Mud cake destroying type oil displacement flushing agent

Abstract

The invention belongs to the technical field of well cementation engineering, and relates to a mud cake destroying type oil displacement flushing agent. The flushing agent is prepared from the following substances in percentage by mass: 8 to 12 percent of lauryl sodium sulfate, 4 to 6 percent of an emulsifier, 0.375 to 2.5 percent of an emulsifying aid, 7.5 to 12.5 percent of a dissolving aid, 6.5 to 8.5 percent of a mud cake breaking agent, 0.5 to 1.0 percent of glass fiber and the balance of water, the emulsifying agent is a mixture of Tween 80 and OP-20; the emulsifying auxiliary agent is polyether L62; the dissolving auxiliary agent is an alcohol; the mud cake breaking agent is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na (Ethylene Diamine Tetraacetic Acid-2Na). Compared with the prior art, the mud cake destroying type oil displacement flushing agent has the advantages that the flushing efficiency is good, the corrosion efficiency is high, the raw materials are easy to obtain, the price is moderate, the effect of destroying a white oil-based drilling fluid mud cake is achieved, and the well cementation efficiency under the white oil-based drilling fluid environment can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of cementing engineering, in particular to a mud cake destroying type oil displacement flushing agent. Background Art

[0002] Surfactant-based oil-displacing flushing agents are widely used in oil fields, especially in cleaning oil stains, lubricants and equipment surfaces. However, in complex oil reservoirs or environments containing high molecular weight substances, their oil-displacing effects are not satisfactory. Especially in oil field environments with high viscosity, high salinity, or a large amount of impurities, the oil-displacing effect of surfactants is limited and is likely to have a certain impact on the environment and water quality.

[0003] With the increasing development and utilization of unconventional oil and gas resources, white oil-based drilling fluids are increasingly widely used in the field of oil drilling due to their better lubricity, thermal stability and rheological properties. However, during drilling, white oil-based drilling fluids are retained on the well wall, making it difficult to clean the well wall and casing, and forming a dense, oil-based mud cake with strong oiliness and hydrophobicity. Conventional water-based cleaning agents cannot directly play a role, and it is extremely difficult to remove during the cementing process, thereby reducing the bonding quality of the cement sheath and affecting the quality of the project. Summary of the invention

[0004] In view of the problems in the prior art, the present invention proposes a mud cake destroying oil displacement flushing agent. The flushing agent of the present invention has good flushing efficiency, high dissolution efficiency, and readily available raw materials at a moderate price.

[0005] The mud cake destroying oil displacement flushing agent of the present invention is composed of the following substances in percentage by mass: 8-12% sodium dodecyl sulfate; 4-6% emulsifier; 0.375-2.5% emulsifying aid; 7.5-12.5% ​​dissolving aid; 6.5-8.5% mud cake destroying agent; 0.5-1.0% glass fiber; and the rest is water.

[0006] The emulsifier is a mixture of Tween 80 and OP-20, with a mass ratio of Tween 80:OP-20 = 1:1.

[0007] The emulsifying aid is polyether L62.

[0008] The dissolving aid is alcohol, such as methanol and isopropanol.

[0009] The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na, with a mass ratio of sodium hydroxide: ammonium persulfate: EDTA-2Na = 1:2:1. Sodium hydroxide consumes asphaltene, ammonium persulfate oxidatively decomposes polymers, and EDTA-2Na chelates and removes insoluble solid phase weighting materials.

[0010] The length of the glass fiber used is 3 mm, and the flushing effect is improved by enhancing the mechanical cleaning ability of the flushing agent, improving its fluidity, improving high temperature resistance and increasing its structural stability.

[0011] The preparation method of the mud cake destroying oil displacement flushing agent is simple, and the steps are as follows: adding water into a reaction kettle, then adding a surfactant, an emulsifier, an emulsifying aid, a dissolving aid, a mud cake destroying agent, a mud cake destroying aid, and glass fiber weighed in proportion into the reaction kettle, and stirring fully to obtain the mud cake flushing agent.

[0012] Compared with the prior art, the mudcake-destroying oil-displacing flushing agent of the present invention has good flushing efficiency, high dissolution efficiency, readily available raw materials and a moderately priced flushing agent formula, which can achieve the effect of destroying the mudcake of white oil-based drilling fluid and improve the cementing efficiency in a white oil-based drilling fluid environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the appearance of the drum surface when it is not flushed; Figure 2 This is the appearance of the drum surface after flushing. DETAILED DESCRIPTION

[0014] Example 1 73.125 parts by weight of clean water are added into a reaction kettle, and then 8 parts by weight of sodium lauryl sulfate, 4 parts by weight of emulsifier, 0.375 parts by weight of polyether L62, 7.5 parts by weight of isopropanol, 6.5 parts by weight of mud cake destroyer, and 0.5 parts by weight of 3mm glass fiber are added in sequence, and the mixture is stirred sufficiently to obtain the mud cake flushing agent of the present invention, and the prepared mud cake is cleaned.

[0015] The emulsifier is a mixture of Tween 80 and OP-20, and the mass ratio is Tween 80:OP-20=1:1.

[0016] The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na; in terms of mass ratio, sodium hydroxide: ammonium persulfate: EDTA-2Na=1:2:1.

[0017] Example 2 65.5 parts by weight of clean water are added into a reaction kettle, and then 10 parts by weight of sodium dialkyl sulfate, 5 parts by weight of emulsifier, 1.25 parts by weight of polyether L62, 10 parts by weight of isopropanol, 7.5 parts by weight of mud cake destroyer, and 0.75 parts by weight of 3mm glass fiber are added in sequence, and the mixture is stirred sufficiently to obtain the mud cake flushing agent of the present invention, and the prepared mud cake is cleaned.

[0018] The emulsifier is a mixture of Tween 80 and OP-20, and the mass ratio is Tween 80:OP-20=1:1.

[0019] The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na; in terms of mass ratio, sodium hydroxide: ammonium persulfate: EDTA-2Na=1:2:1.

[0020] Example 3 57.5 parts by weight of clean water are added into a reaction kettle, and then 12 parts by weight of sodium lauryl sulfate, 6 parts by weight of emulsifier, 2.5 parts by weight of polyether L62, 12.5 parts by weight of isopropyl alcohol, 8.5 parts by weight of mud cake destroyer, and 1 part by weight of 3 mm glass fiber are added in sequence, and the mixture is stirred sufficiently to obtain the mud cake flushing agent of the present invention, and the prepared mud cake is cleaned.

[0021] The emulsifier is a mixture of Tween 80 and OP-20, and the mass ratio is Tween 80:OP-20=1:1.

[0022] The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na; in terms of mass ratio, sodium hydroxide: ammonium persulfate: EDTA-2Na=1:2:1.

[0023] Example 4 66 parts by weight of clean water are added into a reaction kettle, and then 10 parts by weight of sodium lauryl sulfate, 6 parts by weight of emulsifier, 1.25 parts by weight of polyether L62, 7.5 parts by weight of isopropanol, 8.5 parts by weight of mud cake destroyer, and 0.75 parts by weight of 3mm glass fiber are added in sequence, and the mixture is stirred sufficiently to obtain the mud cake flushing agent of the present invention, and the prepared mud cake is cleaned.

[0024] The emulsifier is a mixture of Tween 80 and OP-20, and the mass ratio is Tween 80:OP-20=1:1.

[0025] The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na; in terms of mass ratio, sodium hydroxide: ammonium persulfate: EDTA-2Na=1:2:1.

[0026] Example 5 65.25 parts by weight of clean water are added into a reaction kettle, and then 10 parts by weight of sodium lauryl sulfate, 5 parts by weight of emulsifier, 1.25 parts by weight of polyether L62, 10 parts by weight of isopropanol, 7.5 parts by weight of mud cake destroyer, and 1 part by weight of 3mm glass fiber are added in sequence, and the mixture is stirred sufficiently to obtain the mud cake flushing agent of the present invention, and the prepared mud cake is cleaned.

[0027] The emulsifier is a mixture of Tween 80 and OP-20, and the mass ratio is Tween 80:OP-20=1:1.

[0028] The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na; in terms of mass ratio, sodium hydroxide: ammonium persulfate: EDTA-2Na=1:2:1.

[0029] Comparative Example 1 70.25 parts by weight of clean water are added into a reaction kettle, and then 5 parts by weight of sodium lauryl sulfate, 5 parts by weight of emulsifier, 1.25 parts by weight of polyether L62, 10 parts by weight of isopropanol, 7.5 parts by weight of mud cake destroyer, and 1 part by weight of 3mm glass fiber are added in sequence, and the mixture is stirred sufficiently to obtain the mud cake flushing agent of the present invention, and the prepared mud cake is cleaned.

[0030] The emulsifier is a mixture of Tween 80 and OP-20, and the mass ratio is Tween 80:OP-20=1:1.

[0031] The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na; in terms of mass ratio, the sodium hydroxide, ammonium persulfate and EDTA-2Na are 1:2:1.

[0032] Comparative Example 2 67.75 parts by weight of clean water are added into a reaction kettle, and then 10 parts by weight of sodium lauryl sulfate, 5 parts by weight of emulsifier, 1.25 parts by weight of polyether L62, 10 parts by weight of isopropanol, 5 parts by weight of mud cake destroyer, and 1 part by weight of 3mm glass fiber are added in sequence, and the mixture is stirred sufficiently to obtain the mud cake flushing agent of the present invention, and the prepared mud cake is cleaned.

[0033] The emulsifier is a mixture of Tween 80 and OP-20, and the mass ratio is Tween 80:OP-20=1:1.

[0034] The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na; in terms of mass ratio, sodium hydroxide: ammonium persulfate: EDTA-2Na=1:2:1.

[0035] Experimental example Performance Testing Mud cake cleaning efficiency evaluation experiment: Mud cake preparation method: Use high temperature and high pressure water loss instrument and white oil-based drilling fluid to prepare oil-based mud cake. The steps are as follows: 1. Assembly: Put the rubber ring first, then the filter paper, then the filter screen, tighten the lower cover of the slurry barrel with a wrench, then put the rubber ring, and loosen the upper cover slightly to facilitate the subsequent pouring of drilling fluid; 2. Preheating: first heat to 90℃, pour in drilling fluid, about 3cm from the top, tighten the cover, and heat to 150℃. 3. Inspection: before ventilation, perform air tightness inspection, install the liquid collection cylinder, assemble the ventilation pipeline, and ensure that the vent valve is closed; 4. After heating, open the main valve of the gas tank and slowly increase the pressure, 4.5MPa at the top and 1MPa at the bottom. The pressure difference is 3.5MPa. Then loosen the upper water loss joint, pressurize the air inside, loosen the lower water loss joint to filter out, and start the timer for 10 minutes; 5. After the experiment, disassemble the instrument, remove the mud cake, clean and organize the experimental instrument.

[0036] Experimental method: Cut the prepared mud cake into 4 parts of similar size; weigh the clean cylinder and rubber band of the six-speed rotary viscometer and record it as M 1 ; Use a rubber band to tie the mud cake and filter paper to the wall of the rotating cylinder of the rotational viscometer, weigh the rotating cylinder, and record it as W 1 ; Prepare rinse agents with different components and different mass fractions; rinse the drum at room temperature at a speed of 300 r / min for 10 minutes; after rinsing, remove the drum, air dry it naturally for 5-10 minutes, and weigh the drum, which is recorded as W 2 ; After cleaning and drying the filter paper, weigh the filter paper and record it as M 2 Calculate the total mass of the clean drum, rubber band, and filter paper. M 1 + M 2 , denoted as W 0 ; The flushing efficiency η Calculate according to the following formula, and conduct three sets of parallel tests to obtain the average value. The error of parallel tests shall not exceed 5%; ; W 1 —Total weight of the drum, rubber band, filter paper and mud cake, in grams (g); W 2 —The weight of the drum and residual mud cake after flushing, in grams (g); M 1 —The weight of the clean six-speed viscometer bowl and rubber band, in grams (g); M 2 —The weight of the filter paper in grams (g).

[0037] The data in the embodiments and comparative examples are as follows: .

[0038] It can be seen from the table that the amount of mud cake destroyer added has a significant impact on the flushing efficiency; the mud cake flushing agent has a very good overall effect on the mud cake flushing, with an average flushing efficiency of more than 93%.

Claims

1. A mud cake destroying oil displacement flushing agent, characterized in that: The flushing agent is composed of the following substances in percentage by mass: 8-12% sodium dodecyl sulfate; 4-6% emulsifier; 0.375-2.5% emulsifying aid; 7.5-12.5% ​​dissolving aid; 6.5-8.5% mud cake destroyer; 0.5-1.0% glass fiber; and the rest is water; The emulsifier is a mixture of Tween 80 and OP-20; The emulsifying aid is polyether L62; The dissolution aid is alcohol; The mud cake destroyer is a mixture of sodium hydroxide, ammonium persulfate and EDTA-2Na.

2. The mud cake destroying oil displacement flushing agent according to claim 1, characterized in that: In terms of mass ratio, Tween 80:OP-20 = 1:

1.

3. The mud cake destroying oil displacement flushing agent according to claim 1, characterized in that: In terms of mass ratio, sodium hydroxide: ammonium persulfate: EDTA-2Na = 1:2:

1.

4. The mud cake destroying oil displacement flushing agent according to claim 1, characterized in that: The length of the glass fiber is 3 mm.

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