Rare earth complex trace element tracer agent for oilfield development

Abstract

The invention relates to the technical field of oilfield exploitation, and provides a rare earth complex trace element tracer agent for oilfield development. The method comprises the following steps: firstly, preparing a complexing agent aqueous solution, and dissolving a selected complexing agent in a proper amount of water to obtain the complexing agent aqueous solution; preparing a rare earth salt aqueous solution, reacting the rare earth element powder with dilute acid to generate rare earth salt precipitate, extracting the rare earth salt precipitate, performing evaporative crystallization, drying and crushing to obtain rare earth salt powder, and dissolving the rare earth salt powder in a proper amount of water to obtain the rare earth salt aqueous solution; and then adding the rare earth salt aqueous solution into the complexing agent aqueous solution, placing the mixed solution in a water bath at the constant temperature of 90 DEG C, uniformly stirring, continuously carrying out complexing reaction for 3 hours, crystallizing, crushing and drying to obtain the rare earth complex trace element tracer agent.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield exploitation, in particular to a rare earth complex trace element tracer for oilfield development. Background Art

[0002] With the development of oilfield development technology, the demand for improving oil recovery, optimizing reservoir management and realizing refined reservoir management is increasing. As an important tool, tracer technology can be used to evaluate reservoir material migration, reservoir characteristics, and the effect of production enhancement technology.

[0003] In oilfield development, rare earth complex trace element tracers are an environmentally friendly choice. Compared with traditional chemical tracers, they are low toxic, non-radioactive, highly stable and highly sensitive, which helps reduce pollution to the oilfield environment.

[0004] The Chinese patent announcement number is CN110685673B, which discloses an oil field high-salt and high-alkalinity water-soluble trace element tracer. The trace element tracer is obtained by complexing a soluble rare earth salt with a complexing agent to form a rare earth complex, wherein the complexing agent is one of the five kinds of ethylenediaminetetraacetic acid, sodium sulfosalicylate, glycolic acid, trisodium nitrilotriacetate and pentasodium diethylenetriaminepentaacetate. This tracer is environmentally friendly and pollution-free, and safe to operate; it is resistant to high temperature, high salt and high alkali, but the tracer has poor stability and weak complexing ability.

[0005] Therefore, the present invention proposes a rare earth complex trace element tracer with strong complexing ability, high temperature resistance, strong acid and strong alkali resistance. Summary of the invention

[0006] The invention provides a rare earth complex trace element tracer for oil field development. The rare earth complex trace element tracer is obtained by complexing the rare earth element tracer with a complexing agent aqueous solution.

[0007] The technical solution of the present invention is as follows: a method for preparing a rare earth complex trace element tracer for oil field development is as follows:

[0008] S1: Prepare a complexing agent aqueous solution, dissolve the selected complexing agent in an appropriate amount of water, stir evenly to make it completely dissolved, and obtain a complexing agent aqueous solution; after preparation, the solution should be stored in a cool and dry place, away from direct sunlight to maintain its stability;

[0009] S2: preparing a rare earth salt solution, dissolving a rare earth element powder in an appropriate amount of dilute acid to obtain a rare earth element ion solution, slowly adding sulfuric acid to the rare earth element ion solution, and combining the rare earth element ions with sulfate ions to form a rare earth salt precipitate, then selecting a suitable extractant to extract the rare earth salt precipitate, reacting at room temperature for one hour to obtain a rare earth salt solution, wherein the volume ratio of the extractant to the rare earth salt precipitate is 1:2, and the obtained rare earth salt solution is evaporated and crystallized to obtain rare earth salt crystals, and then the rare earth salt crystals are dried and crushed to obtain rare earth salt powder, and the obtained rare earth salt powder is dissolved in an appropriate amount of water, stirred evenly to completely dissolve it, and a rare earth salt solution is obtained;

[0010] S3: synthesizing the tracer, adding the rare earth salt aqueous solution prepared in S2 to the complexing agent aqueous solution prepared in S1, the volume ratio of the rare earth salt aqueous solution to the complexing agent aqueous solution is 1:3, then placing the obtained mixed solution in a 90°C constant temperature water bath, stirring evenly, continuing the complexing reaction for 3 hours, and finally obtaining a rare earth complex trace element tracer by crystallization, crushing and drying.

[0011] Preferably, the complexing agent is selected from any one of sodium ethylenediaminetetramethylenephosphate, sodium diethylenetriaminepenta(methylenephosphonate), and tetrasodium aminotri(methylenephosphate).

[0012] Preferably, the rare earth element is any one of dysprosium (Dy), cerium (Ce) and erbium (Er).

[0013] Preferably, the dilute acid is dilute sulfuric acid.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention selects sodium ethylenediaminetetramethylene phosphate, sodium diethylenetriaminepenta(methylene phosphonate), and tetrasodium aminotri(methylene phosphate) as complexing agents. Compared with other complexing agents, they have stronger complexing ability, are non-toxic and pollution-free, are environmentally friendly, and can form stable complexes with a variety of metal ions. They have good chemical stability, strong acid and alkali resistance, and high temperature resistance. They can maintain good scale inhibition, corrosion inhibition, and dispersion effects at 200°C, making them still effective in high temperature environments.

[0016] 2. The present invention selects three rare earth elements, namely dysprosium, cerium and erbium, which have a wider application range than the other 14 rare earth elements, lower cost, more active chemical properties, and are convenient for forming rare earth salt precipitation.

[0017] 3. The rare earth complex trace element tracer prepared by the present invention is non-toxic and pollution-free, has stable chemical properties, simple analytical operation, high sensitivity, low preparation cost, and is easily biodegradable, with little pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a flow chart for preparing the soil complex trace element tracer. DETAILED DESCRIPTION

[0019] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0020] The present invention provides a rare earth complex trace element tracer for oil field development, and specific embodiments are as follows.

[0021] Embodiment 1:

[0022] S1: Prepare an aqueous solution of sodium ethylenediaminetetramethylenephosphate, dissolve sodium ethylenediaminetetramethylenephosphate powder in an appropriate amount of water to completely dissolve it, and obtain an aqueous solution of sodium ethylenediaminetetramethylenephosphate, and place the solution in a dark, dry, and cool place for standby use;

[0023] S2: prepare a dysprosium sulfate aqueous solution, dissolve rare earth dysprosium powder in an appropriate amount of dilute hydrochloric acid to obtain a dysprosium chloride solution, slowly add sulfuric acid to the dysprosium chloride solution, and combine dysprosium ions with sulfate ions to form a dysprosium sulfate precipitate, then add 95% ethanol to the precipitate for extraction, react at room temperature for one hour to obtain a dysprosium sulfate solution, the volume ratio of 95% ethanol to the dysprosium sulfate precipitate is 1:2, and the obtained dysprosium sulfate solution is evaporated and crystallized to obtain dysprosium sulfate crystals, and then the dysprosium sulfate crystals are placed in a 50°C oven to dry for one hour, and then the dried crystals are placed in a ball mill to be crushed to obtain soluble dysprosium sulfate powder, and the obtained dysprosium sulfate powder is dissolved in an appropriate amount of water to obtain a dysprosium sulfate aqueous solution;

[0024] S3: Synthesize a tracer. Add the dysprosium sulfate aqueous solution prepared in S2 to the sodium ethylenediaminetetramethylenephosphate aqueous solution prepared in S1. The volume ratio of the dysprosium sulfate aqueous solution to the sodium ethylenediaminetetramethylenephosphate aqueous solution is 1:3. Then place the resulting mixed solution in a 90°C constant temperature water bath and stir evenly. Continue the complexation reaction for 3 hours, then evaporate and crystallize. Place the resulting crystals in a 50°C oven to dry for one hour. Then, place the dried crystals in a ball mill and crush them to obtain a rare earth dysprosium complex trace element tracer.

[0025] Embodiment 2:

[0026] S1: Prepare a sodium diethylenetriamine penta (methylenephosphonate) aqueous solution by dissolving sodium diethylenetriamine penta (methylenephosphonate) powder in an appropriate amount of water to completely dissolve it to obtain a sodium diethylenetriamine penta (methylenephosphonate) aqueous solution, and place the solution in a dark, dry, cool place for later use;

[0027] S2: Prepare a cerium sulfate aqueous solution, dissolve rare earth cerium powder in an appropriate amount of dilute nitric acid to obtain a cerium nitrate solution, slowly add sulfuric acid to the cerium nitrate solution, and combine cerium ions with sulfate ions to form cerium sulfate precipitates, then add toluene to the precipitate for extraction, and react at room temperature for one hour to obtain a cerium sulfate solution, the volume ratio of toluene to cerium sulfate precipitates is 1:2, and the obtained cerium sulfate solution is evaporated and crystallized to obtain cerium sulfate crystals, and then the cerium sulfate crystals are placed in a 50°C oven to dry for one hour, and then the dried crystals are placed in a ball mill to crush to obtain soluble cerium sulfate powder, and the obtained cerium sulfate powder is dissolved in an appropriate amount of water to obtain a cerium sulfate aqueous solution;

[0028] S3: Synthesize the tracer. Add the cerium sulfate aqueous solution prepared in S2 to the sodium diethylenetriamine penta (methylene phosphonate) aqueous solution prepared in S1. The volume ratio of the cerium sulfate aqueous solution to the sodium diethylenetriamine penta (methylene phosphonate) aqueous solution is 1:3. Then place the obtained mixed solution in a 90°C constant temperature water bath and stir evenly. Continue the complexation reaction for 3 hours. Then evaporate and crystallize. Place the obtained crystals in a 50°C oven and dry for one hour. Finally, place the dried crystals in a ball mill and crush them to obtain a rare earth cerium complex trace element tracer.

[0029] Embodiment three:

[0030] S1: preparing a tetrasodium aminotrimethylene phosphate aqueous solution, dissolving tetrasodium aminotrimethylene phosphate powder in an appropriate amount of water to completely dissolve it to obtain a tetrasodium aminotrimethylene phosphate aqueous solution, and placing the solution in a dark, dry, cool place for standby use;

[0031] S2: preparing an erbium sulfate aqueous solution, dissolving rare earth erbium powder in an appropriate amount of dilute nitric acid to obtain an erbium nitrate solution, slowly adding sulfuric acid to the erbium nitrate solution, and combining erbium ions with sulfate ions to form erbium sulfate precipitates, then adding P2O4 to the precipitate for extraction, reacting at room temperature for one hour to obtain an erbium sulfate solution, the volume ratio of P2O4 to the erbium sulfate precipitate is 1:2, the obtained erbium sulfate solution is evaporated and crystallized to obtain erbium sulfate crystals, and then the erbium sulfate crystals are placed in a 50°C oven to dry for one hour, and then the dried crystals are placed in a ball mill to be crushed to obtain erbium sulfate powder, and the obtained erbium sulfate powder is dissolved in an appropriate amount of water to obtain an erbium sulfate aqueous solution;

[0032] S3: Synthesize a tracer. Add the erbium sulfate aqueous solution prepared in S2 to the tetrasodium aminotrimethylene phosphate aqueous solution prepared in S1. The volume ratio of the erbium sulfate aqueous solution to the tetrasodium aminotrimethylene phosphate aqueous solution is 1:3. Then place the resulting mixed solution in a 90°C constant temperature water bath and stir evenly. Continue the complexation reaction for 3 hours, then evaporate and crystallize. Place the resulting crystals in a 50°C oven and dry for one hour. Finally, place the dried crystals in a ball mill and crush them to obtain a rare earth erbium complex trace element tracer.

[0033] Example 4: The difference from Example 1 is that sodium diethylenetriamine penta(methylenephosphonate) is used as the complexing agent, and the remaining steps are the same as those of Example 1.

[0034] Example 5: The difference from Example 1 is that tetrasodium aminotri(methylene)phosphate is used as the complexing agent, and the remaining steps are the same as those in Example 1.

[0035] Example 6: The difference from Example 2 is that sodium ethylenediaminetetramethylenephosphate is selected as the complexing agent, and the remaining steps are the same as those of Example 1.

[0036] Example 7: The difference from Example 2 is that tetrasodium aminotri(methylene)phosphate is used as the complexing agent, and the remaining steps are the same as those in Example 2.

[0037] Embodiment 8: The difference from Embodiment 3 is that sodium ethylenediaminetetramethylenephosphate is selected as the complexing agent, and the remaining steps are the same as those of Embodiment 3.

[0038] Example 9: The difference from Example 3 is that sodium diethylenetriamine penta (methylenephosphonate) is selected as the complexing agent, and the remaining steps are the same as those in Example 3.

[0039] Experimental analysis

[0040] 1. Detect the performance indicators of the rare earth complex trace element tracers prepared in Examples 1 to 9 of the present invention, namely, the acid and alkali resistance and high temperature resistance of the tracers.

[0041] Experimental materials: rare earth complex trace element tracers prepared in Examples 1 to 9 of the present invention.

[0042] Experimental method: The rare earth complex trace element tracer prepared in Examples 1 to 9 was selected, and the rare earth complex trace element tracer prepared in Examples 1 to 9 was respectively prepared into an aqueous solution with a concentration of 50 μg / L, the pH of the tracer aqueous solution was adjusted to 1, the tracer aqueous solution was placed in a constant temperature chamber at 200°C for two months, and the concentration of the tracer aqueous solution was re-detected; the rare earth complex trace element tracer prepared in Examples 1 to 9 was then prepared into an aqueous solution with a concentration of 50 μg / L, the pH of the tracer aqueous solution was adjusted to 12, the tracer aqueous solution was placed in a constant temperature chamber at 200°C for two months, and the concentration of the tracer aqueous solution was re-detected. The results are shown in Table 1.

[0043] Table 1 Acid and alkali resistance of tracers

[0044]

[0045] As can be seen from Table 1, when the rare earth complex trace element tracer prepared by the present invention is prepared into an aqueous solution, it is still stable after being stored in a high acid and high alkali aqueous solution at 200° C. for two months, and the concentration change range is very small, not exceeding 7%, indicating that the rare earth complex trace element tracer prepared by the present invention has excellent high temperature resistance and strong acid and alkali resistance.

[0046] 2. Detection of the stability of the rare earth complex trace element tracers prepared in Examples 1 to 9 of the present invention

[0047] Experimental materials: the high-salt-resistant and high-alkalinity water-soluble trace element tracers described in the three background technologies, the rare earth complex trace element tracers prepared in Examples 1 to 9 of the present invention, chemical plugging agents, and Yaodian Oilfield.

[0048] Experimental method: three oilfield high-salt and high-alkalinity water-soluble trace element tracers described in the background technology are selected as control groups, recorded as control groups 1 to 3, and rare earth complex trace element tracers prepared in Examples 1 to 9 of the present invention are selected as experimental groups, recorded as experimental groups 1 to 9, and Yaodian Oilfield is selected as the experimental oil sample; the tracers of the control groups 1 to 3 and the experimental groups 1 to 9 are all prepared into 50 μg / L aqueous solutions, firstly, the oilfield is plugged, and chemical plugging agents are injected into the Yaodian Oilfield, and then the 12 groups of tracer aqueous solutions are respectively injected into the Yaodian Oilfield, and samples are taken every three days to monitor the tracer; once the tracer is detected, the sample is taken every two days until the tracer reaches a peak concentration; the peak concentration of the tracer and the number of days when the peak concentration occurs are recorded.

[0049] Table 2 Stability of tracers

[0050] project Initial concentration, μg / L Peak concentration, μg / L Days to peak concentration, d Control group 1 50μg / L 45.7 μg / L 47d Control group 2 50μg / L 45.5 μg / L 48d Control group 3 50μg / L 45.6 μg / L 47d Experimental Group 1 50μg / L 43.7 μg / L 54d Experimental Group 2 50μg / L 43.2 μg / L 55d Experimental Group 3 50μg / L 43.4 μg / L 54d Experimental Group 4 50μg / L 43.3 μg / L 53d Experimental Group 5 50μg / L 43.2 μg / L 54d Experimental Group 6 50μg / L 43.5 μg / L 55d Experimental Group 7 50μg / L 43.7 μg / L 53d Experimental Group 8 50μg / L 43.4 μg / L 54d Experimental Group 9 50μg / L 43.3 μg / L 55d

[0051] As can be seen from Table 2, after the water plugging operation is performed on the oil field, the rare earth complex trace element tracer prepared by the present invention has a longer number of days with a peak concentration and a lower peak concentration than the tracer of the control group, indicating that the rare earth complex trace element tracer prepared by the present invention can form a soluble complex with the crystal-forming ions in the oil well, thereby effectively preventing the formation of sediments in the oil well, that is, it has stronger stability and stronger complexing ability.

[0052] In summary, the rare earth complex trace element tracer prepared by the present invention has strong acid and alkali resistance and high temperature resistance, and can still be effective in a high temperature environment at 200°C. Moreover, compared with the control group tracer, the rare earth complex trace element tracer prepared by the present invention has higher stability and stronger complexing ability, and is more suitable for use in oil field exploitation.

[0053] The embodiments of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A rare earth complex trace element tracer for oil field development, characterized in that: The preparation method of the rare earth complex trace element tracer is as follows: S1: Prepare a complexing agent aqueous solution, dissolve the selected complexing agent in an appropriate amount of water and stir evenly to make it completely dissolved, so as to obtain a complexing agent aqueous solution; after preparation, the solution should be stored in a cool and dry place, away from direct sunlight to maintain its stability; S2: preparing a rare earth salt solution, dissolving a rare earth element powder in an appropriate amount of dilute acid to obtain a rare earth element ion solution; slowly adding sulfuric acid to the rare earth element ion solution, the rare earth element ions and sulfate ions combine to form a rare earth salt precipitate, extracting the rare earth salt precipitate with a suitable extractant, reacting at room temperature for one hour to obtain a rare earth salt solution, then evaporating and crystallizing the rare earth salt solution, drying and crushing to obtain a rare earth salt powder, dissolving the rare earth salt powder in an appropriate amount of water to obtain a rare earth salt solution; S3: synthesizing a tracer, adding the rare earth salt solution prepared in S2 to the complexing agent aqueous solution prepared in S1, the volume ratio of the rare earth salt solution to the complexing agent aqueous solution being 1:3, then placing the resulting mixed solution in a 90°C constant temperature water bath, stirring evenly, continuing the complexing reaction for 3 hours, crystallizing, crushing, and drying to obtain a rare earth complex trace element tracer.

2. A rare earth complex trace element tracer for oil field development as claimed in claim 1, characterized in that: In S1, the complexing agent is selected from any one of ethylenediaminetetramethylenephosphate sodium, diethylenetriaminepenta(methylenephosphonic acid) sodium, and aminotri(methylenephosphate) tetrasodium.

3. A rare earth complex trace element tracer for oil field development as claimed in claim 1, characterized in that: In S2, the rare earth element is selected from any one of dysprosium (Dy), cerium (Ce), and erbium (Er).

4. A rare earth complex trace element tracer for oil field development as claimed in claim 1, characterized in that: In S2, the dilute acid is dilute sulfuric acid.

5. A rare earth complex trace element tracer for oil field development as claimed in claim 1, characterized in that: In S2, the rare earth salt precipitate can be any one of dysprosium sulfate, cerium sulfate, and erbium sulfate, and the volume ratio of the extractant to the rare earth salt precipitate is 1:

2.

6. A rare earth complex trace element tracer for oil field development as claimed in claim 1 and claim 5, characterized in that: When the rare earth salt is precipitated as dysprosium sulfate, the extractant is 95% ethanol.

7. A rare earth complex trace element tracer for oil field development as claimed in claim 1 and claim 5, characterized in that: When the rare earth salt is precipitated as cerium sulfate, the extractant is toluene.

8. A rare earth complex trace element tracer for oil field development as claimed in claim 1 and claim 5, characterized in that: When the rare earth salt is precipitated as erbium sulfate, the extractant is P2O4.

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