EP0562914A1 - Washing method of solid particles using a solution containing sophorosides - Google Patents

Abstract

The invention relates to a process for cleaning solid particles impregnated with hydrocarbons. The process uses a solution containing sophorosides. The process is particularly intended for washing drilling debris impregnated with a drilling fluid containing hydrocarbons.

Description

The present invention relates to a method using a solution containing sophorosides, said method being suitable for cleaning solid particles impregnated with hydrocarbons. This process is more particularly intended for washing petroleum drill cuttings.

In the field of oil drilling, the cuttings torn off by the tool are brought to the surface by the upward flow of drilling fluid injected through the channel of the tubular lining. It is very common to use drilling fluids containing hydrocarbons to solve drilling problems in reactive formations in the presence of water, for example certain clays or salt. Drilling fluids suitable for high temperatures can also be based on mineral oil. In particular, in the North Sea, around 75% of wells are drilled with oil-based fluids. In these cases, the cuttings that rise to the surface are impregnated with a relatively large amount of hydrocarbon.

The discharges of these impregnated debris are generally regulated by the local authorities.

• ne plus utiliser de fluides de forage contenant des hydrocarbures,
• transporter à terre les rejets pollués pour leur faire subir un traitement spécifique avant décharge,
• nettoyer les déblais pour pouvoir ensuite les rejeter à la mer.

More particularly, on offshore drilling operations, it is no longer authorized to reject such drill cuttings before subjecting them to additional treatment to comply with the standards in force. The operator must then face the following choices:

• no longer use drilling fluids containing hydrocarbons,
• transport polluted waste ashore to undergo a specific treatment before discharge,
• clean the cuttings so that you can then throw them back into the sea.

The first two choices may not be viable for technical and / or economic reasons. It will then be advantageous to use the third technique by having an efficient and economical means for washing the excavated material on site.

An aqueous formulation intended for cleaning surfaces soaked in oil, for example drill cuttings, is known, in particular from document EP-A-0330379.

However, this document does not recommend the use of sophorosides.

Also known from documents US-4645608 and EP-A-0084411, methods for washing cuttings recommending formulations containing mainly solvents and surfactants or surfactants. Neither of these documents contemplates the use of sophorosides.

The present invention relates to a method for cleaning solid particles impregnated with a polluting fluid comprising hydrocarbons. This process consists in bringing said solids into contact with a washing solution comprising sophorosides.

In this process, said solids can be drill cuttings.

The solution may contain sophorosides in a concentration of between 0.1 to 30 g / liter.

The washing solution can comprise at least one other compound suitable for one of the following functions: adjusting the pH of the solution, dissolving the hydrocarbons, inhibiting swelling and / or dispersion of the solid particles.

According to the method, the cleaned solids can be separated from said washing solution by at least one of the following means: decantation, sieving, centrifugation, filtration or cycloning.

Said washing solution can be separated from said polluting fluid by decantation and / or centrifugation.

The use of sophorosides can now be considered because the patent application FR-90/16211 of the applicant discloses a particularly advantageous process for the manufacture of sophorosides. Indeed, before knowledge of this process, it was particularly difficult and very expensive to manufacture industrial quantities of this product. However, this family of products, known for its use in cosmetology or in the food industry, reveals interesting properties, in particular for washing drill cuttings.

• agents bactéricides quand le produit est sous forme lactone,
• agents émulsifiants dans l'industrie agro-alimentaire (US-3622344) et hydratants dans l'industrie des cosmétiques (US-4305961). Dans ces applications, le produit est sous forme ester.

Sophorosides are currently known for the following two main applications:

• bactericidal agents when the product is in lactone form,
• emulsifiers in the food industry (US-3622344) and moisturizers in the cosmetics industry (US-4305961). In these applications, the product is in ester form.

The definition of these two forms lactone and ester of sophorosides is specified below.

• La diversité des structures possibles de sophorosides donne une grande souplesse d'utilisation et une facilité d'adaptabilité à une application spécifique. Cela est explicité ci-après avec la description des sophorosides.
• Les composés de sophorosides ne sont pas toxiques. Leur innocuité permet d'ailleurs leur utilisation en agro-alimentaire et en cosmétologie.
• Ils sont entièrement biodégradables.
• Ils sont stables, notamment en milieu alcalin contrairement aux esters de sucres. Les fluides de forage sont généralement alcalins.
• Le procédé de fabrication par fermentation divulgué par la demande FR-90/16211 permet d'obtenir de bons rendements.
• Les matières premières, sucres et corps gras, ont un coût faible et une grande disponibilité.

This family of products has the following advantages in particular:

• The diversity of possible structures of sophorosides gives great flexibility of use and ease of adaptability to a specific application. This is explained below with the description of the sophorosides.
• Sophoroside compounds are not toxic. Their safety also allows their use in food and cosmetology.
• They are fully biodegradable.
• They are stable, especially in an alkaline medium, unlike sugar esters. Drilling fluids are generally alkaline.
• The fermentation manufacturing process disclosed in application FR-90/16211 allows good yields to be obtained.
• The raw materials, sugars and fatty substances, have a low cost and a high availability.

Sophorosides are described from 1961 in particular by Gorin et al. in Can. J. Chem., 39, 846-55 (1961), Asmer et al. in J. American Oil Chem. Soc., 65 (9), 1460-6 (Sept. 1988) and by Spencer et al. (US 3205150).

These are extracellular compounds produced during a fermentation process involving a yeast, such as Candida bombicola .

Sophorosides are glycosides resulting from the association of a sugar, sophorose, formed by yeast from two glucose molecules, and a hydroxy fatty acid also produced by yeast from substrates such as hydrocarbons. , saturated or unsaturated fatty acids, fatty acid esters including glycerides, and vegetable oils: rapeseed, sunflower, palm or soybean oils, methyl or ethyl esters of these oils. The hydroxylation of the fatty acid takes place in position ω or more often in ω - 1 with respect to the carboxylic acid function.

Sophorosides are considered to be a mixture of compounds, the structures of which can be represented by the formulas (1) and (2) below:

In formulas (1) and (2), R1 represents hydrogen or an acetyl group (CH3CO-), R2 represents hydrogen or an alkyl radical containing 1 to 9 carbon atoms when R3 is a saturated hydrocarbon radical comprising 7 with 16 carbon atoms, or R2 represents hydrogen or a methyl group when R3 is an unsaturated hydrocarbon radical containing 13 to 17 carbon atoms.

The cyclization of the fatty acid form (formula (1)) to give the lactone form (formula (2)) can be carried out as indicated in formula (2) or on other sites of the sophorose radical, for example those indicated by the arrows.

The sophorosides therefore consist of a mixture of numerous compounds, in particular isomers and counterparts. The composition of this mixture depends on the nature of the substrate and the fermentation conditions. Reference may be made to document FR-2399438 cited in application FR90 / 16211.

The sophorosides can be used as amphiphilic agents thanks to the presence in the molecule of a hydrophilic part formed by the sophorose group and of a lipophilic part constituted by the fatty acid. The amphiphilic character is highlighted in particular by the surface-active properties, for example, lowering of the surface tension of water (Abe et al., US4297340) or of interfacial tension water-hydrocarbon (Gutnick and Minas, Biochem. Soc. Trans., 22S-35S (1987)), emulsifiers or demulsifiers (Cooper and Paddock, Applied and Environmental Microbiology, 47 (1), 173-6 (1984)), wetting agents , etc.

The properties of the direct fermentation product can be modulated depending on the desired result or application. Indeed, by a judicious choice of the substrate, that is to say more precisely the structure and the molecular mass of the hydrocarbons, fatty acids or fatty acid esters involved in the fermentation manufacturing process. , it is possible to adjust, to some extent, the HLB of the product. The concept of HLB or Hydrophilic-Lipophilic Balance, has been described by Griffin in J. Soc. Cosmetic Chemists, 1, 311-24 (1949). Thus, for example, with an HLB of less than about 8, the product obtained will tend to preferably form water-in-oil emulsions. Above this value, the emulsions formed will preferably be of the oil in water type.

In addition, the direct fermentation product may subsequently be the subject of chemical modifications allowing the structure, and therefore the properties of the majority compounds, to be better adapted to the requirements of the application.

• une désacétylation partielle ou totale du groupement sophorose,
• une délactonisation partielle ou totale. La délactonisation consiste en l'ouverture des cycles lactones (formule (2)), ce qui libère le groupement acide carboxylique.
• une estérification du groupement acide carboxylique par des alcools dont la structure et la masse moléculaire constituent également des paramètres d'ajustement des propriétés. Par exemple, selon le brevet US4297340, le HLB varie de 6 (tensio-actif lipophile) à plus de 20 (tensio-actif très hydrophile) lorsque l'alcool employé pour l'estérification possède un nombre d'atomes de carbone qui passe de 18 (alcool stéarylique) à 1 (alcool méthylique).

The chemical modifications of the direct fermentation product can notably consist of:

• partial or total deacetylation of the sophorosis group,
• partial or total delactonization. The delactonization consists in the opening of the lactone cycles (formula (2)), which releases the carboxylic acid group.
• an esterification of the carboxylic acid group with alcohols whose structure and molecular mass also constitute parameters for adjusting the properties. For example, according to patent US4297340, the HLB varies from 6 (lipophilic surfactant) to more than 20 (very hydrophilic surfactant) when the alcohol used for the esterification has a number of carbon atoms which increases from 18 (stearyl alcohol) to 1 (methyl alcohol).

It should be noted that sophorosides are both fully biodegradable and non-toxic, unlike the surfactants generally used in the technical field of the present invention, whether they are ionic, for example alkylaryl sulfonates, or nonionic, for example, polyethoxylated derivatives. These characteristics represent a very interesting advantage over ecological problems.

The invention will be better understood and its advantages will appear more clearly on reading the text below, from the description of experiments in no way limiting the scope of the invention.

Demonstration of the washing capacity of drill cuttings polluted by hydrocarbons, by sophoroside solutions, is done according to the experimental conditions described below.

• a) des déblais modèles constitués d'une argile (Bentonite Clarsol W 100 fournie par la société Milpark Drilling Fluid Co.) imprégnée d'une huile minérale classique, telle celles utilisées dans la formulation des fluides de forage à base d'huile,
• b) des déblais naturels provenant d'un forage en boue à l'huile.

The washing tests were carried out in the laboratory at 30 ° C on two types of cuttings:

• a) model cuttings consisting of a clay (Bentonite Clarsol W 100 supplied by the company Milpark Drilling Fluid Co.) impregnated with a conventional mineral oil, such as those used in the formulation of oil-based drilling fluids,
• b) natural cuttings from an oil mud drilling.

The sophoroside used is the direct fermentation product, called SO1, and which has not undergone any subsequent chemical modification. It contains 46% by weight of sophoroside in acid form (formula (1)) and 54% by weight of sophoroside in lactone form (formula (2)).

• un alcool éthoxylé ou produit A,
• des nonylphénols éthoxylés ou produits B, ayant des valeurs de HLB comprises entre 8,8 et 16,5.

For the purpose of comparison, the following nonionic surfactants were also tested:

• an ethoxylated alcohol or product A,
• ethoxylated nonylphenols or products B, having HLB values of between 8.8 and 16.5.

The tests were carried out according to the following protocol:
- 1 gram of cuttings, impregnated with oil, is washed with 20 ml of an aqueous solution of washing products comprising either sophorosides or said nonionic surfactants: products A or B. The water used is a reconstituted seawater, close to the North Sea water, the composition of which is given below: Ions Na⁺ K⁺ Ca⁺⁺ Mg⁺⁺ Cl⁻ SO4⁻⁻ Total Concent. (g / l) 11.0 0.68 0.33 1.19 19.6 2.80 35.6

The cuttings and the solution are mixed by stirring for 15 minutes using a magnetic bar. The mixture is then centrifuged at 1500 rpm for 15 minutes, to separate the cuttings from the washing solution. The cuttings are then rinsed with 10 ml of sea water. A second centrifugation is then carried out to remove the rinsing water, followed by a second rinsing. Finally, the mixture is filtered on a Millipore filter of 8 micrometers of mesh opening.

On the cake thus recovered, the determination of the residual oil is carried out by the Rock-Eval pyrolysis method (J. Espitalié et al., Revue IFP, 40 (5), 563-79 (Sept.-Oct. 1985) ). This method consists in heating, in temperature programming, under an inert atmosphere, a small sample of rock of approximately 100 mg, in order to determine the content of hydrocarbons contained in this sample. These hydrocarbons are analyzed using a flame ionization detector.

Table 1 below gives the results of washing the cuttings with a solution of sophoroside in seawater: Table 1 WASHING WITH SOPHOROSIDE SOLUTION Concent. in SO1 MODEL DEBLAIS NATURAL DISCOUNTS (g / l) Residual oil (g / kg) Efficiency (%) Residual oil (g / kg) Efficiency (%) 0 56 83 95 40 0.1 11 97 0.5 11 97 1.0 10 97 74 53 2.5 18 95 75 52 5.0 6.7 98 73 54 10 16 95 67 58 20 7.5 98 WASHING OF CUT MODELS BY PRODUCT A Washing fluid Residual oil (g / kg) Efficiency (%) Sea water 56 83 Seawater and Concurrent Product (g / l) 0.01 34 90 0.02 27 92 0.05 23 93 0.5 9 97 1.00 11 97 2.50 23 93 5.00 20 94 10.0 71 79

In the case of model cuttings, the initial quantity of oil measured is approximately 330 g / kg.

In the case of natural cuttings, the quantity of initial oil measured is approximately 160 g / kg.

Efficiency is the ratio, expressed as a percentage, between the quantity of oil removed from the cuttings by washing and the quantity of initial oil in the cuttings considered.

By comparison and to assess the effectiveness of the SO1 solution, we will find in Table 2 above, the results of washing model cuttings with reconstituted seawater, and a solution of product A in water. sea for different concentrations of the product.

Table 3 above gives the results of washing of actual cuttings, with sea water, with a solution of product A according to two concentrations in sea water and with solutions of products B: B1-B2- B3-B4 and B5 having respectively the following HLB values: 8.8-10.8-12.2-13.3 and 16.5.

These experimental results demonstrate the capacity of an aqueous solution of sophoroside SO1 to wash cuttings polluted by hydrocarbons. It is noted that the efficiency of the SO1 solution is good compared to products conventionally used in the profession.

In addition, after washing, the solutions containing sophorosides show a speed of separation, by simple decantation between the oil and the initial solution, greater in comparison with that of the solutions containing the product A or B. This quality is very advantageous for obtain a good efficiency of the washing process and an optimal re-use of the washing fluid.

Given what has been said above on the possibilities of optimizing the mixture and the structure of sophorosides to obtain defined properties, the use of such solutions has great adaptability to types of pollution, as well as to the kinds of polluted solids.

The washing solutions containing sophorosides according to the invention can have formulations comprising other compounds, for example solvents, flocculants or even other surfactants.

• en diminuant la viscosité de l'huile imprégnant les particules solides et en facilitant ainsi l'action détergente,
• en accélérant la décantation de l'huile lors de la phase de séparation entre l'huile et la solution de lavage.

Indeed, the addition to the solution of a solvent, for example of the cyclohexane or hexane type, or equivalent, will promote the cleaning of the cuttings:

• by reducing the viscosity of the oil permeating the solid particles and thus facilitating the detergent action,
• by accelerating the decantation of the oil during the separation phase between the oil and the washing solution.

The volume concentrations of solvents can be between 10 and 20% of the total volume of the solution.

The addition, in the washing solution, of flocculants of fine clay particles is also recommended. In fact, the clayey cuttings do not or hardly disperse in the oil-based drilling fluid. On the other hand, in contact with the aqueous washing solution, they generally tend to react and swell. It is well known that this swelling causes destabilization and dispersion of the solid particles. This dispersion is unfavorable for cleaning because it increases the specific surface of said particles. The flocculating products therefore have the role in particular of avoiding the dispersion of the particles, which facilitates cleaning and at the same time the separation of the solids from the liquid phase. These products can be, for example, polymers of the anionic or cationic polyacrylamide type, polyethylene oxides, mineral salts or quaternary ammonium salts.

• 1) Séparation des particules solides (déblais) du fluide de forage (phase liquide polluante) par décantation, tamisage, centrifugation, cyclonage ou tout autre système de séparation mécanique. Dans les opérations de forage, cette étape est effectuée par l'installation de l'appareil de forage affectée aux traitements mécaniques des fluides de forage pour extraire les déblais de ces fluides.
• 2) Lavage de la phase solide ainsi extraite par immersion dans un volume approprié de solution de lavage et mélange dans un bac de lavage.
• 3) Séparation, lorsque le temps d'action de la solution de lavage est atteint, des solides lavés de la solution de lavage par passage sur un tamis vibrant.
  La phase solide récupérée peut être rejetée si elle est suffisamment propre, ou soumise à nouveau lavage (deuxième étape).
  La phase liquide est alors constituée notamment par la solution de lavage, du fluide polluant et de particules fines de solides.
• 4) Elimination des particules fines de cette phase liquide, par exemple par centrifugation.
  Ces particules peuvent être ensuite rejetées si elles sont suffisamment propres ou subir un traitement supplémentaire par filtration, procédé industriel connu dans le domaine du nettoyage des déblais.
• 5) Décantation et/ou une centrifugation de la phase liquide résultant de l'opération précédente pour séparer le fluide polluant de la solution de lavage.

The implementation of the method according to the invention may notably include the following steps:

• 1) Separation of solid particles (cuttings) from the drilling fluid (polluting liquid phase) by decantation, sieving, centrifugation, cycloning or any other mechanical separation system. In drilling operations, this step is carried out by installing the drilling device assigned to the mechanical treatment of drilling fluids to extract the cuttings from these fluids.
• 2) Washing of the solid phase thus extracted by immersion in an appropriate volume of washing solution and mixing in a washing tank.
• 3) Separation, when the washing solution has reached the action time, of the solids washed from the washing solution by passing through a vibrating sieve.
  The recovered solid phase can be rejected if it is sufficiently clean, or subjected to a new washing (second step).
  The liquid phase is then constituted in particular by the washing solution, the polluting fluid and fine particles of solids.
• 4) Elimination of fine particles from this liquid phase, for example by centrifugation.
  These particles can then be rejected if they are sufficiently clean or undergo an additional treatment by filtration, an industrial process known in the field of cleaning cuttings.
• 5) Decantation and / or centrifugation of the liquid phase resulting from the previous operation to separate the polluting fluid from the washing solution.

The washing solution is then recycled to the washing tank in step 2. The polluting fluid is either stored or recycled in the drilling fluid.

It will not depart from the scope of this invention, if the method is applied to the cleaning of sands or gravel polluted by hydrocarbons discharged either by oil wells in eruption, or by means of storage or transport. In fact, the efficiency of the process according to the invention is not linked to the size or the nature of the solid particles polluted by hydrocarbons.

Claims (6)

1) A method of cleaning solid particles impregnated with a polluting fluid comprising hydrocarbons, characterized in that said solids are brought into contact with a washing solution comprising sophorosides. 2) Method according to claim 1, characterized in that said solids are drill cuttings. 3) Method according to one of the preceding claims, characterized in that said solution comprises sophorosides in a concentration between 0.1 to 30 g / liter. 4) Method according to one of the preceding claims, characterized in that the washing solution comprises at least one other compound suitable for one of the following functions: adjusting the pH of the solution, dissolving the hydrocarbons, inhibiting swelling and / or dispersion of solid particles. 5) Method according to one of the preceding claims, characterized in that the cleaned solids are separated from said washing solution by at least one of the following means: decantation, sieving, centrifugation, filtration or cycloning. 6) Method according to one of the preceding claims, characterized in that said washing solution is separated from said polluting fluid by decantation and / or centrifugation.