RU2348799C1 - Gas well payout bed killing method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil and gas producing industry and can be used for payout bed killing or temporary blocking before repair operations or conservation of gas well of low reservoir pressure. Method of gas well payout bed killing includes sequential well injection of killing liquid containing, wt %: chlorinated hydrocarbon liquid trichloroethylene or a hydrocarbon heavy fluid, or composition "АПК" 10-60, polymethyl hydrosiloxane 0.3-0.4, hydrocarbon liquid condensate or diesel fuel the rest. Thereafter it is forced through into the payout bed, injection of blocking liquids containing, wt %: 11% aqueous calcium chloride solution 36-44, emultal 2-3.5, lubricating additive 1-2, chalk 1.8-2.0, asbestos 2.8-3.0, 0.3% aqueous carboxymethyl cellulose solution 5.8-6.2, hydrocarbon liquid condensate or diesel fuel the rest. Blocking liquid is placed within killed payout bed with injection of squeesing liquid providing delivery of first two liquids to bottom hole and payout bed.

EFFECT: gas well killing accompanied with minimum detrimental effect on filtration capacity of gas collector of acid highly mineralised residual water saturation.

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Description

The invention relates to the oil and gas industry and can be used to jam or temporarily block a reservoir before repair work or conservation of a gas well with low reservoir pressure.

A known method of killing a well by forcing into a formation an aqueous solution thickened with a polymer, in particular polyacrylamide [Ibragimov GZ, Fazlutdinov KS, Khisamutdinov NI A reference guide on the use of chemicals in oil production. - M .: Nedra, 198. - S.130-134].

The disadvantage of this method of killing a well is the irreversible colmatization of the pore space of the rocks of the near-wellbore zone of the formation with polyacrylamide due to the high adsorption-adhesive activity of the thickener macromolecules.

The closest technical solution selected for the prototype is a method of killing oil and gas wells [Patent RU 2111345 C1, E21B 43/12. The method of killing oil and gas wells. Application 96103467/03. Publ. 1998.05.20], the essence of which is that a fluid thickened with a modified polyacrylamide is used for its implementation, the adsorption-adhesive activity of which is significantly reduced due to its radiation γ-radiation, and before pumping the jamming fluid, an anti-colming a composition containing 3-10% sodium pyrophosphate or sodium orthophosphate and 0.2-1.5% surfactant.

The disadvantage of the prototype method is that it cannot be applied in cases where it is necessary to suppress the reservoir represented by terrigenous rocks with an acidic nature of the residual water saturation, due to the high salinity of the pore waters with a dominant content of calcium chloride and bromide, since in this case, the decolmatant proposed in the prototype method, that is, the sodium salt of pyrophosphoric or phosphoric acid, once in the formation, will cause the formation of a heavy sediment in the form of calcium pyrophosphate or orthophosphate, which partially or completely clogs the reservoir filtration channels, providing a well-reservoir hydrodynamic connection. An example of productive formations with an acidic nature of pore water are subsalt terrigenous deposits of deposits of the Siberian platform [Oil and gas hydrogeology of the south of the Siberian platform. // A.S. Antsiferov, A.S. Artemenko, O.V. Zekhova, etc. - M .: Nedra, 1983. - 192 p.].

The technical task of the invention is the development of a method of killing a gas well, which has a minimal negative impact on the filtration-capacitive properties of a gas reservoir with acidic highly mineralized residual water saturation.

The problem is solved in that in the method of killing a productive formation of a gas well, which includes sequential injection into the well and then into the formation of killing fluid that hydrophobizes the pore surface of the rocks of the near-wellbore zone of the formation and pushes the hydrocarbon fluid saturating it into the depth of the formation, and a blocking fluid forming at the input porous rock filtration channels a strong fiber-powder layer that prevents the inter-pore contamination of the rocks of the reservoir, as a liquid silencing spacers use a composition composition, wt.%: chlorinated hydrocarbon liquid (or trichlorethylene, or heavy hydrocarbon liquid, or APC composition) 10-60; polymethylhydrosiloxane 0.3-0.4, hydrocarbon liquid (condensate or diesel fuel) - the rest, and the emulsion-dispersion composition, wt.%: 11% aqueous solution of calcium chloride 36-44; emulsion 2-3.5; SMAD 1-2; chalk 1.8-2.0; asbestos 2.8-3.0; 0.3% aqueous solution of carboxymethyl cellulose 5.8-6.2; hydrocarbon liquid (condensate or diesel fuel) - the rest.

To prepare the kill fluid use reagents manufactured by domestic industry:

- summer diesel fuel (DT) according to GOST 305-82 as amended. 1-4;

- trichlorethylene (TCE) according to TU 2631-022-44493179-98 or a heavy hydrocarbon liquid (UTZh - waste upon receipt of TCE) according to TU 6-01-12275-82 or the composition of the agro-industrial complex according to TU 6-2122-232-05763458-97 ( hydrocarbon chlorine waste - a mixture of heavy chlorinated hydrocarbons);

- polymethylhydrosiloxane (PMGS) grade 136-157 (M) according to TU 6-02-694-76 rev.

The purpose of the killing fluid is to push hydrocarbon products deep into the reservoir while simultaneously treating the surface of the flow channels of the bottom-hole zone of the formation with a hydrophobizing liquid PMGS, which, being adsorbed on the surface of pores and channels of sandstone, gives them water-repellent properties, as a result of which their flooding is prevented and the conditions for hydrocarbon production are improved from the reservoir in the process of re-conservation of the well and development of the reservoir.

The purpose of the components in the killing fluid is as follows:

- diesel fuel or condensate play the role of a PMGS solvent delivering a water repellent to the formation;

- chlorinated hydrocarbon liquids (TCE, UTZH or AIC) - regulators of the density of kill fluids in a wide range of this indicator (Table 1);

- polymethylhydrosiloxane - a hydrophobizer of the surface of pores and channels of rocks of the near-wellbore zone of the reservoir (Table 2).

It can be seen that the polar liquid (water) moistens the hydrophilic surface well, but does not spread on the surface of the samples once treated with the kill fluid.

The following reagents are required to prepare blocking fluid:

- summer diesel fuel according to GOST 305-82 as amended. 1-4;

- an emultul according to TU 2458-014-22288198-01;

- SMAD-1 according to TU 2458-001-50780546-01;

- asbestos grade A-6K-5;

- chalk according to GOST 12085-88;

- calcium chloride according to GOST 450-77;

- carboxymethyl cellulose according to TU 2231-057-07508003-2002.

Using a blocking fluid, a fiber-powder screen is formed on the wall section of the inlet channels of the porous rock and the inter-pore contamination of the rocks of the near-wellbore zone of the formation is prevented.

The purpose of the components in the killing fluid is as follows:

- diesel fuel (condensate) - hydrocarbon base;

- emulsifier and SMAD-1 - emulsifiers of emulsions of the second kind;

- asbestos, chalk - acid-soluble reagents for the formation of wall colmatization layer;

- calcium chloride - a mineralizer of the aqueous dispersed phase, identical to the main mineralizer of the residual pore water of the silenced object;

- carboxymethyl cellulose - stabilizer emulsion-dispersion composition.

Table 1 Killing fluid code The composition of the kill fluid, wt.% Killing fluid properties UTZ PMGS DT Density, g / cm ³ Dynamic viscosity, cP - - - one hundred 0.82 2.07 1-g 10 0.40 89.6 0.86 1.89 2-g twenty 0.36 79.64 0.90 1,67 3G thirty 0.30 69.7 0.95 1.51 4-g 40 0.40 59.6 1.01 1.48 5-g fifty 0.40 49.6 1.06 1.34 6-g 60 0.30 39.7 1.20 0.85 - one hundred - - 1.55 0.65 table 2 No pp Quartz plate surface treatment conditions Water wetting angle of a quartz plate, deg. one The surface of the quartz plate is moistened with 2-G damping fluid and dried in an upright position 56 2 The surface of the quartz plate is moistened with 5-G quenching liquid and dried in an upright position 54 3 The surface of the quartz plate is moistened with a 6-G damping fluid and dried in an upright position 55 four The surface of the quartz plate is moistened with distilled water and dried upright. 42

Examples of the preparation of process fluids and the implementation of the method of killing a productive formation of a gas well

Example 1. Preparation of kill fluid

The components of the kill fluid (diesel fuel, UTZ, polymethylhydrosiloxane) are dosed in a predetermined ratio, poured into the capacity of the cementing unit and mixed according to the “capacity-pump-capacity” scheme until the density indicator is equalized. The fluid killing composition, wt.%: Diesel fuel 45.2; UTZ 54.4; PMGS 0.4, has a density of 1.05 g / cm ³ , a dynamic viscosity of 0.959 cP.

Example 2. Preparation of blocking fluid

a) Preparation of a dispersion medium

From the tanker, 1.2 tons of diesel fuel are pumped to the mixer. There, with stirring, 105 kg of emulsal are added. Stirred for 10 minutes. 45 kg of SMAD-1 are introduced into the resulting solution. All together stirred for 20 minutes.

b) Preparation of the dispersed aqueous phase

1.16 m ^{3 of} water are placed in the capacity of the cementing unit and 144 kg of calcium chloride are added (calculated on dry matter). Stirred according to the scheme "capacity-pump-capacity" until the salt is completely dissolved and a solution with a density of 1.10 g / cm ^{3 is} obtained.

c) Preparation of a 0.3% aqueous solution of CMC

In the second tank of the cementing unit, a 0.3% solution of carboxymethyl cellulose (CMC) is prepared, for which 179.5 L of water is poured into the tank and 0.54 kg of CMC is poured into it. Stirred for 0.5 hours to dissolve the polymer in the entire volume of liquid.

d) Emulsification

In an clay mixer containing a solution of emulsal and SMAD-1 in diesel fuel, prepared according to claim 2.1, an aqueous solution of calcium chloride with a density of 1.10 g / cm ³ obtained according to claim 2.2 is fed with a thin stream from the unit’s capacity. At the end of the supply of the aqueous phase, the total mass in the clay mixer is stirred for 1 hour.

e) stabilization

Into the clay mixer, where the emulsion composition prepared according to clause 2.4 is located, add 90 kg of asbestos (rubbed through the net), 60 kg of chalk and 180 l of 0.3% CMC solution. The total mass of the blocking fluid is stirred for 2 hours.

The technological properties of the obtained blocking fluid are determined using standard measuring tools included in the borehole equipment. Table 3 provides information on the composition and properties of blocking fluid options.

Example 3. The implementation of the method of killing a productive formation of a gas well

In the case of open plugs, the kill fluid prepared in accordance with Example 1 is sequentially pumped through the “chain”, the blocking fluid obtained in accordance with Example 2 is a pumping fluid, which is water or a hydrocarbon-based drilling fluid. After this, the annular space is closed and pressure is created in the pipe space so that the entire volume of the killing fluid penetrates the bottom-hole section of the reservoir, then the pressure is increased by 1 ... 2 MPa, so that a wall collating screen from blocking fluid components is formed. Maintain the well with closed plugs in the tubing and annulus for 12 ... 24 hours, monitoring the pressure in the well. The absence of pressure growth indicates the success of the operation to kill the reservoir.

The possibility of restoring the permeability of sandstones after completion of the operations using the proposed method is confirmed by filtration experiments performed on a high-pressure installation UIPK-1M.

Conducting a filtration study

The work uses sandstone samples of the Parfenovo horizon of the Kovykta field, prepared in a standard way for filtration studies.

After creating residual water saturation with formation water with a density of 1.244 g / cm ³ and a pH of 3.6, having a composition, g / l: Ca ⁺² 106.64; Mg ⁺² 9.35; K ⁺ 7.44; Na ⁺ 0.36; Cl ^- 226.97; Br ^- 4.68, killing fluid is supplied to the end of the sample and pumped through the sample in an amount of 1.5 pore volumes, then blocking fluid is supplied in the same direction and pressure is created up to 7.1 MPa. Filtration is continued until the stabilization of the process of liquid penetration into the core. After this, the permeability (K ₁ ) of the sandstone is determined by the decan, feeding it into the sample from the opposite end. Then the input end face of the sandstone sample is brought into contact with a clay acid solution, simulating the effect of a clay acid bath of the following composition, wt.%: HCl 5; NH ₄ HF ₂ 1.7; water is the rest. The exposure time of the clay-acid bath (without pumping it through the sample) is 4 hours.

After the clay bath, the permeability (K ₂ ) of the sandstone is determined by the decan, again feeding it into the sample from the opposite end.

The results of the assessment of the effects of kill fluids and blocking and aging in a clay-acid bath on the sandstone samples of the Parfenov horizon of the Kovykta deposit are given in Table 4.

The data obtained confirm the possibility of implementing the proposed method of killing terrigenous formations with low reservoir pressure and acidic nature of the residual water saturation and show the efficiency of reservoir release with complete restoration of its initial permeability when creating depression and pumping hydrocarbon fluid from the opposite end of the sandstone sample.

Claims (1)

A method of killing a productive formation of a gas well, including sequentially injecting a killing fluid into the well that impedes the inter-pore colmatation of the formation filtration channels of the formation rocks, and forcing it into the formation, blocking fluid, wall-mounted colmatating filtration channels of the formation near-wellbore formation rocks, and placing the blocking fluid in the interval of the formation being plugged, squeezing fluid, providing delivery of the first two fluids to the bottom of the well and into the reservoir, characterized in that as silencers use the composition composition, wt.%: chlorinated hydrocarbon liquid - trichlorethylene or heavy hydrocarbon liquid, or APC composition 10-60, polymethylhydrosiloxane 0.3-0.4, hydrocarbon liquid - condensate or diesel fuel - the rest, and as a liquid blocking use an emulsion-dispersion composition, wt.%: 11% aqueous solution of calcium chloride 36-44, emulsion 2-3.5, SMAD 1-2, chalk 1.8-2.0, asbestos 2.8-3 0, 0.3% aqueous solution of carboxymethyl cellulose 5.8-6.2, hydrocarbon liquid - condensate or diesel livo - rest.