Long-acting tracers and methods of making same

Abstract

A preparation method of a long-acting tracer is disclosed: a water-soluble rare earth salt is added to a nano-silicon dioxide dispersion liquid; triethylene tetramine and hexyl hydroxamic acid are added dropwise, and stirring reaction is carried out; the solvent is removed, and drying is carried out to obtain a product. In addition, the long-acting tracer and the application thereof are also disclosed. The long-acting tracer product is non-toxic, harmless and non-radiation, has high detection precision, does not react with reservoir fluid, has simple injection construction, and has better long-term release performance.

Description

Technical Field

[0001] This invention belongs to the field of oilfield well detection technology; it relates to a long-acting tracer and its preparation method. Background Technology

[0002] For water-injection oilfields, wellbore monitoring technology is an important method for monitoring oilfield production dynamics and evaluating the degree of formation heterogeneity. Wellbore monitoring technology includes traditional logging tools and tracer detection technology. Traditional logging tools are used to determine the reservoir production status of each section of horizontal / vertical wells; the advantages are that there are many measurement parameters and real-time data transmission; the disadvantages are that the scope of application is narrow, the process is complex, the cost is high, the risk is high, and downhole operations are required.

[0003] Inter-well tracing technology involves injecting tracers into oil and gas development wells and monitoring the information between the reservoir and the well by testing the tracer content in the samples. By analyzing the changes in the tracer production curve, the distribution patterns of formation parameters can be determined, thereby enabling dynamic monitoring and description of the reservoir and the well.

[0004] Well-to-well tracer technology initially used inorganic salts as tracers, which had large quantities and low precision. It then went through two stages: radioactive isotope tracers and stable isotope tracers, and has now developed to the current tracer technology that uses small quantities and has high precision.

[0005] Compared to inorganic salts, radioactive isotopes, and stable isotope tracers, trace element tracers have significant advantages: First, they are diverse and do not interfere with each other, meeting the requirements for synchronous testing of single well groups, multiple adjacent well groups, or the entire block, as well as stratified testing; second, trace element tracers are non-toxic, non-radioactive, and pose no environmental or safety hazards, and injection and sampling do not require professional authorization, allowing oilfield workers to complete the process independently; third, trace elements possess excellent thermal and biological stability, meeting the monitoring requirements of complex reservoir conditions such as long-term operation, large well spacing, and high temperatures, and require small quantities, with increasingly sophisticated testing instruments and related supporting technologies.

[0006] Quanran (Yinchuan) Technology Co., Ltd. disclosed a new type of data information material, intelligent slow-release tracer and its method, in Chinese patent application CN112065372A. The tracer includes tracer components and encapsulating materials. The encapsulating materials can intelligently control the release conditions and release rate of the tracer components. It includes two types: water-soluble and oil-soluble. The water-soluble intelligent slow-release tracer releases the tracer uniformly when it comes into contact with water, but does not release it when it comes into contact with oil; the oil-soluble intelligent slow-release tracer releases the tracer when it comes into contact with oil, but does not release it when it comes into contact with water. The release rate is uniform and controllable, the release cycle is long, the preparation method is simple and efficient, pollution-free, safe and environmentally friendly. The tracer monitoring technology is used to monitor the oil production and fluid production profiles of various sections of oil and water wells for a long time.

[0007] Jebeton Petroleum Technology Group Co., Ltd. disclosed a slow-release long-acting tracer and its preparation method in Chinese patent application CN113653486A, solving the problems of complex and uncommon tracer preparation processes in existing technologies. The preparation method of the long-acting tracer includes the following steps: heating and softening bisphenol A type epoxy resin; adding a tracer to the epoxy resin to obtain system A; sequentially adding a diluent and additives to system A, stirring until homogeneous to obtain system B; adding a curing agent to system B, and curing to obtain the slow-release long-acting tracer. The preparation process is mild, has a short cycle time, and is easy to mold. By adjusting the process parameters, the release rate of the tracer's active ingredient can be adjusted to meet the requirements of different applications, enabling large-scale mass production and showing good application prospects.

[0008] However, existing long-acting tracers have poor long-term release performance. Summary of the Invention

[0009] The purpose of this invention is to provide a tracer with better long-term release performance and its preparation method.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for preparing a long-acting tracer, comprising the following steps:

[0011] Water-soluble rare earth salts were added to the nano-silica dispersion and stirred to ensure uniform dispersion.

[0012] Add an aqueous solution of triethylenetetramine and hexylhydroxamic acid dropwise, and continue stirring the reaction for 1-5 hours;

[0013] The solvent was removed by vacuum distillation, and the product was washed and dried to obtain a long-lasting tracer.

[0014] According to the preparation method of the present invention, the weight ratio of water-soluble rare earth salt to nano-silica is 1:(8-12).

[0015] According to the preparation method of the present invention, the water-soluble rare earth salt is selected from yttrium nitrate hexahydrate.

[0016] According to the preparation method of the present invention, the weight ratio of the water-soluble rare earth salt to triethylenetetramine is 2:(3-5).

[0017] According to the preparation method of the present invention, the weight ratio of the water-soluble rare earth salt to hexyl hydroxamic acid is 2:(1-2).

[0018] According to the preparation method of the present invention, the average particle size of the nano-silica is 10-100 nm.

[0019] According to the preparation method of the present invention, the preparation method of the nano-silica dispersion is as follows:

[0020] Disperse 20-30 parts of nano silica, 10-15 parts of surfactant Triton X-100 and 5-8 parts of n-octanol in 100-120 parts of water and stir at 50-70℃ for 1-5 hours to obtain a nano silica dispersion.

[0021] According to the preparation method of the present invention, the water-soluble rare earth salt is added in solution form by dissolving 1 part of the water-soluble rare earth salt in 8-12 parts of an ethanol / water solution with a volume ratio of 9:1.

[0022] On the other hand, the present invention provides a long-acting tracer prepared according to the method of the present invention.

[0023] In another aspect, the present invention provides an application of the long-acting tracer described in the present invention for inter-well tracer detection.

[0024] Compared with existing technologies, the long-lasting tracer according to the present invention is non-toxic, harmless, and radiation-free; it has high detection accuracy and ppb-level tracer capability; it does not react with reservoir fluids and is resistant to acids, alkalis, and salts; it does not affect the performance of fracturing fluids or subsequent production operations; and its injection is simple and convenient. In particular, the tracer product according to the present invention has better long-term release performance. Detailed Implementation

[0025] It must be noted that, unless the context clearly specifies otherwise, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” can include one or more referents (i.e., two or more, including two).

[0026] Unless otherwise specified, numerical ranges in this invention are approximate and therefore may include values ​​outside of said range. The numerical range may be expressed in this invention as from “about” a particular value and / or to “about” another particular value. When such a range is expressed, another aspect includes from said one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation using the antecedent “about,” it should be understood that said particular value forms another aspect. It should also be understood that each endpoint in a numerical range is significant in relation to and independent of another endpoint.

[0027] The reference to the weight parts of a specific element or component in the composition or article in the specification and the final claims refers to the weight relationship between that element or component and any other element or component in the composition or article, expressed in parts by weight.

[0028] In this invention, unless specifically indicated otherwise, or implied by the context or customary practice in the art, all solutions referred to herein are aqueous solutions; when the solute in the aqueous solution is a liquid, all fractions and percentages are by volume, and the volume percentage of a component is based on the total volume of the composition or product containing that component; when the solute in the aqueous solution is a solid, all fractions and percentages are by weight, and the weight percentage of a component is based on the total weight of the composition or product containing that component.

[0029] The terms “comprising,” “including,” “having,” and similar expressions used in this invention are not intended to exclude the presence of any optional components, steps, or procedures, whether or not any optional components, steps, or procedures are specifically disclosed. For the avoidance of any doubt, unless stated to the contrary, all methods claimed by using the term “comprising” may include one or more additional steps, equipment parts or components, and / or substances. In contrast, the term “consisting of” excludes any components, steps, or procedures not specifically described or enumerated. Unless otherwise stated, the term “or” refers to members listed individually and in any combination.

[0030] Furthermore, the contents of any patent or non-patent documents referenced in this invention are incorporated herein by full citation, especially regarding definitions disclosed in the relevant field (where there is no inconsistency with any definitions specifically provided herein) and common knowledge.

[0031] In this invention, unless otherwise specified, all parts are parts by weight, temperatures are expressed in °C or at ambient temperature, and pressures are at or near atmospheric pressure. Room temperature means 20-30 °C. Various variations and combinations of reaction conditions exist (e.g., component concentrations, desired solvents, solvent mixtures, temperature, pressure, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the method. Only reasonable routine experiments are required to optimize such method conditions.

[0032] Example 1

[0033] 20 parts of 22nm nano-silica, 10 parts of surfactant Triton X-100 and 5 parts of n-octanol were dispersed in 100 parts of water and stirred at 60℃ for 3 hours to obtain a nano-silica dispersion.

[0034] Two parts of yttrium nitrate hexahydrate were dissolved in 20 parts of an ethanol / water solution with a volume ratio of 9:1, and then added to a nano-silica dispersion. The mixture was stirred for 0.5 h to ensure uniform dispersion. Four parts of triethylenetetramine and one part of hexylhydroxamic acid aqueous solution were added dropwise. After the addition was complete, the reaction was stirred for another 2 h. The solvent was removed by vacuum distillation, and the product was washed three times with water and dried to obtain the long-lasting tracer product.

[0035] The FTIR infrared absorption spectrum shows that the long-lasting tracer product has an absorption rate of 3265 cm⁻¹. -1 2954cm -1 2949cm -1 2873cm -1 2845cm -1 1708cm -1 1660cm -1 1576cm -1 1471cm -1 1422cm -1 1379cm -1 1124cm -1 1066cm -1 968cm -1 722cm -1 A characteristic absorption peak exists at this location.

[0036] Example 2

[0037] 30 parts of 22nm nano-silica, 15 parts of surfactant Triton X-100 and 8 parts of n-octanol were dispersed in 120 parts of water and stirred at 60℃ for 3 hours to obtain a nano-silica dispersion.

[0038] Dissolve 3 parts of yttrium nitrate hexahydrate in 25 parts of an ethanol / water solution with a volume ratio of 9:1, and add the solution to a nano-silica dispersion. Stir for 0.5 h to ensure uniform dispersion. Add dropwise 6 parts of triethylenetetramine and 2 parts of hexylhydroxamic acid in an appropriate amount of aqueous solution. After the addition is complete, continue stirring for 2 h. Remove the solvent by vacuum distillation, wash three times with water, and dry to obtain the long-lasting tracer product.

[0039] Comparative Example 1

[0040] 20 parts of 22nm nano-silica, 10 parts of surfactant Triton X-100 and 5 parts of n-octanol were dispersed in 100 parts of water and stirred at 60℃ for 3 hours to obtain a nano-silica dispersion.

[0041] Two parts of yttrium nitrate hexahydrate were dissolved in 20 parts of an ethanol / water solution with a volume ratio of 9:1, and then added to a nano-silica dispersion. The mixture was stirred for 0.5 h to ensure uniform dispersion. Four parts of an appropriate amount of triethylenetetramine aqueous solution were added dropwise, and the reaction was continued with stirring for 2 h after the addition was complete. The solvent was removed by vacuum distillation, and the product was washed three times with water and dried to obtain the long-lasting tracer product.

[0042] Performance testing

[0043] 0.2% of the long-acting tracers from Example 1 and Comparative Example 1 were added to 40-70 mesh supporting ceramic particles, respectively. The recovery rate (y*100) of a flushing flow rate of 0.8 mL / min as a function of time (x) under a temperature of 60℃ and a sealing pressure of 40 MPa was investigated. The results showed that the release curves of the long-acting tracers from Example 1 and Comparative Example 1 were both linear, with linear relationships of y = 0.1628x - 0.9750 and y = 0.3417x + 0.1623, respectively; the release rate of the former at 90 min was only 44% of that of the latter.

[0044] Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications, substitutions, deletions, corrections or adjustments to the technical solutions of this invention, and these equivalent technical solutions also fall within the scope defined by the claims of this invention.

Claims

1. A method for preparing a long-acting tracer, characterized in that, Includes the following steps: Water-soluble rare earth salts were added to the nano-silica dispersion and stirred to ensure uniform dispersion. Add an aqueous solution of triethylenetetramine and hexylhydroxamic acid dropwise, and continue stirring the reaction for 1-5 hours; The solvent was removed by vacuum distillation, and the product was washed and dried to obtain a long-lasting tracer product. The water-soluble rare earth salt is selected from yttrium nitrate hexahydrate; The weight ratio of water-soluble rare earth salts to nano-silica is 1: (8-12); The weight ratio of water-soluble rare earth salt to triethylenetetramine is 2:(3-5); The weight ratio of water-soluble rare earth salt to hexyl hydroxamic acid is 2:(1-2); The preparation method of nano-silica dispersion is as follows: Disperse 20-30 parts of nano silica, 10-15 parts of surfactant Triton X-100 and 5-8 parts of n-octanol in 100-120 parts of water and stir at 50-70℃ for 1-5 hours to obtain a nano silica dispersion.

2. The preparation method according to claim 1, wherein, The average particle size of the nano-silica is 10-100 nm.

3. The preparation method according to claim 1, wherein, Water-soluble rare earth salts are added in solution form by dissolving 1 part of water-soluble rare earth salt in 8-12 parts of an ethanol / water solution with a volume ratio of 9:

1.

4. A long-acting tracer, characterized in that, It is obtained by any one of the preparation methods according to claims 1-3.

5. An application of the long-acting tracer according to claim 4, characterized in that, Used for inter-well tracer detection.