RU2563466C2 - Repair-insulating packing compound based on quick-stone magnesite cements - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention refers to a repair-insulating packing compound based on magnesite cements and can be used in the oil and gas industry when drilling and servicing oil, gas and water wells. The repair-insulating packing compound based on magnesite cements containing magnesium oxide and water comprises magnesium sulphate heptahydrate, sodium hexametaphosphate and nitrilotrimethylphosphonic acid additionally in the following proportions, wt %: magnesium oxide 44.71-55.56, magnesium sulphate heptahydrate 13.33-22.47, water 29.47-35.77, sodium hexametaphosphate 0.1-2.7, nitrilotrimethylphosphonic acid 0.1-1.14.

EFFECT: creating the repair-insulating packing compound based on magnesite cements possessing the following properties: controllability and predictability of the setting time of the packing stone to the exact minute in various barothermal conditions from sub-zero (minus 5°C) temperatures to 180°C; preventing the structural characteristics loss when the material exists in a water-bearing medium; providing the sedimentation stability of the solution.

7 dwg, 1 tbl

Description

The invention relates to repair-insulating grouting compositions based on magnesian binders and can be used in the oil and gas industry for drilling and repairing oil, gas and water wells in order to eliminate the absorption of flushing fluid, repair-insulating work in order to eliminate water inflows as well as when cementing annular space and casing strings.

Well-known grouting material (RF patent No. 2295554, priority date 02/03/2006) used for cementing annular space and casing strings in the intervals of the anhydrous part of an open section in oil and gas wells in the temperature range of 10-30 ° C with the following content of ingredients, wt. %:

The disadvantage of this material is its limited use, since it is intended for use only in the intervals of the anhydrous part of the open hole section in the temperature range of 10-30 ° C and has low waterproofing properties, since it does not provide reliable isolation of the absorption zones of the washing liquid in fine and large pores , fractured, cavernous and mixed rocks with intense and catastrophic uptake of flushing fluid.

A well-known grouting composition (RF patent No. 2293100, priority date 10.24.2005) for isolating the absorption zones of washing fluids in order to regulate the thickening and setting time with the following content of ingredients, wt. %:

The disadvantages of this composition are the difficulty of regulating technological properties and the difficulty of predicting the setting time of the material. This composition is characterized by short terms of thickening and setting, reduced sedimentation stability of the solution, significant decreases in strength characteristics under waterflooding conditions, insufficiently high values of volumetric expansion of cement stone.

Known magnesia binder using magnesium sulfate (RF patent No. 2428390, priority date 07/05/2010), used in the manufacture of building materials, the manufacture of plates and panels, as well as building dry mixes. The composition has increased water resistance at a sufficiently high strength and has the following content of components, wt. %:

The disadvantages of this composition are the inapplicability in the oil industry, the difficulty of regulating the technological properties of the material solution, the inability to predict the setting time of the material.

Known magnesia grouting material (RF patent No. 2374293, priority date 04.07.2008), used for cementing casing strings and installing tight and strong bridges in oil, gas and gas condensate wells with a maximum static temperature of up to 55 ° C, with the following components, wt . %:

The disadvantages of this composition are the difficulty of regulating the technological properties of the solution, the difficulty of predicting the setting time of the material, a significant decrease in strength characteristics in conditions of water cut.

The closest analogue in technical essence and the achieved effect is a thermosetting composition for treating a well (Canadian patent No. 2175144, priority date 04/26/1996) for plugging wells with a predicted setting temperature of cement stone containing a mixture of solids and aqueous fluid with the following component composition, wt . %:

The aqueous liquid is a saline solution containing a salt selected from the group consisting of calcium chloride, sodium chloride and magnesium chloride. Used in a ratio of approximately 1 liter of aqueous liquid to 1.25 kg of solids.

The disadvantages of the closest analogue are the loss of strength characteristics during the stay of the material in the aquatic environment (everywhere in all downhole conditions there is an aqueous medium), insufficient temperature range of application. After a week-long stay of the material in an aqueous medium, a more than twofold loss of strength characteristics occurs, which is explained by the gradual dissolution of the chemicals that are the basis of the composition. Sedimentation instability of the obtained solutions (the solid phase precipitates rather quickly in the solution) can lead to the fact that the required borehole interval, which must be covered by the composition, will not be isolated due to precipitation of the solid phase.

The objective of the claimed invention is the creation of a repair-insulating grouting composition based on magnesian binders, leveling the disadvantages of the prototype, and also which, depending on the quantitative content of its constituent components, can achieve such technical result as: controllability of the setting time of the repair-insulating grouting composition based magnesian binders in various temperature conditions inside the wells from minus (minus 5 ° C) temperatures to 180 ° C.

The task and the specified technical result in the repair-insulating grouting composition based on magnesia binders containing magnesium oxide and water, respectively, is solved and achieved by the fact that it additionally contains heptahydrate magnesium sulfate, sodium hexametaphosphate and nitrilotrimethylphosphonic acid with the following components, wt. %:

Expressing the consistency of the solution in units of Verdun consistency (Vs), it should be noted that the setting profile of the repair-insulating cement composition based on magnesia binders prepared using the claimed invention changes from instant setting of such cement composition in 3 minutes to 100 Vc (with a minimum the content of sodium hexametaphosphate and nitrilotrimethylphosphonic acid). Moreover, depending on the quantitative content of the components, the setting is adjusted to minutes.

The strength of the repair-insulating grouting composition based on magnesian binders prepared using the claimed invention, the compressive strength is 20 MPa, the bending strength is 13.5 MPa, that is, the claimed grouting composition is elastic and plastic.

The following components are used to prepare the claimed repair and insulation grouting composition based on magnesian binders.

1. Magnesium oxide (MgO) according to GOST 4526-75 "Reagents. Magnesium oxide. Technical conditions ”(with a percentage of magnesium oxide of not less than 97%), which is a white powder, almost insoluble in water, well soluble in acids. It is a solid phase of the structure of the claimed repair-insulating cement composition based on magnesian binders and provides an increase in its strength characteristics after hardening.

2. Seven-water magnesium sulfate (MgSO ₄ * 7H ₂ O) according to GOST 4523-77 "Reagents. Magnesium sulfate 7-water. Technical conditions ”(with a percentage of the basic substance of at least 99%), which is a white crystalline powder, soluble in water. It is a structural builder of the claimed repair-insulating grouting composition based on magnesian binders and ensures its water resistance after hardening.

3. Sodium hexametaphosphate (Na ₆ P ₆ O ₁₈ ) according to GOST 20291-80 “Technical sodium polyphosphate. Technical conditions ”(with a percentage of the basic substance in terms of P ₂ O ₅ not less than 61.5%). It is an inhibitor and is used to regulate the setting time of the claimed repair and insulation grouting composition based on magnesian binders. An increase in the content of sodium hexametaphosphate has a linear effect on the setting time, that is, with an increase in the percentage, the setting time increases proportionally and has a linear relationship.

4. Nitrilotrimethylphosphonic acid (C ₃ H ₁₂ NO ₉ P ₃ ), for example, manufactured by Khimprom OJSC (Chuvash Republic) according to TU 2439-347-05763441-2001 (with a percentage of the main substance of at least 90%). It is an inhibitor and is used to regulate the setting time of the claimed repair and insulation grouting composition based on magnesia binders at high temperatures inside the well. An increase in the content of nitrilotrimethylphosphonic acid depending on the temperature inside the well has a linear effect on the setting time, that is, when the percentage is increased, the setting time increases proportionally and has a linear relationship.

Depending on the borehole conditions (depth of interval (s), temperature, pressure, lithological and stratigraphic data, etc.) and the type of borehole work (elimination of wash fluid absorption, repair and insulation works, etc.), various characteristics of the declared repair and repair work are required insulation grouting composition based on magnesian binders, namely: high compressive strength, high bending strength of the material, the stability of the material when exposed to water and temperature.

In this regard, the quantitative content of the components of the claimed repair-insulating grouting composition based on magnesian binders can be changed within the indicated ranges of values, so as to obtain certain necessary operational characteristics from it.

For example, for conditions where high compressive strength characteristics are required, and bending strength characteristics are not important (for example: an overlapping (insulating) bridge, some types of repair and insulation works (RIR)), and high temperatures inside the wells predominate (for example, from 65 ° C to 180 ° C), the component composition of the claimed repair-insulating grouting composition based on magnesian binders can have the following ranges of values, mass. %:

And for conditions where high strength characteristics for bending are required (struggle against casing flows), and also low temperatures inside the wells predominate (for example, from minus 5 ° С to 65 ° С), the component composition of the declared repair-insulating grouting composition based on magnesian binders can have the following ranges of values, mass. %:

Below are examples of the implementation of the claimed repair-insulating grouting composition based on magnesian binders when conducting RIR in various wells, with various conditions, including temperature.

The following equipment was used to prepare the claimed repair and insulation grouting composition based on magnesian binders: a tank with mixers, for example, USO-16, cementing unit CA-320, a mixing plant, for example, US6-30.

The preparation of the claimed repair-insulating grouting composition based on magnesian binders was carried out by simple mixing using the above equipment at atmospheric pressure and a temperature corresponding to the ambient temperature.

First, magnesium oxide was added to water and stirred for 5-10 minutes. Then heptahydrate of magnesium sulfate and stirred for 15-20 minutes. Next, sodium hexametaphosphate was stirred for 15-20 minutes. And finally nitrilotrimethylphosphonic acid was stirred for 15-20 minutes.

Example 1

Territory, place of application: Stavropol Territory, Azyk-Sulatskoye field.

Characterization, description of the well:

- Depth of leakage interval 2205-2210 m according to geophysical research (GIS).

- Production casing with a diameter of 146 mm.

- The injectivity of the reservoir in the specified interval is 60 m ³ / day in water.

The purpose of the application (the problem to be solved) is to conduct RIR with a low injectivity of the formation, to predict and achieve the setting of the claimed repair-insulating cement slurry based on magnesia binders after 6 hours at a temperature of 100 ° C, in conditions of well watering.

The composition of the claimed repair-insulating grouting composition based on magnesian binders: magnesium oxide - 50.2%, heptahydrate of magnesium sulfate - 14.89%, water - 33.11%, sodium hexametaphosphate - 0.8%, nitrilotrimethylphosphonic acid - 1, 0%

Figure 1 shows the dependence of the setting of the claimed repair-insulating cement composition based on magnesian binders in example 1 at different temperatures and in different time ranges.

As can be seen from the graph, the setting of the claimed repair-insulating grouting composition based on magnesian binders at 100 ° C occurred after 6 hours (bottom line).

Example 2

Territory, place of application: Western Siberia, well. 2063L, bush No. 27 of the Vategansky field.

Characterization, description of the well:

- The production casing with a diameter of 146 mm was lowered to a depth of 2225 m, a window was cut at a depth of 1883 m.

- The diameter of the side trunk is 123.8 mm.

- Material installation interval: 2500-2668 m along the trunk.

- The well is filled with technical water.

- Formation pressure R _pl - 183.5 atm.

- The temperature of the reservoir T _PL , calculated by the gradient in the field conditions of 90 ° C.

The purpose of the application (the problem to be solved) is to eliminate the absorption of the drilling fluid, to predict and achieve the setting of the claimed repair-insulating cement slurry based on magnesian binders after 90 minutes at a temperature of 90 ° C in formation water.

The composition of the claimed repair-insulating grouting composition based on magnesian binders: magnesium oxide - 48.34%, hemihydrous magnesium sulfate - 16.73%, water 33.09%, sodium hexametaphosphate - 0.73%, nitrilotrimethylphosphonic acid - 1.11 %

In FIG. 2 shows the dependence of the setting of the claimed repair-insulating cement composition based on magnesian binders in example 2 at different temperatures and in different time ranges.

As can be seen from the graph, the setting of the material at 90 ° C occurred after 90 minutes (bottom line).

Example 3

Territory, place of application: Stavropol Territory, Pushkarskoye field.

Characterization, description of the well:

- Depth of leakage interval 3000-3100 m according to well logging data.

- Production casing with a diameter of 146 mm.

- Pickup 300 m ³ / day in water.

The purpose of the application (the problem to be solved) is to conduct RIR with high injectivity of the formation, to predict and achieve the setting of the claimed repair-insulating grouting composition based on magnesia binders after 50 minutes at a temperature of 130 ° C in the conditions of well watering.

The composition of the claimed repair and insulation grouting composition based on magnesia binders: magnesium oxide - 44.71%; hemihydrous magnesium sulfate - 19.16%, water - 34.59%, sodium hexametaphosphate - 0.4%, nitrilotrimethylphosphonic acid - 1.14%.

In FIG. 3 shows the dependence of the setting of the claimed repair-insulating grouting composition based on magnesian binders according to example 3 at different temperatures and in different time ranges.

As can be seen from the graph, the setting of the claimed repair-insulating grouting composition based on magnesian binders at 130 ° C occurred after 50 minutes (bottom line).

Example 4

Territory, place of application: Orenburgskoye oil and gas condensate field.

Characterization, description of the well:

- The interval of occurrence of the reservoir 2050-2180 m (along the trunk).

- Barrel diameter 215.9 mm (open barrel).

- The well is filled with brine based on NaCl with a density of 1.14 g / cm ³ .

The purpose of the application (the problem to be solved) is to kill the well, to predict and achieve the setting of the claimed repair-insulating grouting composition based on magnesia binders after 54 minutes at a temperature of 40 ° C in conditions of well watering.

The composition of the claimed repair and insulation grouting composition based on magnesian binders: magnesium oxide - 53.24%; hemihydrous magnesium sulfate - 15.12%, water - 30.24%, sodium hexametaphosphate - 1.2%, nitrilotrimethylphosphonic acid - 0.2%.

In FIG. 4 shows the dependence of the setting of the claimed repair-insulating grouting composition based on magnesian binders according to example 4 at different temperatures and in different time ranges.

As can be seen from the graph, the setting of the claimed repair-insulating grouting composition based on magnesia binders at 40 ° C occurred after 54 minutes (bottom line).

Example 5

Territory, place of application: Nenets Autonomous Okrug, Severo-Saremboyskoye field.

Characterization, description of the well:

- Well depth 150 m;

- barrel diameter 490 mm (open barrel);

- The well is filled with drilling fluid.

The purpose of the application (the problem to be solved) is to eliminate the absorption of the drilling fluid, to predict and achieve the setting of the claimed repair-insulating cement slurry based on magnesian binders after 34 minutes at a temperature of minus 5 ° С.

The composition of the claimed repair-insulating grouting composition based on magnesian binders: magnesium oxide - 55.34%, heptahydrate magnesium sulfate - 14.99%, water 29.47%, sodium hexametaphosphate -0.1%, nitrilotrimethylphosphonic acid - 0.1 %

The setting time is controlled by the ratio of the solids content, i.e. increasing or decreasing the content of magnesium oxide in relation to the seven-water magnesium sulfate, at such low temperatures inhibitors are used in extremely small quantities.

In FIG. 5 shows the dependence of the setting of the claimed repair-insulating cement composition based on magnesian binders according to example 5 at different temperatures and in different time ranges.

As can be seen from the graph, the setting of the claimed repair-insulating grouting composition based on magnesian binders at minus 5 ° C occurred after 34 minutes (bottom line).

Example 6

Territory, place of application: Stavropol Territory, Pushkarskoye deposit.

Characterization, description of the well:

- Depth 3700 m.

- Production casing with a diameter of 146 mm.

- The well is filled with technical water.

- Pickup 330 m ³ / day in water.

The purpose of the application (the problem being solved) is RIR, to predict and achieve the setting of the claimed repair-insulating grouting composition based on magnesian binders after 90 minutes at a temperature of 180 ° C.

The composition of the claimed repair-insulating grouting composition based on magnesian binders: magnesium oxide - 45.10%, seven-water magnesium sulfate - 18.28%, water - 34.48%, sodium hexametaphosphate - 1.0%, nitrilotrimethylphosphonic acid - 1, fourteen%.

In FIG. 6 shows the dependence of the setting of the claimed repair-insulating grouting composition based on magnesian binders at various temperatures and in different time ranges.

As can be seen from the graph, the setting of the claimed repair-insulating grouting composition based on magnesia binders at 180 ° C occurred after 90 minutes (bottom line).

Moreover, by analyzing the graphs in FIG. 1-6, it should be noted that the upper line on them shows an increase in the test temperature from room temperature to the required temperature, and the lower line shows the change in the consistency of the material over time under the influence of temperature.

The table shows the operational characteristics of the claimed repair-insulating cement composition based on magnesia binders in accordance with the above examples.

Moreover, the characteristics presented were determined in accordance with GOST 310.4-81 “Cements. Methods for determining the tensile strength in bending and compression. "

The results obtained on the change in the strength of the declared repair-insulating grouting composition based on magnesia binders in the aqueous medium for compression and bending were calculated by the difference between the strengths of the specified composition in the aqueous medium after 7 days and in the air after 24 hours.

All RIRs using the declared repair-insulating cement slurry based on magnesian binders were successfully completed, and when RIR was installed on the bridges, the bridge was always detected in the indicated interval.

However, the following should be noted.

It has been experimentally established that it is not possible to achieve controllability of the setting time of the claimed repair-insulating grouting composition based on magnesian binders inside the wells from minus (minus 5 ° С) temperatures to 180 ° С, at temperatures exceeding these limits.

In this regard, the claimed repair and insulation grouting composition based on magnesia binders provides the specified technical result only in this temperature range.

It was also established that it is the combined use of sodium hexametaphosphate and nitrilotrimethylphosphonic acid in the declared ranges of their values that ensures the achievement of the indicated technical result, since the following dependence was also established: the lower the temperature inside the well within the specified temperature range, the more sodium hexametaphosphate should be added and less nitrilotrimethylphosphonic acid. And at high temperatures inside the well, the established dependence takes on the opposite character, namely: the higher the temperature inside the well within the marked temperature range, the less sodium hexametaphosphate and more nitrilotrimethylphosphonic acid should be added.

This relationship is confirmed by the above examples, as well as the graph shown in FIG. 7, where:

1 - temperature increase inside the well in the range from minus 5 ° C to 180 ° C;

2 - change in the content of sodium hexametaphosphate in the range of 0.1-2.7 wt.%;

3 - change in the content of nitrilotrimethylphosphonic acid in the range of 0.1-1.14 wt.%.

It should also be noted that the claimed repair-insulating grouting composition based on magnesian binders has increased sedimentation stability compared to other magnesia cements based on magnesium oxide and magnesium chloride, which is especially important when installing cement bridges and many RIRs.

Claims (1)

Repair-insulating grouting composition based on magnesian binders containing magnesium oxide and water, characterized in that it additionally contains seven-water magnesium sulfate, sodium hexametaphosphate and nitrilotrimethylphosphonic acid with the following components, wt.%:

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