RU2401941C1 - Procedure for thermo-chemical treatment of oil formation - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: procedure for thermo-chemical treatment of oil formation consists in separate pumping components of combustible-oxidising composition COC and originator of combustion OC via two oil-well tubing OWT arranged coaxially relative to each other. Also an end of an external OWT is lowered below the end of the internal OWT at distance sufficient for time of contact of COC and OC in a reaction volume. COC is supplied into a treated zone of the oil formation via annular space between external and internal OWT. OC is supplied via an internal OWT. COC corresponds to a water solution with hydrogen index pH 4-7 including wt %: nitre 5-25, carbamide-urea mixture CUM - 32 the rest, CO - water solution with pH 12 - 14 including wt %: alkali metal nitrite 15- 45, water - the rest or boron hydride of alkali metal 15-45, alkali 3 - 45, water - the rest. Notably, weight of CO containing nitrite of alkali metal is 1-80 % of weight COC, and weight of CO containing boron hydride of alkali is 1-30 % of COC weight.

EFFECT: reduced explosion hazard of process, increased efficiency of oil yield stimulation, and expanded heated zone of formation due to reduced time for introduction of big amount of heat into formation.

5 cl, 2 tbl

Description

The invention relates to the oil industry, in particular to methods for thermochemical treatment of an oil reservoir using a composition based on chemical reagents, and can be used to activate or renew oil wells with high oil viscosity, the productivity of which is reduced due to paraffin-hydrated and asphalt deposits, clogging the filtration channels and disrupting the connection of the well with the fluid-bearing formation, as well as to regulate the development process and increase oil recovery permeability heterogeneous.

A known method of thermochemical treatment of the bottom-hole zone of the formation and the wellbore, comprising introducing into the well through a tubing string (tubing) an aqueous solution of a combustible oxidizing composition (GOS) containing ammonium salts of organic or inorganic acids, followed by introduction into the GOS of at least , one agent that initiates the exothermic reaction: alkali metal hypochlorites, nitrous acid salts, while the introduction of the initiator and GOS is carried out separately: GOS is fed via tubing to the perforated zone, combustion initiator (IG) is fed into zone CRP arrangement according to the annulus between the tubing and the casing (RU 2102589 C1, E 21 B 43/25, 1998).

The introduction of a combustion initiator into the GOS through the annulus often leads to damage to the outer surface of the tubing, which limits the life of the latter.

A known method of thermochemical treatment of a reservoir, including separate injection into the processing zone of the fuel-oxidative composition and delivery to the processing zone of the combustion initiator, which is used as a composition based on alkali metal borohydride and methanol or diethyl ether in an amount of 5-95 wt.%, Or alkali in the amount of 5-25 wt.% and / or solid isopropylcarborane in the amount of 5-40 wt.%, and the fuel-oxidative composition contains a complex compound of oxalic acid diamide and nitric acid (18-36 wt.%), acetic acid p salicylic acid (4-5 wt.%), potassium permanganate (0.01-0.05 wt.%), isopropylcarborane (5-15 wt.%), water (9-18 wt.%) and ammonium nitrate - the rest (RU 2153065 C1, ЕВВ 43/24, 1999).

The delivery of the combustion initiator in the known invention is carried out by lowering the sealed container with the combustion initiator into the tubing string by means of a production winch and subsequent destruction of the container by exploding a cord torpedo installed along the entire length of the container, when the container contacts the cord winch and the power source installed in the shoe of the tubing string.

The disadvantage of the invention in terms of the method is its complexity and the risk of processing, in part of the composition, the disadvantage is the increased explosiveness of the GOS associated with a small amount of water in the composition. The water content (less than 22-23%) in an aqueous solution of ammonium nitrate is not technologically advanced because at a temperature below 30 ° C, a suspension is formed, which complicates the injection by field pumps.

Known fuel-oxidizing composition for thermochemical treatment of the bottom-hole formation zone containing the starting components in the following ratio, wt.%: Nitrate 2.0-25.0; a complex compound of alkanolamine with nitric acid up to 100, while GOS contains at least one of the following as alkanolamine: ethanolamine, diethanolamine, triethanolamine, predominantly ethanolamine bound to nitric acid in an equimolar ratio, and GOS contains ammoniac as saltpeter, potassium, sodium, calcium, mainly ammonium nitrate. Additionally, GOS may contain no more than 3.0% by weight of the main components of the target additives, such as potassium permanganate, isopropyl methacarborane, acetic acid (RU 2192543 C1, ЕВВ 43/22, Е21В 43/25, 10.11.2002).

The known invention has a sufficiently high fire and explosion safety. However, the invention has a significant drawback - the industry does not currently produce a complex compound of organic amines, and nitration (nitriding) of organic amines in commercial conditions is not always feasible.

Closest to the claimed one is a method of thermochemical treatment of a productive formation, comprising separately injecting through a tubing string into the treatment zone a composition of reactive components comprising a combustible oxidizing composition containing a complex organic compound with nitric acid, nitrate, water and a combustion initiator, first, the GOS is pumped, and then the initiator of combustion from a number of alkali metal borohydrides is delivered to the GOS location zone, while in the GOS, as ompleksnogo etanolaminnitrat compound administered, and the combustion initiator is added in an amount of 2-50% by weight of the fuel and the oxidizing composition in the form of compressed powder in pills borohydride coated with paraffin or colophony, a composition in the following ratio, wt.%:

Combustion-oxidizing composition:

Ethanolamine Nitrate 40-82 Saltpeter 1,0-20 Water 15.0-50

Initiator:

Alkali metal borohydride, mainly sodium borohydride 2.0-10.0

(RU 2219332 C1, E21B 43/22, E21B 43/25, 12.20.2003).

In addition, not more than 10 wt.% Of one of the acids: nitric, acetic, and phosphoric can be introduced into the composition of GOS.

A disadvantage of the known solution is the above-mentioned need for ethanolamine nitrate in the field. The disadvantage is the use of solid alkali metal borohydrides, lowered into the well in capsules on a wireline and capable of initiating decomposition of the decomposition of a relatively small portion of GOS, injected into the well opposite the reservoir.

In the known inventions, in the standard one-time initiation of the GOS layer, placed in the well opposite the reservoir, the mass of the column for safety reasons usually does not exceed 1 ton. A single initiation is carried out by a pulse of heat released in the medium previously prepared in the well of the GOS column. A heat pulse occurs after descent into the well on a geophysical cable of gunpowder charges, or capsules with a solid chemical initiator, destroyed by an explosion of the detonation cord.

After decomposition of a portion of GOS weighing 1-2 tons, the operation of delivering a new portion of GOS to the zone of the productive formation and lowering a new initiating charge is repeated. With a well depth of 2-3 km, the described scheme allows several tons of GOS to be burned in the well during the day.

This method of periodic delivery of liquid GOS and solid IG to the bottom cannot provide a sufficiently fast heat supply to the formation.

Below are abbreviations (abbreviations): BS, GOS and IG.

BS - binary mixtures - aqueous solutions of chemicals that are pumped through two separate channels and react opposite the reservoir under the packer, generating gas and heat, rapidly leaving the reservoir under pressure created by the reaction itself.

GOS - combustible-oxidative composition - the first (main) component of BS, generating heat in the decomposition (combustion) reaction when interacting with a combustion initiator.

IG - the initiator of combustion - the second component of the BS, initiating the beginning of the decomposition (combustion) of the GOS.

The objective of the invention is to improve the method due to the new composition of the composition for the rapid supply of heat to the well with the aim of thermochemical treatment of the bottom-hole formation zone (BHP) and a method for continuously supplying a large mass of GOS and IG liquid solutions through different channels that react when they merge and mix, generating heat and gas leaving the reservoir due to the pressure created by the reaction.

The technical result of the invention is to reduce the explosiveness of the process, increase the efficiency of stimulating oil recovery, expand the heated zone of the formation and its depth by reducing the time of introducing large amounts of heat into the formation.

The specified technical result is achieved by the fact that the method of thermochemical treatment of the oil reservoir involves the separate injection of components of the fuel-oxidizing composition of the GOS and the initiator of combustion of IG through two tubing tubing coaxially located relative to each other, while the end of the outer tubing is lowered to a distance below the end of the inner tubing sufficient to ensure the contact time of GOS and IG in the reaction volume. GOS is fed into the treated zone of the oil reservoir through the annular space between the external and internal tubing, IG is supplied via the internal tubing, GOS is an aqueous solution with a pH of 4-7, including, wt.%: Nitrate 5-25, urea-ammonia mixture KAS-32 - the rest, IG - an aqueous solution with a pH of 12-14, including, wt.%: alkali metal nitrite 15-45, the rest water, or alkali metal borohydride 15-45, alkali 5-45, water - the rest, and the mass of IG, containing alkali metal nitrite is 1-80% by weight of GOS; the weight of IG containing alkali metal borohydride is 1-3 0% by weight of GOS.

Physico-chemical characteristics of KAS-32 are given in table 1

Table 1 Mass fraction of nitrogen N,% 31.7-32.3 Mass ratio between urea and ammonium nitrate 0.74-0.80 Alkalinity in terms of free ammonia,% 0.02-0.1 pH of liquid nitrogen fertilizers CAS 7.0 Density, kg / cm ³ , at 20 ° С 1306-1337 Crystallization temperature, ° С -2

Ammonium, potassium or sodium, mainly ammonia, are used as nitrate, and a solution of the corresponding metal hydroxide, mainly sodium hydroxide, is used as an alkaline solution for the components of the combustion initiator. The composition of the fuel-oxidative composition can additionally be introduced no more than 20 wt.% Nitric, hydrofluoric or phosphoric acid. The composition of the fuel-oxidative composition can additionally be introduced no more than 5 wt.% Water-soluble metal salt from a series including Fe (NO ₃ ) ₃ , Mn (NO ₃ ) ₂ · 6H ₂ O, MnSO ₄ · 6H ₂ O, KMnO ₄ , K ₂ MnO ₄ , K ₂ CrO ₄ , Na ₂ CrO ₄ , K ₂ Cr ₂ O ₇ , Na ₂ Cr ₂ O7 ₇ , Co (NO ₃ ) ₃ , NH ₄ VO ₃ , NaVO ₃ , KVO ₃ . The mass of IG containing alkali metal nitrite, with respect to the mass of GOS, is from 1 to 80%, the mass of IG containing alkali metal borohydride, with respect to the mass of GOS, is from 1 to 30%, preferably 10%.

All reagents used in the proposed method are available for use and are produced by domestic industry. So, water KAS-32 is produced in large volume as a liquid fertilizer. As additives that improve energy release, GOS contains ammonia, potassium or sodium, mainly ammonium nitrate (up to 25 wt.%), As well as acids - hydrochloric, hydrofluoric, nitric or phosphoric - not more than 20 wt.%).

An alkaline metal hydroxide is used as an alkaline aqueous solution for dissolving IG components.

The feed rate of the reagents is calculated taking into account the contact time and features of the well being processed (packer location, sump depth, allowable heating of cement stone, etc.). It should also be taken into account that the energy release during the decomposition of GOS becomes stable after heating the walls of the reactor to a temperature of 100-200 ° C.

The reactor is the volume of the external tubing, located below the end of the inner pipe, from which the IG flow should exit. GOS, as a rule, should be pumped along the annular gap between the pipes. When creating the flow, it is necessary that the end of the inner pipe be higher than the end of the outer pipe (or the end of the outer pipe should be lower than the end of the inner pipe) at a distance sufficient to ensure a contact time of at least 15-20 seconds in the GOS and IG reactor.

The method of application of the composition, if possible, should include the use of standard field and geophysical equipment:

- a design of coaxial two or three tubing (tubing, casing, coiled tubing);

- check valves that turn off the BS supply when the pressure and temperature in the reaction zone are increased to a dangerous level (under the packer);

- a device for optimizing the chemical process and continuous monitoring of tubing heating near the packer, for example, using the KTMF-1M thermocouple cable.

The use of known substances in a new combination using a device for pumping GOS and IG reagents through separate channels allows the optimized mode of sustainable combustion with an increased volume of gas evolution in the presented set of features of the formula. IG reagents, as well as salts of water-soluble metals, enhance the oxidative potential of GOS components. These compounds act as combustion regulators, controlling and modifying the kinetics of the process, and are active radical carriers capable of incorporating into the natural process of decomposition of GOS.

An IG solution is a substance that stabilizes the combustion process, which, when meeting with GOS, enters into an active reaction of heat and gas evolution. IG substances are so active in the reaction with GOS that when fed through the central channel (via tubing, or through a flexible pipe) they create a constantly working “wick” that provides stable support for the GOS decomposition process when it is pumped along the annular gap in the “pipe in pipe” design whose axis, as a rule, coincides with the axis of the casing.

Thus, the GOS decomposition (combustion) reaction is controlled by a controlled supply of substances that initiate and stabilize the reaction process, which is accompanied by the release of heat and gas in the wellbore opposite the reservoir.

It was experimentally found that with increasing heat release and, correspondingly, the combustion temperature, the reaction mode itself changes: instead of the predominant formation of CO ₂ , H ₂ O and N ₂ , NO, CO, and in small amounts of H ₂ also begin to form (stand out) in noticeable amounts. After reaching a stable decomposition mode of GOS, i.e. after heating the walls of the reactor to a temperature of 100-150 ° C, it is possible to reduce the feed rate by several times and switch to a cheaper mode of heat generation, as Of the three main reagents — sodium borohydride, sodium nitrite, and UAN, UAN is the cheapest.

The claimed combination of features of the formula, in contrast to the known solutions, allows for a continuous reaction by pumping GOS and IG with field pumps at a speed of 2-4 liters of GOS per second. The IG injection rate relative to the GOS injection rate is from 1 to 10% in the case of using borohydride and from 10 to 100% in the case of using nitrite.

Standard fishing equipment can also be used to supply reagents with a low space velocity, for example 0.1-0.5 l / s. To do this, when downloading, tees are used with sockets for calibrated washers and bypasses, which ensure the separation of flows in the desired ratio. Thus, it can be expected that the proposed combination of GOS and IG components within the injectivity of the reservoir can provide rapid injection of reagents and heating of the formation zone surrounding the well.

Solutions are delivered to the place of use in containers adapted for transportation. The proposed composition has high energy and the ability to maintain a high temperature PZP (average up to 150-200 ° C and, if necessary, up to 300 ° C).

A distinctive feature of the proposed compositions of the compositions is the intense evolution of gas during the processing of wells. This allows you to rely on a gas lift gain, as upon injection, BS react without the formation of a condensed phase and are mainly gas-forming.

To improve the energy balance during the processing of complex wells, not more than 5 wt.% Technological additives from a number of water-soluble metal salts specified in the formula can be introduced into the composition of GOS.

Thus, the composition in the proposed method is technologically safe, does not lose its characteristics during transportation, and in combination with the methods of the method allows for controlled thermochemical processing of any (terrigenous, carbonate, complex) oil and gas formations.

Table 2 shows examples of compositions compositions GOS and IG with an indication of their characteristics.

table 2 The name of the components of the composition The quantitative ratio of the components of the composition according to the examples, wt.% one 2 3 four 5 GOS Urea-ammonia mixture KAS-32 89 80 75 70 60 Ammonium nitrate* 5 10 fifteen 16 25 Nitric acid** 5 10 10 10 10 Water Soluble Metal Salts Fe (NO ₃ ) ₃ - - KMnO ₄ K ₂ Cr ₂ O ₇ IG Sodium nitrite 45 thirty Water 55 70 Sodium borohydride 40 thirty twenty Sodium hydroxide*** 10 5 5 Water fifty 65 75 The number of IG in relation to GOS 40 10 5 3 80 Properties of compositions by examples Combustion temperature (calculated), ° С 200-300 150-250 150-200 150-200 150-200 pH GOS four 5 5 5 6 pH IG fourteen 13 12.5 12 12 * If necessary, sodium or potassium nitrate can be used in the same proportions. ** If necessary, nitric acid can be replaced with hydrochloric, hydrofluoric or phosphoric acid. *** If necessary, hydroxides of other alkali metals can be used.

Claims (5)

1. A method for thermochemical treatment of an oil reservoir, including separate injection of components of the GOS fuel and oxidizing composition and IG initiator through two tubing tubing coaxially located relative to each other, while the end of the outer tubing is lowered to a distance sufficient to ensure the contact time of GOS and IG in the reaction volume, GOS is fed into the treated zone of the oil reservoir through the annular space between the external and internal tubing, IG is fed through the internal tubing, GOS - an aqueous solution with a hydrogen pH of 4-7, including, wt.%: nitrate 5-25, urea-ammonia mixture KAS-32 rest, IG - an aqueous solution with pH 12-14, including, wt.%: alkali metal nitrite 15-45, the rest water, or alkali metal borohydride 15-45, alkali 3-45, the rest water, and the mass of IG containing alkali metal nitrite is 1-80% by weight of GOS, the mass of IG containing alkali metal borohydride is 1-30% of the mass of GOS. 2. The method according to claim 1, characterized in that ammonium, potassium or sodium nitrate is used as nitrate. 3. The method according to claim 1, characterized in that nitric, hydrochloric, hydrofluoric or phosphoric acid in an amount of not more than 20 wt.% Is additionally added to GOS. 4. The method according to claim 1, characterized in that the water-soluble metal salt of a series including iron, manganese, chromium, cobalt, vanadium, in an amount of not more than 5 wt. 5. The method according to claim 5, characterized in that Fe (NO ₃ ) ₃ , Mn (NO ₃ ) ₂ · 6H ₂ O, Mn (SO ₄ ) · 6H ₂ O, KMnO ₄ , are used as a water-soluble salt of these metals K ₂ MnO ₄ , K ₂ CrO ₄ , Na ₂ CrO ₄ , K ₂ Cr ₂ O ₇ , Na ₂ Cr ₂ O ₇ , Co (MO ₃ ) ₃ , NH ₄ VO ₃ , NaVO ₃ , KVO ₃ .