RU2380394C2 - Viscous elastic composition for borehole operations - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: borehole insulation work compositions can be used for water flow insulation, for between borehole gas flow and other maintenance works. Borehole insulation works viscouse-elastic composition contains wt %: polyvinyl spirit 2.9-6.9, triethanolamine titanate - TEAT 1 0.3-0.6, GKJ-10 or GKJ-11 0.1-0.3, aluminium powder 0.1-0.4, the rest is water.

EFFECT: borehole insulation works efficiency increase.

1 tbl, 3 ex

Description

The invention relates to the oil and gas industry, in particular to viscoelastic compositions (WCS) for insulation work in wells that can be used to isolate water inflow into a well, to eliminate annular gas showings and other repair work.

Analysis of the current level of technology showed the following:

known composition for isolating water inflow into the well, the formulation of which has the following ratio of ingredients, wt.%:

Sodium silicate 10.3-12.9 Polyhydric alcohol 2.2-8.5 Aluminum chloride 2.3-4.6 Glass microspheres 0.2-0.3 Water rest

(see RF patent No. 2205269 of 06/13/2001, according to CL EV 33/138, published in Bull. No. 15, 2003).

The disadvantage of this composition is the lack of effectiveness of insulation work in wells. This is due to the following reasons: the use of a composition with the indicated gelation time (see the description table) in the field will lead to unproductive costs and the cost of ongoing work to isolate water inflow into the well. As a result of the interaction of aluminum chloride and sodium silicate, a gel is formed that is unable to bind water in which the ingredients of the composition were dissolved. The specified composition formulation does not provide gel formation with high strength indicators, since as a result of the reaction

2AlCl ₃ + 3NaSiO ₃ = Al ₂ (SiO ₃ ) ₃ + 6NaCl

A polycrystalline aluminum silicate system is formed in which the bonds between the crystals are weaker than the chemical bonds inside the crystals. In addition, the liquid phase of the composition that has penetrated to a small depth in the formation forms a weak gel and does not contribute to the production of an elastic-plastic screen, which can lead to a violation of this insulation due to formation water pressure and formation deformation. This is due to the fact that the polyhydric alcohol in the composition does not chemically interact with sodium silicate, and forms gel-like glycides or glycolates, which are low-strength complex compounds that only regulate the gelation time of the insulating composition, but do not participate in the formation of the structural strength of the insulation screen. They are easily destroyed at an elevated temperature of the formation, because of which the main strength of the insulating screen is provided by the fragile glassy reaction products of sodium silicate and aluminum chloride, which will not provide effective isolation of water inflow into the well;

- the WCS is known for isolating formation waters, eliminating interstratal and annulus flows (repair and insulation works in wells) containing an organosilicon liquid and an alcohol-containing solution. As an organosilicon liquid, it contains aqueous-alcoholic solutions of sodium ethylsiliconate - GKZH-10 or sodium methylsiliconate - GKZH-11, and as an alcohol-containing solution - an aqueous solution of polyvinyl alcohol with a concentration of 5.0-7.5% with a volume ratio of 1: 1 (see RF patent No. 2032068 of 07.27.1992, according to CL E21B 33/138, publ. In Bull. No. 9, 1995). The disadvantage of this WCS is the lack of effectiveness of insulation work in wells. This is due to the following reasons: at the indicated proportions of HCL ingredients, salting out of polyvinyl alcohol occurs under the action of GKZh-10 or GKZh-11, which results in a small amount of gel as a result and a sufficiently large amount of liquid (“excess water”) is released. In the pore space of a flooded formation, structurally unbound (“excess") water located in the WCS forms channels for filtering formation water, which will increase the permeability of the insulating screen and lead to inefficiency of the insulation work. In addition, GKZH-10 or GKZH-11 is a weak water repellent, which contributes to the further penetration of water into the reservoir. HCL does not have the necessary adhesion to the metal of the pipes due to the following: the specified HCG give the HCL hydrophobic properties, and the metal surface of the pipes has hydrophilic properties. This does not provide a strong connection between the WCS and the metal surface in contact with it;

- as a prototype taken VUS for repair and waterproofing, the formulation of which has the following ratio of ingredients, vol.%:

Water-alkaline solution - GKZH-11N 50,0 An aqueous solution of PVA 5-10% concentration with 2.5-5.0% of its weight aluminosilicate microspheres 50.0

(see RF patent No. 2211306 of March 11, 2002, according to class E21B ZZ / 138, publ., 2003).

The disadvantage of this WCS is the lack of effectiveness of insulation work in wells. This is due to the following reasons: the use of this WCS involves the sequential download of the ingredients included in the recipe of the WCS, which in commercial conditions leads to unproductive costs. The gelation time of the composition is unregulated and therefore, instant formation of WCS can occur when the ingredients are mixed, which will lead to the formation of an insulating screen of small thickness and will not further ensure the penetration of the ingredients into the porous medium. At the indicated quantitative proportions of HCL ingredients, the salting out of polyvinyl alcohol occurs under the action of GKZh-10 or GKZh-11, which results in the insignificant volume of the gel insufficiently strong in structure as a result and a sufficiently large amount of liquid (“excess water”) is released. In the pore space of the flooded formation, structurally unbound (“excess") water located in the WCS forms channels for filtering formation water, which will increase the permeability of the insulating screen and lead to inefficiency of the insulation work. In addition, GKZH-10 or GKZH-11 is a weak water repellent, which contributes to the further penetration of water into the reservoir. VUS does not have the necessary adhesion to the pipe metal due to the following: GKZh-10 or GKZh-11 give the VUS hydrophobic properties, and the metal surface of the pipes has hydrophilic properties. The above does not provide a strong connection between the WCS and the metal surface in contact with it. When forcing the WCS into the formation, especially if it is composed of sandstone, aluminosilicate microspheres will be filtered on the surface of the formation. The latter prevents the penetration of the composition into small and medium pores of the reservoir. Mainly large pores and cracks are filled, the insulating screen will be heterogeneous, not continuous, which will ultimately lead to insufficient efficiency of the ongoing insulation work in the wells. There is no ingredient that promotes gas evolution in the HCL formulation. There is no increase in volume and, as a result, there is no complete saturation of the WCS of the isolation zone. The use of this WCS for the elimination of intercolumnar gas manifestations is ineffective.

The technical result that can be obtained by implementing the present invention is as follows: the efficiency of insulation work in wells is increased using a hydraulic control system with improved technological properties due to adjustable gelation time, which ensures penetration of the composition into a porous medium, increased adhesion to pipe metal and strength the resulting gel, a more complete saturation of the isolation zone of the WCS due to an increase in its volume resulting from intensive about gas evolution.

The technical result is achieved using the well-known WCS for insulation in wells containing polyvinyl alcohol, an organosilicon liquid, an aluminum-containing additive and water, characterized in that it additionally contains triethanolamine titanate - TEAT-1, and as an organosilicon liquid - aqueous-alcoholic solutions of sodium ethylsiliconate - GKZH-10 or sodium methylsiliconate - GKZH-11, as an aluminum-containing additive - aluminum powder in the following ratio of ingredients, wt.%:

Polyvinyl alcohol 2.9-6.9; TEAT-1 0.3-0.6; GKZH-10 or GKZH-11 0.1-0.3; aluminum powder 0.1-0.4; water the rest. The inventive WMC meets the condition of "novelty." Polyvinyl alcohol according to TU 6-05-313-85, aluminum powder according to TU-5494-95, GKZh-10, GKZh-11 - 30% aqueous-alcoholic solution of sodium ethylsiliconate or sodium methylsiliconate TU 6-02 -696-76. TEAT-1 according to TU 6-09-11-2119-93. It is a viscous, resinous mass of dark color.

The preparation of the WCS is based on the reaction of polycondensation of PVA with TEAT-1

In the process of polycondensation, a spatial mesh frame is formed, the cells of which are filled with immobilized water, which determines the high strength characteristics of the WCS. High strength characteristics make it possible to achieve complete plugging of the pores of the insulated formation, increasing the efficiency of insulation work in wells

The inventive WCS is characterized by increased adhesion to the metal of the pipes, which is due to the following: polyvinyl alcohol and TEAT-1 are pronounced hydrophilic compounds that well wet the metal surface of the pipes, which also has hydrophilic properties, resulting in close contact between the molecules and functional groups of polyvinyl molecules alcohol, TEAT-1 and metal. Next, there is a direct interaction of the crosslinkable polymer and the metal surface, which is caused by various forces - from Van der Waals to chemical. Such intermolecular interaction of the contacting phases leads to increased adhesion, which corresponds to the minimum interfacial energy. The course of the described processes leads to the formation of a durable fluid-tight sealing frame, reliably adhered to the surface of the pipes, eliminating the annular gas manifestations.

The above polyconvinyl alcohol and TEAT-1 polycondensation reaction proceeds slowly, since the hydrolysis of triethanolamine titanate proceeds simultaneously. In this case, mixed hydroxo-aqua complexes are formed, which then react with the hydroxyl groups of PVA. The gelation process does not proceed instantly, but at a low rate, depending on the concentration of PVA and the concentration of TEAT-1 introduced into the solution. To control the gelation time of a mixture of polyvinyl alcohol and TEAT-1, GKZh-10 or GKZh-11 is added to it. As a result of the addition of GKZh-10 or GKZh-11, the gelation time of the system can be controlled. The gelation time is in the range from 60 minutes to 90 minutes. The indicated time provides the penetration of the WCS into the porous medium and is sufficient for the preparation and injection of the WCS during the insulation work in the wells.

In an aqueous solution, hydrolysis of GKZh-11 or GKZh-10 occurs with the formation of sodium hydroxide.

Sodium hydroxide reacts with triethanolamine titanate, and active molecules of titanium (IV) hydroxide are formed, which easily enter into the polycondensation reaction with the hydroxyl groups of PVA.

(C ₆ H ₁₂ O ₃ N) ₄ Ti ₃ +12 NaOH → 3 Ti (OH) ₄ +4 C ₆ H ₁₂ O ₃ NNa ₃

The resulting sodium salt of triethanolamine is instantly hydrolyzed, like all alkali metal alcoholates.

C ₆ H ₁₂ O ₃ NNa ₃ + H ₂ O → C ₆ H ₁₅ O ₃ N + 3 NaOH

As can be seen from the above schemes, sodium hydroxide is not consumed in the process of reactions, that is, in this case we have an example of homogeneous alkaline catalysis.

With poor-quality cementing, under-grouting material may occur, as a result of which the space between the columns remains unfilled and intercolumn gas manifestations occur. In order to fill this space to the fullest extent, as well as during isolation of water inflow into the well, it is necessary to introduce an additive in the WUS that allows it to increase in volume. As a gas-generating additive, aluminum powder is used. The role of the ingredient, providing intensive gas evolution in the inventive WCL, is performed by TEAT-1. This is due to the following: triethanolamine forms an organic base when reacted with water

C ₆ H ₁₅ O ₃ N + H ₂ O → C ₆ H ₁₅ O ₃ NHOH

Aluminum powder reacts with this base to produce hydrogen gas

2 Al + 6 C ₆ H ₁₅ O ₃ NHOH + 6 H ₂ O → 2 [C ₆ H ₁₅ O ₃ N] ₃ [Al (OH) ₆ ] +6 H ₂ ↑

Aluminum powder also reacts with sodium hydroxide formed during the hydrolysis of the sodium salt of triethanolammonium With ₆ H ₁₂ About ₃ NNa ₃ , an additional amount of hydrogen is released. Thus, intense gas evolution occurs.

2 Al + 6 NaOH + 6 H ₂ O = 2 Na ₃ [Al (OH) ₆ ] +3 H ₂ ↑

When aluminum and TEAT-1 powders are used together, the pores are uniformly distributed in the form of polydisperse in size, closed, deformed into regular polyhedrons with a glossy surface of the pore layer, separated by thin, but dense and identical cross-sectional pore septa. The above reactions allow us to conclude that triethanolamine titanate is the initiator of gas evolution, which was not previously known.

The joint use of ingredients in the claimed intervals in the inventive WCS with improved technological properties increases the efficiency of insulation work in wells using WCS.

The content in the WCS of polyvinyl alcohol of less than 2.9 wt.% Is impractical, since it does not provide gel formation, and more than 6.9 wt.% Is economically and technologically impractical, since there is no significant improvement in technological properties.

The content in the VUS TEAT-1 of less than 0.3% is impractical, since it does not provide the formation of a strong cross-linked gel and there is no intense gas evolution, and more than 6.0 wt.% Is impractical, since it leads to instant gelation, complications may arise during pumping process of use.

The content in the WCS of aluminum powder in an amount of less than 0.1 wt.% Does not provide relief of the gel-like structure, and more than 0.4 wt.% Leads to excessive foaming of the WCS and a decrease in gel strength.

The content in the HCL GKZH-10 or GKZH-11 in an amount of less than 0.1 wt.% Is impractical due to the inability to control the gelation time, and more than 0.3 wt.% Leads to accelerated crosslinking of the mixture, resulting in complications when pumping in process of use.

Thus, according to the above, the SCC ensures the achievement of the claimed technical result. Not identified by available sources of fame, technical solutions having features that match the distinctive features of the invention according to the claimed technical result.

The inventive HUS meets the condition of "inventive step".

In more detail, the essence of the claimed invention is described by the following examples.

In more detail, the essence of the claimed invention is described by the following examples.

Example (fishing). Work is underway to eliminate intercolumn gas occurrences at well No. 93 of the Peschano-Umetsky gas condensate storage facility, intercolumn pressure is 0.72 MPa.

Initial data Column The diameter of the column, mm Departure Depth, m Cement rise behind the column, m Direction 426 8 to the mouth Conductor 324 224 to the mouth Intermediate 245 729.5 623 from the mouth Operational 168 1075.5 368 from the mouth

GKK column head 125-146 × 219-245. Fountain fittings AFT 2 ^l / 2 ^" × 350.

MCP _{245 × 324 is} equipped with a bend (2 ") with a valve and quick-disconnect connection. The volume of WCS to fill the MCP _245x324 taking into account the elimination of gas in the reservoir of the Boykov horizon V _VUS is determined by the formula

where V _to - the internal volume of the conductor to the depth of descent, m ³ ;

V _CR - the volume of the intermediate column on the outer diameter, m ³ ;

D _to - the inner diameter of the conductor (with a wall thickness of 5 = 12 mm), m;

D _CR - the outer diameter of the intermediate column, m;

K is a safety factor of 2;

L is the depth of the descent of the conductor, m;

V _WCS = 0.785 · (0.3 ² -0.245 ² ) · 224 · 2 = 10.55 m ³ .

Prepare 10.55 m ³ WCS with a density of 1000 kg / m ³ in the following ratio of ingredients, wt.%:

Polyvinyl alcohol 6.9 TEAT-1 0.6 Aluminum powder 0.4 GKZH-11 0.3 Water 91.8.

9593 l (91.2 wt.%) Of water heated to a temperature of 80 ° C are poured into a 15 m ³ container, 760 kg (6.9 wt.%) Of polyvinyl alcohol are added in portions, mixed thoroughly until completely dissolved, circulating with a pump unit CA-320, do not allow foaming and the formation of large lumps. 42.2 kg (0.4 wt.%) Of aluminum powder is introduced into the prepared solution of polyvinyl alcohol with stirring. In a separate container TEAT-1 in the amount of 63.4 kg (0.6 wt.%) Is dissolved in 60 l (0.6 wt.%) Of water, heated to a temperature of 45 ° C. This solution is combined with a solution of polyvinyl alcohol and then 26.4 L (0.3 wt.%) GKZH-11 is added, mixed thoroughly. At the outlet with a valve, the composition is pumped into the well, after having previously pumped buffer liquid (process water) into it in a volume of 5 m ³ .

Having completed the injection, the valve is closed and the well is left to sediment for a period of 6 hours to acquire the WCS of the necessary technological properties.

HCL has the following properties: gel time τ _g = 60 min, adhesion to metal P _m = 0.13 MPa, gel strength P = 0.007 MPa, HCL ratio k = 1.3, water permeability: before treatment 3.8 μm ² - 10 ' ³ , after processing - 0, clogging coefficient K = 100%.

Work is underway to isolate water inflows at well No. 1008 of the Medvezhye deposit.

Initial data

The outer diameter of the production casing d, mm 219 Depth of descent of the production string, m 1260 Perforation interval, m 1133-1173 Current gas-water contact, m 1170 Insulated interval power, m 1173-1167

The volume of VUS for isolation VVUS calculated by the formula

V _WCS = 0.785 · (D ² -d ² ) · h · m · k _s ,

where D is the diameter of the insulation zone, m;

h is the power of the isolated interval, m;

m is the average open porosity of the reservoir;

k _s - fill factor of the pore space of the isolated interval, k _s *** 0.40-0.45.

Hence

V = 0.785 · (2.0 ² -0.219 ² ) · 6 · 0.32 · 0.45 = 2.7 m ³ .

Prepare 2.7 m ³ WCS with a density of 1000 kg / m ³ in the following ratio of ingredients, wt.%:

Polyvinyl alcohol 6.9 TEAT-1 0.6 Aluminum powder 0.4 GKZH-11 0.3 Water 91.8

2.46 m ³ (91.2 wt.%) Of water heated to a temperature of 80 ° C is poured into a container of 5 m ³ capacity, 186.3 kg (6.9 wt.%) Of polyvinyl alcohol are added in portions, mixed thoroughly until complete dissolution, circulating by the CA-320 pumping unit, preventing foaming and the formation of large lumps. In the prepared solution of polyvinyl alcohol, 10.8 kg (0.4 wt.%) Of aluminum powder is introduced with stirring. In a separate container TEAT-1 in the amount of 16.2 kg (0.6 wt.%) Is dissolved in 16.2 l (0.6 wt.%) Of water, heated to a temperature of 45 ° C. This solution is combined with a solution of polyvinyl alcohol and 8.1 L (0.3 wt.%) GKZH-11 is added, mixed thoroughly.

The VUS is injected into the well using a cementing unit ЦА-320 M in 2nd or 3rd gears (diameter of bushings D _W = 100 mm). The total injection time of the insulation composition is calculated by the formula

T = V / Q,

where Q is the performance of the CA-320 Q unit in this gear, m ³ / s.

In 2nd gear unit: T = 2.7 / 0.003 = 900 s = 15 min.

With 3rd gear unit: T = 2.7 / 0.0058 = 466 s = 7.76 min.

The volume of displacement fluid required for forcing the insulating composition in water cut is calculated using the formula V _ave = 0,785 · [d ² · L _{CNT CNT} + d _² · (L _n -L _CNT)]

where d _tubing is the inner diameter of the tubing, m;

l _tubing - the suspension depth of the tubing, m;

D _in - the inner diameter of the operational casing string, m;

L _p - the upper mark of the perforation interval, m. D _tubing = 0.078 m, L _tubing = 1129 m, d _{in '} = 0.203 m, L _p = 1133 m. Therefore, V _pr = 0.785 · [0.078 ² · 1129 + 0, 2032 · (133-1129)] = 5.52 m ³ . The time for pushing the insulating composition into the well is:

at 2nd gear unit: T _ave = 5.52 / 0.003 = 1840 c = 30.66 min; at the 3rd gear of the unit: T = 5.52 / 0.0058 = 952 s = 15.86 min.

The WCS has the following properties: τ _g = 60 min, P _m, = 0.13 MPa, P = 0.007 MPa, k = 1.3, water permeability: before treatment 3.8 μm ² · 10 ^-3 , after treatment - 0, K = 100%. Examples (laboratory).

Example No. 1.

To prepare 1000 g of WCS in 900 g (90 wt.%) Of water, 29 g (2.9 wt.%) Of polyvinyl alcohol are dissolved in a water bath. In an aqueous solution of polyvinyl alcohol, 1 g (0.1 wt.%) Of aluminum powder is introduced with stirring. Separately, 66 g (6.6 wt.%) Of water are dissolved in 3 g (0.3 wt.%) Of TEAT-1. This solution is combined with a solution of polyvinyl alcohol, stirred and then 0.84 ml (0.1 wt.%) GKZH-11 is added. Mixed. Leave to observe the gel formation time, and after 24 hours determine its properties.

The WCS has the following properties: τ _g = 90 min, P _m = 0.10 MPa, P = 0.0048 MPa, k = 1.1, water permeability: before treatment 4.0 μm ² · 10 ^-3 , after treatment 0.012 μm ² · 10 ^-3 , K = 99.7%. The adhesive properties of the resulting polymer material with a metal surface were determined by a known method (Danyushevsky BC, Aliev PM, Tolstykh MF. Reference manual for grouting materials. M: Nedra, 1987, p. 350-353.).

Strength was determined by the method (Popov L.N., Popov N.L. Laboratory work in the discipline "Building materials and products": Textbook. Manual. M.: INFA-M, 2005, p.146-148).

The study of core plugging ability is based on the methods developed by SevKavNIPIgaz for the formation and testing of cemented permeable sand cores. The studies were carried out on an advanced installation UIPK-1M [Universal installation for testing the gas permeability of core / V.G. Mosienko, R.A. Gasumov, S.V. Nersesov // Sat. scientific Tr. VNIIgaz. - 1997. - S. 54-56.].

The multiplicity of WCS was determined as the ratio of the volume of the WCS after the introduction of gas-releasing additives to its initial volume (Workshop on colloid chemistry: Textbook / edited by M.I. Gelfman - St. Petersburg: "Lan", 2005. - p. 211-218) .

Example No. 2.

Prepare 1000 g of VUS, g / wt.%:

Polyvinyl alcohol 49 / 4.9 TEAT-1 4.0 / 0.4 GKZH-11 2.0 / 0.2 (use 1.68 ml p = 1190 kg / m ³ ) Aluminum powder 3.0 / 0.3 Water 942 / 94.2

All operations are performed as in example 1. The WCS has the following properties: τ _g = 75 min, P _m = 0.12 MPa, P = 0.0056 MPa, k = 1.2, water permeability: before treatment 3.9 μm ² · 10 ^-3 , after processing - 0, K = 100%.

Example No. 3.

Prepare 100 g WCS, g / wt.%:

Polyvinyl alcohol 69 / 6.9 TEAT-1 6.0 / 0.6 GKZH-10 3.0 / 0.3 (use 2.52 ml p = 1190 kg / m ³ ) Aluminum powder 4.0 / 0.4 Water 918 / 91.8

All operations are carried out as in example 1.

WCS has the following properties: τ _g = 60 min, P _m = 0.13 MPa, P = 0.007 MPa, k = 1.3 water permeability: before treatment 3.8 μm ² · 10 ^-3 , after treatment - 0, K = 100%.

Thus, the claimed technical solution meets the conditions of "novelty", "inventive step" and "industrial applicability", that is, is patentable.

Claims (1)

A viscoelastic composition for insulation work in wells containing polyvinyl alcohol, an organosilicon liquid, an aluminum-containing additive and water, characterized in that it additionally contains triethanolamine titanate - TEAT-1, and as an organosilicon liquid - aqueous-alcoholic solutions of sodium ethylsiliconate - GKZh-10 or sodium methylsiliconate - GKZh-11, and as an aluminum-containing additive - aluminum powder in the following ratio of ingredients, wt.%:
Polyvinyl alcohol 2.9-6.9 TEAT-1 0.3-0.6 GKZH-10 or GKZH-11 0.1-0.3 Aluminum powder 0.1-0.4 Water rest