Method for the treatment and prevention of asphaltene-paraffin-vax precipitates in oil-wells, wellheads and pipelines by the use of biocolloid suspensions

Abstract

The method for the prevention, reduction and / or removal of asphaltene-paraffin-vax precipitates on surfaces in contact with crude oil within oil-wells from bottom hole to well head, in flow lines and pipelines by the use of biocolloid suspensions comprises the steps of: adding together (a) microorganism(s) capable of reacting with, solubilizing of and / or resistant to the components of crude oil, (b) organic or inorganic additives, or (c) a mixture thereof into the pipes; and allowing the so formed suspension containing the microorganisms to act for a desired time. The suspension is used for the decomposition, washing-off and removal of solid hydrocarbons and mixtures of long chain hydrocarbons, as well as for the prevention of formation thereof.

Description

[0001] The present invention relates to a method for the prevention, reduction and / or removal of asphaltene-paraffin-vax precipitates on surfaces in contact with crude oil within oil-wells from bottom hole to wellhead, in flow lines and pipelines by the use of biocolloid suspensions. In particular, the method comprises adding together (a) microorganism(s) capable of reacting with, solubilizing of and / or resistant to the components of crude oil, (b) organic or inorganic additives, or (c) a mixture thereof into the pipes, and the so formed suspension containing the microorganisms is allowed to act for a desired time. The said suspension can be used for the decomposition, washing-off and removal of solid hydrocarbons and mixtures of long chain hydrocarbons, as well as for the prevention of formation thereof. [0002] The term “asphaltene-paraffin-vax precipitate” means in general a mixture of natural crystalline crude-oil paraffins, solid asphaltenes and / or solid hydrocarbon resins havin...

AI Technical Summary

Benefits of technology

[0013] (iv) the application of scraper only solves the cleaning of tubing, but, at the same time, the deposition of asphaltene-paraffin-vax precipitates continues at the wellhead and near the well, thereby decreasing the flow cross-section.

[0040] In the method according to the invention, microorganisms selected in an appropriate way are used, and a “film carrying bacteria” is formed in the treated pipes by the use of a combination of appropriate additives. This film provides the living and operating conditions for the microbes. In addition to this, the additives of the microorganisms used for the inhibition of the formation of asphaltene-paraffin-vax precipitates are supplemented with tensides and materials increasing viscosity, which, in part or on the whole, are biodegradable. These are advantageous from a technological standpoint, and on the other hand, provide a retard carbon source for the microbes, therefore their use can provide the approach and attachment of microbes to the inner metal surfaces of the pipes for a longer period of time, and can provide for the living conditions thereof. It was especially surprising to find that the combination of the additives according to the invention enables the long-standing survival of a self-sustaining bacterial layer on the wall of the pipe. This, in contrast to the state of the art solutions, enables the continuous cleansing of the surfaces in contact with crude oil. Without restricting the scope of the invention by theory, the survival of the bacterial layer on the surfaces in contact with crude oil might be due to the combined effects according to the invention, of the additives used. In this respect, it is especially noteworthy that by the addition of materials increasing viscosity to the film carrying bacteria, the inherently viscous precipitates can be broken up, therefore decrease of their viscosity is achieved.

Problems solved by technology

One of the main problems of crude oil production is the removal of the mixture of long chain solid hydrocarbons, paraffins, vaxes and asphaltenes deposited from the crude oil onto the walls of production devices.

These are lowered down into the well on a steel cable with a reel using human power or machinery at predetermined time intervals, generally every few days, to a depth of 300 to 400 m. This method has several disadvantages: (i) the scraper with the solid hydrocarbon stuck to it narrows the cross-section of the pipe, therefore acts as a local resistance or piston, which is not desirable under certain circumstances; (ii) due to the breakage of the steel cable, the scraper often remains in the production pipe of the oil-well, the rescue of which causes significant production losses and extra cost; (iii) special devices, personnel and experience is necessary for the movement of the scraper within the production pipe; (iv) the application of scraper only solves the cleaning of tubing, but, at the same time, the deposition of asphaltene-paraffin-vax precipitates continues at the wellhead and near the well, thereby decreasing the flow cross-section.

This method has several disadvantages: (i) special loading and receiving chambers and locking system is necessary for the insertion and removal of the mechanical cleaning devices at the receiving stations; (ii) the cleaning devices are often stuck in the pipelines, consequently causing production loss and their removal is very expensive; (iii) these devices are sensitive, therefore their replacement is essential after a certain time.

This method has several disadvantages: (i) the transportation and heating of materials necessary for the treatment is difficult to carry out, especially during winter, it requires machinery and energy, and also can pose danger of fires and accidents.

Besides the several advantages of the chemical methods, the following disadvantages are present: (i) most of the reagents are prepared in chemical factories far from the site of application and by the use of complicated processes, therefore the price and transportation means significant extra cost; (ii) in case of diluents, amounts necessary for the treatment (3 to 35 m3) compensates the relatively low price, and the treatment itself must be repeated at every one to two months; (iii) in order to achieve long-lasting effects, in most of the cases reagents must be fed continuously, which requires construction of specific well equipments, injection pumps.

There are oilfields where the older technology does not enable continuous feed, and the periodical treatments are not sufficient to achieve the desired results.

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