Metal corrosion testing method and device for air foam flooding of oil field

Abstract

The invention discloses a metal corrosion testing method and device for air foam flooding of an oil field. The method comprises the following steps: preparing a wire beam electrode sample for air foam flooding; putting the prepared tow electrode sample into a corrosion solution, injecting foam liquid and gas into the surface of the tow electrode sample together, and controlling the size of foam; and testing the wire bundle electrode sample covered with part of foam to characterize the air foam flooding metal corrosion condition of the oil field. The invention provides a corrosion test method with adjustable air / foam and selectable metal, which can determine gas-liquid-solid three-phase interface corrosion dynamic information and metal corrosion difference of a bubble area / non-bubble area, and can explore air foam flooding metal corrosion characteristics and mechanisms under different oil field working conditions. And the corrosion inhibitor can also be used for researching the corrosion inhibition mechanism of the corrosion inhibitor on metal corrosion under the air foam flooding condition.

Description

Technical Field

[0001] The invention belongs to the field of metal corrosion testing, and relates to a metal corrosion testing method and a device for oil field air foam flooding. Background Art

[0002] In order to solve the practical problem of blocking natural and artificial fractures in ultra-low permeability reservoirs and transmitting driving force, air foam flooding technology was proposed to improve the recovery rate. Air foam flooding organically combines air flooding with foam flooding, and combines the advantages of air flooding and foam flooding. On the one hand, the gas source is abundant, the cost is low, and it has the traditional gas injection effect, flue gas drive and thermal effect. On the other hand, it can inhibit gas channeling in high permeability layers, reduce water content, and improve sweep coefficient and oil recovery efficiency.

[0003] However, with the continuous use of air foam flooding technology, serious oxygen and carbon dioxide corrosion has been caused to the pipeline, affecting the production safety of the oil field operation area. This is because with the continuous injection of air, crude oil and oxygen will undergo combustion reactions and low-temperature oxidation reactions, resulting in the gradual consumption of oxygen to generate carbon dioxide, carbon monoxide, ketones, acids, and acid substances. These carbon dioxides dissolve in water to form carbonated water solutions. At the same time, if the oxygen consumption is not complete or air channeling occurs, the highly corrosive carbon dioxide and / or oxygen water solutions have a strong corrosive effect on the ground gathering and transportation pipelines of the production system.

[0004] At present, the research on metal corrosion in air foam flooding mainly involves placing corrosion coupons into a high-temperature and high-pressure reactor containing air foam liquid to test the corrosion law of the metal. This method can only provide an average corrosion rate, and based on this, the mechanism of air foam flooding affecting metal corrosion is not clear, and there is no corresponding research progress, which seriously affects the understanding of the metal corrosion law of air foam flooding and the development of anti-corrosion measures. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art, to provide a metal corrosion testing method and device for oil field air foam flooding, and to solve the problem that the prior art lacks research on the mechanism of air foam flooding affecting metal corrosion.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A metal corrosion testing method for oilfield air foam flooding comprises the following steps:

[0008] Preparation of wire bundle electrode samples for air foam flooding;

[0009] The prepared wire bundle electrode sample is placed in a corrosion solution, and air foam liquid and gas are injected into the surface of the wire bundle electrode sample;

[0010] Tests were performed on wire bundle electrode specimens with foam covering.

[0011] Furthermore, the preparation method of the wire bundle electrode sample is:

[0012] An array mold with openings is designed, and metal wires with conducting wires are inserted into corresponding positions according to the array arrangement. The wires are encapsulated and cured with epoxy resin, and after curing, wire bundle electrode samples for air foam flooding are formed.

[0013] Furthermore, the metal wire in the wire bundle electrode sample is J55, P110, N80 carbon steel wire, 3Cr, 5Cr, 9Cr, 13Cr alloy steel or stainless steel, the single wire diameter is 0.02-0.3 cm, and the wire bundle spacing is 0.05-0.3 cm.

[0014] Furthermore, at least one injection tube site is provided in the wire bundle electrode sample, and the injection tube site is located in the gap of the wire bundle or occupies the position of the metal wire.

[0015] Furthermore, the method of injecting the air foam liquid and the gas into the surface of the wire bundle electrode sample is:

[0016] The pre-prepared foam liquid is compressed by air to form bubbles that adhere to the surface of the wire bundle electrode sample, and the bubble size is controlled by the gas volume to determine the amount of electrode area or metal wire covered.

[0017] Furthermore, the test method of the wire bundle electrode sample with foam covering is:

[0018] The current and potential distribution of the wire bundle electrode samples covered with foam after different immersion times are tested using a wire bundle electrode test system, or the electrochemical information of the metal wire inside and outside the bubble is tested using an electrochemical workstation.

[0019] A device for implementing the metal corrosion testing method for oil field air foam flooding, comprising a syringe and an injection pipe;

[0020] One end of a plurality of the injection tubes is connected to a syringe, and the other end of a plurality of the injection tubes is arranged in the wire bundle electrode sample, and air foam liquid and gas are arranged in the syringe.

[0021] Furthermore, the diameter of the injection tube is the same as that of the metal wire, and the end of the injection tube is flush with the working surface of the wire bundle electrode sample.

[0022] Furthermore, the ends of the plurality of injection tubes are arranged in the gaps between the wire bundles in the wire bundle electrode sample or occupy the positions of the metal wires.

[0023] Furthermore, the injection pipe is a plastic hose, and a controller is provided on the injection pipe.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a metal corrosion test method for oil field air foam flooding, wherein a wire bundle electrode sample for air foam flooding is prepared by designing a template, a foam liquid and a gas are injected into the surface of the wire bundle electrode sample through a syringe, and finally a wire bundle electrode sample test system is used to perform an electrochemical test on a single wire or the entire wire bundle electrode sample. The present invention provides an air / foam adjustable, metal-selective corrosion test method, which can clarify the corrosion kinetic information of the gas-liquid-solid three-phase interface, as well as the metal corrosion difference between the bubble zone and the non-bubble zone, can explore the characteristics and mechanism of metal corrosion in air foam flooding under different oil field working conditions, and can also be used to study the corrosion inhibition mechanism of corrosion inhibitors on metal corrosion under air foam flooding conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a schematic diagram of a wire bundle electrode sample for air foam flooding occupying the middle metal wire gap of the present invention.

[0028] Figure 2 It is a schematic diagram of the wire bundle electrode sample for air foam flooding occupying the position of the metal wire of the present invention.

[0029] Figure 3 It is a schematic diagram of the wire bundle electrode device after injection of air foam liquid of the present invention.

[0030] Among them, 1-wire bundle electrode sample, 2-air foam liquid and gas, 3-injector, 4-injection tube, 5-controller. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0033] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0034] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0035] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0037] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0039] The present invention provides a metal corrosion testing method for oil field air foam flooding, comprising the following steps:

[0040] Step 1: Prepare wire bundle electrode sample 1 for air foam flooding.

[0041] The preparation method of the wire bundle electrode sample 1 for air foam flooding is specifically to design an array mold with openings, insert metal wires with conductive wires into corresponding positions according to an array arrangement, and encapsulate and cure them through epoxy resin to form the wire bundle electrode sample 1 for air foam flooding after curing.

[0042] In step 1, the metal wire in the wire bundle electrode sample 1 for air foam flooding is J55, P110, N80 carbon steel wire, 3Cr, 5Cr, 9Cr, 13Cr alloy steel, stainless steel or other alloy materials, the single wire diameter is 0.02-0.3 cm, and the wire bundle spacing is 0.05-0.3 cm.

[0043] At least one injection tube site is provided in the wire bundle electrode sample 1, and the injection tube site is located in the gap between the wire bundles in the wire bundle electrode sample 1 or occupies the position of the carbon steel wire.

[0044] Step 2: Place the wire bundle electrode sample 1 prepared in step 1 into the corrosion solution, inject the air foam liquid and gas 2 into the surface of the wire bundle electrode sample 1, and control the size of the bubbles.

[0045] The method of injecting air foam liquid and gas 2 through the syringe 3 is specifically as follows: the wall of the syringe 3 is covered with the pre-prepared foam liquid, the gas is compressed into bubbles by the syringe 3 and attached to the surface of the wire bundle electrode sample 1, and the size of the bubbles is controlled by the gas volume to determine the amount of electrode area or metal wire covered.

[0046] Step 3: Test the wire bundle electrode sample 1 with foam covering obtained in step 2.

[0047] The testing method of the wire bundle electrode sample 1 covered with foam is specifically to use a wire bundle electrode testing system to test the current and potential distribution of the wire bundle electrode sample 1 covered with foam after different immersion times or to use an electrochemical workstation to test the electrochemical information of the metal wire inside and outside the bubble.

[0048] like Figure 3 As shown, the present invention also provides a device to implement a metal corrosion testing method for oil field air foam flooding, comprising an injection pipe 4 and a syringe 3.

[0049] One or more injection tubes 4 are arranged in the wire bundle electrode sample 1 for air foam flooding. The diameter of the injection tube 4 is the same as that of the metal wire. The head of the injection tube 4 is flush with the working surface of the wire bundle electrode sample 1, and the tail is longer than the tail of the wire bundle electrode sample 1. The tail is connected to a syringe 3, and air foam liquid and gas 2 are arranged in the syringe 3.

[0050] The injection tube 4 in the wire bundle electrode sample 1 for air foam flooding can be located at the gap between the wire bundles or at the position of a certain metal wire. The injection tube 4 is a plastic hose, and a controller 5 is provided on the injection tube 4, which can control the size of the bubble by controlling the amount of gas injected by the injector 3.

[0051] The present invention clarifies the corrosion kinetics information of the three-phase interface through electrochemical testing of a single wire or the entire wire bundle electrode sample 1, can explore the metal corrosion characteristics and mechanism of air foam drive under different oil field conditions, clarify the corrosion difference between the bubble area and the non-bubble area, and can also study the corrosion inhibition mechanism of corrosion inhibitors on metal corrosion under air foam drive conditions.

[0052] Embodiment 1:

[0053] like Figure 1 As shown, a 10×10 array mold with independent openings in the middle is designed, wherein the aperture is 0.2 cm. J55 carbon steel wires with conductors are arranged in a 10×10 array and an injection tube 4 with a length of 15 cm is inserted into the position of the independent opening in the middle, and then encapsulated with epoxy resin and cured to form a wire bundle electrode sample 1 for air foam flooding;

[0054] Then, the wall of the syringe 3 is filled with the pre-prepared foam liquid, and the foam liquid is compressed with air containing 2% oxygen through the syringe 3 to form bubbles attached to the surface of the wire bundle electrode sample 1, and the bubble size is controlled by the gas volume to determine the coverage of the 3×3 carbon steel wire array;

[0055] Finally, the wire beam electrode test system was used to test the potential distribution of the wire beam electrode covered with foam after being immersed in a deoxygenated 0.1 mol / L sodium chloride solution for 1 hour. Among them, the average potential of the oxygen-reduced air foam coverage area was -800mv, and the average potential of the non-oxygen-reduced air foam coverage area was -600mv. This shows that the oxygen-reduced air foam coverage area is the anode, and the non-oxygen-reduced air foam coverage area is the cathode. The potential difference between the two is 200mV, and the oxygen-reduced air foam coverage area will be accelerated.

[0056] Embodiment 2:

[0057] Design a 5×5 array mold with independent openings in the middle, where the hole diameter is 0.1 cm. Arrange P110 carbon steel wires with conductors in a 5×5 array, insert an injection tube 4 with a length of 10 cm into the position of the independent opening in the middle, and encapsulate with epoxy resin and solidify to form a wire bundle electrode sample 1 for air foam flooding;

[0058] Then, the wall of the syringe 3 is filled with the pre-prepared foam liquid, and the air is compressed into the foam liquid through the syringe 3 to form bubbles attached to the surface of the wire bundle electrode sample 1, and the bubble size is controlled by the air volume to determine the coverage of the 2×2 carbon steel wire array;

[0059] Finally, the current density of the carbon steel wire inside and outside the bubble was tested by using the wire beam electrode test system when it was immersed in an undeoxygenated 0.1 mol / L sodium chloride solution for 1 hour. The current density of the air bubble coverage area was 3.4×10 -6 A / cm 2 The current density in the non-air foam coverage area is -3.35×10-6 A / cm 2 , indicating that the carbon steel wire in the air foam covered area is the anode, while the carbon steel wire in the uncovered area is the cathode. The overall current density is 0, and there is no tendency of galvanic corrosion.

[0060] Embodiment 3:

[0061] like Figure 2 As shown, a 5×5 array mold is designed to occupy the hole position, wherein the hole diameter is 0.05 cm. 3Cr alloy steel wires with conductors are arranged in a 5×5 array, and an injection tube 4 with a length of 10 cm is inserted into the corresponding position of the hole position, and the wire bundle electrode sample 1 for air foam flooding is formed after being encapsulated and cured with epoxy resin;

[0062] Then, the wall of the syringe 3 is filled with the pre-prepared foam liquid, and 10% oxygen is compressed into the foam liquid through the syringe 3 to form bubbles attached to the surface of the wire bundle electrode sample 1, and the bubble size is controlled by the gas volume to determine the coverage of the 2×2 3Cr alloy steel wire array;

[0063] Finally, the wire beam electrode test system was used to test the potential of the 3Cr alloy steel wire inside and outside the bubble after being immersed in a deoxygenated 0.1mol / L sodium chloride solution for 0.5h. The potential of the carbon steel wire in the 10% oxygen foam coverage area was -820mV, and the potential of the carbon steel wire in the non-10% oxygen foam coverage area was -520mV. This shows that the 10% oxygen foam coverage area is the anode, and the non-10% oxygen foam coverage area is the cathode. The potential difference between the two is 300mV, resulting in severe galvanic corrosion. The risk of local corrosion perforation of the carbon steel wire in the 10% oxygen foam coverage area is extremely high.

[0064] Comparative Example:

[0065] Design a 10×10 array mold occupying the hole position, wherein the hole diameter is 0.2 cm. Arrange the J55 carbon steel wire with the conductor in a 10×10 array and insert the injection pipe 4 with a length of 15 cm into the corresponding hole position, and encapsulate and cure with epoxy resin to form a wire bundle electrode sample 1 for air foam flooding;

[0066] Then, the wall of the syringe 3 is filled with the pre-prepared foam liquid, and the air is compressed into the foam liquid through the syringe 3 to form bubbles attached to the surface of the wire bundle electrode sample 1, and the bubble size is controlled by the gas volume to determine the coverage of the 2×2 J55 carbon steel wire array;

[0067] Finally, the wire beam electrode test system was used to test the potential distribution of the wire beam electrode covered with foam in a deoxygenated 0.1 mol / L sodium chloride solution for 0.5 h. The average potential of the nitrogen foam covered area was -550 mv, and the average potential of the non-nitrogen foam covered area was -520 mv. The potential difference between the two was 30 mV, and the potential difference between the nitrogen foam covered area and the non-covered area was not large, and there was no obvious difference in corrosion between the two.

[0068] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A metal corrosion test method for oil field air foam flooding, characterized in that: The following steps are involved: Preparing a wire bundle electrode sample for air foam flooding (1); The prepared wire bundle electrode sample (1) is placed in a corrosion solution, and the air foam liquid and the gas (2) are injected into the surface of the wire bundle electrode sample (1); A wire bundle electrode sample (1) with a foam cover was tested.

2. A metal corrosion testing method for oil field air foam flooding according to claim 1, characterized in that: The preparation method of the wire bundle electrode sample (1) is as follows: An array mold with openings is designed, metal wires with conducting wires are inserted into corresponding positions according to the array arrangement, and epoxy resin is used for encapsulation and curing. After curing, a wire bundle electrode sample (1) for air foam flooding is formed.

3. The metal corrosion testing method for oil field air foam flooding according to claim 1 is characterized in that: The metal wire in the wire bundle electrode sample (1) is J55, P110, N80 carbon steel wire, 3Cr, 5Cr, 9Cr, 13Cr alloy steel or stainless steel, the single wire diameter is 0.02-0.3 cm, and the wire bundle spacing is 0.05-0.3 cm.

4. The metal corrosion testing method for oilfield air foam flooding according to claim 1 is characterized in that: At least one injection tube site is arranged in the wire bundle electrode sample (1), and the injection tube site is located in the gap of the wire bundle or occupies the position of the metal wire.

5. The metal corrosion testing method for oil field air foam flooding according to claim 1 is characterized in that: The method of injecting the air foam liquid and the gas (2) into the surface of the wire bundle electrode sample (1) is: The foam liquid prepared in advance is compressed by air to form bubbles which are attached to the surface of the wire bundle electrode sample (1), and the size of the bubbles is controlled by the gas volume to determine the amount of electrode area or metal wire covered.

6. The metal corrosion testing method for oil field air foam flooding according to claim 1 is characterized in that: The test method of the foam-covered wire bundle electrode sample (1) is as follows: The current and potential distribution of the wire bundle electrode sample (1) covered with foam after different immersion times are tested using a wire bundle electrode testing system, or the electrochemical information of the metal wire inside and outside the bubble is tested using an electrochemical workstation.

7. A device for implementing the metal corrosion testing method for oil field air foam flooding according to any one of claims 1 to 6, characterized in that: It comprises a syringe (3) and an injection tube (4); One end of the plurality of injection tubes (4) is connected to a syringe (3), and the other end of the plurality of injection tubes (4) is arranged in a wire bundle electrode sample (4). Air foam liquid and gas (2) are arranged in the syringe (3).

8. The device for implementing a metal corrosion testing method for oilfield air foam flooding according to claim 7, characterized in that: The diameter of the injection tube (4) is the same as that of the metal wire, and the end of the injection tube (4) is flush with the working surface of the wire bundle electrode sample (1).

9. The device for implementing a metal corrosion testing method for oil field air foam flooding according to claim 7, characterized in that: The ends of the plurality of injection tubes (4) are arranged in the gaps between the wire bundles in the wire bundle electrode sample (1) or occupy the positions of the metal wires.

10. The device for implementing a metal corrosion testing method for oil field air foam flooding according to claim 7, characterized in that: The injection pipe (4) is a plastic hose, and a controller (5) is provided on the injection pipe (4).

Images