Rheological behavior of oils in a magnetic field

Abstract

The influence of magnetic treatment parameters on the rheological properties of oils has been investigated. It has been noted that the strongest effect on these properties is produced by the regime of magnetic treatment -steady-state or flowing, the volume rate of oil flow, and the induction value of the magnetoactivator magnetic field. The optimal regimes of magnetic treatment have been determined. It has been shown that treatment of oil with a magnetic field promotes a decrease in the solidification temperature and the amount of asphalt-resin deposits.At present, the most acute problems in oil production are paraffinization of wells and exhaust lines, as well as a high accident rate of pipelines. This is due to the complete absence of pipes with a protective coating and the insufficient number of applied inhibitors preventing corrosion and the formation of asphalt-resin-paraffin deposits (ARPD). Providing the necessary decrease in the rate of corrosion and ARPD, the inhibitors are irrevocably lost; they require special dosing equipment and considerable working expenses. An alternative technique is magnetic treatment (MT) of pumped liquids, which in the last few years has proved to be good in the oil fields of Russia, Vietnam, China, and other countries owing to the low cost of MT devices and the practically complete absence of working expenses [1-6].Magnetoactivators found the widest practical use for controlling ARPDs and deposits of salts on the walls of oil wells [1, 2, 6]. Settling in the process of evaporation on the walls of pipes, rods, and on other parts of the well equipment, mixtures of salts, paraffin, and resin-asphalt substances (RAS) decrease the flow rate of oil in the pipes, hinder the operation of pumps, and considerably shorten the intervals between cleanings. Magnetoactivators equipped with centering elements are fixed in any part of the tubing string (TS) of the well below the zone of intensive deposition of ARPDs. The application of magnetoactivators decreases the rate of corrosion of pipelines 2-10 times, increases the intercleaning period of operation of TSs by a factor of more than 10, and enables the effect of MT to last for up to 72 h [1, 4, 5].However, production tests in a number of oil fields revealed both positive effects and negative consequences in using magnetoactivators for combating oil deposits [2]. The absence of theoretical substantiation of the mechanism of magnetic actions on oil dispersive systems (ODS) often makes it impossible to predict in good time the possible effect of this action and design magnetoactivators with optimal parameters. The scientific explanation of results obtained in practice is limited by the insufficient theoretical treatment of the problem of the action of magnetic forces (MF) because of the complexity of the structural and energy transformations proceeding in substances with different structures at the micro-and macrolevels.Several qualitative theories that form the basis of the mechanism of MF action on ODSs are known. These are: "colloidal" hy...

Apparent Disaggregation of Colloids in a Magnetically Treated Crude Oil

“…Table shows mean values and standard deviations for RI in four types of oil samples employed in our experiments. In agreement with previously reported studies, − a statistically significant effect was achieved only in the case of magnetic treatment of a flowing (agitated) crude oil. Namely, a decrease of RI by ca.…”

“…It is true, however, that there are insufficient experimental data on long-term changes in the state of aggregation after magnetic treatment of crude oils, although viscosity reduction has been observed by many authors. [18][19][20][21][22][23][24][25][26][27] Some indirect evidence of post-treatment disaggregation was obtained by microscopy of deposits [19][20][21] and by measuring the number of inhibition (paramagnetic, etc.) centers.…”

“…centers. 25,27 The direct detailed experiments have demonstrated only temporary orientation of some petroleum constituents under the action of an applied magnetic field. [28][29][30] In the present paper, we describe experimental studies of a magnetically treated crude oil by optical methods, which have been shown to be sensitive to the state of asphaltene aggregation.…”

“…It is true, however, that there are insufficient experimental data on long-term changes in the state of aggregation after magnetic treatment of crude oils, although viscosity reduction has been observed by many authors. − Some indirect evidence of post-treatment disaggregation was obtained by microscopy of deposits − and by measuring the number of inhibition (paramagnetic, etc.) centers. , The direct detailed experiments have demonstrated only temporary orientation of some petroleum constituents under the action of an applied magnetic field. − In the present paper, we describe experimental studies of a magnetically treated crude oil by optical methods, which have been shown to be sensitive to the state of asphaltene aggregation. − …”