Compound for blocking and shutting wells. RU patent 2245996.

IPC classes for russian patent Compound for blocking and shutting wells. RU patent 2245996. (RU 2245996):

E21B43/12 - Methods or apparatus for controlling the flow of the obtained fluid to or in wells (E21B0043250000 takes precedence;valve arrangements E21B0034000000)

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FIELD: oil and gas extractive industry.

SUBSTANCE: compound includes water and inhibiting salt, as inhibiting salt contains processed electrolyte - side product during production of magnesium via electrolysis from carnallite, and additionally as reducer of filtering and thickener - carbooximethylcellulose polymer, and as colmatation agent - magnesium oxide with following relation of components in percents of mass: processed electrolyte - side product of magnesium production via electrolysis from carnallite 10.0-15.0, carbooximethylcellulose 2.5-3.0; magnesium oxide 1.0-2.0, water 80.0-86.5.

EFFECT: higher efficiency.

3 tbl

The invention relates to the field of oil and gas, in particular compositions for blocking and plugging of oil, gas and gas condensate wells, and can be used at the enterprises of the oil and gas industry when conducting capital repair of wells (red).

The main requirements for blocking and killing fluids during repair works are: high viscosity; wide adjustment range of structural-mechanical properties; low rate of filtration; the inadmissibility of violation of reservoir properties (CFP) and operational characteristics of the reservoir; not scarce raw components; simple cooking technique in field conditions; ensuring the safety of cattle.

Known liquid for killing wells [RF patent №2203304, E 21 In 43/12], including, wt.%: glycerin - 50,0-60,0; alfacell - 1,5-2,0; potassium chloride - 2,0; disolve - 0,5; AFM - 5,0-15,0; water - the rest.

The disadvantages of this fluid is a low viscosity, low pseudoplastic-type and blocking properties.

In addition, a high percentage of expensive glycerol leads to a high cost when performing cattle.

The closest technical solution chosen for the prototype is the liquid for killing wells [RF patent №2151162, 7 From 09 To 7/00], including, wt.%: filler-lignin - 2,0; inhibitory salt, which is taken MOP - 5,0; complex polymeric reagent kbps - 2,5-3,0; organosilicon reagent NGL-10 - 0,4-0,6; surfactant surfactant is 0.5; the water - the rest.

The disadvantages of the kill fluid is a low viscosity, low pseudoplastic-type and blocking properties, and high filtration in a porous medium, not allowing to preserve the original permeability of the formation after blocking and plugging of wells.

The task of the invention is to increase the efficiency of blocking and plugging of wells while maintaining the FES of the reservoir rocks and the reduction in the cost of works at cattle.

The technical result in the claimed invention is to develop a process fluid for blocking and plugging of oil, gas and gas condensate wells with different geological and technical conditions having a high viscosity, low rate of filtration and having pseudo-plastic properties, which increase the blocking properties, reducing the number of penetrating into the layer of filtrate, which contributes to the preservation of reservoir properties wellbore zone (PPP), reducing completion time and o well at dormantly mode.

The task and the technical result is achieved by the fact that the composition for plugging the oil, gas and gas condensate wells, including water and inhibitory salt, unlike the prototype contains as inhibiting salt electrolyte used is a by - product in the production of magnesium by electrolysis of carnallite and additionally as filtrate agent and thickener is a polymer cancel, and as plugging - magnesium oxide in the following ratio, wt.%:

- electrolyte exhaust - side

the product in the production of

magnesium by electrolysis of carnallite - 10,0-15,0

- cancel - 2,5-3,0

- magnesium oxide - 1,0-2,0

- water - 86,5-80,0

The composition of the spent electrolyte are shown in table 1.

Table 1 composition of the spent electrolyte Component Content,% vol. Potassium chloride (KCl) 68,0 magnesium Chloride (MgCl 2 ) 4,0-9,0 sodium Chloride (NaCl) 12,0-24,0 calcium Chloride (l 2 ) 0,7-1,4 Water (H 2 O) not more than 4.0

Comparative analysis of the prototype allows us to conclude that the claimed fluid blocking and plugging of wells differs from the known fact that the quality of the filtrate agent and thickening agent contains a polymer cancel, as acid-soluble plugging magnesium oxide, and as a reagent that allows to adjust the density of the fluid to lower the freezing temperature and to inhibit the swelling of clays is used, the electrolyte used is a by - product in the production of magnesium by electrolysis of carnallite. The result is the rate of filtration decreases and the viscosity increases. The introduction of acid-soluble plugging, which creates a dense crust that prevents the penetration of the filtrate into the reservoir and then it can be easily removed, while the initial permeability of the formation is fully restored.

In addition, pseudoplasticity, which has the claimed composition, increases its blocking properties, reducing the number of penetrating into the layer of filtrate.

The electrolyte used is in bereznjaki JSC “Agropromkaly (TU 1714-453-0578538-99), is a by-product in the production of magnesium by electrolysis of carnallite and is intended for use as fluxes used in the metallurgical industry and in agriculture. The electrolyte used not gets frozen, toxic compounds in the air does not form, non-flammable, pozharovzryvobezopasen, hygroscopic, radiation safe.

The polymer cancel (carboxymethylcellulose technical) production by JSC “KARBOCHEM - Perm (TU 2231-002-50277563-00). In part blocked liquid polymer Kamal is a filtrate agent and acts as a thickener solution. The polymer Kamal is a fine powder pale yellow, soluble in water. The degree of polymerization of the polymer cancel 600-800.

Magnesium oxide (GOST 4526-75) - white fine powder, insoluble in water. Soluble in acids. In this part of the reagent is plugging. The main function of plugging is the ability to form on the surface of the filter in the borehole permeability crust, which is then removed by acid treatment.

The mutual influence of ingredients allows you to get the fluid to block oil, gas and gas condensate wells with pseudo-plastic properties (the ability to have a low viscosity at high shear rates characteristic of flow in pipes, and high viscosity at low shear rates characteristic of the flow in the reservoir).

To evaluate the rheological properties of the used indices n and K, which characterizes the behavior of the flow and consistency of the liquid. The values of effective viscosity and dynamic shear stress are shown in table 2.

Table 2 composition and technological parameters of the liquid for blocking and plugging of wells Components, % ρ, g/cm 3 T, f, cm 3 CHC, DPA τ Oh , DPA η & a MP; MPa·n To Composition No. 1 (prototype) Filler-lignin 2,0 potassium Chloride 5,0 100 - 3,2- Integrated polymeric reagent 2,5-3,0 1,05 -180 -3,6 - - - - - the Organosilicon reagent NGL-10 0,4-0,6 surfactant of 0.5 Water the rest Composition No. 2 (claimed) Electrolyte exhaust 10,0 Kamal 2,5 1,10 422 2,8 55/55 637 75 0,44 6,83 magnesium Oxide 1,0 Water 86,5 Composition No. 3 (claimed) Electrolyte exhaust 15,0 Kamal 3,0 1,13 240 1,6 59/59 512 83 0,52 3,79 magnesium Oxide 2,0 Water 80,0

Thus, the claimed composition gives a fluid blocking and plugging of oil, gas and gas condensate wells new quality that allows to draw a conclusion on inventive step.

For experimental verification of compositions were prepared with different amount of ingredients. While the ratio of recovery of permeability of all solutions was 100%.

Technology of preparation of a liquid for blocking and plugging of wells is as follows.

First, cook 10-15%aqueous electrolyte solution waste, then add the polymer cancel, after mixing on a laboratory stirrer and complete dissolution of the polymer add the calculated amount of magnesium oxide. With the addition of magnesium oxide liquid is stirred for 30-35 minutes. The technological parameters of the solution is measured on standard devices.

For measurement of the rheological properties is using a rotational viscometer “OFITE-800” (table 3).

The preparation of an aqueous electrolyte solution waste with a concentration of less than 10% is impractical because the lowering of the freezing temperature of the liquid when this happens slightly, in addition, at low salt weakly manifested clogging properties.

The processing solution of the polymer cancel with a concentration of less than 2.5% no effect, as the solution, having a relatively small filtering, does not have satisfactory rheological characteristics.

Table 3 Values of effective viscosity and dynamic stress at different shear rates N, rpm γ, c -1 Composition No. 2 (claimed) Composition No. 3 (claimed) Composition No. 4 (claimed) Composition No. 5 (inventive) τ, DPA ηMPa· τ, DPA ηMPa·c τ, DPA ηMPa· τ, DPA ηMPa·600 1022 145 148 139 136 23 23 22 22 300 511,2 106 208 97 190 14 27 12 24 200 340,8 88 257 84 246 10 30 9 25 100 170,4 60 354 58 342 6 33 4 27 60 102,2 45 445 43 425 4 35 3 30 30 51,1 30 515 29 563 2 40 2 40 6 10,22 10 950 9 900 0,5 50 1 50 3 5,11 6 1100 8 1500 0,5 98 1 96 note - the composition No. 1 (prototype) data on the rheological characteristics are missing

The main function of the magnesium oxide is the ability to form on the surface of the filter in the borehole permeability crust, which then can be easily removed by acid treatment. When the concentration of the plugging is less than 1.0% clogging properties of this filler hardly show.

The increase in the concentration of ingredients in the solution is impractical because it does not improve the parameters of the solution (the value of n increases, and parameter decreases, which indicates the deterioration of the blocking properties).

The best parameters have the claimed compositions No. 2 and No. 3, are shown in tables 2 and 3. These compounds have low filter, high viscosity and good pseudo-plastic properties.

These properties of the developed composition allow it to be used as a fluid block and kill with the repair of wells.

Preparation of the blocking material and the technology works well is the following.

In Chanak unit CA-320M pour the calculated amount of water heated (in winter conditions) to a temperature of 30-40°add the calculated amount of electrolyte extract and mix thoroughly until the salt is completely dissolved.

Then in the resulting water-salt solution is added the calculated amount of polymer cancel and stirred until complete dissolution of the polymer.

In the obtained polymer-salt solution is added to the estimated amount of the plugging - magnesium oxide and the resulting mixture is stirred for 30 minutes. Measure the technological parameters of the obtained solution.

Before working, make a straight flush well in polutorakratnomu the volume of the tubing. Then through tubing, with an open annular valve, the blocking composition is pressed to the tubing and into the well annulus in the calculation of the overlap structure of the entire perforation interval and above. The amount of the blocking material should be 5.0 to 10.0 m 3 depending on the geological and technical conditions of the well.

Composition for blocking and plugging of wells, including water and inhibitory salt, characterized in that the inhibiting salt it contains the electrolyte used is a by - product in the production of magnesium by electrolysis of carnallite, and in addition, the filtrate agent and thickener is a polymer cancel, and as plugging - magnesium oxide in the following ratio, wt.%: