Technologies and methods for enhancing heavy oil treatment processes

UDK: 622.276.8:665.622.43

Key words: high-viscosity oil, crude oil treatment technologies, enhanced oil treatment procedures and techniques

Authors: N.G. Ibragimov (Tatneft PJSC, Almetyevsk), A.N. Sudykin, R.Z. Sakhabutdinov, F.R. Gubaidulin, S.N. Sudykin, I.I. Urazov (TatNIPIneft, RF, Bugulma)

Heavy oil emulsions are highly resistant to breakdown. This requires high heating temperatures, higher demulsifier concentrations and longer settling times for crude oil dehydration. One of the solutions to improve the performance of oil dehydration and desalting entails enhancement of mass-exchange processes using static mixer and coalescer. These are tubular elements with a dump packing where optimal emulsion flow conditions are provided to ensure adequate mixing and coalescing.

To process extra-viscous oil (2000-9000 mPa·s) to commercial standards hard-mode thermomechanical dehydration technology has been implemented. It provides for heating of crude oil to 85 - 90 ºС and high-degree dehydration using coalescing elements and electrical dehydrators. Appropriate electric-field intensity range has been determined at 1.5-2.0 kV/cm. To breakdown complex emulsions (intermediate emulsion layers, liquid oil sludge), when other dehydration techniques fail, water evaporation method has been designed. This method involves separate heating and evaporation stages. It has been found that with water mass content increase from 1 to 10%, evaporation temperature should also increase from 109 to 180 ºС while the pressure at the heating stage should increase from 0.14 to 1.0 mPa. Ultrasonic treatment is a promising method for breaking stable oil-water emulsions.  Ultrasonic waves induce mechanical oscillations in the emulsion, thus facilitating collisions between water droplets. With optimal process conditions, this results in coalescence and water settling. Favorable ultrasound parameters have been identified for extra-viscous oil treatment. These are frequency (100 kHz), specific acoustic output (100-200 W/dm³), treatment intensity (up to 5 W/sm²), and treatment time (less than 5 min).

Technologies for enhancement of heavy oil dehydration and desalting processes developed and implemented in Tatneft enabled to reduce oil treatment CAPEX and OPEX, improve reliability of operations and ensure recovery of marketable oil corresponding to 1^st Group of Quality.
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