RU2360099C1 - Method of restriction of water inrush in well - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method of restriction of water inrush in well consists in preparing and pumping water solution of silicon-organic liquid - SL into well; water solution of SL is obtained by mixing it with reservoir water of 1000-1180 kg/m³ density at following ratio of components, vol. %: SL 20-70, reservoir water of 1000-1180 kg/m³ density 30-80, additionally before and after pumping water solution of SL water solution of sodium silicate of 1050-1100 kg/m³ is pumped at following ratio of reagents, vol. %: water solution of sodium silicate of 1050-1100 kg/m³ 20-40; said solution of SL 60-80.

EFFECT: increased efficiency of water insulating operations due to reduced time for gel-forming, reduced general time of insulating operations, due to elimination of emergency situations at simultaneous expanding functionality of method under conditions of low temperature well.

1 tbl, 12 ex

Description

The proposal relates to the oil industry, in particular to methods of limiting water inflow into production wells, and can be used using a coiled tubing installation.

A known method of limiting water inflow into a well, comprising sequentially injecting into the well an aqueous solution of sodium silicate and a hardener (initiator of the polymerization of sodium silicate) [AS 1423726, IPC ЕВВ 33/13, publ. BI No. 34, 1988]. An aqueous solution of sodium silicate (water glass) reacts with a hardener (hydrochloric acid solution), resulting in the formation of silica sol.

The disadvantages of the method include the fact that the silica formed as a result of the polymerization reaction is not sufficiently resistant to erosion by formation water, which in turn reduces the life of the insulating screen.

A known method of isolating water inflow in a well, comprising injecting a mixture of an organosilicon compound with hydrochloric acid as a hardener and holding the mixture in the formation for the duration of gelation. The gelation time is determined depending on the specific injectivity of the well [RF Patent No. 2071548, IPC ЕВВ 33/138, publ. BI No. 1, 1997].

The disadvantage of this method is the poor filterability of the mixture in a porous medium due to the rapid formation of gel particles of polysilicic acid, which reduces the efficiency of water isolation.

The closest technical solution to the proposed proposal is a method of limiting water inflow in the well, including the preparation and injection into the well of an aqueous solution of organosilicon liquid [Stroganov V.M., Stroganov A.M. Organosilicon grouting materials AKOR: ways and prospects of development. Interval No. 6, 2006, pp. 24-30]. The injection is carried out in parallel through a tee in the tubing of the AKOR BN organosilicon liquid and water with a pH <6.5 or the AKOR BN-water waterproofing composition prepared in the measuring unit of the cementing unit and is pumped through the tubing into the well. The volume ratio of the waterproofing composition AKOR BN - water is selected depending on the required gelation time. However, the composition can only be used for formations with a temperature above 40 ° C. The gelation time of the composition at temperatures below 40 ° C is more than 32 hours, which negatively affects the success of waterproofing works in low temperature wells. It is technologically difficult to carry out waterproofing compositions with AKOR BN organosilicon liquid with a short gel time due to the exothermic nature of the curing reaction and, as a result, an emergency situation, in particular when using modern coiled tubing technologies (flexible pipes) for well repair.

The technical task of the proposal is to increase the efficiency of water insulation works by reducing the time of gelation, the total time of insulation work, eliminating emergency situations while expanding the technological capabilities of the method in low temperature wells.

The problem is solved by the proposed method of limiting water inflow in the well, including the preparation and injection into the well of an aqueous solution of organosilicon liquid (QL).

New is that an aqueous solution of QOL is obtained by mixing it with produced water with a density of 1000-1180 kg / m ³ in the following ratio of reagents, volume. %:

QL 20-70 formation water with a density of 1000-1180 kg / m ³ 30-80

additionally, before or after injection of an aqueous solution of QOL, an aqueous solution of sodium silicate with a density of 1050-1100 kg / m ^{3 is} pumped in the following ratio of reactants, volume. %:

aqueous solution of sodium silicate with a density of 1050-1100 kg / m ³ 20-40 the specified solution of QOL 60-80

An analysis of the patent and scientific and technical literature allowed us to conclude that there are no technical solutions containing essential features of the claimed method that perform a similar task, therefore, we can conclude that the criterion is “inventive step”.

As an organosilicon liquid, for example, AKOR-BN 102, AKOR-BN 101 (TU 2458-001-01172772-99), product 119-296T (TU 2229-266-05763441-99), product 119-296 (TU 6- 05-05763441-43-92), VTOKS (TU 6-02-1-045-94), ethyl silicate-32 (TU 2435-397-05763441-2003), etc.

An aqueous solution of sodium silicate with a density of 1050-1100 kg / m ^{3 is} obtained by diluting a glass of sodium liquid (sodium silicate) according to GOST 13078-81 with fresh water to an appropriate density.

An aqueous solution of organosilicon liquid is obtained by mixing it with produced water with a density of 1000-1180 kg / m ³ in the following ratio of reagents, volume. %:

organosilicon liquid 20-70 formation water with a density of 1000-1180 kg / m ³ 30-80

It should be noted that most existing waterproofing materials have a high viscosity and cannot be used with a flexible pipe. Due to the use in the proposed method of an aqueous solution of organosilicon liquid and an aqueous solution of sodium silicate with a viscosity of less than 25 MPa · s, it is possible to conduct waterproofing work using a flexible pipe.

The essence of the proposal is as follows. An aqueous solution of sodium silicate with a density of 1050-1100 kg / m ³ , a buffer liquid and an aqueous solution of an organosilicon liquid, or an aqueous solution of an organosilicon liquid, a buffer liquid and an aqueous solution are sequentially pumped through a flexible pipe or tubing that has been lowered into the interval of insulation work. sodium silicate. As a buffer fluid, oil or fresh water is used in a volume of 0.2-0.3 m ³ . The buffer is injected to separate the injected components in order to avoid structuring of the waterproofing composition during the pumping process when the organosilicon liquid interacts with sodium silicate.

After contacting the components, the composition turns into an insoluble solid polymer mass, which reliably clogs the pores of the formation.

After the components are pumped into the insulated interval, the water-proofing composition is structured throughout the volume. To a non-pumpable state, the composition cures within a few minutes, the maximum curing occurs 8 hours after pumping. The amount of cement material formed is 100% of the volume of injected components.

It is known that in order to prevent an excessive increase in injection pressure above the permissible, the dynamic viscosity of process fluids for repair work using a flexible pipe with a diameter of 25.4-38.1 mm should not exceed 10-30 MPa · s. The diluted aqueous solutions of sodium silicate and organosilicon liquid used in the proposed method satisfy this requirement.

Below are examples that confirm the feasibility of the proposal.

Example 1

An aqueous solution of sodium silicate with a density of 1050 kg / m ^{3 is} prepared by diluting a glass of sodium liquid (sodium silicate) according to GOST 13078-81 with fresh water.

Density is determined by a glass hydrometer (GOST 18481-81).

Next, prepare an aqueous solution of organosilicon liquid AKOR BN 102 by mixing the organosilicon liquid AKOR BN 102 with produced water in the following reagent ratio, volume. %:

silicone fluid AKOR-BN 102 20 formation water with a density of 1000 kg / m ³ 80

The dynamic viscosity of the prepared aqueous solutions of sodium silicate and organosilicon liquid is determined on a VISCO STAR rotational viscometer.

The initial dynamic viscosity of an aqueous solution of sodium silicate is 10 MPa · sec.

The test temperature is maintained using a thermostatic bath with an accuracy of ± 1 ° C. The test temperature is 20 ° C. The insulation coefficient after 8 hours is 100%.

Testing the water-insulating ability of the proposed method was carried out on reservoir models 80 cm long and 2.7 cm inner diameter, filled with 0.2-0.3 mm fractions of quartz sand, which allow simulating the injection of reagents into the reservoir and continuously monitoring their flow rate according to the scheme: “Well-formation” and “formation-well”. The reservoir model was saturated with water, the initial water permeability was determined, then the studied compositions were pumped. The total volume of injected components of the waterproofing composition was equal to the pore volume of the reservoir model. The model was left for 8 hours in a thermostat at a given temperature from 10 to 40 ° C in order to structure the waterproofing composition. After that, water was pumped back to determine the permeability according to the Darcy formula and to calculate the insulation effect. The insulation effect was determined by the formula:

E = (K ₁ -K ₂ ) / K ₁ · 100;

where K ₁ - the permeability of the reservoir model before plugging, μm ² ;

To ₂ - the permeability of the reservoir model after plugging, μm ² .

The research results are presented in the table.

Examples 2-12 are produced analogously to example 1.

Examples 1-5, 11 The injection sequence of the waterproofing composition for determining the isolation coefficient on the reservoir models was carried out in the following sequence: an aqueous solution of sodium silicate, a buffer liquid and an aqueous solution of organosilicon liquid.

Examples 6-10, 12. The injection sequence of the waterproofing composition to determine the isolation coefficient on the formation models was carried out in the following sequence: an aqueous solution of organosilicon liquid, a buffer liquid and an aqueous solution of sodium silicate.

The optimal amount, concentration and volume ratio of an aqueous solution of sodium silicate and organosilicon liquid were determined during laboratory tests, taking into account the achievement of structuring of the waterproofing composition in the entire volume under the indicated conditions of use.

When the content of an aqueous solution of sodium silicate in the waterproofing composition is less than 20 volume. %, and a density of less than 1050 kg / m ³ , as well as with an aqueous solution of organosilicon liquid content of more than 80 volume. %, the efficiency of insulation work at low temperatures is not ensured.

When using an aqueous solution of sodium silicate with a density of more than 1100 kg / m ³ and when the content of an aqueous solution of sodium silicate is more than 40 volume. %, and an aqueous solution of organosilicon liquid of less than 60%, it is impossible to pump through a flexible pipe, because the viscosity of an aqueous solution of sodium silicate is 51 MPa · sec.

From table 1 it can be seen that the proposed compositions have a high insulation efficiency (98-100%), which indicates the high efficiency of the proposed method of limiting water inflow in the well.

Thus, in this proposal, a result is achieved — an increase in the efficiency of waterproofing works using an organosilicon liquid under various temperature conditions. Due to the rapid structuring of the waterproofing composition, the proposed method allows to reduce the total time for repair and insulation works and can be used for insulation in formations with high absorption capacity.

Claims (1)

The method of limiting water inflow in the well, including the preparation and injection into the well of an aqueous solution of organosilicon liquid - QOL, characterized in that the aqueous QOL solution is obtained by mixing it with produced water with a density of 1000-1180 kg / m ³ in the following reagent ratio, vol.%:
QL 20-70 formation water with a density of 1000-1180 kg / m ³ 30-80,
additionally, before or after injection of an aqueous solution of QOL, an aqueous solution of sodium silicate with a density of 1050-1100 kg / m ^{3 is} pumped in the following ratio of reactants, vol.%:
aqueous solution of sodium silicate density 1050-1100 kg / m ³ 20-40 the specified solution of QOL 60-80.