FR2757408A1 - PROCESS FOR OXIDIZING PRETREATMENT OF OLEFIN-BASED SLUDGE-CONTAMINATED DRILLING WASTE - Google Patents

Abstract

The invention concerns a method for the pre-treatment of drillings containing sludge, recuperated at ground level, particularly olefin based synthetic sludge characterised in that it comprises at least an oxidising step using an oxidising agent with an acid pH.

Description

 The present invention relates to a pretreatment method drill cuttings lifted from the well by the sludge, and more particularly large cuttings removed by sieving and remain impregnated with sludge. It relates more particularly to cuttings impregnated sludge containing olefins.

 During a drilling, the sludge plays an essential role; it ensures the return of cuttings from the ground dug at the bottom of the well, their lubrication by coating, and the cooling of the drill bit. At the outlet of the well, the fragments of mineral rock constituting these cuttings are separated from the mud by successive sieving and decantation. The sludge thus screened and decanted can be recycled in the well for a new drilling cycle.

 Along with this recycling of sludge, there is the problem of the recovery and storage of cuttings. If it is already difficult on a production field, it is much more difficult to solve on an oil platform, because the environmental regulatory constraints are much more stringent, especially since it is economically more viable to reject them at sea.

 In addition, this disposal at sea of the cuttings will depend essentially on the nature of the sludge used which is more or less toxic or biodegradable.

 Different types of sludge are used for drilling. These are, first of all, water sludge whose majority organic fraction is based on cellulose, cellulose derivatives and acrylic acid derivatives. These sludges are easily biodegradable and do not cause any potential degradation of the environment.

 Oil sludge is favored economically; they consist essentially of a stabilized inverse emulsion of water in oil, generally hydrocarbons of diesel type, and their rheological properties are adjusted by means of viscosifying, densifying and other additives. However, they represent a very high risk of pollution as organic and toxic.

 A third type of sludge, called substitute sludge, is used mainly to replace oil sludges containing aromatic molecules, but they are still considered too polluting by their organic load. They are formulated either from stabilized emulsion esters or from mixtures of esters and olefins or polyalphaolefins, branched or linear.

 While these sludges have some of the performance close to oil sludge, they are nonetheless slow and / or slightly biodegradable.

 To improve the biodegradation of these sludges, enzymatic treatments from a sludge chemically modifying lipase have been envisaged to improve the biodegradation of ester-based sludges, but such pretreatment is ineffective for sludge-based sludge. olefins or polyolefins.

 The object of the present invention is therefore to accelerate the biodegradation of olefin-based substitution sludges by specific pretreatment of the olefins and polyolefins used, a prerequisite for accelerated biodegradation. It aims to chemically modify the sludge to accelerate its subsequent bacteriological degradation.

 In the context of the present invention, sludge is understood to mean any pure synthetic organic phase containing especially olefins or polyalphaolefins and used as drilling mud, the drilling mud formulated, all cuttings consisting of mud impregnated rocks, and raw sludge. obtained after sieving cuttings, still containing the rock fines.

 The subject of the present invention is therefore a process for the pretreatment of drilling muds recovered on the surface of the soil containing hydrocarbons comprising at least one olefinic bond with a view to their biodegradation, characterized in that it comprises at least one oxidation step of said sludge by means of an oxidizing agent at acidic pH.

 By acidic pH, it is understood a lower pH 4 and preferably between 0 and 1. The treatment process according to the invention can be carried out at ambient temperature. However, it may be favorable to increase this temperature from 20 to over 1000C to increase the kinetics of the reaction.

 In the context of the present invention, the oxidizing agent will preferably be chosen from the group consisting of nitrates, sulphates, chlorates, perchlorates, persulfates, nitrogen oxides and peracetates. Similarly, to reach a pH of less than 4 for the aqueous oxidizing solution, the oxidizing agent is mixed with at least one strong mineral or organic acid such as hydrochloric acid, sulfuric acid, perchloric acid nitric acid, phosphoric acid, trichloroacetic acid.

 In a preferred embodiment of the invention, the oxidizing agent is the nitrate anion and the preferred acid is nitric acid.

This choice is particularly favorable in that the traces of nitrogen products resulting from oxidation by these compounds may constitute a source of assimilable nitrogen by the bacteria used during the subsequent biodegradation.

 In the context of the present invention, the sludge to be treated consists of any organic phase comprising at least one olefinic bond, the rocks impregnated with this organic phase and the sludge recovered after sieving the cuttings. Generally, these sludges to be treated contain from 1 to 10% by weight of hydrocarbon compounds comprising from 8 to 30 carbon atoms, preferably from 12 to 20 carbon atoms, and at least one olefinic bond.

 The preferred oxidizing solution contains a solution of dilute nitric acid with a concentration of less than or equal to 300 g / l.

 After oxidation of the sludge, the treatment according to the present invention comprises the following steps in the particular order given below. Thus, after oxidation, the sludge is separated (for example by centrifugation) from the oxidizing aqueous solution which can thus be recycled.

The solid fraction of the sludge is then neutralized with a basic compound selected from the group consisting of lime and alkaline or alkaline earth salts, especially marine salts or even simply seawater. The last pretreatment operation consists of to reject the oxidized sludge in the sea, the oxidized organic compounds still present in the sludge being biodegraded by the bacteria present in the ocean. These oxidized organic compounds are in the form of carboxylic acids, ketones or readily biodegradable alcohol.

 In the case of an acidic treatment, the treated sludge will comprise only a limited quantity of limestone, preferably not more than 15% by weight, in order to avoid a major dissolution of the cuttock causing a large release of gas, in particular carbon dioxide. .

 A second object of the present invention is the device necessary for the implementation of the method characterized in that it comprises an oxidation capacity (1) in which are introduced respectively by two conduits (2) and (3), the sludge to be treated, the aqueous oxidizing agent solution having a pH of less than 4, the said capacity comprising a third pipe (4) for evacuating the gases formed by oxidation and a fourth pipe (5) for evacuating the oxidizing solution / mixture oxidized sludge to a separation unit (6) comprising a pipe (7) for recycling the oxidizing aqueous solution to the pipe (3) and a pipe (8) directing the oxidized sludge recovered in the neutralization unit (9) fed neutralizing agent by at least one line (10).

 In a preferred embodiment of this device, the gases formed at the time of oxidation are recovered and directed by line (4) to a gas treatment unit (12). When the recovered gases are loaded with nitrogen oxides (NOx), this treatment consists in producing, according to the techniques known per se, from these gases nitric acid which is recycled in the oxidation capacity of the device for avoid evaporation of toxic gases.

 Of course, this method and this device according to the invention are applicable to the treatment of substitution sludges containing olefinic compounds recovered on the surface, in particular those collected on the high seas.

 To illustrate the process of the invention, various figures are given.

 Figure 1 corresponds to the diagram of a device for implementing the invention.

 FIG. 2 represents a curve showing the efficiency of the process of the invention as a function of the temperature and the concentration of the oxidizing solution.

 Figure 3 shows two curves demonstrating the influence of the process on the subsequent biodegradation rate, between pretreated cuttings and untreated cuttings.

 In FIG. 1, the device according to the invention comprises an oxidation capacity (1) comprising two ducts (2) and (3) respectively for the introduction of the sludge to be treated and for the aqueous solution of oxidizing agent of pH below 4. This oxidation capacity comprises a third pipe (4) for evacuation of gases formed by oxidation and a fourth pipe (5) for discharging the oxidizing solution / oxidized sludge mixture to a separation unit (6) for example a centrifuge, comprising a pipe (7) for recycling the oxidizing aqueous solution to the pipe (3) and a pipe (8) directing the oxidized sludge recovered in the neutralization unit (9) supplied with neutralizing agent with least one pipe (10). As neutralizing agents, it is possible to introduce lime or simply sea water.

 The gases formed at the time of oxidation are recovered and directed via line (4) to a gas treatment unit (12) where the gases charged with nitrogen oxides (NOx) are converted into nitric acid in a manner known in the art. either, this acid being recycled via the pipe (14) into the supply pipe (3) oxidizing agent.

 The examples given below are given as an illustration of the invention, without wishing to limit the scope thereof.

EXAMPLE I
The present example is intended to illustrate the oxidation of olefin mixtures by an acidic oxidizing compound.

Two olefin mixtures were tested. These are two base oils used to formulate the corresponding drilling muds
isoteq, marketed by Baker Hughes which is a mixture of internal olefins (IO) in C16 (50%) and C18 (50%) containing a double bond in the C7-C8 position and optionally a methyl group in the C8 position.

- Ultidrill, marketed by Dowell / IDF which is a mixture of olefins called "Linear Alpha Olefine" (LAO) containing unsaturation in the C1 position. Several synthetic LAO blends have been patented by Dowell (Patent WO 9506695). The base oil used in this study consists of C12 (1k), C14 (57%) olefins and
C16 (41k), which corresponds in the Dowell patent to the fluid referenced "C14-C16 LAC".

 The base oil (Ultidrill or Isoteq) is emulsified in a dichloroethane: water mixture. The reaction mixture consists of 7 ml of water, 3 ml of dichloroethane, 250 mmol / l of base oil (0.75 ml of Isoteq or 0.68 ml of Ultidrill), and 36 mg of cetyltrimethylammonium bromide (CTAB ) as a phase transfer agent. The reaction is started by adding various amounts of oxidizing agent. At the end of the reaction, the two phases are separated by decantation after solid liquid extraction using dichloromethane containing, as internal standard, dodecane in a 1/1000 ratio, and analyzed by gas chromatography on a BPX column (apolar) 50m × 0.25mm DI. with temperature gradient. The reactivity of these olefin mixtures was tested for various oxidizing acid mixtures after contact for 24 hours at 800C. The activity of the chemical treatment is estimated by comparing the amount of unoxidized olefins at the end of the reaction with the amount of olefins introduced before the oxidation. The results are given in Table I below.

TABLE I

<tb><SEP> Oil <SEP> from <SEP> base <SEP> Isoteq <SEP> Ultidrill
<tb><SEP> Oxidative <SEP> Solution <SEP> (% <SEP> Degraded) <SEP> (% <SEP> Degraded)
<tb><SEP><SEP> nitric acid <SEP> 65 <SEP> 70
<tb><SEP> (1 <SEP> mol / l)
<tb> acid <SEP> hydrochloric acid <SEP> 0 <SEP> 0
<tb><SEP> (lmol / l)
<tb> acid <SEP> hydrochloric acid <SEP> 35 <SEP> 38
<tb><SEP> (lmol / l) <SEP>
<tb> + <SEP> nitrate <SEP> of <SEP> sodium
<tb><SEP> (mol / 1) <SEP>
<tb><SEP> nitrate <SEP> of <SEP> sodium <SEP> 0 <SEP> 0
<tb><SEP> (1mol / l) <SEP>, <SEP> pH = 7
<Tb>
It can be seen from Table 1 that the internal olefins contained in the Isoteq mixture and the terminal olefins contained in the Ultidrill mixture react with nitric acid (Imol / l) at 800 ° C. This activity does not come from a simple electrophilic addition of a strong protonic acid, HZ, on the double bond, since hydrochloric acid H-Cl under the same reaction conditions does not cause any degradation. The activity observed for nitric acid can be reconstituted by a HCl /
NaN03.

EXAMPLE II
This example describes the influence of temperature and olefin dilution on oxidation.

The operating conditions for dilution and the analyzes after extraction are identical to those described in Example I. The tests are carried out on the only Isoteq base oil: only changes the dilution rates of the oxidizing solutions. The results obtained are given in Table II
TABLE II

<tb><SEP>%<SEP> of degraded <SEP> olefins
<tb><SEP> oxidizing <SEP> solution <SEP> 250C <SEP> 600C <SEP> 700C <SEP> 800C
<tb><SEP> 24h <SEP> 24h <SEP> 4h <SEP> - ~ <SEP><SEP> 24h
<tb><SEP><SEP> nitric acid <SEP> 0 <SEP> 6 <SEP> 0 <SEP>><SEP> 65
<tb><SEP> (2 <SEP> mol / l)
<tb> acid <SEP> nitric (lmol / l) <SEP> 0 <SEP> 3 <SEP> 0 <SEP> 70
<tb><SEP> + <SEP> nitrate <SEP> of <SEP> sodium
<tb><SEP> (mol / 1) <SEP>
<tb> nitric acid <SEP> (2mol / l) <SEP> 0 <SEP> 6 <SEP> 0 <SEP> no
<tb><SEP> + <SEP> nitrate <SEP> of <SEP> sodium <SEP> determined
<tb><SEP> (lmol / l)
<Tb>
The attack of olefins with dilute nitric acid requires activation by a high reaction temperature (800C). For lower temperatures, the reaction rate decreases sharply.

EXAMPLE III
The present example aims to compare the treatment efficiency of dilute nitric acid and well known oxidants such as oxygen peroxide (H2O2) and sodium chlorate (NaOCl), even in the presence of oxidation catalysts. . Table III below includes the reaction conditions and the results obtained.

TABLE III

<tb><SEP> Oil <SEP> from <SEP> base <SEP> Isoteq <SEP> Ultidrill
<tb><SEP> Oxidative <SEP> Solution <SEP> (% <SEP> Degraded) <SEP> (% <SEP> Degraded)
<tb> a <SEP> NaOCl <SEP> (250mmol / l) <SEP><<SEP> 1 <SEP> c <SEP> 1 <SEP>
<tb> b <SEP> NaCCl <SEP> (250mmol / l) <SEP><<SEP> 1 <SEP><1
<tb><SEP> + TPA-Fe <SEP> (5mmol / l)
<tb> C <SEP> H202 <SEP> (500 <SEP> mmol / l) <SEP> 0 <SEP> 0
<tb> d <SEP> H202 <SEP> (500mmol / l) <SEP> 0 <SEP> 0
<tb> + <SEP> Fe (II) <SEP> (25mmol / l)
<tb><SEP> + <SEP> HC1 <SEP> (pH3)
<tb><SEP> e <SEP> nitric acid <SEP><SEP> 65 <SEP> 70
<tb><SEP> (lmol / l)
<Tb>
dichloroethane / acetonitrile / water mixture, 5: 4: 1; 250 mmol / l olefins, 10 mmol / l CTAB, T = 400C or 700C, 24h.

 b same conditions as a, TPA = tris-N-methylpyridine-amine.

 dichloroethane / water mixture, 10:10; 250 mmol / l olefins; pH = 3; T = 700C; 24.

 d Same conditions as c, Fe (II) = Fe (SO4) 2 (NH4) 2.

 e Conditions of Example I.

 It is found that these oxidants are not effective compared to the diluted nitric acid.

EXAMPLE IV
The present example tends to illustrate the oxidation of olefins trapped in cuttings, these cuttings having been impregnated with drilling muds and more particularly by a sludge containing isoteq oil marketed by Baker-Hugues.

 In the present example, cuttings A are drilled in a clay matrix mineral layer consisting of quartz, barite, albite, pyrite, microcline and kaolinite, impregnated with 6% of isoteq oil.

 The cuttings A, after having been finely ground with the pestle, is suspended in water at a rate of 35% by weight, corresponding to a level of 2% by weight of impregnated isoteq oil. The stirring is carried out by means of a magnetic bar, then the temperature of the suspension is brought to 800C. The addition of the oxidizing solution marks the beginning of the reaction; after addition, stirring at 80 ° C is maintained for two hours.

TABLE IV

<tb><SEP> Oxidative <SEP><SEP>%<SEP> solution of olefins
<tb><SEP> degraded
<tb><SEP><SEP> nitric acid <SEP> 85
<tb><SEP> (mol / 1) <SEP> (6.5%)
<tb><SEP> perchloric acid <SEP><SEP>
<tb><SEP> (lmol / l) <SEP>
<tb><SEP> acid <SEP> sulfuric acid <SEP> 0
<tb><SEP> (mol / 1) <SEP>
<tb> acid <SEP> hydrochloric acid <SEP> 0
<tb><SEP> (mol / 1) <SEP>
<tb> acid <SEP> hydrochloric acid <SEP> 60
<tb> (lmol / l) <SEP> + <SEP> nitrate <SEP> from
<tb><SEP> sodium <SEP> (lmol / l)
<tb><SEP> nitrate <SEP> of <SEP> sodium <SEP> 0
<tb><SEP> (lmol / l), <SEP> pH = 7
<Tb>
The results of this Table IV confirm that the olefins trapped in the cuttings are degraded by the action of dilute nitric acid (lmol / l, 6t) at 800C.

As in Example 1, the action of strong acids such as hydrochloric acid, sulfuric or perchloric acid alone is zero under the conditions of the reaction. The activity observed for nitric acid can be reconstituted with a HCl / NaNO3 mixture. Note that these results are significantly better than in Example I.

EXAMPLE V
The purpose of this example is to illustrate the effect of temperature on the nitric acid treatment efficiency of olefins entrapped in drill cuttings, in particular A cuttings impregnated with isoteq oil as described in Example IV.

TABLE V

<tb><SEP> concentration in <SEP>% <SEP> of <SEP> degraded olefins
<tb><SEP> HNO3
<tb><SEP> 20 <SEP> OC <SEP> 60 <SEP> OC <SEP> 80 <SEP> OC
<tb><SEP> 1.2 <SEP> mol / l <SEP> 15 <SEP> 90 <SEP> 90
<tb><SEP> 3 <SEP> mol / l <SEP> 90 <SEP> 96 <SEP> 97
<tb> a <SEP> 3 <SEP> mol / l <SEP> + <SEP> NO2 <SEP> 97 <SEP> 98 <SEP> 98.5
<Tb>
a Solution of dilute nitric acid, doped by a sparge of nitrous vapors NOx.

 The results in this table show that the degradation of the olefins impregnated in the cuttings (suspension containing 2% by weight of olefins) is efficiently carried out at ambient temperature for a nitric acid concentration of 3 mol / l (20W). It is therefore found that it is possible to degrade olefins even at room temperature but with a higher concentration of nitric acid. In addition, when the 3 mol / l nitric acid solution is doped by a sparging of nitrous vapors, the degradation of the olefins is more extensive.

 Comparing these results with those of Example I concerning the degradation of the oils, one operates at a much lower temperature for almost identical reaction kinetics.

 In terms of kinetics, FIG. 2 shows the efficiency of the method of the invention as a function of time.

Each item listed, was obtained by stopping the reaction at the desired time. This reaction is stopped by immersing the reaction mixture in ice and then extraction of the residual olefins with dichloromethane and analysis by gas chromatography as described in Example I. It can be seen from this figure that the treatment with acid diluted nitric acid is very effective since after thirty minutes of reaction more than 80% of the starting olefins are degraded.

EXAMPLE VI
The purpose of the present example is to compare the treatment efficiency according to the invention compared with conventional oxidizing treatments on impregnated cuttings, in particular cuttings A impregnated with isoteq oil as described in Example IV.

One operates according to the invention as described in the example
IV. The results are summarized in Table VI below.

TABLE VI

<tb><SEP> Oxidative <SEP><SEP>%<SEP> solution of olefins
<tb><SEP> degraded
<tb><SEP> a <SEP> NaCCl <SEP> (250mmol / l) <SEP><<SEP> 1
<tb><SEP> b <SEP> H2 2 <SEP> (2.5mol / l) <SEP><1
<tb><SEP> C <SEP> H2C2 <SEP> (2.5mol / 1) <SEP><1
<tb> + complex <SEP> of <SEP> Fe (25mmol / l)
<tb><SEP> + <SEP> HC1 <SEP> (pH3)
<tb><SEP> d <SEP><SEP> nitric acid <SEP> 85
<tb><SEP> (mol / 1) <SEP> (6.5%)
<Tb>
at T = 700C, reaction time = 1h
b T = 500C, reaction time = 1h
c T = 500C, reaction time = 1h, the iron complexes tested being Fe (SO4) 2 (NH4) 2, TPA-Fe, iron oleate
d conditions of Example IV.

 This table shows that the two conventional oxidants, even in the presence of catalysts, do not allow to oxidize olefins impregnated in cuttings unlike nitric acid.

EXAMPLE VII
The present example aims to describe the efficiency of the method according to the invention for different types of cuttings.

 In addition to the cuttings A described in Example IV, two other types of cuttings B and C were studied.

 The cuttings B are drilled in a clay layer of composition similar to that of cuttings A but also comprising calcite.

 The cuttings C are drilled in a mineral layer containing more than 80k in weight of limestone.

The results of these tests for different types of impregnation of these cuttings are given in the table.
VII below.

TABLE VII

<tb><SEP><SEP>%<SEP> Suspension of Degraded <SEP> Olefins
<tb><SEP> Cuttings <SEP> A <SEP> (6% <SEP> isoteq) <SEP> 90
<tb><SEP> Cuttings <SEP> B <SEP> (3.5 <SEP>% <SEP> isoteq) <SEP> 92
<tb> a <SEP> Clear <SEP> B <SEP> (3.5 <SEP>% <SEP> isoteq) <SEP> + <SEP> 3.5 <SEP>% <SEP> 88
<tb><SEP> oil <SEP> Ultidrill
<tb><SEP> Cuttings <SEP> C <SEP> (6 <SEP>% <SEP> Ultidrill) <SEP> 4
<tb><SEP> b <SEP> 50% <SEP> Clear <SEP> B <SEP> + <SEP> 50% <SEP> Clear <SEP> C <SEP> 5
<Tb>
a suspension of cuttings B, impregnated with 3.5 kg by weight of isoteq and to which was added 3.5 kg by weight of ultidrill oil in relation to the quantity of cuttings
b Suspension comprising 35 W by weight of cuttings consisting of 50 k by weight of cuttings B, impregnated with 3.5% by weight of isoteq and 50 W by weight of cuttings C impregnated with 6% by weight of ultidrill oil.

 The method according to the invention, with nitric acid is also effective with respect to the degradation of olefins impregnated on two cuttings from two different clay layer drilling. On the other hand, on calcareous cuttings, the process according to the invention is not so effective because of the rapid rise in pH. It is preferable to have a limestone level in the lowest possible mineral matrix, less than 30%.

EXAMPLE VIII
The present example is intended to illustrate the effectiveness of the process according to the invention for accelerating the biodegradation operations of the olefinic hydrocarbons trapped in cuttings.

 Two samples of cuttings A containing 6% of isoteq oil were compared. The first, Al, was treated by the process of the invention as described in Example 5 (Temperature 200C, 3M HNO 3) and then neutralized with seawater.

The second, A2 did not undergo any oxidation.

 Several reactors with a capacity of 1.51 are filled with sediments containing an unsuitable bacterial flora (109 bacteria / g of sediment) having a microaerophilic layer 1 to 2 mm thick, below which they are anaerobic. Al and A2 are buried to a depth of 2 cm in these sediments and are kept in incubation for twenty days. In these reactors, the cuttings are therefore both in the micro-aerophilic layer and in anaerobiosis. They undergo degradation by mainly denitrifying and sulphate-reducing bacteria, then methanogens.

 Samples were taken every five days to measure the amount of oxidized olefins. The results are given in Table VII below and the oxidative degradation curves of cuttings A1 and A2 are given in FIG.

TABLE VIII

<tb> Time <SEP> (days) <SEP> Cuttings <SEP> no <SEP> oxidized <SEP> Washed <SEP> Oxidized <SEP> washed
<tb><SEP> (mg <SEP> C) <SEP> A2 <SEP> (mg <SEP> C) <SEP> A1
<tb><SEP> O <SEP> 0 <SEP> O <SEP>
<tb><SEP> 3 <SEP> 10 <SEP> 40
<tb><SEP> 5 <SEP> 15 <SEP> 42
<tb><SEP> 7 <SEP> 20 <SEP> 52
<tb><SEP> 10 <SEP> 27 <SEP> 67
<tb><SEP> 12 <SEP> 32 <SEP> 69
<tb><SEP> 14 <SEP> 34 <SEP> 73
<tb><SEP> 17 <SEP> 39 <SEP> 83
<tb><SEP> 19 <SEP> 41 <SEP> 87
<tb><SEP> 20 <SEP> 43 <SEP> 89
<Tb>
As the rate of biodegradation corresponds to the slope of each of the curves of FIG. 3, it appears clearly that the cuttings A1 which underwent the oxidative pretreatment according to the process of the invention are more easily biodegraded than the cuttings A2 that have not been subjected. to this pretreatment.

Claims (12)

REVENDICATTONS 1 - Pretreatment method of organic drilling muds  syntheses recovered from the soil surface, in particular  sludges containing hydrocarbons with  less an olefinic bond, characterized in that  comprises at least a first oxidation step of the  said sludge by means of an oxidizing agent at acidic pH. 2 - Process according to claim 1 characterized in that  the oxidation step is carried out at a pH below 4 at  a temperature between ambient and over 1000C. 3 - Process according to one of claims 1 and 2  characterized in that the oxidizing agent is selected from  group consisting of nitrates, sulphates,  chlorates perchlorates, persulfates, oxides  nitrogen and peracetates. 4 - Method according to one of claims 1 to 3  characterized in that the oxidizing agent is mixed with  minus one of the strong mineral or organic acids, chosen  in the group consisting of hydrochloric acid,  sulfuric acid, nitric acid and acid  trichloroacetic. 5 - Process according to one of claims 1 to 4  characterized in that the oxidizing agent is the anion  nitrate and the acid is nitric acid. 6 - Process according to one of claims 1 to 5  characterized in that the oxidizing solution is  consisting of a nitric acid solution diluted  water at a concentration less than or equal to 300g / l. 7 - Method according to one of claims 1 to 6  characterized in that the sludge belongs to the group  constituted by any organic phase containing  hydrocarbons comprising at least one bond  olefinic, rocks impregnated with this phase  organic matter and the sludge recovered after sieving  cuttings. 8 - Method according to one of claims 1 to 7  characterized in that the sludge contains from 1 to 10% by  olefinic compounds of the group consisting of  the olefins of carbon chain length varying from 8  at 30 carbon atoms, and preferably from 12 to 20  carbon atoms. 9 - Process according to one of claims 1 to 8  characterized in that the molar ratio of the agent  oxidant and olefin is greater than or equal to 5/1  (mol / mol), preferably equal to 10/1 (mol / mol). 10 - Method according to one of claims 1 to 9  characterized in that it comprises in addition to the step  oxidation of the sludge, several stages of treatment  consists in  - separate the oxidized cuttings in suspension from the  oxidizing solution that is recycled,  - neutralize the oxidized cuttings with a basic compound  selected from the group consisting of mineral salts  such as salts present in seawater, and by  lime,  - finally, reject the oxidized cuttings.  il - Device for implementing the process defined by  one of the claims of 1 10 characterized in that  comprises an oxidation capacity (1) in which are  introduced respectively by two ducts (2) and (3),  the cuttings crushed to be treated, the aqueous solution  oxidizing agent having a pH of less than 4, the said capacity  comprising at its base a third pipe (4)  of the gases formed by oxidation and a  fourth pipe (5) for evacuating the solution mixture  oxidizing / oxidized cuttings to a separation unit (6)  comprising a pipe (7) for recycling the solution  oxidizing water towards the pipe (3) and a pipe  (8) directing the cuttings recovered in a unit of  neutralization (9) supplied with neutralizing agent by  at least one pipe (10). 12 - Device according to claim 11 characterized in that  that the gases recovered by the pipe (4) are directed  to a gas treatment unit (12). 13 - Application of the process according to one of the claims  from 1 to 10 in the treatment of substitute sludge  loaded with cuttings, recovered from the surface  soil, especially those collected at sea.