RU2487911C1 - Method for regeneration of propping agent mudded with oil and chemicals - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for regeneration of propping agent mudded with oil and chemicals at respective equipment, including roasting of propping agent at temperature of 350-500°C with subsequent cooling up to 30-35°C and washing by a mix of benzene and toluene in successive rations of 1:1, 1:2, 1:3, 3:1, 2:1 and then by aqua-alcoholic solution with alcohol content of 45-50%, drying at temperature of 70-95°C with subsequent cooling up to 30-35°C and fractioning.

EFFECT: simplification of method, improvement of efficiency, cost reduction.

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Description

The invention relates to the oil industry and can find application in the regeneration of oil and chemically contaminated proppants and their subsequent use as a proppant in hydraulic fracturing.

After hydraulic fracturing, part of the proppant remains in the wellbore (in case of unsuccessful work or proppant removal from the fracture). The proppant recovered from the wellbore is contaminated with petroleum products and chemicals of various nature. This proppant is not suitable for repeated use as a proppant due to the negative effect on hydraulic fluid fracturing. Thus, the issue of regeneration of oil and chemically contaminated proppant is relevant.

A known method of processing oil sludge (RF patent No. 2026831, publ. 01/20/1995), including the sampling, preparation, pumping of oil sludge and grinding of mechanical impurities.

There is also a method of preparing oil sludge for processing (RF patent No. 2261894, publ. 10.10.2005) in known industrial plants using centrifugal separation of sludge in a decanter, including heating the sludge to a temperature of at least 70 ° C, feeding heated sludge to a vibrating screen and separation of mechanical impurities larger than 0.15 mm, the direction of the flow of the purified oily liquid into the intermediate tank and the supply of sludge prepared for processing to the raw material tank of known plants or directly to the decanter.

Known methods are not intended for the processing and disposal of solid petroleum waste, which include oil-contaminated proppant.

A known method for the disposal of oil-contaminated proppant (RF patent No. 2344006, published on 01.20.2009) on existing equipment, including steaming proppant at a temperature of at least 100 ° C to separate it from oil products, washing in a washing solution using surface-active substances at rotational mixing until complete purification from petroleum products, drying at a temperature of 50-300 ° C, using purified proppant as a filler in a mixture for the preparation of bricks or concrete mix for filling floors during production cinder blocks.

The known method is not intended for the regeneration of oil and chemically contaminated proppants for the purpose of further use as a proppant in hydraulic fracturing.

A known method of utilizing proppant (RF patent No. 2353642, publ. 04/27/2009), including washing proppant in a washing solution using surface-active substances with rotational stirring until complete purification from oil products, drying at a temperature of 100-300 ° C, application on proppant granules of phenol-formaldehyde resin novolac coating heated to a temperature of 120-180 ° C, followed by cooling, curing, fractionation and using the obtained proppant during hydraulic fracturing.

The disadvantages of this invention are the complexity of the process of regeneration of contaminated proppant, its high cost, due to the fact that:

- precise control of the proppant washing process is necessary, for which purpose equipment for monitoring petroleum products on the proppant surface built into the production line is needed;

- in order to get “environmentally friendly” and people who will continue to work with the final product along the production chain, an accurate selection of monomers is necessary to obtain a resin from them, and again control the content of the residues of these monomers in the final resin. Equipment for monomer control should be as close as possible to production, while the cost of this equipment is tens, and sometimes hundreds of millions of rubles.

However, the polycondensation process (the process of obtaining phenol-formaldehyde resins) is difficult to control for monomer residues. The monomers involved in the process of obtaining novolac resin are toxic substances. Such monomers and partially the polymer itself — phenol-formaldehyde resin — affect the quality of hydraulic fracturing fluid, and ultimately it will be difficult for the end-user service companies to work with such a finished product. In addition, you need a permit to work with toxic substances and disposal of liquid after washing, which is economically disadvantageous.

The task to be solved by the alleged invention is aimed at simplifying the process of regenerating contaminated proppant, increasing efficiency, and reducing production costs.

The technical result consists in the simplicity, accessibility, effectiveness of the proposed method of regeneration of oil and chemically contaminated proppant, in the use of low-cost equipment and components and improving the ecological environment.

The technical result is achieved by the fact that the method of regeneration of oil and chemically contaminated proppant on existing equipment involves proppant firing at a temperature of 350-500 ° C, followed by cooling to 30-35 ° C, washing in a mixture of benzene-toluene, used sequentially in the ratios 1: 1, 1: 2, 1: 3, 3: 1, 2: 1, and then in a water-alcohol solution containing 45-50% alcohol, drying at a temperature of 70-95 ° C, followed by cooling to a temperature of 30-35 ° C and fractionation.

The combination of features characterizing the claimed invention allows to obtain the above technical result, namely: firing at a temperature of 350-500 ° C followed by washing with various low boiling solvents simplify the process of regeneration of contaminated proppant, make it accessible and effective. The exclusion of expensive equipment and components from the process reduces its cost. In addition, the absence in the production process of toxic substances that adversely affect hydraulic fracturing fluid has a positive effect on the environment.

The method of regeneration of oil and chemically contaminated proppant is as follows.

After hydraulic fracturing, the used oil and chemically contaminated proppant is fired from oil products in UZG-1M furnaces with a temperature of 360 ° C (± 10 ° C) for firing oil-containing contaminants. After firing, the proppant is cooled to a temperature of 30-35 ° C, then the cooled proppant is washed in a counterflow heat exchanger at room temperature and atmospheric pressure, where a mixture of benzene and toluene is added successively in the ratios: first 1: 1, then 1: 2, 1: 3 and then 3: 1, 2: 1, after which a water-alcohol solution with an alcohol content of 45% is added until complete purification from chemical impurities of oil products and firing residues. After washing, the proppant passes through the conveyor to the dryer drum, where it is dried at a temperature of 80 ° C, then again cooled to a temperature of 30-35 ° C and sent to a vibrating screen, where the proppant is divided into fractions. After dividing into fractions, proppant is used as a proppant for hydraulic fracturing, which does not affect the quality of hydraulic fracturing fluid.

Table Proppant API Proppant Characteristics HB, g / cm ³ Durability at 7.5 psi,% Regenerated 1,6 6.33 New 1.6-1.62 6-12

Based on the data in the table, it follows that the regenerated proppant fully meets the proppant quality requirements according to API standards (American Petroleum Institute is a US non-governmental organization engaged in research of all aspects and provides activities to regulate issues in the oil and gas industry) and is suitable for injection into a well .

Using the proposed method allows with maximum quality and lowest cost on existing equipment to regenerate oil and chemically contaminated proppant and reduce the cost of production of proppant used in hydraulic fracturing, which allows the production of hydraulic fracturing to be virtually waste-free, significantly improve the environment.

The claimed invention is tested in a limited liability company "Gazpromneft-Khantos." The estimated annual savings from use is 15.5 million rubles.

Claims (1)

A method of regenerating oil and chemically contaminated proppant on existing equipment, including proppant firing at a temperature of 350-500 ° C followed by cooling to 30-35 ° C and washing in a benzene-toluene mixture used sequentially in the ratios 1: 1, 1: 2 , 1: 3, 3: 1, 2: 1, and then in a water-alcohol solution with an alcohol content of 45-50%, drying at a temperature of 70-95 ° C, followed by cooling to a temperature of 30-35 ° C and dividing into fractions .