High-salt-tolerant foaming agent for foam drilling

Abstract

The application discloses a high-salt-resistant foaming agent, which can meet the requirements of drilling construction in complex strata by coping with harsh geological conditions in the process of foam drilling and multiple requirements of foam inhibition and foaming capacity. The foaming agent is composed of the following components in percentage by mass: 12-60wt% main foaming agent, 10-30wt% auxiliary foaming agent, and the balance of water. The main foaming agent is a betaine zwitterionic surfactant containing a polyether chain segment, and the auxiliary foaming agent is an amino propionic acid type zwitterionic surfactant. The foaming agent system prepared by the application has the advantages of temperature resistance of 140 DEG C, salt resistance of 360000mg / L NaCl, excellent foaming effect, good salt resistance and good inhibition effect on hydration of mud shale.

Description

Technical Field

[0001] This invention relates to a high-salt resistant foaming agent for foam drilling, specifically to high-salt upper formations with frequent interbedded sandstone and mudstone, low-pressure, low-permeability, and high-temperature formations, belonging to the field of oilfield drilling fluid treatment agents. Background Technology

[0002] Foam drilling is a drilling method that uses honeycomb foam fluid formed by mixing air or nitrogen with foaming agent base fluid as drilling fluid. Foam fluid has a lower density and smaller bottom hole clamping effect than conventional mud drilling fluid. It can not only effectively control drilling fluid circulation loss and improve mechanical drilling speed, but also reduce reservoir damage and protect low-pressure oil and gas reservoirs.

[0003] Currently, a large amount of research has been conducted on the basic theories of foam application in oil fields in China, especially in oil field drilling. There is a lot of research and application of foam, but there is relatively little research on high-efficiency high-salt resistant foam. Now, as oil fields enter the middle and late stages of oil production, the formation conditions are harsh, and the emergence of more and more high-salt formations has greatly limited the application of the already unstable foam. Existing foams can no longer meet the requirements of the field.

[0004] Betaine amphoteric surfactants containing polyether segments are a modified type of betaine amphoteric surfactant. The introduction of ethylene oxide or propylene oxide polyether segments makes the product milder, less irritating, and exhibits superior salt and acid / alkali resistance. Aminopropionic acid-type amphoteric surfactants also possess strong salt and acid / alkali resistance. Furthermore, due to their positive charge, they also have a certain inhibitory effect on clay hydration, effectively suppressing clay hydration and enhancing wellbore stability. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a high-salt-resistant foaming agent to meet the harsh geological conditions and multiple requirements for foam suppression and foaming ability during foam drilling.

[0006] This invention utilizes betaine-containing amphoteric surfactants containing polyether segments and aminopropionic acid-type amphoteric surfactants to provide a foaming agent resistant to high salt and acids and alkalis. It has foaming, inhibiting, high salt resistance, and acid and alkali resistance properties. The system has a simple composition and is easy to control and use.

[0007] This invention provides a high-salt resistant foaming agent for foam drilling, comprising the following components: 12-60 wt% main foaming agent, preferably 15-50 wt%; 10-30 wt% auxiliary foaming agent, preferably 10-20 wt%; and water as the balance.

[0008] The main foaming agent is a zwitterionic surfactant containing polyether segments and betaine.

[0009] The aforementioned foaming agent is an aminopropionic acid-type zwitterionic surfactant;

[0010] The aforementioned high-salt resistant foaming agent can withstand saturated NaCl solution;

[0011] The structure of the polyether-segment betaine zwitterionic surfactant is as follows:

[0012] or

[0013] or

[0014] R is selected from any one of straight-chain alkyl, branched alkyl, or cycloalkyl groups having 8-16 carbon atoms, preferably straight-chain alkyl groups having 8-12 carbon atoms. x=1~4, m=1~3, n=1~2, preferably x=3~4, m=2~3, n=1~2;

[0015] The structure of the aminopropionic acid-type zwitterionic surfactant is as follows:

[0016]

[0017] R is selected from any one of straight-chain alkyl, branched alkyl or cycloalkyl with 8-18 carbon atoms, preferably a straight-chain alkyl with 10-14 carbon atoms.

[0018] The preparation method of the present invention is simple: the main foaming agent and the auxiliary foaming agent are dissolved in water separately and then mixed together.

[0019] The main application field of this invention is oilfield drilling. It is suitable for formations with frequent interbedded sandstone and mudstone in the upper formation with high salt content, high hardness, strong abrasiveness and poor drillability, as well as low-pressure formations with poor wellbore stability.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The foaming agent of the present invention is resistant to saturated NaCl solution and has good foaming effect and good foam stability. Compared with the prior art, it provides a foaming agent for drilling that is resistant to high salt and has excellent comprehensive performance, and can maintain good foam performance under complex formation conditions.

[0022] (2) The foaming agent used in this invention has a certain cationicity, which has a certain inhibitory effect on the hydration of rock cuttings, and significantly improves the rolling recovery rate of rock cuttings compared with clear water.

[0023] (3) The foaming agent system of the present invention has a simple composition, is easy to prepare, has comprehensive functions, and is also non-toxic and harmless to the environment.

[0024] This invention is a treatment agent for oilfield drilling, suitable for formations involving frequent interbedded sandstone and mudstone layers in high-salt upper formations, and low-pressure, low-permeability formations.

[0025] The foaming agent system prepared by this invention is resistant to saturated NaCl solution, exhibits good foaming effect, and has a strong inhibitory effect on shale hydration. Compared with the prior art, this invention provides a foaming agent for drilling that is resistant to high salt and has excellent comprehensive performance, maintaining good foaming performance under complex formation conditions. Detailed Implementation

[0026] Example 1

[0027] Weigh 30g of betaine zwitterionic surfactant containing polyether segments (containing EO chains, R=C). 12 H 25 Slowly add the straight-chain alkyl group (x=3) to 25g of water and stir until completely dissolved; weigh out 20g of aminopropionic acid type zwitterionic surfactant (R=C 12 H 25 Slowly add the straight-chain alkyl group to 25g of water and stir until completely dissolved. Finally, mix the two solutions and stir evenly to obtain foaming agent 1.

[0028] Example 2

[0029] Weigh 25g of betaine zwitterionic surfactant containing polyether segments (containing EO chains, R=C). 10 H 21 Slowly add the straight-chain alkyl group (x=3) to 30g of water and stir until completely dissolved; weigh 15g of aminopropionic acid-type zwitterionic surfactant (R=C 12 H 25 Slowly add the straight-chain alkyl group to 30g of water and stir until completely dissolved. Finally, mix the two solutions and stir evenly to obtain foaming agent 2.

[0030] Example 3

[0031] Weigh 40g of betaine zwitterionic surfactant containing polyether segments (containing EO chains, R=C). 12 H 25 The straight-chain alkyl group (x=3) is slowly added to 25g of water and stirred until completely dissolved; 10g of aminopropionic acid-type zwitterionic surfactant (R=C) is weighed out. 14 H 29 Slowly add the straight-chain alkyl group to 25g of water and stir until completely dissolved. Finally, mix the two solutions and stir evenly to obtain foaming agent 3.

[0032] Example 4

[0033] Weigh 50g of betaine zwitterionic surfactant containing polyether segments (containing EO chain, R=C8H). 17 Slowly add the straight-chain alkyl group (x=4) to 20g of water and stir until completely dissolved; weigh out 10g of aminopropionic acid type zwitterionic surfactant (R=C 12 H 25 Slowly add the straight-chain alkyl group to 20g of water and stir until completely dissolved. Finally, mix the two solutions and stir evenly to obtain foaming agent 4.

[0034] Example 5

[0035] Weigh 15g of betaine zwitterionic surfactant containing polyether segments (containing EO chains, R=C). 10 H 21 Slowly add the straight-chain alkyl group (x=4) to 35g of water and stir until completely dissolved; weigh out 15g of aminopropionic acid-type zwitterionic surfactant (R=C 12 H 25 Slowly add the straight-chain alkyl group to 35g of water and stir until completely dissolved. Finally, mix the two solutions and stir evenly to obtain foaming agent 5.

[0036] Example 6

[0037] Weigh 20g of betaine zwitterionic surfactant containing polyether segments (containing EO chain, R=C8H). 17 Slowly add the straight-chain alkyl group (x=4) to 35g of water and stir until completely dissolved; weigh 10g of aminopropionic acid-type zwitterionic surfactant (R=C 10 H 21 Slowly add the straight-chain alkyl group to 35g of water and stir until completely dissolved. Finally, mix the two solutions and stir evenly to obtain foaming agent 6.

[0038] Example 7

[0039] Weigh 35g of betaine zwitterionic surfactant containing polyether segments (containing EO chain, R=C8H). 17 Slowly add the straight-chain alkyl group (x=3) to 25g of water and stir until completely dissolved; weigh out 15g of aminopropionic acid-type zwitterionic surfactant (R=C 14 H 29 Slowly add the straight-chain alkyl group to 25g of water and stir until completely dissolved. Finally, mix the two solutions and stir evenly to obtain foaming agent 7.

[0040] Test Example 1

[0041] Weigh 0.5g of the above foaming agent and add it to simulated water with a mineralization of 360,000 mg / L NaCl. The foaming performance is then tested using the high-speed stirring method.

[0042] Test Example 2

[0043] Weigh 1.5g of the above foaming agent and add it to 300g of water. After hot rolling at 140℃ for 16 hours, cool to room temperature and test the foam performance using the high-speed stirring method.

[0044] Test Example 3

[0045] Weigh 1.5g of the above foaming agent, add it to 300g of clean water, then add 20g of rock chips, heat and roll at 140℃ for 16h, filter the rock chips, dry and weigh them, and measure its ability to inhibit rock chip hydration.

[0046] Comparative Example 1

[0047] A foaming agent FP-1 commonly used in foam drilling by a certain drilling company was used. The foaming performance and the ability to inhibit cuttings hydration were measured before and after high temperature, and compared with the present invention, referring to the methods of test examples 1, 2 and 3.

[0048] The specific test data is as follows.

[0049] Table 1 Foam Performance

[0050]

[0051] Table 2. Suppression of Shale Hydration Properties

[0052] sample Rock cuttings rolling recovery rate / % Water Comparison 13.2 Foaming System 1 27.8 Foaming System 2 26.9 Foaming System 3 21.5 Foaming system 4 24.6 Foaming system 5 31.4 Foaming system 6 29.7 Foaming System 7 28.1 Comparative Example 1 15.8

[0053] As can be seen from the test data of Examples 1-7 and Comparative Example 1 in Tables 1-2 above, the cationic foaming system of the present invention still has excellent foaming performance under high temperature and high salt conditions, exhibiting excellent temperature resistance (140℃) and salt resistance (360000 mg / L NaCl), significantly improving the rolling recovery rate of rock cuttings relative to clear water, and its performance in all aspects is superior to commercially available foaming agents.

[0054] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. Similarly, in this application, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0055] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A high-salt-resistant foaming agent for foam drilling, characterized in that, This foaming agent system contains the following components: Main foaming agent 12-60wt% Foaming agent 10-30 wt% Water balance; The main foaming agent is a zwitterionic surfactant containing polyether segments and betaine. The aforementioned foaming agent is an aminopropionic acid-type zwitterionic surfactant; The structure of the polyether-segment betaine zwitterionic surfactant is as follows: or or R is selected from any one of straight-chain alkyl, branched alkyl or cycloalkyl with 8-16 carbon atoms, x=1-4, m=1-3, n=1-2; The structure of the aminopropionic acid-type zwitterionic surfactant is as follows: R can be any one of straight-chain alkyl, branched alkyl, or cycloalkyl having 8-18 carbon atoms.

2. The high-salt-resistant foaming agent for foam drilling as described in claim 1, characterized in that, The main foaming agent component is 15-50 wt%.

3. The high-salt-resistant foaming agent for foam drilling as described in claim 1, characterized in that, The foaming agent component is 10-20 wt%.

4. The high-salt-resistant foaming agent for foam drilling as described in claim 1, characterized in that, The structure of the polyether-segment betaine zwitterionic surfactant is as follows: R is selected from straight-chain alkyl groups with 8-12 carbon atoms, x=3-4, m=2-3, n=1-2.

5. The high-salt-resistant foaming agent for foam drilling as described in claim 1, characterized in that, The aminopropionic acid type zwitterionic surfactant: R is selected from straight-chain alkyl groups having 10-14 carbon atoms.

6. The high-salt-resistant foaming agent for foam drilling as described in any one of claims 1-5, characterized in that, The high-salt resistant foaming agent can withstand saturated NaCl solution.

7. The method for preparing the high-salt-resistant foaming agent for foam drilling as described in any one of claims 1-6, characterized in that, Dissolve the main foaming agent and auxiliary foaming agent separately in water, and then mix and stir them evenly to obtain the final product.

8. The application of the high-salt-resistant foaming agent for foam drilling as described in any one of claims 1-6, characterized in that... Used in oilfield drilling, it is suitable for formations with frequent interbedded sandstone and mudstone layers in the upper strata, high salt content, high hardness, strong abrasiveness, and poor drillability, as well as low-pressure formations with poor wellbore stability.

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