Method for determining and evaluating effectiveness of asphalt paraffin deposit solvents

FIELD: construction.

SUBSTANCE: method for determining and evaluating effectiveness of asphalt paraffin deposit solvents involves selection of samples of asphalt paraffin deposits from oil equipment, application of the deposits on a metal plate, weight determination, attack by a solvent. Besides, the method includes weight determination as a result of attack by the solvent, fixation of results, hanging of the metal plate with the applied sample on the balance hook, continuous measurement of the sample weight, determination of weight of the metal plate with the sample, lowering it into a vessel with the test solvent, the vessel thermostatic control, fixing of the results; similar preparation of other samples and lowering them into the vessel with other solvent, conduction of similar measurements, comparison of the test data of different solvents and taking into account the "wall effect". In this case, the sample with native (without fusing) structure is used; the metal plate with the applied sample is hung on the hook of the torsion balance arm, and comparison of the test data of different solvents is performed by kinetic curves of their dissolution, obtained via the anamorphosis. At that, the order of dissolution reactions and limiting stages, rate constants of dissolution, time during which the half of the amount of the asphalt paraffin deposits pass into a solution, provided that the process flows as the first-order reaction, as well as the effective activation energy of the deposit destruction are calculated, and effectiveness of asphalt paraffin deposit solvents is estimated by the received values of kinetic parameters at one or another temperature.

EFFECT: increase of assessing accuracy of reagent effectiveness in order to remove the asphalt paraffin deposits, in this case the kinetic aspects of the process of their dissolving and temperature interaction mode with solvents are taken into account.

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The technical field to which the invention relates.

The invention relates to the oil industry and can find application in assessing the effectiveness of solvents for the removal of asphalt, resin and paraffin deposits formed on the surfaces of process equipment used in the mining, transportation and storage of oil.

The technical result of the invention is to improve the accuracy of estimation of efficiency of reagents for removal of deposits, which takes into account the kinetic aspects of the process of their dissolution and temperature interaction with solvents.

The level of technology

There are several laboratory methods of evaluating the effectiveness of solvents ARPD:

Method 1. Sample paraffin is heated to the softening temperature, thoroughly mixed and formed into a cylinder by size 12×20 mm, Then cooled and placed in a pre-weighted basket of brass (steel) with grid cell size of 1.5×1.5 mm Size wafers 70×15×15 mm Basket with hanging ASPO weighed and placed in a sealed glass cell, which is poured study the solvent volume of 100 ml, the Temperature of the experiment is 30°C. After 4 hours the basket with the rest of the destroyed part of ASPO removed and dried to constant weight. Destroyed, but not dissolved callaspo, dropped out of the baskets in the cell is filtered off, dried to constant mass and weighed. According to the results of the experiment is determined by the ratio of the mass balance of deposits in the basket and the filter to the mass of the original sample). The error of the experiment is 10%. The cleaning ability of the composite is measured by the difference between the deposits taken for analysis, and the remnants of deposits in the basket. Solvent capacity is determined by the number of deposits, created with true solvent solution (1. Nahimov NM, Askarov R.K., Sharifullin AV, Kozin VG Oil industry, 2002. No. 2. - S).

Method 2. Time experience varies from 1 to 8 h in dynamic and static modes. Samples of sediment by weight of 5, 10 and 15 mg in the form of a cylinder and plate thickness 8 mm in baskets (with the size of the holes of the mesh of 1 mm) is immersed in the solvent. In static mode, the sample is placed in the solvent and kept in a stationary state. Solubility studies of sediments in the static mode for 8 h hold without change of solvent and with the change it after 4 hours In static mode, the thickness of the softened layer on the surface of a cylindrical sample ARPD depends on time of exposure to the solvent. In dynamic mode, the glasses hanging baskets strengthen in the cassette and rotate with a frequency of 150-180 min^-1. All samples after 4 hours weigh what I moreover, some samples after 4 hours immersed in the same solvent, and the other filled with the same volume of fresh solvent. Given that the gas temperature in the zone of intensive ARPD is 9-12°C, studies on the solubility (removal) of the sediment is carried out at a temperature of 10, 12, 20 and 30°C. the temperature of the experience is supported by a thermostat (2. Safin YEAR Oil industry. - 2004. No. 7. - P.106).

Method 3. Sample paraffin is melted, homogenized and formed into the form of a cylinder with a diameter of 13 mm and a height of 20 mm, the Sample is weighed and placed in a basket made of steel mesh with a mesh size of 1.0×1.0 mm Diameter wafers 50 mm, height 20 mm Basket with hanging ASPO placed in a sealed cell, which is poured study the solvent volume of 100 ml, the Temperature of the experiment 20°C. the Duration of the experiment 2 or 3 hours. The basket with the rest of the destroyed part of ASPO removed and dried. The solvent is filtered off from the undissolved precipitate at the bottom of the cell. The filter is dried. Weigh not destroyed part of ASPO of the baskets and the precipitate on the filter. Determine washing, dispersing and dissolving capacity of the solvent (3. Turakulov MB selection Criteria effective hydrocarbon solvents to remove ARPD: author. Diss. Kida. chem. Sciences. - Krasnodar, 2005).

Method 4. Deposits placed is in a glass, dipped in a water bath with a temperature of 70-90°C and leave to full melting of sediments. Metal plates grind, dehydrated, dried and immersed in the molten glass sediment to a height of 45 mm Layer of sediment on the plate should be of a thickness of 1.5-2.0 mm, Then remove the plate and leave in the open air for not less than 2 hours. In the cylinder pour solvent in an amount of 10 cm³, lower back plate to a height of 3/4 of the height of the applied layer. Every 15-30 minutes visually detect change within 2 hours of swelling, dyeing solvent, peeled, cleaned surface in percent (4. Rogachev M.K., Strizhnev C.V. Struggle with sediments during oil extraction. - M.: OOO "Nedra-business Center", 2006. - 295 S.: ill.).

Method 5. Of sediment form balls with a diameter of 10-15 mm, weighed, the ball is placed in the grid from a wire and lowered into the solvent volume 25 cm³. Tests carried out 2 hours every 15-30 min raise and lower the grid scale, simulating the work of a well. Take out a grid with deposition, dried in the open air, weighed, the efficiency of the solvent is determined by the formula:

E=(m-m₁)·100/m %,

where m₁- the mass of the sediments after the experiment, g; m is the mass of sediment collected for the experiment,

Visually determine penetrating the solvent capacity of the intensity of the coloration of the solvent and the presence of the dispersed phase (5. STP-153-2001. The laboratory methods for determining solvent, and removing the ability of the solvent paraffin. // Standard enterprise ANK Bashneft. - 2001.).

Method 6. A portion of the paraffin is melted in a water bath with a temperature of (80±0,5)°C, homogenized by stirring, then the contents of the glass is poured into a mold. To test the strength of the build-up of deposits form by deposition of the overturn. The form with ARPD leave for days for drying to constant mass in the open air. The thickness of the deposits varies from 0 to 4 mm. Before conducting tests to determine the mass of forms with paraffin. The form with paraffin dipped in a glass of solvent by volume of 50 cm³mounted on the platform mixing device. After 1 hour the forms were removed, dried and weighed. For each sample are at least two parallel definitions. To provide dynamic mode mixing device. Speed when the experiment is equal to (165±5) min^-1. Experience time is 1 hour.

If the deposition stayed in shape after the test, determine the effectiveness of e by the formula:

E=(m₁-m₂)·100/m₁, %.

For the analysis of e_cftake the average of the results of two parallel determinations of e₁and e₂(6. Gerasimova E.V. Razrabotka.saitov effectiveness evaluation and selection of solvents wax and paraffin deposits in oil field equipment: author. Diss. Kida. chem. N. - Ufa, 2009).

Method 7. From the well or from the downhole equipment conduct sampling of organic deposits such as paraffin. A sample is taken from the undamaged structure. Heated above the melting temperature of the metal sample plate napravlyayut sample so that melted only a small thickness of the sample in contact with the plate. The rest and the majority of the sample remain unchanged. Cool metal plate with the deposited sample. Metal plate with the deposited sample ASPO hung on pan hook analytical balance GR-200 and immersed in a container of solvent by volume 100 cm³, cooled using circulating thermostat series LOIP LT-200, mounted on the table or platform mixing device (if necessary studies solubility in dynamic mode). The temperature of the solvent to maintain an accuracy of ±0.1°C, temperature gradient by volume of the bath is not more than ±0.1°C. When applying paraffin heated to the melting temperature of the metal surface occurs grip sediment surface due to the difference in temperature between the sediments and metal. Thus, the adhesive strength of the samples with the surface and eliminates the measurement error associated the traveler with the seal structure of deposits in the process of formation of the sample. To maintain a constant temperature used thermostat LT-200. Analytical balance GR-200 provide automatic adjustment of the response for adaptation to vibration and changes in the external environment with an accuracy of ±0.0001 g, have a hook for hanging samples. thermostat is also equipped with a special supply circuit with thermal insulation effect. To exclude the influence of the environment the plant is equipped with a protective cover (7. N.G. Ibragimov, IGOR Guskov, Shafigullin R.I., Gilmanova D.R., A.I. Pavlov, Malanichev S.E., Zakharova E.F., Shvetsov MV Patent. Of the Russian Federation No. 2429344 of the Russian Federation, IPC E21B 43/22 "Method of evaluating the effectiveness of solvents organic deposits" on the application number 2010142778/03; Claimed 20.10.2010; Publ. 20.09.2011 bull. No. 26. - prototype).

The disadvantages of the above methods are as follows:

1. The formation of the sample AFS "modeling" manually, resulting in the seal structure of deposits. The amount of compaction depends on the strength of pressure, which is a subjective factor.

2. The heating or melting of the original paraffin prior to forming or coating of the sample leads to a change in the structure of the sediments, compaction and, as a consequence, the change in solubility.

3. Visual analysis of the dissolving capacity of the solvent. This method of assessment may not give the actual characteristics of the test R is storytale.

4. In "method baskets" is not considered that the solvent acts on the ASPO from all sides, while in practice a comprehensive contact ASPO and the solvent does not occur.

Thus, these disadvantages reduce the reliability assessment of the effectiveness of solvents ARPD.

The objective of the invention is to increase the reliability assessment of the effectiveness of paraffin solvents due to the fact that there is no sample preparation, and therefore, excluded inaccuracies associated with changes in solubility when the compaction and melting, eliminated the human factor that determines the degree of compaction of the sample, possible continuous measurement of the mass change of the sample deposits, eliminates errors arising from the movement of the baskets during lifting and lowering, it is possible to examine patterns of dissolution time in different temperature regimes.

Is the task due to the fact that in the method of determining and evaluating the effectiveness of solvents, paraffin, including the selection of oil equipment ARPD samples, the application of the metal surface, determination of the mass, the effect of the solvent, the mass determination for impact, record the results, according to the invention using the sample with undisturbed structure, as the metal surface IP is result metal plate, which without fusion is applied to the sample, a spring with a metal plate coated with the sample suspended on the hook of the torsion beam weights, then determine the mass of the metal plate with the sample and lowered into the vessel with the test solvent, the vessel thermostatic, mass measurements carried out continuously, the results of the fix. Similarly prepared samples and lowered into the vessel with another solvent, conduct similar measurements, comparing the test data of different solvents and the resulting anamorphoses kinetic curves of their dissolution calculate the order of the reactions of dissolution and the rate-limiting step (n); rate constants for dissolution (K, min^-1); the time at which half the amount of deposits will go into solution (τ_1/2, min), provided that the process proceeds as a first order reaction; the effective activation energy of destruction deposits (E_akJ/mol). On the obtained values of the kinetic parameters evaluate the effectiveness of solvents ARPD.

The invention

Reliable laboratory evaluation of the effectiveness of paraffin solvents necessary for the proper choice of solvent and improve washing efficiency of oilfield equipment from high molecular weight deposits. Existing methods of evaluating the effectiveness of solvents is not DOS is overni, because when they use samples of sediments deformed due to heat or melt structure. In the proposed invention solves the problem of increasing the reliability of the assessment of the effectiveness of paraffin solvents. The problem is solved as follows.

From oilfield equipment carry out sampling of ARPD. The metal plate is applied to the sample of native ASPO, the plate on the spring is hung on the hook of the torsion beam weights W-500, which have several advantages over equal armed weights (type analytical): with sufficient accuracy the weighing process is significantly shortened and simplified, scales, portable and easy to use. Then the metal plate is dipped into a container of solvent by volume of 70 cm³, cooled using circulating thermostat series JULABO F25 - MS installed on the table. The temperature of the solvent to maintain an accuracy of ±0.1°C, temperature gradient by volume of the bath is not more than ±0.1°C. Because the sample paraffin is applied to the plate without fusion, the measurement error associated with the seal structure of deposits in the process of formation of the sample is excluded.

General view of the facility to determine the effectiveness of the dissolution of the deposits is presented in figure 1. The installation consists of the weights torsion W-500; 1 - locking; 2 - recognitiona; 3 - pointer of the mass; 4-spring; 5 - metal plate; 6 - vessel with the solvent; 7 - thermostat Julabo F25 - MC.

Feature of the proposed method is the use of samples with undisturbed in the melt structure, and the possibility of continuous measurement of the mass change of the sediments. This eliminates the effect of the subjective factor and the effect of the movement of the sample in the solvent.

Thus, the evaluation of solubility according to this method eliminated the human factor, the impact on deposits, the result is the preservation of the structure of deposits, which determines the precise definition and assessment of the effectiveness of solvents.

Specific example

Under the proposed method conduct identification and evaluation of the effectiveness of gas condensate used on irishsam field for removal of deposits (samples taken from the surface of tubing (tubing) on irishsam field PC (I)) and the model aliphatic-aromatic solvent consisting of hexane and benzene in the ratio of 1:1 (MBG). From oilfield equipment selected samples of paraffin and put on a metal plate. The metal plate coated with the sample ASPO hung on the spring on the hook torsion weights W-500 and lowered into the vessel with what rastvoritele. Continuously record the readings of the scales. Given that the gas temperature in the zone of intensive ARPD is 9-12°C, studies on the solubility of the sediment is carried out at a temperature of 10 and 25°C. the temperature of the experience is supported by a thermostat. The degree of dissolution (α) is calculated as the ratio of dissolved paraffin to its originally taken the total mass in the sample.

Figure 2 in the coordinates of the degree of dissolution (α) - time (τ) presents the obtained kinetic curves of dissolution of deposits in hydrocarbon solvents. It is seen that the dissolution rate of deposits in gas condensate, compared with GBS, significantly depends on the temperature. The geometry of the obtained curves shows that the dissolution of deposits in the tested reagents proceeds with maximum initial velocity. In the case of GBS, it can be explained sufficiently high chemical activity of the solvent, and in the case of gas condensate - the influence of temperature. However, with increasing dissolution rate of the process gradually decreases, the saturation of a fixed volume of liquid soluble material. Using expression (1) are constructed logarithmic anamorfose kinetic curves of dissolution of deposits in the studied solvents, which is shown in figure 3. The parameter n is defined as the tangent of the slope of the trend lines, lets set the ü limiting stage of dissolving paraffin.

The kinetic parameters of dissolution is determined from the following expressions:

$$\alpha =1-e^{-kt}{n}^{}\left(1\right)$$

where α is the degree of dissolution of deposits; k is a constant that determines the rate constant of dissolution; n is a constant that determines the nature of the process: when n<1 - diffusion process; n>1 - kinetic process; n=1 for first order reaction, the rate of chemical interaction is comparable to the speed of diffusion. The rate constants of dissolution is found by the formula:$$K=n{k}^{\frac{1}{n}},\left(2\right)$$

Formula (3) allows to calculate the time for which the solution will move half the amount of sediment in gas condensate and GBS, provided that the dissolution of deposits in the hydrocarbon flows as a first order reaction:

$$t_{\frac{1}{2}}=\frac{In2}{k},\left(3\right)$$

The results are presented in the table. The table shows that the process time is osenia ARPD in gas condensate at 10°C is diffusion controlled (the value of the reaction order n=0.5), and when heated condensate to 25°C, the process moves from diffusion in the kinetic mode (n=1,25). It is shown that in the binary system, the process of dissolution of deposits at different temperatures proceeds as a first order reaction (n=1), i.e. the dissolution rate of deposits in GBS is not limited by the speed of physical and chemical interaction at the interface or diffusion. Rate constants for dissolution (K) and the periods of half-transformation (τ_1/2) ARPD binary mixture at 10°C and condensation at 25°C are almost the same, indicating that the same dilution capacity and cold composite and hot condensate. It is seen that the activation energy of destruction ARPD in GBS almost 10 times less compared with the condensate, which indicates a high activity of aliphatic-aromatic solvents. Therefore, if the process of dissolution of sediment in the test reagent at a certain temperature has the following kinetic parameters: reaction order of dissolution is equal to the unit; low values of τ_1/2and activation energy, the use of such a solvent to remove deposits will be most effective.

The table also includes the results of tests conducted on the prototype. It is seen that the fusion of the samples leads to a significant distortion of the results, compared with when the samples nanos is conducted on the surface without fusion. Rate constants for dissolution differ in order, and the activation energy increases 4 times.

Thus, based on the tests, we can conclude that the technical result of the invention is to improve the accuracy of determining and evaluating the effectiveness of solvents, which takes into account the kinetic aspects of the process of dissolving paraffin, will lead to lower operating costs and improve the efficiency of the solvents used for the removal of deposits in the extraction, transportation and storage of oil.

Method of determining and evaluating the effectiveness of solvents asphalt, resin and paraffin deposits

The kinetic parameters of dissolution of sediment in gas condensate and MBG
The model system	The rate-limiting step, n	The constant velocity of dissolution, K, min-1	Time,$$t_{1/2}{t}_{\frac{1}{2}}$$, min	The activation energy of destruction deposits, EakJ/mol
Education is EC	t,°C
ASPO + Gas condensate	10	0,50±0,04	to 8.45*10-5	-	292,60
25	1,25±0,08	4,42*10-2	15,68
ASPO + MBG 1:1	10	1,00±0,07	3,10*10-2	22,36	31,64
25	1,05±0,13	6,10*10-2	11,36
ASPO + MBG 1:1 (testing the prototype)	10	0,83±0,06	2,91*10-3	-	118,6
25	0,91±0,09	3,G8*10-2	18,84

Method of determining and evaluating the effectiveness of solvents asphalt, resin and paraffin deposits, including the selection of oil equipment samples asfaltova Rabinovich deposits, the coating deposits on the metal plate, the definition of mass, the effects of solvent, determination of the mass effect of the solvent, recording of results, the suspension of the metal plate with a printed sample on the hook scales, continuous measurement of the mass of the samples, determination of the mass of the metal plate with the sample, lowering it into a vessel with the test solvent, the temperature of the vessel, record the results, and similar preparations other samples and lowering them into a vessel with another solvent, carrying out similar measurements, comparing the test data of different solvents and considering "murine effect, characterized in that uses the sample with native (without fusion) structure, metal plate coated with the sample suspended on the hook of the torsion beam scales, and comparing the test data of different solvents is carried out on the obtained anamorphoses kinetic curves of their dissolution: they expect the order of the reactions of dissolution and the rate-limiting step; the rate constants of dissolution; the time during which half the amount of oil deposits will go into solution under the condition that the process proceeds as a first order reaction; the effective activation energy of destruction deposits and the obtained values of the m kinetic parameters evaluate the effectiveness of solvents asphalt, resin and paraffin deposits at varying temperature.