Separation method for high-water-content crude oil

Abstract

The invention discloses a separation method for high-water-content crude oil and relates to the field of petroleum refining and chemical engineering. The method comprises the following steps: (1) enabling a mixed solution of oil, gas and water to enter a gas-liquid separating tank through a charging pipe, and carrying out gas-liquid separation; (2) further removing micro liquid droplets entrained in a gas phase from gas, separated in the step (1), by a mist catching device, and then discharging the gas from the device; (3) enabling a liquid phase, separated in the step (1), to enter an oil-water separator for oil-water separation; and (4) enabling dehydrated crude oil to pass through an upper-part oil collecting pipe of an oil-water separation tank body in a rising manner, and discharging the crude oil from the device; and further deoiling separated water through oil sorbent bars of a water phase region, and then, discharging the water from the device. By adopting the method, oil-gas-and-water three-phase mixed solutions of any ratio can be treated, the operating flexibility is high, and the efficiency of gas-liquid separation and oil-water separation is high; due to the combined action of electrostatic field and highfield, an efficient dehydration effect can be guaranteed; and the oil sorbent bars can be used for efficiently lowering the oil content of drainage water.

Description

technical field [0001] The invention belongs to the technical field of oilfield exploitation, and in particular relates to a method for rapidly separating oil, gas and water extracted from high water-cut oilfields. Background technique [0002] The oil-gas-water mixture extracted from oilfields at home and abroad needs to be separated to obtain qualified commercial crude oil before it can be exported for sale. At present, the conventional separation process in oilfields is as follows: the well fluid first enters the first-stage separator, and uses the density difference between oil, gas and water to carry out natural gravity sedimentation to separate the natural gas and most of the water in the mixed liquid to achieve pre-separation of three phases. Then it enters the secondary separator, and under the action of chemical agents, the mixed liquid is further separated. The water content of the separated crude oil is less than 30%, preferably less than 20%, which meets the requ...

AI Technical Summary

Problems solved by technology

This separation method requires large volume of equipment, high investment, and low separation efficiency. Especially in the late stage of oil field exploitation, the water content of the well fluid produced is more than 90%, which often causes the crude oil to remain watery after the first two stages of three-phase separators. If it is higher than 30%, it will affect the normal operation of electric dehydration. On the one hand, it will cause the oil content in the drainage to not meet the standard, which will bring environmental protection problems. On the other hand, it will affect the quality of commercial crude oil, thereby affecting the benefits of the enterprise

[0003] Aiming at the problems existing in oil field three-phase separation technology, foreign scholars put forward the concept of electrostatic coalescence dehydration, and successively developed the electrostatic coalescer (EPIC) based on pulsed DC electric field, the electrostatic coalescer (ECE) based on AC electric field, On-line electrostatic coalescer (IEC), container built-in electrostatic coalescer (VIEC), low water content electrostatic coalescer (LOWACC) and other technologies, in which EPIC and ECE are set in front of the separator for the coalescence and growth of water droplets , and then accelerate the separation of oil and water in the separator. Its disadvantages are: it cannot handle emulsions with a water content greater than 60%, and the grown water droplets treated by an electrostatic field are prone to rupture before entering the separator, and there are certain requirements for the gas content; VICE It is installed inside the separator and is designed as a square grid-shaped perforated wall. The electrode unit module in each hole contains a step-up transformer, which can promote the growth of water droplets and accelerate the separation of oil and water. The disadvantage is that the manufacturing process of the electrode module is complicated and it will run for a long time. It is prone to failure; LOWACC needs to be used in conjunction with VICE. Usually, LOWACC is set after two VICEs are processed. Its main function is to treat crude oil with low water content to meet the requirements of commercial crude oil. The disadvantage is that the residence time of VICE is only 2-5s , while the residence time of LOWACC needs 30-140S, resulting in some equipment of LOWACC being slender and occupying a large space

Although this technology can improve the efficiency of oil-water separation and the processing capacity of the device, the structure of the electrode is complicated, and the residence time of water washing is relatively short, which may easily cause excessive oil content in the drainage

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