Water-based tracer agent for oilfield development and preparation method of water-based tracer agent

Abstract

The invention discloses a water-based tracer agent for oilfield development and a preparation method of the water-based tracer agent, and relates to the technical field of tracer agents. The water-based tracer agent for oilfield development is in a liquid state at normal temperature, is gasified at about 80 DEG C, and comprises a perfluoromethyl cyclopentane (PMCP perfluoromethyl cyclopentane, PECH polyepichlorohydrin, PMCH perfluoromethyl cyclohexane and PDCH perfluorodimethyl cyclohexane) tracer agent solution, porous nano silicon dioxide microspheres and a resin composition solution. Wherein the resin composition solution forms a colloidal film on the surface of the porous nano silicon dioxide microsphere. According to the water-based tracer, the perfluoromethyl cyclopentane tracer solution is dispersed in the nano silicon dioxide microspheres, so that the nano silicon dioxide microspheres can protect the perfluoromethyl cyclopentane tracer solution after the water-based tracer is infiltrated and injected into an underground water system (casing) with a relatively high temperature; volatilization caused by the fact that the temperature of the water system is higher than the boiling point 48 DEG C of perfluoromethyl cyclopentane is avoided, and deviation of the tracing effect in a high-water-temperature environment is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of tracers, in particular to a water-based tracer for oilfield development and a preparation method thereof. Background Art

[0002] In order to clearly grasp the time, location, flow rate and flow characteristics of water breakthrough during CCUS carbon capture in oil fields and fire drive production, enhance the effect of profile adjustment and water plugging, feedback reservoir geological parameters, and effectively improve the recovery rate, oilfield tracer technology came into being. Oilfield tracer technology is one of the field production test technologies. Its technology is to inject tracers from injection wells, and then sample the surrounding production wells according to certain sampling regulations to monitor the changes of tracers over time, which can guide the design of oil well production and the adjustment of oilfield development in the later stage.

[0003] Oilfield tracers can qualitatively describe reservoir conditions, such as: the propulsion direction and speed of injected fluids, evaluation of volume sweep efficiency, fluid shielding, directional flow trends, heterogeneous characteristics of reservoirs, determination of remaining oil saturation and distribution, etc., which are of great significance for the exploitation, design, cross-linking and subsequent adjustments of oil fields and water wells.

[0004] The tracers commonly used in oil fields are mainly chemical tracers, radioactive isotope tracers, stable isotope tracers and trace material tracers. Chemical tracers are the first generation of oil field tracers, including soluble inorganic salts, fluorescent dyes, halogenated hydrocarbons and low molecular weight alcohols. Its research and development and use have opened up the application of tracer technology in oil field development. Subsequently, radioactive isotope tracers, stable isotope tracers and trace material tracers have been promoted and used as the second, third and fourth generation oil field tracers respectively.

[0005] For example, Chinese patent publication number CN1262850C discloses a method for tracing oil well tracers using a non-water-soluble reagent and its analysis and detection method. The tracing method uses fluorobenzoic acid (FBAs) as a tracer, and uses some sample pretreatment methods such as filtration, derivatization, and solid phase extraction during analysis and detection, and then uses gas chromatography-mass spectrometry technology to perform trace analysis on the tracer, which is the fourth generation of oil field tracers.

[0006] Currently, some companies use perfluoromethylcyclopentane as the fourth-generation oilfield tracer. It is safe, stable, and comes in many types. It is generally used as a water-based tracer. However, there is a problem that perfluoromethylcyclopentane has a low boiling point and works best when used in water systems at room temperature. If there is a geothermal environment and the groundwater temperature is higher than 48°C, the perfluoromethylcyclopentane in the water system will easily volatilize and remain in the rocks and soil, causing inaccurate later detection results. Summary of the invention

[0007] The present invention aims at the above technical problems, overcomes the disadvantages of the prior art, and provides an aqueous tracer for oilfield development and a preparation method thereof.

[0008] The technical solution further defined in the present invention is an aqueous tracer for oilfield development, comprising:

[0009] Perfluoromethylcyclopentane tracer solution;

[0010] Porous nano-silica microspheres;

[0011] A resin composition solution;

[0012] The resin composition solution forms a colloidal coating on the surface of the porous nano-silica microspheres.

[0013] Furthermore, the perfluoromethylcyclopentane tracer solution is located in the micropores of the porous nano-silica microspheres and adheres to the outside of the colloidal coating.

[0014] The aforementioned aqueous tracer for oilfield development, the resin composition solution comprises the following components by weight:

[0015] Polypropylene resin 50 parts

[0016] 36 parts wax

[0017] 4 parts of crosslinking agent

[0018] 60 parts of solvent.

[0019] In the aforementioned aqueous tracer for oilfield development, the cross-linking agent is at least one of DCP, BPO, DTBP and DBHP.

[0020] The above-mentioned aqueous tracer for oil field development, the perfluoromethylcyclopentane tracer solution is at least one of PMCP (perfluoromethylcyclopentane), (PECH polyepichlorohydrin), (PMCH perfluoromethylcyclohexane).

[0021] The present invention also provides a method for preparing an aqueous tracer for oilfield development, which is used to prepare any of the above-mentioned aqueous tracers for oilfield development, and comprises the following steps:

[0022] S1, taking a quantitative perfluoromethylcyclopentane tracer solution, immersing a quantitative porous nano-silica microsphere in the solution, and stirring to obtain a silica tracer microsphere solution;

[0023] S2, preparing a resin composition according to predetermined components, and dissolving the resin composition in a solvent to obtain a resin composition solution;

[0024] S3, in a sealed environment, prepare clean water with a height of 2 mm, and spray the silica tracer microsphere solution and the resin composition solution through two atomizing nozzles respectively, and fill the entire sealed environment, maintain the curing temperature for 3 hours, and obtain a semi-finished product;

[0025] S4, drying the semi-finished product at low temperature to obtain crystals, taking a quantitative perfluoromethylcyclopentane tracer solution, dissolving the crystals therein, and obtaining a finished aqueous tracer for oilfield development.

[0026] In the above-mentioned method for preparing an aqueous tracer for oilfield development, in step S4, the temperature of low-temperature drying is 40-47°C.

[0027] In the above-mentioned method for preparing an aqueous tracer for oil field development, in step S1, the stirring speed is 200 r / min.

[0028] In the aforementioned method for preparing an aqueous tracer for oilfield development, in step S3, the solidification temperature is 42-45°C.

[0029] The beneficial effects of the present invention are:

[0030] (1) In the present invention, since the perfluoromethylcyclopentane tracer solution is dispersed in the nano-silica microspheres, after the aqueous tracer penetrates into the underground water system with a relatively high temperature, the nano-silica microspheres can protect the perfluoromethylcyclopentane tracer solution, thereby preventing volatilization caused by the water system temperature being higher than the boiling point of perfluoromethylcyclopentane, 48° C., and preventing deviation of the tracing effect in a relatively high water temperature environment;

[0031] (2) In the present invention, in order to further improve the protectiveness of the nano-silica microspheres for the perfluoromethylcyclopentane tracer, a resin composition solution is added to form a layer of glue coating outside the microspheres, which can prevent the perfluoromethylcyclopentane tracer solution from volatilizing under a high temperature environment. During detection, the sample can be added to a solvent such as ethanol or methanol, and the tracer can be detected after the solvent destroys the glue coating;

[0032] (3) In the present invention, after the formation of the colloidal coating, the perfluoromethylcyclopentane tracer solution is continued to be mixed with the nano-silica microspheres, so that perfluoromethylcyclopentane also exists in the tracer solution, and the obtained aqueous tracer is liquid at room temperature and vaporizes at about 80 degrees Celsius, which is convenient for the tracer to be used under normal temperature conditions;

[0033] (4) In the present invention, nano-silica microspheres are used as the protective shell. On the one hand, they have strong mechanical and chemical resistance and can avoid being damaged. On the other hand, their nano-scale size can flow with the groundwater system and prevent them from being retained along the way. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the state when the colloidal film is coated with nano-silica microspheres.

[0035] Among them, 1. Colloidal coating; 2. Nano-silica microspheres. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present invention clearer, a detailed description is given below in conjunction with the accompanying drawings and specific embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0037] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to an element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0039] The invention provides a method for preparing an aqueous tracer for oilfield development, and provides several embodiments and comparative examples to verify the tracing effects of tracers prepared under different formulation conditions under different conditions.

[0040] Embodiment 1 comprises the following steps:

[0041] S1, taking 10 parts of perfluoromethylcyclopentane-based tracer solution, immersing 3 parts of porous nano-silica microspheres therein, and stirring at 200 r / min to obtain a silica tracer microsphere solution.

[0042] In this step, the porous nano-silica microspheres can be fully infiltrated and absorbed by the perfluoromethylcyclopentane-based tracer solution.

[0043] S2, preparing a resin composition according to predetermined components, and dissolving the resin composition in a solvent to obtain a resin composition solution.

[0044] S3, in a sealed environment, prepare clean water with a height of 2 mm, and spray the silica tracer microsphere solution and the resin composition solution through two atomizing nozzles respectively, and fill the entire sealed environment, maintain the curing temperature for 3 hours, and the curing temperature is 42-45°C to obtain a semi-finished product.

[0045] After atomization spraying, the silica tracer microsphere solution forms mist and contacts with the resin composition solution. The resin composition solution will then cover the silica microspheres and form a gelatinous coating after falling into clean water.

[0046] S4, drying the semi-finished product at a low temperature of 40-47° C. to obtain crystals, taking 50 parts of a perfluoromethylcyclopentane-based tracer solution, dissolving the crystals therein, and obtaining a finished aqueous tracer for oilfield development.

[0047] Comparative Example 1

[0048] The other conditions remain unchanged, and the difference from Example 1 is that after step S3 is completed, the finished tracer product is obtained.

[0049] Comparative Example 2

[0050] The other conditions remain unchanged, and the difference from the example is that no resin composition is used to form the gel-like coating.

[0051] Comparative Example 3

[0052] Tested using perfluoromethylcyclopentane based tracer solution.

[0053] Test method: Set up a corresponding underground water channel with a depth of 1m, a width of 10cm, a length of 3m and a height of 20cm. Cover the top of the channel with sand, gravel and soil, and divide the water channel into three sections. The first section is a normal temperature section of 20-30℃, the second section is a medium temperature section of 48-50℃, and the third section is a high temperature section of 65-70℃. The finished tracer is dripped into each channel, and samples are taken for testing after 24 hours, and the sample endpoint concentration is recorded.

[0054] The initial concentrations in the embodiment and the comparative example are the same, and the water channel contains simulated formation water (mineralization degree is 2×10 4 mg / L).

[0055] The test results are shown in Table 1.

[0056] Table 1 Test results of various embodiments and comparative examples

[0057]

[0058] It can be seen from the table that Example 1 has the best detection effect, has excellent tracing performance in both the medium temperature section and the high temperature section, and has strong chemical resistance and stability.

[0059] By comparing Example 1 with Comparative Example 1, it can be found that the perfluoromethylcyclopentane tracer solution added last has a certain influence on the disappearance effect, but the overall effect and performance are not greatly affected.

[0060] By comparing Example 1, Comparative Example 2 and Comparative Example 3, it can be found that the presence of the colloidal coating and the microspheres is a decisive factor affecting the tracing effect of the tracer.

[0061] Since the perfluoromethylcyclopentane tracer solution is dispersed in the nano-silica microspheres, after the aqueous tracer penetrates into the groundwater system with a higher temperature, the nano-silica microspheres can protect the perfluoromethylcyclopentane tracer solution, avoiding volatilization caused by the water system temperature being higher than the boiling point of perfluoromethylcyclopentane 48°C, thereby preventing deviation in the tracing effect in a higher water temperature environment.

[0062] In addition, in order to further improve the protectiveness of nano-silica microspheres against perfluoromethylcyclopentane tracers, a resin composition solution was added to form a layer of glue coating on the outside of the microspheres, which can prevent the perfluoromethylcyclopentane tracer solution from volatilizing under high temperature conditions. During detection, the sample can be added to solvents such as ethanol and methanol. After the solvent destroys the gel coating, the tracer can be detected.

[0063] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. An aqueous tracer for oilfield development, characterized in that: include: Perfluoromethylcyclopentane tracer solution; Porous nano-silica microspheres; A resin composition solution; The resin composition solution forms a colloidal coating on the surface of the porous nano-silica microspheres.

2. The aqueous tracer for oilfield development according to claim 1, characterized in that: The perfluoromethylcyclopentane tracer solution is located in the micropores of the porous nano-silica microspheres and adheres to the outside of the gelatinous coating.

3. The aqueous tracer for oilfield development according to claim 1, characterized in that: The resin composition solution includes the following components by weight: Polypropylene resin 50 parts 36 parts wax 4 parts of crosslinking agent 60 parts of solvent.

4. The aqueous tracer for oilfield development according to claim 3, characterized in that: The cross-linking agent is at least one of DCP, BPO, DTBP and DBHP.

5. The aqueous tracer for oil field development according to claim 1, wherein the perfluoromethylcyclopentane tracer solution is at least one of PMCP (perfluoromethylcyclopentane), (PECH polyepichlorohydrin), (PMCH perfluoromethylcyclohexane).

6. A method for preparing an aqueous tracer for oilfield development, used for preparing any one of claims 1 to 5, characterized in that: The steps include: S1, taking a quantitative perfluoromethylcyclopentane tracer solution, immersing a quantitative porous nano-silica microsphere in the solution, and stirring to obtain a silica tracer microsphere solution; S2, preparing a resin composition according to predetermined components, and dissolving the resin composition in a solvent to obtain a resin composition solution; S3, in a sealed environment, prepare clean water with a height of 2 mm, and spray the silica tracer microsphere solution and the resin composition solution through two atomizing nozzles respectively, and fill the entire sealed environment, maintain the curing temperature for 3 hours, and obtain a semi-finished product; S4, drying the semi-finished product at low temperature to obtain crystals, taking a quantitative perfluoromethylcyclopentane tracer solution, dissolving the crystals therein, and obtaining a finished aqueous tracer for oilfield development.

7. The method for preparing an aqueous tracer for oil field development according to claim 6, characterized in that: In step S4, the low-temperature drying temperature is 40-47°C.

8. The method for preparing an aqueous tracer for oil field development according to claim 6, characterized in that: In the step S1, the stirring speed is 200 r / min.

9. The method for preparing an aqueous tracer for oil field development according to claim 6, characterized in that: In the step S3, the curing temperature is 42-45°C.

10. The method for preparing an aqueous tracer for oil field development according to claim 6, characterized in that: When detecting the tracer, an ethanol solvent is required to destroy the gelatinous coating.

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