CN116066016A - Realization method for underground heat source of oil and gas well - Google Patents

Abstract

A method for realizing a downhole heat source in oil and gas wells and its application mainly includes the following four steps: 1. Running a drilling tool; 2. Reaching a predetermined position to open a drop basket; Specific process: use aluminothermic reaction at a certain position in the underground: add ignition agent and combustion enhancer, aluminum and metal oxides (such as ferric oxide, chromium oxide, manganese dioxide, etc.) react under high heat conditions. The released heat melts the low-melting eutectic alloy material, and the molten alloy reaches the sealing area under the action of pressure. The reaction pressure, temperature and reaction speed are controlled by adding metal oxides, silicon dioxide and other inhibitors. The downhole seal is achieved through the expansion properties of the eutectic alloy.

Description

A realization method for downhole heat source of oil and gas wells

technical field

The invention relates to a method for realizing a downhole heat source for oil and gas wells and its application. The present invention has other applications such as workover operations of oil and gas production wells, integrity sealing of wells, underground storage of nuclear waste, sealing of wells such as carbon dioxide sequestration, and the like.

Background technique

The term "thermite reaction" as used in this patent refers to a broad class of chemical reactions that can be defined as an exothermic reaction, including the reaction of a metal with a metal or metalloid oxide to form a more stable oxide and the corresponding Metal or non-metal oxides of reactants.

The thermite method was invented by German chemist Hans Goldschmidt in 1893 and patented two years later. Therefore, this reaction is also called "Goldsmith method" or "Goldsmith process". The original purpose of the research was to prepare high-purity metals without carbon smelting, but Goldsmith keenly discovered that thermite could be used for welding. The first commercial application of the thermite method to weld rails was in Essen, Germany in 1899.

Thermite is a mixture of aluminum powder and high-melting-point metal oxides (such as ferric oxide powder) in proportion. When in use, it is ignited by adding an oxidant, and the reaction proceeds violently to obtain alumina and simple substances and release a large amount of heat. The temperature It can reach about 2500°C, which can melt the generated elemental substance. This reaction is called the thermite reaction. The principle of thermite reaction can be applied in production, such as welding rails and so on. Using certain metal oxides (such as V2O5, Cr2O3, MnO2, etc.) instead of iron oxide can also be used as thermite. When the aluminum powder reacts with these metal oxides, enough heat is generated to make the reduced metal in a molten state at a higher temperature and separate from the formed slag, thereby obtaining a purer metal. This method is commonly used in industry to smelt refractory metals, such as vanadium, chromium, manganese, etc. It utilizes the heat released when aluminum is oxidized.

Thermite has been used in the drilling industry for blowout prevention (US Patent 5159983), explosive sealing of casing perforations (US Patent 5613557), gas generation downhole tool actuation (US Patent 6925937), perforation and hydraulic fracturing (US Patent Application Publication 2011 /0146519) and downhole metal bonding members (US Patent Application Publication 2012/0255742). There are numerous other patents for welding and dismantling thermite in surface applications, but these are not considered relevant for drilling and completion sealing applications.

Contents of the invention

The object of the present invention is to provide a method for realizing the downhole heat source of oil and gas wells in view of the deficiencies in the prior art.

It is used for workover operations of oil and gas production wells and integrity sealing of wells, as well as sealing of wells for underground storage of nuclear waste, carbon dioxide sequestration, etc., and other applications.

Its technical scheme is as follows:

A method for realizing downhole heat sources of oil and gas wells, comprising the following steps:

The drop basket is lowered into the well sealing position through the drilling tool, the thermite reaction charge is placed on the drop basket, the thermite reaction charge is ignited, and the well closure operation is completed after the thermite reaction charge is burned.

Further, the thermite reaction charge is compressed during the combustion process.

Further, the surface of the falling basket is covered with insulating dense load-bearing material.

Further, the aluminothermic reaction charge includes oxidant and aluminum powder in a ratio of 3:1.

Further, the oxidizing agent is iron powder or iron oxide.

Further, the thermite reaction charge is ignited from above to make the thermite reaction charge burn from top to bottom.

Further, the thermite reaction charge contains a diluent.

Further, the diluent is calcium oxide, aluminum oxide or silicon dioxide.

Further, the thermite reaction charge is diluted by mass by 5% to 75% by the diluent.

Further, the thermite reaction charge is diluted by mass by 10% to 50% by the diluent.

Further, the reaction velocity of the diluted thermite reaction charge is reduced to 0.5-1 cm/sec.

The beneficial effects of the present invention are:

Realize workover operations for oil and gas production wells and integrity sealing of wells, as well as reliable sealing of wells for underground storage of nuclear waste and carbon dioxide sequestration.

Description of drawings

Fig. 1 is a schematic diagram of running into a drilling tool;

Fig. 2 is a schematic diagram of opening the positioning of the basket;

Fig. 3 is a schematic diagram of filling the thermite reaction charge;

Figure 4 is a schematic diagram of pressurization.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only, and are not intended to limit the scope of the present invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.

The invention discloses a method for realizing an underground heat source and sealing a well, comprising the following steps: lowering the thermite reaction charge into the well at the position where the well is to be sealed, the thermite reaction charge is placed on the drop basket; the effect of the drop basket Provide support for the thermite reaction charge at said location; apply a large mass load to the thermite reaction at said location; ignite the thermite reaction charge at the bottom of the charge and conduct aluminum in the thermite reaction charge thermal reaction while applying a relatively large pressure load to the thermite reaction charge.

The method comprises the steps of: lowering the thermal agent reaction material at the position of the sealed well, wherein the thermal agent reaction material lowered into the well is added with one or more additives to dilute calcium oxide, silicon dioxide, etc. to ease the thermal agent reaction in The exothermic reaction generated during ignition, mitigation includes reducing the reaction temperature and reaction rate of the thermite reaction to meet the specific design goals of the sealed well; Melting point alloy metals.

In a non-pressurized thermite reaction, the product is a porous matrix of metal oxides and metals. The porosity is caused by voids entrained during the reaction, some of which is retained due to the inability of the powder to be compacted to maximum density, other porosity is created by gas bubbles entrained in the very small amount of gas produced during the reaction. The resulting porosity of the reacted material reduces its potential strength, making it permeable for fluid flow.

Through the ignition and combustion reaction of the loaded thermite, in order to reduce the porosity of the reaction material, the load is formed by pressing during the reaction process, so that the thermite reaction is more firmly integrated into the surrounding dielectric material. To further reduce the porosity of the final product, lower melting oxides or eutectic materials such as calcium oxide can be added to the thermite to lower the melt temperature of the product and maintain its liquid form for a longer period of time . Of course, the exact pressure range for pressing depends on the particular application, such as the size of the wellbore, the length of the desired plugged zone, the mixture used in the thermite reactive charge, and other factors.

The mass of stoichiometric mixture of iron oxide and aluminum powder is about 3:1 respectively. At this mixing ratio, the reaction is relatively fast, violent and uncontrollable under atmospheric conditions. It generates a large amount of heat energy, and the peak temperature is close to 2500-3000℃.

However, in order to seal the well, the reaction must be controlled to control the reaction products and form an integrally molten, flowable seal material. A base mixture of diluents and/or additives can be used to control the burn rate, peak temperature, and end product with superior mechanical properties. For example, diluting an aluminum/iron oxide thermite formulation with alumina (also a product of the reaction) slows down the reaction and slows the reaction so that the thermite reaction is completely sealed with very little (gas) pressure build-up. The stoichiometric aluminum/iron oxide thermite has a nominal peak temperature of 2965°C, whereas by adding 75% by mass alumina powder to the original mixture, the peak reaction temperature can be controlled below 1700°C while still maintaining combustion . Dilutions greater than this percentage cannot sustain thermite reaction, so 75% by mass is considered a practical upper limit for dilution. The diluted thermite reaction charge results in a slow, controllable reaction rate down to 0.1 cm/sec compared to the original/undiluted thermite mixture which burns at 10 - 100 cm/sec. We recognize that a slow, controllable thermite reaction by diluting the thermite reaction at lower temperatures is desirable for oil well sealing applications and can be adapted to a variety of thermite reactions for oil well sealing agent design. A burn velocity of about 1 cm/sec is considered suitable for some oil well sealing applications.

In one instance, this dilute nature allows thermite to be designed with a relatively cooler lower portion that reacts first, heating the wellbore to a plastic state rather than a molten state. It expands radially and squeezes the casing outward, filling the annulus between the casing and the borehole/formation wall. The relatively hot aluminizer reaction charge on top of the aluminizer then ignites and melts through the casing and into the rock/formation wall. The cooler lower portion prevents molten material from the relatively hotter upper plug from flowing or falling into the annular space between the casing and the formation wall, negating its sealing effect. The radial load is applied by pressure to improve its sealing performance.

An example of this embodiment is shown in FIG. 2 . In order to separate the casing from the borehole wall in the formation, there is an annular gap between the borehole wall and the casing. Put the thermite reaction material into the drop basket through the cable or drill pipe, and place the drop basket to carry the thermite at the position where the oil well is to be sealed.

Thermite reacts in the form of material, for example, a mixture of powdered aluminum and iron oxides, which has been diluted by adding one or more additives, such as alumina, calcium oxide, or silica. Thermite reaction produces a mild exotherm Ignite when reacting material. The purpose of slowing down the exothermic reaction is to reduce the reaction temperature and reaction rate within the aluminothermically reactive materials that they would otherwise have without one or more additives. The purpose of moderate heating in this example is to heat the casing to the plastic temperature so that during combustion the radial expansion of the thermal agent causes the casing to expand radially, essentially squeezing the formation and Close the annular gap.

Thermite igniters may be electrical in nature and any suitable chemical, electrical or pyrotechnic igniter may be used. The details of the igniter are well known to those skilled in the art and are not particularly important.

As shown in Figure 3. After the igniter is ignited, the thermite in the layer reacts and expands radially outward to gradually squeeze the sleeve to squeeze the sealing area into the cooling expansion seal.

Accordingly, in a first aspect of this embodiment, a method of sealing a well is disclosed, the method comprising the steps of: lowering the thermite reactant material downhole to a location to be sealed, firing the igniter, and aluminum in the layer The hot agent reacts and expands radially outward to gradually squeeze the sleeve to the sealing area to squeeze into the cooling expansion seal. When the thermite reaction has been ignited with the addition of one or more diluent additives and an exothermic reaction, that is, in the absence of one or more additives, a substantial reduction in the thermite reaction dose within the The reaction temperature and reaction speed are to meet the specific design target requirements of the sealed well, and ignite the thermal agent reaction charge to make the thermal agent reaction charge burn, as shown in Figure 4: Press and squeeze the reaction material to squeeze into the sealing area and cool it Expansion seal.

It is worth noting that many metal/oxide thermite formulations are available to achieve specific goals. The basic aluminum/iron oxide formulation presented here is by way of example and not limitation, with the understanding that other thermite reaction formulations may be suitable for specific applications.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (11)

1. The realization method for the underground heat source of the oil and gas well is characterized by comprising the following steps of:

and (3) the falling basket is put into a well sealing position through a drilling tool, an aluminothermic reaction charge is placed on the falling basket, the aluminothermic reaction charge is ignited, and the well sealing operation is finished after the aluminothermic reaction charge is burnt.

2. The method of claim 1, wherein the pressurizing is performed during combustion of the thermite reaction charge.

3. The method of claim 2, wherein the surface of the landing basket is coated with an insulating dense load bearing material.

4. The method for realizing a downhole heat source for an oil and gas well according to claim 3, wherein the aluminothermic reaction charge comprises an oxidant and aluminum powder in a ratio of 3:1.

5. the method of claim 4, wherein the oxidizing agent is iron powder or iron oxide.

6. A method of realising a downhole heat source for oil and gas wells according to any of claims 1-5 wherein the thermite reaction charge is ignited from above to burn the thermite reaction charge from above.

7. The method of claim 6, wherein the thermite reaction charge comprises a diluent.

8. The method of claim 7, wherein the diluent is calcium oxide, aluminum oxide or silicon dioxide.

9. A method of realising a downhole heat source for oil and gas wells according to claim 8, wherein the thermite reaction charge is diluted by the diluent by an amount between 5% and 75% by mass.

10. A method of realising a downhole heat source for oil and gas wells according to claim 8, wherein the thermite reaction charge is diluted by the diluent by an amount between 10% and 50% by mass.

11. The method of claim 10, wherein the reaction rate of the diluted thermite reaction charge is reduced to 0.5-1 cm/sec.

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