RU2256064C1 - Method for removing paraffin precipitations in tubing pipes of oil wells - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: method includes washing tubing pipes using solvent - condensed light hydrocarbons, produced using centrifugal forces of hydraulic cyclone, with insertion of it through behind-pipe space into said tubing columns and circulation with down-pump operating in towards-self mode. Said solvent contains admixture in form of special surfactant, washing is performed at temperature close to temperature of melting of paraffin with loss of said solvent 5-10 m³ in one well.

EFFECT: higher efficiency, broader functional capabilities.

Description

The invention relates to the oil industry and can be used to remove paraffin deposits, mainly in tubing.

There are various ways to prevent the formation and removal of asphalt-resin-paraffin deposits (see Lyushin S.F., Rogulin V.A. Feasibility study on the use of methods to combat paraffin deposits (Transactions of BashNIPIneft. - 1982. - Issue 64. - P.130- 133) using mechanical thermal, chemical, and various combinations thereof.

The disadvantage is the low efficiency of the known methods.

A known method (see Babalyan G.A., Akhmadeev M.Kh. Investigation of the process of coalescence of droplets in emulsions by the method of high-speed filming. DAN SSSR, 1968, vol. 179, No. 1. - P.123-125), which consists in using solvents for carbon disulfide paraffin and carbon tetrachloride.

The disadvantage is that the use of the above solvents is limited by their high fire resistance and toxicity, and chlorinated hydrocarbons adversely affect the oil refining process: they “poison” the catalysts and degrade the quality of the resulting oil products.

The closest analogue is the method for removing paraffin deposits in the tubing of oil well pumps, which consists in flushing them with a solvent, which uses condensed light hydrocarbons obtained by the centrifugal forces of a hydrocyclone, and then introducing them through the annulus into well tubing (see USSR author's certificate No. 1832714, S09K 7/02, 10.06.1996).

The technical result of the invention is to increase the efficiency of the method by intensifying the process of removing paraffin deposits due to their partial dissolution.

In the method of removing paraffin deposits in tubing tubing of oil wells, which consists in flushing them with a solvent - condensed light hydrocarbons obtained by the centrifugal forces of a hydrocyclone, introducing it through the annulus into said tubing and circulating while operating “on itself” a submersible pump, a surfactant, diproxamine-157M, is introduced into the specified solvent, washing is carried out at a temperature close to the melting point of paraffin, at the rate indicated of solvent of 5-10 m ³ per well.

It is known that asphalt-resin-paraffin deposits are formed mainly on the walls of tubing and when oil moves to the treatment plants, they are deposited, therefore experiments were carried out, the purpose of which was to observe the washing of paraffin wax from a metal surface and dissolving them with stirring. The experiments were carried out with two samples:

1) washing from a metal plate;

2) the dissolution of balls made from paraffin deposits of various fields.

One sample was prepared as follows. A well-washed and fat-free metal plate was covered with a layer of paraffin, previously melted in a glass. Then the plate was kept for 4 hours and weighed to the 4th sign. Another sample is a ball of paraffin wax weighing about 3 g, mounted on a copper ring.

Samples were placed in a volumetric glass thermostatic glass with light hydrocarbons or with a composition consisting of light hydrocarbons and various types of surfactants. At certain time intervals, the degree of removal of paraffin deposits was determined qualitatively (visually) and quantitatively (by weighing the samples). According to these data, the effectiveness of washing deposits from a plate or dissolving and breaking balls from paraffin deposits was evaluated. The basis for laboratory studies on the dissolution and destruction of paraffin condensed by light hydrocarbons obtained using the field of centrifugal forces of a hydrocyclone was the fact that the hydrocarbon solvent, having well wetted the paraffin deposits, partially dissolved them. To reduce the surface tension of the solution and dispersion of paraffin crystals, surfactants are introduced into the composition of light hydrocarbons, for example, diproxamine - 157M.

It is well known that the decisive link in crystal formation is the appearance of crystallization centers. Therefore, to inhibit this process, depressants are used that modify and disperse paraffin crystals, which slow down the process of paraffin crystallization. To prevent paraffinization at the crystallization centers and to improve their washing process, we studied the effect of the additive depressant ECA 4242 (USA).

For laboratory studies of the dissolution of paraffin deposits in light hydrocarbons, not pure paraffin was used, but paraffin deposits selected at fields in various regions of the country. For example, in ASPO Samotlor and Tuymazinsky deposits contains a relatively large amount of solid paraffins with a high melting point. And refractory paraffins are sparingly soluble in light hydrocarbons, therefore, an increase in the temperature of these solvents is required.

The dissolution of paraffins is also hampered by the high content of asphaltenes in the deposits, since their initial washing is necessary.

Light hydrocarbons selected using the field of centrifugal forces of a hydrocyclone at UKPN-2 have the following mass hydrocarbon composition,%: C ₁ - 0; C ₂ - 0.95; C ₃ - 10.15; iC ₄ - 4.73; nC ₄ - 19.8; iC ₅ - 15.22; nC ₅ - 10.38; nC _{6 + Σ} - 38.07.

Studies have shown that the paraffin deposits of the Tuymazinsky deposit are washed and dissolved more easily than the paraffin deposits of the Samotlor deposit. Raising the treatment temperature to 323K slightly affects the solubility of paraffins, so the treatment temperature should be close to the melting point of paraffins.

Further testing of the method was carried out in situ.

In Oktyabrskneft NGDU, industrial tests were carried out to flush wells with the aim of removing paraffin deposits.

The experiments were carried out in wells, the waxing period of which after heat treatment was from 10 to 30 days.

In the tubing of deep pumping wells, light hydrocarbons obtained using a hydrocyclone unit were pumped through the annulus. Circulation was carried out at each well for 2 days with a deep-well pump operating "on itself".

The consumption of light hydrocarbons was 5 - 10 m ³ per well. 30 wells were processed. The duration of the effect after one treatment of the wells ranged from 30 days to 200 days.

Using the proposed method will allow high-efficiency use of light hydrocarbons to combat paraffin in the oil collection and production system and, on the other hand, will destroy the armor shells of the emulsion droplets, and therefore, intensify the process of oil preparation.

Claims (1)

A method of removing paraffin deposits in tubing tubing of oil wells, which consists in flushing them with a solvent - condensed light hydrocarbons obtained by the centrifugal forces of a hydrocyclone, introducing it through the annulus into said tubing and circulating while operating “on itself” deep a pump, characterized in that a surfactant, diproxamine-157M, is introduced into said solvent, washing is carried out at a temperature close to the melting point of paraffin and said solvent flow rate of 5-10 m ³ per well.