Thick oil viscosity reducer, preparation method and use method thereof
Technical Field
The invention relates to the technical field of petroleum exploitation, in particular to a thick oil viscosity reducer, a preparation method and a use method thereof.
Background
With the decrease of the conventional crude oil and the progress of the oil exploitation technology, the efficient development of the thick oil has more and more obvious significance. Heavy oil is a kind of crude oil with high asphaltene and colloid content and high viscosity, and the crude oil with relative density more than 0.92(20 ℃) and underground viscosity more than 50mPa.s is generally called the heavy oil. The viscosity reduction of the thick oil is a necessary link in the development process because the thick oil contains more colloids, asphaltenes, waxes and the like, so that the viscosity of the thick oil is high, the mobility of the thick oil in a reservoir stratum, a shaft and the like is poor, and the development is difficult.
The existing viscosity reduction method for thick oil comprises the following steps: thermal viscosity reduction, dilution viscosity reduction and chemical viscosity reduction of thick oil or combination of the methods. The oil recovery cost of the thermal viscosity reduction and the dilution and viscosity reduction of the heavy oil is high, especially the oil recovery cost of an abnormal low-temperature stratum (such as the depth of a heavy oil reservoir is 2000m, and the temperature of the stratum is only 65 ℃) is high, and the requirement of the oil field on the low-cost and high-efficiency development of the heavy oil is difficult to meet. The chemical viscosity reduction is to reduce the viscosity of an oil-water mixture by using a viscosity reducer, so that the thick oil can smoothly flow in a stratum, a shaft or a transportation pipeline, and the chemical viscosity reduction is a main viscosity reduction mode.
Viscosity reducers are classified into water-soluble viscosity reducers and oil-soluble viscosity reducers according to solubility, and can be classified into anionic viscosity reducers and nonionic viscosity reducers according to main components. However, the existing viscosity reducer has poor viscosity reducing effect or higher cost, and is difficult to have the viscosity reducing effect and meet the requirement of low cost.
Disclosure of Invention
In view of the above, the present invention aims to provide a viscosity reducer for thick oil, a preparation method and a use method thereof. The thick oil viscosity reducer provided by the invention can effectively reduce the viscosity of thick oil and has lower cost.
The invention provides a thick oil viscosity reducer which comprises the following components in percentage by mass:
preferably, the alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate.
Preferably, the polyoxyethylene alkylphenol ether is polyoxyethylene octyl phenol ether and/or polyoxyethylene nonyl phenol ether.
Preferably, the polyoxyethylene sorbitan fatty acid ester is tween 80 and/or tween 60.
Preferably, the sodium alkyl benzene sulfonate is sodium dodecyl benzene sulfonate.
Preferably, the water comprises industrial water and/or formation water.
The invention also provides a preparation method of the thick oil viscosity reducer in the technical scheme, which comprises the following steps:
mixing polyoxyethylene alkylphenol ether, polyoxyethylene sorbitan fatty acid ester, sodium alkyl benzene sulfonate, alkaline substance and water to obtain the thick oil viscosity reducer.
Preferably, the mixing speed is 200-600 r/min, and the mixing time is 5-30 min.
The invention also provides a use method of the thick oil viscosity reducer, which comprises the following steps:
mixing the thick oil viscosity reducer with the thick oil to carry out viscosity reduction reaction;
the thick oil viscosity reducer is the thick oil viscosity reducer in the technical scheme or the thick oil viscosity reducer prepared by the preparation method in the technical scheme.
Preferably, the mass ratio of the dosage of the thick oil viscosity reducer to the total amount of the thick oil viscosity reducer and the thick oil is more than or equal to 25%.
The invention provides a thick oil viscosity reducer, which comprises: 0.2 to 2 percent of polyoxyethylene alkylphenol ether; 0.1 to 1.5 percent of polyoxyethylene sorbitan fatty acid ester; 0.2 to 5 percent of sodium alkyl benzene sulfonate; 0.1 to 1.5 percent of alkaline substance; the balance of water. In the thick oil viscosity reducer provided by the invention, an alkaline substance reacts with petroleum acid carried by thick oil to form specific surface activity, and the specific surface activity and other three surfactants in the viscosity reducer act synergistically to play a plurality of viscosity reducing effects such as emulsification viscosity reduction, adsorption viscosity reduction, demulsification viscosity reduction in an oil pipeline and the like in a stratum and a shaft, so that the viscosity of the thick oil is effectively reduced, and the fluidity of the thick oil is improved; the viscosity reducer component can be adsorbed on the inner wall of a rock pore and the pipe wall to form a hydrophilic film, so that the flowing friction of the thickened oil is reduced, and the fluidity of the thickened oil is improved. In addition, in the viscosity reducer, the alkaline substance reacts with petroleum acid carried by the thickened oil to generate the surfactant, so that the dosage of the surfactant can be reduced, and the cost is reduced.
Test results show that the viscosity reducer can reduce the viscosity of Xinjiang thick oil from 11600mPa.s to below 620mPa.s, and the viscosity reduction rate reaches more than 94%.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a graph showing the effect of viscosity reduction rate at different water contents;
FIG. 2 is a graph showing the effect of viscosity at different water contents.
Detailed Description
The invention provides a thick oil viscosity reducer which comprises the following components in percentage by mass:
in the thick oil viscosity reducer provided by the invention, an alkaline substance reacts with petroleum acid carried by thick oil to form specific surface activity, and the specific surface activity and other three surfactants in the viscosity reducer act synergistically to play a plurality of viscosity reducing effects such as emulsification viscosity reduction, adsorption viscosity reduction, demulsification viscosity reduction in an oil pipeline and the like in a stratum and a shaft, so that the viscosity of the thick oil is effectively reduced, and the fluidity of the thick oil is improved; the viscosity reducer component can be adsorbed on rocks and pipe walls to form a hydrophilic film, so that the flow friction of the thickened oil is reduced, and the fluidity of the thickened oil is improved. Moreover, the viscosity reducer provided by the invention has excellent temperature resistance, and still shows a stable viscosity reduction effect at higher and lower temperatures. In addition, in the viscosity reducer, alkaline substances react with petroleum acid carried by the thickened oil to generate a specific emulsion, the thickened oil in the stratum can be emulsified into a tiny emulsion and carried to pore throats, the dosage of the surfactant can be reduced, and the cost is reduced.
In the present invention, the polyoxyethylene alkylphenol ether is preferably polyoxyethylene octyl phenol ether and/or polyoxyethylene nonyl phenol ether. More preferably polyoxyethylene octylphenol ether. In the present invention, the source of the polyoxyethylene alkylphenol ether is not particularly limited, and may be any commercially available product.
In the invention, the mass ratio of the polyoxyethylene alkylphenol ether in the thick oil viscosity reducer is 0.2-2%; in some embodiments of the invention, the mass ratio of the polyoxyethylene alkylphenol ether in the thick oil viscosity reducer is 0.3%, 0.5%, 0.8% or 1%.
In the present invention, the polyoxyethylene sorbitan fatty acid ester is preferably tween 80 and/or tween 60; more preferably tween 80. In the present invention, the source of the polyoxyethylene sorbitan fatty acid ester is not particularly limited, and may be a commercially available product.
In the invention, the mass ratio of the polyoxyethylene sorbitan fatty acid ester in the thick oil viscosity reducer is 0.1-1.5%; in some embodiments of the invention, the mass ratio of the polyoxyethylene sorbitan fatty acid ester in the thick oil viscosity reducer is 0.1%, 0.3%, or 0.5%.
In the present invention, the sodium alkylbenzenesulfonate is preferably sodium dodecylbenzenesulfonate. In the present invention, the source of the sodium alkylbenzenesulfonate is not particularly limited, and may be a commercially available product.
In the invention, the mass ratio of the sodium alkyl benzene sulfonate in the thick oil viscosity reducer is 0.2-5%; in some embodiments of the invention, the mass ratio of the sodium alkyl benzene sulfonate in the thick oil viscosity reducer is 0.5%, 1% or 2%.
In the invention, the alkaline substance is preferably one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate; in order to reduce the cost of the viscosity reducer, one or more of sodium hydroxide, sodium carbonate and sodium bicarbonate are more preferable. The alkaline substance is adopted to react with petroleum acid carried by the thickened oil to form a specific O/W type emulsion (the sodium salt reacts with the petroleum acid in the thickened oil to form sodium oxolate soap, and the potassium salt reacts with the petroleum acid to form potassium oxolate soap), on one hand, the emulsion can emulsify the thickened oil in the stratum into tiny emulsion and carry the tiny emulsion to pore throats, so that the dosage of other surfactants is reduced, and the cost is reduced; on the other hand, the emulsion and the other three surfactants have synergistic effect and play a role in multiple viscosity reduction such as emulsification viscosity reduction, adsorption viscosity reduction, demulsification viscosity reduction in an oil pipeline and the like in a stratum and a shaft together, so that the viscosity of the heavy oil is effectively reduced, and the high-efficiency development of an abnormal low-temperature heavy oil reservoir can be realized.
In the invention, the mass ratio of the alkaline substance in the thick oil viscosity reducer is 0.05-1.5%; in some embodiments of the invention, the mass ratio of the basic substance in the thick oil viscosity reducer is 0.05%, 0.1% or 0.5%.
In the present invention, the water preferably comprises industrial water and/or formation water.
In the heavy oil viscosity reducer, the mass ratio of each component is as follows:
preferably, the mass ratio of each component is as follows:
under the proportion, the viscosity reduction rate of the thick oil can be improved to more than 99%.
In the thick oil viscosity reducer provided by the invention, an alkaline substance reacts with petroleum acid carried by thick oil to form specific surface activity, and the specific surface activity and other three surfactants in the viscosity reducer act synergistically to form a specific viscosity reducer solution, the viscosity reducer solution is mixed with the thick oil to form a low-viscosity O/W type emulsion, internal friction during flowing of the thick oil emulsion is converted from friction between oil and oil to friction between water and water, and resistance in the flowing process is greatly reduced; in addition, surfactant molecules in the viscosity reducer system are adsorbed on the pipe wall of the oil pipe or the pore wall of rock to form a layer of hydrophilic film, so that the inner wall of the pipeline has hydrophilicity, and the internal friction of the thick oil emulsion and the friction between the thick oil emulsion and the pipe wall are water-phase friction, thereby reducing friction resistance and improving fluidity.
The invention also provides a preparation method of the thick oil viscosity reducer in the technical scheme, which comprises the following steps:
mixing polyoxyethylene alkylphenol ether, polyoxyethylene sorbitan fatty acid ester, sodium alkyl benzene sulfonate, alkaline substance and water to obtain the thick oil viscosity reducer.
The types, the use amounts, the sources and the like of the ethylene alkylphenol ether, the polyoxyethylene sorbitan fatty acid ester, the sodium alkyl benzene sulfonate, the alkaline substance and the water are consistent with those in the technical scheme, and are not described in detail herein.
In the invention, the mixing speed is preferably 200-600 r/min. The mixing time is preferably 5-30 min.
The invention also provides a use method of the thick oil viscosity reducer, which comprises the following steps:
mixing the thick oil viscosity reducer with the thick oil to carry out viscosity reduction reaction;
the thick oil viscosity reducer is the thick oil viscosity reducer in the technical scheme or the thick oil viscosity reducer prepared by the preparation method in the technical scheme.
In the invention, the thickened oil is preferably thickened oil with the viscosity of 50 ℃ dehydrated thickened oil being less than or equal to 20000 mPa.s.
In the invention, before the viscosity reduction reaction is carried out, the viscosity reducer is preferably mixed with the formation water for a sensitivity test, and after the viscosity reducer is well compatible with the formation water, the viscosity reducer is mixed with the thick oil for the viscosity reduction reaction. The method for carrying out the sensitivity test is not particularly limited, and may be carried out in a manner known to those skilled in the art.
In the invention, the mass ratio of the dosage of the thickened oil viscosity reducer to the total amount of the thickened oil viscosity reducer and the thickened oil is preferably more than or equal to 25%, and the viscosity reduction rate of the thickened oil can reach more than 94% at the ratio. The mass ratio is more preferably 30 to 90%, and the viscosity reduction rate of the heavy oil can be increased to more than 99% at the mass ratio. The mass ratio is further preferably 30-50%, and under the proportion, the viscosity reduction rate of the thick oil can be increased to more than 99%, a stable O/W type emulsion can be formed, the development effect is improved, the recovery efficiency is improved, and excessive load on subsequent oil-water separation cannot be caused.
In the present invention, it is preferable that the constant temperature water bath treatment and the stirring are sequentially performed after the mixing. The temperature of the constant-temperature water bath is preferably 25-100 ℃, and more preferably 35-70 ℃; the time of the constant-temperature water bath is preferably 1 hour. The stirring speed is preferably 200-500 r/min; the stirring time is preferably 2-5 min; the temperature of the stirring is preferably the same as that in the thermostatic water bath. During the stirring process, viscosity reduction reaction occurs between the viscosity reducer and the thick oil, so that the viscosity of the thick oil is effectively reduced.
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
Examples 1 to 11 and comparative examples 1 to 2
S1, mixing polyoxyethylene octyl phenol ether (OP-10), tween 80, sodium dodecyl benzene sulfonate, sodium hydroxide and formation water to obtain the viscosity reducer. Wherein the formation water is formation water of a thickened oil test block in Xinjiang, the mineralization degree of the formation water is 9543mg/L, and the water type is NaHCO3Form (iv), see table 1 for full composition analysis.
TABLE 1 analysis of the composition of formation water in Xinjiang heavy oil test blocks
S2, taking 280g of thick oil in a thick oil test block of Xinjiang, keeping the temperature of the thick oil in a constant-temperature water bath at 50 +/-1 ℃ for 1h, stirring the thick oil to remove free water and bubbles in the thick oil, and quickly testing the viscosity mu of the thick oil at 50 +/-1 ℃ by using a rotational viscometer0。
S3, placing the thick oil obtained in the step S2 in a beaker, adding 120g of viscosity reducer, placing the beaker in a thermostatic water bath with the temperature of 50 +/-1 ℃ for 1 hour, placing a stirring paddle in the center of the beaker and 2-3 mm away from the bottom of the beaker, adjusting the rotating speed to 250r/min, and stirring for 2min under the thermostatic condition.
S4, testing the viscosity mu of the thick oil emulsion obtained in the step S3 at 50 +/-1 ℃ by using a rotational viscometer test.
S5, calculating the viscosity reduction rate of the thickened oil according to the formula (1):
in the formula (1), the reaction mixture is,
f is viscosity reduction rate,%;
μ0viscosity, mpa.s, of the thick oil sample at 50 ℃;
mu is the viscosity of the thick oil emulsion after viscosity reduction treatment by adding a viscosity reducer, and is mPa.s.
The ratios of the components in the viscosity reducer in step S1 and the calculation results obtained in step S6 are shown in Table 2.
TABLE 2 viscosity reducer formulation and viscosity reduction Effect
As can be seen from the test results in Table 2, compared with comparative examples 1-2, the viscosity reducing effect can be obviously improved in examples 1-11 of the present invention, and it is proved that the viscosity reducing agent (polyoxyethylene alkylphenol ether 0.2-2%, polyoxyethylene sorbitan fatty acid ester 0.1-1.5%, sodium alkyl benzene sulfonate 0.2-5%, alkaline substance 0.05-1.5%, and water balance) formed by specific components according to a specific ratio can obviously improve the viscosity reducing effect on thick oil. In examples 1 to 11, the viscosity reducing effect of examples 8 to 11 is further significantly improved, and it is proved that, when the components are in the preferable ratio (0.5% to 1% of polyoxyethylene alkylphenol ether, 0.1% to 0.5% of polyoxyethylene sorbitan fatty acid ester, 1% to 2% of sodium alkyl benzene sulfonate, 0.5% of alkaline substance, and the balance of water), the viscosity reducing effect on thick oil can be significantly improved, the viscosity of thick oil can be reduced to less than 75mpa.s, and the viscosity reducing rate can be more than 99%.
Examples 12 to 21 and comparative example 3
The viscosity reduction treatment was performed according to the viscosity reduction process in examples 1 to 11, wherein,
the dosage of the thickened oil is respectively as follows: 400g, 360g, 320g, 280g, 240g, 200g, 160g, 120g, 80g, 40 g;
the dosage of the viscosity reducer is respectively as follows: 0g, 40g, 80g, 120g, 160g, 200g, 240g, 280g, 320g and 360 g.
The formula of the viscosity reducer is as follows: OP-100.5%, Tween 800.1%, sodium dodecyl benzene sulfonate 2%, sodium hydroxide 0.5%, and the balance of formation water.
The viscosity reducing effect is seen in table 3:
TABLE 3 viscosity reduction Effect of viscosity reducer under different oil-water ratio conditions
Note: in Table 3, "oil-water ratio" means the ratio of the amount of the viscosity-reducing agent to the amount of the viscous oil; the water content refers to the ratio of the dosage of the viscosity reducer/(the viscosity reducer + the thickened oil).
The water content and the viscosity reduction effect are plotted, as shown in fig. 1 and fig. 2, fig. 1 is a graph of the effect of the viscosity reduction rate under different water contents, and fig. 2 is a graph of the viscosity effect under different water contents.
As can be seen from Table 3 and FIGS. 1-2, the higher the water content in the thickened oil emulsion, the lower the viscosity of the thickened oil, and the better the viscosity reduction effect. When the water content is increased to 25%, the viscosity of the thickened oil is sharply reduced from 11600mPa.s to 620mPa.s, and the viscosity reduction rate is 94.66%. After the water content is increased to 30%, the viscosity is reduced to be below 65mPa.s, the viscosity reduction rate reaches more than 99.44%, the viscosity is lower, and the method is more favorable for mining.
Analyzing the viscosity reduction effect and the type of the formed emulsion, wherein the thickened oil emulsion with the water content of less than or equal to 25 percent is a W/O type emulsion, and the thickened oil emulsion with the water content of more than or equal to 30 percent is an O/W type emulsion; the water content range of 25-30% is the transition range, i.e. the range in which emulsion phase inversion occurs. According to the actual mining requirement, when the water content is more than or equal to 30%, the viscosity reduction effect is better; when the water content is more than or equal to 30% and less than or equal to 50%, stable O/W type emulsion can be formed, the viscosity of the thickened oil is effectively reduced, the exploitation effect and the recovery ratio of the thickened oil are improved, and excessive load can not be caused to subsequent oil-water separation.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.