Oil well bore colloid plugging dissolving agent and preparation method thereof

Abstract

The present invention relates to the technical field of oilfield chemistry, and is a dissolving agent for colloid blockages in oil well bores and a preparation method thereof, wherein the raw materials of the former include, by mass percentage, 45% to 60% of a main agent, 10% to 20% of a penetrant, 1% to 5% of EVA, 5% to 10% of a surfactant, and 10% to 15% of a mutual solvent; wherein the main agent is a mixture of dipentene, petroleum ether, and straight-chain alkanes. The present invention provides a dissolving agent for colloid blockages in oil well bores with dipentene, petroleum ether, and straight-chain alkanes as main dissolving agents, which can effectively remove high-content colloid blockages in the bores, and achieve the purpose of efficiently and thoroughly removing mixed blockages in the bores, and the preparation method thereof is convenient to manufacture and operate, and is convenient for production and on-site promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, and is an oil wellbore colloid plugging material dissolving agent and a preparation method thereof. Background Art

[0002] At present, with the continuous in-depth development of oil fields, in order to maintain formation pressure and replenish formation energy, most oil reservoir blocks have entered the middle and late stages of water injection development. With the changes in the formation properties and fluid properties of the oil reservoir, various problems that affect the normal production of oil wells have come one after another. The blockage of organic matter in the wellbore and pipeline of the oil well is one of the very difficult problems, which causes the oil well pump rod to break, pump leakage, pump jam, etc., which seriously affect the normal production of the oil well. At present, the conventional treatment methods for organic blockages in wellbore and pipeline are mainly hot washing wax removal, chemical wax dissolution and wax prevention, downhole tool wax prevention, etc. However, through sampling and analysis, it is found that in addition to the short-chain wax components, the organic blockages in the wellbore of the oil well also contain long-chain colloid and asphaltene components. The colloid and asphaltene components in these blockages cannot be effectively and thoroughly removed by the existing conventional wax removal and wax prevention methods, resulting in the phenomenon of lying wells caused by wellbore blockage even after the oil well implements wax removal measures, which greatly reduces the production time of the oil well, affects the oil well output, and increases the cost of well repair measures. For example, the oil wells in Luliang Operation Area of ​​Xinjiang Oilfield have been found to have high annual well repair costs in recent years. After multiple attempts to optimize the wax removal method and increase daily maintenance costs, the wax sticking rate of the oil wells in the block is 8%, which is still 6 to 7 percentage points higher than other blocks, and the well repair costs show a significant increase every year. According to research and analysis, there are three main reasons. First, the wax content of crude oil in this well area is 13%, and the average wax precipitation point is 28°C, which is easier to wax and the wax deposition depth is deeper than other blocks; second, the wax melting point of this well area is high, and the average wax melting point is higher than 85°C. It is difficult for the hot wellbore to reach the wax melting point; third, through chemical analysis, the colloid content of the wellbore blockage in this block accounts for 45.4% (wax, colloid, and asphaltene account for 76.2% of the blockage), which makes it difficult for the single wax removal and prevention method in this block to have a significant effect.

[0003] In summary, there is an urgent need to develop chemical products that can dissolve the colloidal components in the blockages in order to safely and efficiently remove the blockages in the wellbore and pipelines, reduce the number of wax-stuck wells in the block, and increase the production rate of oil wells. Summary of the invention

[0004] The present invention provides an oil well bore colloid blockage dissolving agent, which overcomes the above-mentioned deficiencies of the prior art and can effectively solve the problem that the existing single wax removal and prevention treatment method is difficult to remove the oil well bore colloid blockage.

[0005] One of the technical solutions of the present invention is achieved through the following measures: an oil well bore colloid blockage dissolving agent, the raw materials include, by mass percentage, 45% to 60% of a main agent, 10% to 20% of a penetrant, 1% to 5% of EVA (ethylene-vinyl acetate copolymer), 5% to 10% of a surfactant, and 10% to 15% of a mutual solvent; wherein the main agent is a mixture of dipentene, petroleum ether and straight-chain alkanes.

[0006] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions:

[0007] The straight-chain alkane is a C5 to C8 straight-chain alkane, and the mass ratio of dipentene, petroleum ether and straight-chain alkane in the main agent is 2 to 4:1 to 3:1.

[0008] The straight-chain alkane is n-heptane, and the mass ratio of dipentene, petroleum ether and straight-chain alkane in the main agent is 3:2:1.

[0009] The above-mentioned penetrant is one or two of fatty alcohol polyoxyethylene ether and dioctyl sodium sulfosuccinate.

[0010] The mutual solvent is one or both of methanol and ethylene glycol.

[0011] The above surfactant is oleic acid diethanolamide.

[0012] The above-mentioned oil well bore colloid plugging agent is prepared by the following method:

[0013] The first step is to uniformly mix the required amount of dipentene, petroleum ether and straight-chain alkane to obtain a main agent;

[0014] The second step is to add the required amount of EVA to the main agent, stir and dissolve evenly to obtain a mixed solution;

[0015] The third step is to add the required amount of penetrant, surfactant and mutual solvent to the mixed solution obtained in the second step in sequence, and stir evenly to obtain the oil wellbore colloid plugging agent.

[0016] In the first step, the mixing time is 15 min to 25 min, and the mixing temperature is controlled between 15° C. and 30° C.

[0017] In the second step, the stirring is performed at 45° C. to 60° C. for 75 min to 90 min.

[0018] In the third step, the stirring temperature is 30°C to 35°C, and the stirring speed is 30r / min to 45r / min.

[0019] The second technical solution of the present invention is achieved by the following measures: a method for preparing a dissolving agent for colloid blockage in oil well bore, which is carried out according to the following steps:

[0020] The first step is to uniformly mix the required amount of dipentene, petroleum ether and straight-chain alkane to obtain a main agent;

[0021] The second step is to add the required amount of EVA to the main agent, stir and dissolve evenly to obtain a mixed solution;

[0022] The third step is to add the required amount of penetrant, surfactant and mutual solvent to the mixed solution obtained in the second step in sequence, and stir evenly to obtain the oil wellbore colloid plugging agent.

[0023] In view of the problem that the existing single wax removal and prevention method is difficult to remove colloid blockages in oil well bores, the present invention provides an oil well bore colloid blockage dissolving agent with dipentene, petroleum ether and straight-chain alkanes as main dissolving agents, which can effectively remove high-colloid blockages in the borehole and achieve the purpose of efficiently and thoroughly removing mixed blockages in the borehole. The preparation method is convenient to manufacture and operate, and is convenient for production and on-site promotion and application. DETAILED DESCRIPTION

[0024] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; the normal temperature and room temperature in the present invention generally refer to the temperature of 15°C to 25°C, and are generally defined as 25°C.

[0025] The present invention will be further described below in conjunction with embodiments:

[0026] Example 1: The oil well bore colloid blockage dissolving agent comprises, by mass percentage, 45% to 60% of a main agent, 10% to 20% of a penetrant, 1% to 5% of EVA, 5% to 10% of a surfactant, and 10% to 15% of a mutual solvent; wherein the main agent is a mixture of dipentene, petroleum ether, and straight-chain alkanes.

[0027] According to the component determination, the colloid content in the blockage is as high as 45.4%, so in the present invention, dipentene, petroleum ether and straight-chain alkane are selected as the main agent in the oil well bore colloid blockage dissolving agent to effectively dissolve the colloid component. At the same time, the EVA in the raw material can increase the function of preventing the colloid in the crude oil from precipitating.

[0028] Example 2: As an optimization of the above example, the straight-chain alkane is a C5 to C8 straight-chain alkane, and the mass ratio of dipentene, petroleum ether and straight-chain alkane in the main agent is 2 to 4:1 to 3:1.

[0029] Example 3: As an optimization of the above example, the straight-chain alkane is n-heptane, and the mass ratio of dipentene, petroleum ether and straight-chain alkane in the main agent is 3:2:1.

[0030] Example 4: As an optimization of the above example, the penetrant is one or two of fatty alcohol polyoxyethylene ether and dioctyl sodium sulfosuccinate. In view of the denseness of the wellbore blockage, in order to ensure that the dissolving agent can quickly penetrate the blockage under a relatively low temperature (less than 28°C), fatty alcohol polyoxyethylene ether and dioctyl sodium sulfosuccinate are selected as penetrants in the present invention, which can play a synergistic role with the main agent and greatly increase the colloid dissolution rate.

[0031] Example 5: As an optimization of the above example, the mutual solvent is one or both of methanol and ethylene glycol.

[0032] Example 6: As an optimization of the above example, the surfactant is oleic acid diethanolamide.

[0033] Example 7: As an optimization of the above example, the oil well bore colloid plugging agent is prepared by the following method:

[0034] The first step is to uniformly mix the required amount of dipentene, petroleum ether and straight-chain alkane to obtain a main agent;

[0035] The second step is to add the required amount of EVA to the main agent, stir and dissolve evenly to obtain a mixed solution;

[0036] The third step is to add the required amount of penetrant, surfactant and mutual solvent to the mixed solution obtained in the second step in sequence, and stir evenly to obtain the oil wellbore colloid plugging agent.

[0037] Example 8: As an optimization of the above example, in the first step, the mixing time is 15 min to 25 min, and the mixing temperature is controlled between 15°C and 30°C.

[0038] Example 9: As an optimization of the above example, in the second step, stirring is performed at 45°C to 60°C for 75 min to 90 min.

[0039] Example 10: As an optimization of the above example, in the third step, the stirring temperature is 30°C to 35°C, and the stirring speed is 30r / min to 45r / min.

[0040] Example 11: The oil well bore colloid plugging dissolving agent, the raw materials by weight percentage include 60% main agent, 15% penetrant, 1% EVA, 9% surfactant, 15% mutual solvent, and is obtained by the following method: First, add the required amount of dipentene, petroleum ether, and n-heptane to the reactor at room temperature in proportion, mix evenly, and stir for 15 minutes. Then add the required amount of EVA to the reactor, control the temperature at 50°C, and stir for 75 minutes. Finally, add the required amount of penetrant to the reactor, stir at 30°C for 10 minutes, and then add the surfactant and mutual solvent to obtain the oil well bore colloid plugging dissolving agent.

[0041] In this embodiment, the main agent is a mixture of dipentene, petroleum ether and n-heptane in a mass ratio of 3:2:1, the penetrant is fatty alcohol polyoxyethylene ether, the mutual solvent is methanol, and the surfactant is oleic acid diethanolamide.

[0042] Example 12: The oil well bore colloid plugging agent dissolving agent, the raw materials by weight percentage include 55% main agent, 20% penetrant, 2% EVA, 8% surfactant, 15% mutual solvent, obtained by the following method: First, add the required amount of dipentene, petroleum ether, and n-heptane to the reactor at room temperature in proportion, mix evenly, and stir for 20 minutes. Then add the required amount of EVA to the reactor, control the temperature at 55°C, and stir for 80 minutes. Finally, add the required amount of penetrant to the reactor, stir at 30°C for 10 minutes, and then add the surfactant and mutual solvent to the reactor to obtain the oil well bore colloid plugging agent dissolving agent.

[0043] In this embodiment, the main agent is a mixture of dipentene, petroleum ether and n-heptane in a mass ratio of 3:2:1, the penetrant is dioctyl sodium sulfosuccinate, the mutual solvent is methanol, and the surfactant is oleic acid diethanolamide.

[0044] Example 13: The oil well bore colloid plugging dissolving agent, the raw materials include 50% main agent, 20% penetrant, 5% EVA, 10% surfactant, 15% mutual solvent by weight percentage, and is obtained by the following method: First, add the required amount of dipentene, petroleum ether, and n-heptane in a reactor at room temperature in proportion and mix them evenly, and stir for 20 minutes. Then add the required amount of EVA to the reactor, control the temperature at 55°C, and stir for 90 minutes. Finally, add the required amount of penetrant to the reactor, stir at 30°C for 10 minutes, and then add the surfactant and mutual solvent to the reactor to obtain the oil well bore colloid plugging dissolving agent.

[0045] In this embodiment, the main agent is a mixture of dipentene, petroleum ether and n-heptane in a mass ratio of 3:2:1, the penetrant is a mixture of fatty alcohol polyoxyethylene ether and dioctyl sodium sulfosuccinate, the mutual solvent is ethanol, and the surfactant is oleic acid diethanolamide.

[0046] Comparative Example 1: The difference from Example 11 is that no penetrant is added.

[0047] Comparative Example 2: Commercially available mixed benzene type chemical wax remover.

[0048] The oil well bore colloid plugging dissolving agent prepared in Example 11 of the present invention and the dissolving agent prepared in Comparative Example 1 were used to dissolve the plugging material collected on site in the LU2175 well, and the experimental results are shown in Table 1. As can be seen from Table 1, the dissolving agent in Comparative Example 1 without adding a penetrant has a lower dissolving amount of the plugging material than the oil well bore colloid plugging dissolving agent in Example 11 at 45°C and 25°C.

[0049] At present, there is no evaluation standard for oil well bore colloid blockage dissolving agent. The present invention adopts the following experiment to test the solubility of the oil well bore colloid blockage dissolving agent, and adopts the commercially available mixed benzene type chemical paraffin removal agent (Comparative Example 2) to compare the effect.

[0050] ① Take three portions of 15 mL of the oil well bore colloid plug dissolving agent prepared in Example 13 and the chemical paraffin remover of Comparative Example 2, and place them in a 45°C constant temperature water bath. ② Weigh 6 portions of about 1 g of well bore colloid plugs respectively, and add them to the oil well bore colloid plug dissolving agent and paraffin remover. ③ After fully dissolving for 2 hours, filter and dry at 90°C for 2 hours, and weigh to calculate the dissolution efficiency. The experimental results are shown in Table 2.

[0051] It can be seen from Table 2 that the oil well bore colloid blockage dissolving agent of the present invention has an average dissolving efficiency of 74.58% for organic blockages in the borehole, which is much higher than the average value of 24.82% for dissolving blockages by chemical wax removers currently used in the block, and has a relatively good effect on dissolving blockages in the boreholes of different wells, and the effect is universal.

[0052] The oil well bore colloid plugging dissolving agent prepared in Example 13 of the present invention was used to perform periodic chemical removal of bore bore plugging in three wells (LU2115, LUHW1431, and LU2123) selected on site. The single dosing amount on site was 400 kg, the dosing cycle was 30 days, and the auxiliary dosing pump truck implemented intermittent dosing. After the periodic dosing, no well bore plugging and rod sticking occurred, and the average pump inspection cycle of the three wells was extended by 105 days, achieving good results.

[0053] In summary, the present invention provides an oil well bore colloid blockage dissolving agent and a preparation method thereof, which makes up for the shortcoming of the existing wax removal agent that only dissolves wax. For well bore blockages with high colloid content, the colloid can be dissolved well, thereby efficiently and thoroughly removing the mixed blockages in the well bore.

[0054] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

[0055]

Claims

1. A dissolving agent for colloid blockage in oil wells, characterized in that The raw materials include, by mass percentage, 45% to 60% of a main agent, 10% to 20% of a penetrant, 1% to 5% of EVA, 5% to 10% of a surfactant, and 10% to 15% of a mutual solvent; wherein the main agent is a mixture of dipentene, petroleum ether and straight-chain alkanes, the straight-chain alkanes are straight-chain alkanes of C5 to C8, the mass ratio of dipentene, petroleum ether to straight-chain alkanes in the main agent is 2-4:1-3:1, the penetrant is one or two of fatty alcohol polyoxyethylene ether and dioctyl sodium sulfosuccinate, the mutual solvent is one or two of methanol and ethylene glycol, and the surfactant is oleic acid diethanolamide.

2. The oil well bore colloid plugging dissolving agent according to claim 1, characterized in that The straight-chain alkane is n-heptane, and the mass ratio of dipentene, petroleum ether and straight-chain alkane in the main agent is 3:2:

1.

3. The oil well bore colloid plugging dissolving agent according to claim 1, characterized in that Prepared as follows: The first step is to uniformly mix the required amount of dipentene, petroleum ether and straight-chain alkane to obtain a main agent; The second step is to add the required amount of EVA to the main agent, stir and dissolve evenly to obtain a mixed solution; The third step is to add the required amount of penetrant, surfactant and mutual solvent to the mixed solution obtained in the second step in sequence, and stir evenly to obtain the oil wellbore colloid plugging agent.

4. The oil well bore colloid plugging dissolving agent according to claim 3, characterized in that In the first step, the mixing time is 15 min to 25 min, and the mixing temperature is controlled between 15° C. and 30° C.

5. The oil well bore colloid plugging dissolving agent according to claim 3 or 4, characterized in that In the second step, stirring is performed at 45°C to 60°C for 75 min to 90 min; or / and, in the third step, the stirring temperature is 30°C to 35°C, and the stirring speed is 30 r / min to 45 r / min.

6. A method for preparing the oil well bore colloid plugging dissolving agent according to claim 1, characterized in that Follow these steps: The first step is to uniformly mix the required amount of dipentene, petroleum ether and straight-chain alkane to obtain a main agent; The second step is to add the required amount of EVA to the main agent, stir and dissolve evenly to obtain a mixed solution; The third step is to add the required amount of penetrant, surfactant and mutual solvent to the mixed solution obtained in the second step in sequence, and stir evenly to obtain the oil wellbore colloid plugging agent.

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