilities (0.5-2.0% concentration) is taken into a tanker using a pump or cementing unit CA-320 and polymer VPK-402 is added to the same tanker at a rate of 300-400 mg / l (mass fraction of the main substance 38-40%) and transported to the oil field. The injection of the IAIP-1 bioreagent is carried out into the injection well in a volume of 10–20 m ³ at a well injection rate of 100–300 m ³ / day, and at an injection rate of more than 300 m ³ / day, 20–30 m ³ . The tip of the IAIP-1 bioreagent is pushed from the bottomhole zone with freshwater or biochemically purified waters. At the end of their injection into the well, they are canned for 5 days to adapt the microorganisms of the IAIP-1 bioreagent to reservoir conditions. Then, the well is launched under sewage injection in the normal mode. After the injection, IAIP-1 conduct a complex of geological, physical and biochemical studies.

When obtaining results indicating a significant accumulation of bio-formations in the near-wellbore zone and a decrease in the effect of IAIP-1 exposure, 0.2% aqueous solutions of LPE-11 are injected into the same intervals of the formation based on the injectivity of the injection well (at an injection rate of 100-500 m ³ / day required volume in commodity form - 1 t). Then a set of studies is carried out and, when the effect is reduced, the IAIP-1 bioreagent is again pumped into the well in the same volume and sequence, then after 6-12 months LET-11v.

At this stage, the destruction of bio-formations due to the death of a significant number of microorganisms is achieved, prevention of the negative effect of increased concentrations of hydrogen sulfide (H ₂ S), uncorking of pores and channels and, as a result, an increase in additional oil produced.

The results of experimental research are given in table. 4. (experience - with the processing of LPE-11 c, control - without biocidal treatment). From the data table. Figure 4 shows that after treatment with the IAIP-1 bioreagent, the hydro- and piezoconductivity and permeability decrease, which is obviously associated with selective blockage of the growing IAIP-1 biomass. Additional oil production per year for the prototype (control) is only 331 tons, and for the proposed (experience) 2065-6600 tons

Thus, the application of the proposed method can significantly increase the effectiveness of bio-exposure on the formation by improving the biochemical activity of the reagent, destruction and dispersion of bio-formations in the bottom-hole zone of the formation, increasing the coverage of the formation by water flooding.

Claims (1)

A method of developing an oil field, including the injection of excess activated sludge through a secondary well after secondary settling tanks of biological treatment plants and sequentially after 6-12 months. an aqueous solution of bactericide and oil production through a production well, characterized in that the specified activated sludge treated with polydimethyl diallylammonium chloride is used as a nutrient substrate at a concentration of 300-400 mg / dm with a mass fraction of the main substance of 38-40%, and LET is pumped as a bactericide 11 century