Oil-based drilling fluid comprising a temperature-stable and non-polluting emulsifying system.

(54) Title: OIL-BASED WELL FLUID INCLUDING A TEMPERATURE-STABLE, NON-POLLUTANT EMULSIFYING SYSTEM.

(54) Title: OIL-BASED DRILLING FLUID COMPRISING A TEMPERATURE-STABLE AND NON-POLLUTING EMULSIFYING SYSTEM.

(57) Summary

The invention relates to a temperature-stable and toxicity-free well fluid particularly adapted for high pressure / high temperature drilling, comprising an emulsifying system, which includes at least one alkoxylated, polyalkoxylated or non-alkoxylated superamid, optionally associated with a non-ionic cosurfactant. The oil-based well fluids that comprise such a system, by obtaining temperature-stable inverse emulsions, can be used at temperatures up to 200YC.

(57) Abstract

The invention concerns a temperature-stable and toxicity-free drilling fluid particularly adapted to high pressure / high temperature drilling, comprising an emulsifying system, itself including at least an alkoxylated, polyalkoxylated or non-alkoxylated superamide, optionally associated with a non-ionic cosurfactant . The oil-based drilling fluids comprising such a system, by obtaining temperature-stable reverse emulsions, can be used at temperatures up to 200 C.

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(12) DEMANDE INTERNATIONALE PUBL1ÉE EN VERTU DU TRAITE DE COOPÉRAT1ON EN MATIERE DE BREVETS (PCT) (19) Organization Mondiaie de la Propriété Intellectuelle

Bureau intemational (43) Date of publication Internationale 13 décembre 2001 (13.12.2001)

<img file="MXPA02012012A_D0002.tif" />

IIIIIM (10) Number of publication internationale

WO 01/94495 Al (51) Classification internationale des brevets⁷: C09K 7/06, C08G 65/26, 65/329, B01F 17/22 (21) Number of the international claim:

PCT / FR01 / 01722 (71) Deposants (pour tous les États designés sauf US): INSTITUT FRACAIS DU PETROLE [FR / FR]; 1 et 4 avenue Bois Préau, 'F-92852 Rueil-Malmaison Cedex (FR). RHODIA CHIMIE (FR / FR); 40 Rue Haie Coq, F-93306 Aubervilliers Cedex (FR).

(22) Date de dépót intemational: 5 June 2001 (05.06.2001) (25) Langue de dépót: franqais (26) Langue de publication: franjáis (30) Données relative á la priorité:

00/07198 6 June 2000 (06/06/2000) FR (72) Inventeurs; et (75) Inventeurs / Déposants (pour US seulement): DALMAZZONE, Christine (FR / FR); 2 rae Saint Symphorien, F-78000 Versatile (FR). AUDIBERT-HAYET, Annie [FR / FR]; 10, place Blanche de Castille, F-78290 Croissy sur Seine (FR). LANGLOIS, Bruno [FR / FR]; 32. avenue Emile-Zola, F-91700 Sainte Geneviéve des Bois (FR). TOUZET, Sylvie [FR / FR]; 81, avenue Saint-Exupéry, F-92160 Antony (FR).

[Suite sur la page ¡vivante] = (54) Title: OIL-BASED DRILLING FLUID COMPRISING A TEMPERATURE-STABLE AND NON-POLLUTING EMULSI = FYING SYSTEM m (54) Titre: FLUIDE DE PUITS A BASE D'HUILE COMPRENANT UN SYSTEME EMULSIFIANT STABLE IN TEMPERA = TURE ET NON POLLUANT

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WO 01/94495 Al +20 0 -20 -40 -60 * 80 * 100 (57) Abstract: The invention concerns a temperature-stable and toxicity-free drilling fluid particularly adapted to high pressure / high temperarme drilling, comprising an emulsifying system , itself including at least an alkoxy iated, polyalkoxylated or non-alkoxylated superamide, optionally associated with a non-ionic cosurfactant. The oil-based drilling fluids comprising such a system, by obtaining temperature-stable reverse emulsions, can be used at temperatures up to 200 'C.

[Suite sur la page suivante]

OIL-BASED WELL FLUID INCLUDING A SYSTEM. TEMPERATURE STABLE EMULSIFIER AND NON-POLLUTANT

Description of the Invention

The present invention relates to the use of a non-toxic emulsifying system capable of stabilizing a water-in-oil emulsion, as well as at elevated temperatures, for the formulation of oil-based well fluids used under HP / HT drilling conditions ( high pressure / high temperature), i.e. up to about 200 ° C.

When drilling a well, and more particularly an oil well, it is mandatory to use a well fluid, in particular a drilling fluid, also called "drilling mud", to transport the debris generated by drilling to the surface. This well fluid must also allow the cooling and lubrication of the tool, support the walls of the well, exert a sufficient counter pressure and, lastly, avoid the deterioration of the formation.

Two main types of well fluids are used: water-based or 'aqueous mud' fluids and oil-based or 'oily mud'. Aqueous muds are much more economical and ecological than oily muds, but the latter have obvious operational advantages, REF .: 143741 particularly in the case of drilling very deep wells (HP / HT); good friction reduction, inert fluid with respect to the rocks of the formation and particularly the clays, little deterioration of the production area, etc.

Typically, oily slurries are water-in-oil emulsions, containing 5 to 40% by volume of a dispersed saline aqueous phase. These inverse emulsions mainly comprise three types of compounds:

• emulsifiers to ensure the stability of the emulsion;

• organophilic clays to control rheological properties, and more particularly thixotropy;

• thickening agents, such as barium sulfate (or barite), to adjust the density of the fluid.

Two major problems arise with regard to the use of oily muds for very deep drilling:

• a problem of stability in the temperature of the emulsions: the emulsifiers ensure that the stability of the emulsions must, in effect, keep the water droplets in emulsion up to temperatures close to 200 ° C. If the emulsion is separated by coalescence from the water droplets, the fluid loses its rheological properties and, above all, there is a risk of seriously damaging the formation;

• an environmental problem, the emulsifiers used must not only be effective, but also as less toxic as possible.

In general, moving from traditional systems based on oils rich in aromatics of the diesel type to formulations based on oils that are less harmful to the environment, the sludge becomes less stable with temperature. This may be due to the stability with temperature of the oil used, such as vegetable asters, or to the emulsifying system that does not allow a stability of the emulsion at the highest temperatures. The limit is around 150 ° C, which often leads to filtration control problems at elevated temperatures. This loss of properties is the origin of the problems of damage to the deposits (water infiltration) and of important losses of productivity of the well drilled with these fluids.

In accordance with the present invention, it is proposed to use an emulsifying system in well fluids that ensures the stability of the oily mud up to approximately 200 ° C and that, in addition, presents a reduced toxicity.

The main emulsifier consists of at least one alkoxylated, polyalkoxylated or non-alkoxylated superamide, as described in the French patent application FR-A-2 7 98 387 under the name RHODIA CHIMIE, published on March 16, 2001.

By the term "superamides", the family of alkanolamides obtained by transamidification with at least one alkanolamine of at least one ester of fatty acid and of a monoalcohol or of an oil of vegetable or animal origin (triglyceride) is designated in a general way. . There are alkanolamides obtained by amidification of a fatty acid. However, these are obtained in the form of a mixture comprising amide, amine, fatty acid and water. Typically, in these alkanolamides, the amide concentration is equal to 60-65% by weight. In contrast, in the case of superamides, the final mixture generally contains more than 90% by weight of amide, which is an obvious advantage. Indeed, during the synthesis of the superamid, the alcohol from the developed fatty acid ester is distilled during the course of the reaction, making the latter complete. In this way, the superamides manufactured according to the process described in the aforementioned patent application contain a minimum of residual amines and are thus less toxic than the equivalent amides manufactured according to the classical processes known to man from The matter.

Thus, the invention proposes an oil-based well fluid, stable with temperature, non-eco-toxic and particularly adapted to drilling at high pressure / high temperature, which comprises an aqueous phase dispersed in an immiscible continuous phase and characterized because it comprises an emulsifying system which itself comprises at least one alkoxylated, polyalkoxylated or non-alkoxylated superamide, comprising a proportion greater than 90% of at least one compound that corresponds to one of the general formulas:

[R ^ CON (R²) -CH2CHR³-O- (CHR⁴-CHR⁵O) m- (CH2CH₂O) n] p^x (TO GO¹-CON- [CH2CHR³-O- (CHR⁴-CHR⁵O) m- (CH2CH₂O) n^x] ₂ (II) in which:

- R¹ represents a hydrocarbon radical, in particular aliphatic, at C7-C30, preferably at C10-C22, linear or branched, saturated or not, optionally bearing at least one hydroxyl group;

- R² represents a hydrogen atom or a hydrocarbon radical in Ci-C₄;

- R³ represents a hydrogen atom or a hydrocarbon radical at C1-C4;

- R⁴ and R⁵, identical or not, they represent a hydrogen atom or an alkyl radical comprising 1 or 2 carbon atoms, provided that at most one of these two radicals is a hydrogen atom;

- X represents a hydrogen atom, a Ci-Ce hydrocarbon radical, a phosphate, carboxylate, sulfate or sulfonate group;

- m is a mean number between 0 inclusive and 20;

- n is a mean number between 0 inclusive and 50; and

- p is worth 1 or 2, according to the nature of X.

The case where n = 0 and m = 0 is a particular case of the invention. The corresponding superamides are not polyalkoxylated superamides.

The radical R¹ is more particularly a hydrocarbon radical, linear or branched, saturated or not, in Ci₀C22, which derives from a saturated or unsaturated fatty acid, optionally bearing at least one hydroxyl group. Preferably, the radical comprises at least one ethylenic unsaturation.

As examples of Cio-C saturated fatty acids_?2Among others, lauric, capric, decanoic, stearic, isostearic, gadollenic and myristic acids can be mentioned. As the C10-C22 fatty acids that carry at least one ethylenic unsaturation, mention may be made, without intention of limitation, of the linderic, myristoleic, palmitoleic, oleic, petroselenic, doeglyic, erucic, linoleic, linolenic, isanic, stearodic, arachidonic acids. , 5 quipanodic and ricinoleic. Among the acids mentioned above, the radical R¹ it is derived more particularly from fatty acids chosen from palmitoleic, oleic, petro-oleic, erucic, linoleic, linolenic and ricinoleic acids.

Radicals R² and R³, identical or not, each represents a hydrogen atom or a hydrocarbon radical at Ci ~ C4, which is more particularly saturated. Preferably, the radicals R² and R³ each represents a hydrogen atom, a methyl, ethyl, propyl or isopropyl, butyl or isobutyl radical.

Radicals R⁴ and R⁵ each is preferably chosen from hydrogen or the methyl radical, provided that one of these, but not both simultaneously, represents a hydrogen atom. Thus, according to this preferred embodiment, the corresponding radical 20 is derived from propylene oxide.

As already indicated above, m, which represents a mean number, varies between 0 inclusive and 20. Likewise, n, which represents a mean number, varies between 0 inclusive and 50.

The compounds according to the present invention are preferably in the non-ionic form. The radical

X thus represents a hydrogen atom or a hydrocarbon radical in Ci-C₆. In this case, the value of the coefficient p is 1.

As indicated above, the superamides used in the invention are obtained by transamidification of a fatty acid and monoalcohol ester or an oil of vegetable or animal origin (triglyceride), by means of an alkanolamine such as monoethanolamine or diethanolamine. . The use of superamides derived from diethanolamine, optionally alkoxylated or polyalkoxylated and corresponding to the formula (II) mentioned above, can be advantageous according to the invention.

As examples of oils of vegetable origin, mention may be made, among others, of rapeseed, sunflower, peanut, olive, walnut, corn, soybean, flax, hemp, grape seeds, copra, palm, cotton grains, babassu, jojoba, sesame, castor bean and coriander. Rapeseed oil is preferred.

As oils of animal origin, mention can be made, among others, of sperm whale, dolphin, whale, seal, sardine, herring, shark, cod liver, beef leg, as well as beef, pork, horse and beef fats. lamb (tallow).

Finally, superamides can be obtained from products (esters of fatty acids and monoalcohols) that result from alcoholysis reactions, more precisely from methanolysis, of the oils mentioned above. These products are thus alkyl esters, more precisely methyl esters, formed on the fatty acid mixtures contained in these oils.

The purity of the amides used in the emulsifying systems used in the well fluids of the invention (more than 90% by weight) confers them, by comparison with the lower purity amides, for example that have amounts in pure amides of the In the order of 60-65%, properties improved, not only from the point of view of toxicity, but also from the point of view of the stability of the emulsions.

In preparing the oil-based well fluids according to the invention, the continuous phase or the oily phase can contain all types of base oil commonly used to form this type of fluid: for example diesel, crude oil, essence, kerosene or, as is now recommended for reasons of environmental protection, low toxicity hydrocarbon cuts, as defined (Ultidrill® from DOWELL SCHLUMBERGER) or n -alkanes (XP07® from BAROID or EDC 95-11® from Total Solvants), whose main characteristic is not containing or containing very few aromatic hydrocarbons, which are mainly responsible for the strong toxicity of classic base oils.

The concentration in the base oil can be between 60 and 95%, preferably between 70 and 90% by volume. The amount of water used for the manufacture of such fluids is between 5 and 40%, preferably between 10 and 30%, by volume of fluid. This aqueous phase can be fresh water, salt water such as sea water or a brine. The presence of strong concentrations in NaCl, CaCl₂, CaCO₃or CaSO₄ it has no negative effect on the stability of the produced emulsion, the emulsifying agent being non-ionic, therefore not very sensitive to the presence of salts.

In the well fluids of the invention, superamides can be found alone or in mixtures.

The main emulsifier as defined above is preferably used with a cosurfactant, preferably nonionic, such as for example a fatty acid, a dicarboxylic acid or a carboxylate. By way of example, mention may be made of the fatty acids of tall oil.

The exact composition of the well fluid depends on the particular application for which this fluid is intended. However, in most cases, concentrations in emulsifiers ranging from 10 to 30% by volume relative to the aqueous phase will be sufficient to obtain satisfactory results. The co-surfactant can represent, for example, from about 40 to 90% by weight of the emulsifying system.

The fluid may contain 5 to 25% by weight of lime, 1 to 15% by weight of organophilic treated clay (such as benthone) and at least one thickening agent such as barium sulfate (or barite), in a enough to achieve a density of about 2.4. It can also contain up to about 10% by weight of filtrate reducer. It is still possible to add a glycol, for example ethylene glycol, a polyglycol, glycerol or a polyglycerol, for example in a proportion of 5 to 40% by weight relative to the emulsifying system.

Well fluid prepared in this way can be used for drilling, completion or workover of a well by circulating it in sufficient quantity to obtain the investigated results.

The stability of the emulsions and of the well fluids (particularly of drilling muds) according to the invention can be tested in different ways: stability tests in specimens also called "bottle tests" on primary emulsions at different temperatures; API electrical stability tests on complete sludge before and after aging; and HP / HT filtration tests before and after aging. The calorimetric measurements carried out in DSC before and after aging, carried out on complete sludge, also make it possible to quantify the influence of aging in temperature on the size of the emulsion droplets.

The following examples illustrate the invention without limiting the scope. Unless otherwise indicated, the percentages are given by weight.

In these examples, the emulsifying systems defined below were used:

- TAI: commercial system: Interdrill Emul HT® and Interdrill LORM® (88% -12% by weight) used for comparison.

- TA2 (according to the invention): mixture of 35% by weight of superamide SAI and 65% by weight of fatty acid. The superamid SAI results from the reaction of one mole of rapeseed oil with 2.5 moles of diethanolamine. The fatty acid is a tall oil fatty acid sold under the brand name Résinoline BD2® by the company DRT-GRANEL. It contains in particular 48 to 55% by weight of oleic acid and 30 to 40% by weight of linoleic acid, with a maximum amount of palmitic and stearic acids of 3% by weight and a maximum amount of linolenic acid of 2% by weight .

- TA3 (according to the invention): mixture of 50% by weight of superamide SA2 and 50% by weight of fatty acid (Résinoline BD2®). Superamide SA2 results from the reaction of one mole of rapeseed methyl ester with 1 mole of monoethanolamine.

- TA4 (according to the invention): mixture of 20% by weight of superamide SA3 and 80% by weight of fatty acid (Résinoline BD2®). The superamid SA3 results from the reaction of one mole of high-cup rapeseed methyl ester of erucic acid (C₂₂) with 1 mole of monoethanolamine.

- TA5 (according to the invention): mixture of 50% by weight of superamide SA4 and 50% by weight of fatty acid (Résinoline BD2®). The superamid SA4 results from the reaction of one mole of high-cup rapeseed methyl ester of erucic acid with 1 mole of monoethanolamine, followed by the reaction of the formed amide (SA3) with 1 mole of propylene oxide.

<td>TA6</td><td>(of</td><td>agree with</td><td>the</td><td>invention): mix</td><td>of</td><td> 20%</td><td>in</td>

<td>weight</td><td>of</td><td>superamid</td><td>SA3</td><td>defined above</td><td>and</td><td> 80%</td><td>in</td>

<td>weight</td><td>of</td><td>fatty acid</td><td colspan="2">(Résinoline BD2®). This</td><td colspan="2">mixture</td><td>I know</td>

adds 25% by weight, in relation to the emulsifier, of glycerol, optimized by the high amount of solids in the formulations.

TA7 (according to the invention): mixture of 50% by weight of superamide SA3 defined above and 50% by weight of fatty acid (Résinoline BD2®). This mixture is added 16% by weight, in relation to the emulsifier, of glycerol, optimized by the high amount of solids in the formulations.

- TA8 (according to the invention): mixture of 50% by weight of superamid SAI defined above and 50% by weight of fatty acid (Résinoline BD2®). This mixture is added 16% by weight, in relation to the emulsifier, of glycerol, optimized by the high amount of solids in the formulations.

Example 1: Stability test in test tubes or "bottle tests" on primary emulsions.

Emulsifiers were first evaluated on simplified systems or primary emulsions, relative to a commercial emulsifier system (Interdrill Emul HT® and Interdrill LORM® from DOWELL-SCHLUMBERGER).

Formulation:

- Base oil: Ultidrill® mineral oil

- Brine: water at 20% by weight of CaCl₂

- Emulsifying systems used: TAI, TA2, TA3 and

TA5.

The total amount of emulsifiers was varied from 3 to 15% by weight relative to the volume of brine.

The emulsifiers are solubilized in 56 ml of oil and mixed for 2 min at 7200 trs / min with a Silverson mixer. Brine (14 ml) and lime (1.4 g of Ca (OH)₂) are added with mixing and stirring is maintained for 15 min at 7200 trs / min. The 70 ml of the mixture is then poured into a 100 ml graduated cylinder. The stability of the emulsion is observed after 2 hours and after 24 hours.

The results, expressed as a percentage of emulsified phase in relation to the initial volume, are shown in the table below.

Table 1

<td></td><td colspan="4">% emulsion after 2 hours</td><td colspan="4">% emulsion after 24 hours</td>

<td>Emulsifier</td><td>TAI</td><td>TA2</td><td>TA3</td><td>TA5</td><td>TAI</td><td>TA2</td><td>TA3</td><td>TA5</td>

<td>3% by weight</td><td> 39</td><td> 65</td><td> 99</td><td> 67</td><td> 31</td><td> 49</td><td> 86</td><td> 50</td>

<td>7.5% by weight</td><td> 48</td><td> 97</td><td> 99</td><td> 96.4</td><td> 33</td><td> 66</td><td> 94</td><td> 52.9</td>

<td>15% by weight</td><td> 86</td><td> 99</td><td> 100</td><td> 97.2</td><td> 40</td><td> 97</td><td> 99</td><td> 62</td>

It is found that the emulsifying systems according to the invention make it possible to obtain a stability of the primary emulsion that is much more important than the comparative system. The formulation comprising the TA3 emulsifying system according to the invention gives the best results.

Example 2: Stability test in test tubes or "bottle tests" on primary emulsions.

The effect of aging of the emulsions at atmospheric pressure temperatures between 20 and 70 ° C was also observed on various emulsifying systems.

Formulation:

- Base oil: Ultidrill® mineral oil (Hl) or EDC 95-11® (H2)

- Brine: water at 20% by weight of CaCl₂

- Emulsifying systems used: TAI, TA3 and TA4.

The results are represented in the table below.

Table 2

<td>Oil</td><td colspan="3">Hl</td><td colspan="4">H2</td>

<td>System emulsifier</td><td>TAI</td><td>TA3</td><td colspan="2">TA4</td><td>TAI</td><td>TA3</td><td>TA4</td>

<td>Stability at 20 ° C</td><td> &lt;30'</td><td>&gt; 96 h</td><td colspan="2">&gt; 96 h</td><td> &lt;30'</td><td>&gt; 96 h</td><td>&gt; 96 h</td>

<td>Stability at 50 ° C</td><td> &lt;30'</td><td>&gt; 1 h</td><td colspan="2">&gt; 18 h</td><td> &lt;30'</td><td>&gt; 1 h</td><td>&gt; 23 h</td>

<td>Stability at 70 ° C</td><td> &lt;30'</td><td> &lt;30'</td><td colspan="2"> &gt;30'</td><td> &lt;30'</td><td>&lt;1 h</td><td>&gt; 3 h</td>

It is also found that the emulsifying systems according to the invention allow a greater stability of the emulsion with temperature.

Example 3: Complete sludge stability

Different emulsifying systems were compared in the complete formulation. The mixing of the different components is carried out with a Hamilton Beach mixer and the emulsion is carried out in the Silverson mixer equipped with an emulsifying grid.

288 ml of base oil is poured into a bolus of

Hamilton Beach and add under low speed mixing 14 g of emulsifying system, 3 g of filter reducer (Versatrol or Truflo 100) and 12.5 g of lime Ca (OH)₂, speed 15 «low speed» for 5 min. Then 7 g of organophilic treated clay ("bentone 38") are added and mixing is continued for 5 min, "low speed". 7 4 ml of brine comprising 20 g of CaCl₂ per 100 g of distilled water are gradually added and stirring is maintained for 10-20 min ("low speed"). 452 g of barite (thickener) are then added progressively and the mixture is stirred at medium speed ("medium speed" setting) for 20 min. The final stage of manufacture of the sludge is carried out with a Silverson L4RT apparatus, with the standard equipment provided with an emulsifying grid. The mixture is stirred at 6600 trs / min for 10 minutes.

The well fluid is then evaluated before and after aging for 16 hours at 180 ° C, following the API tests of rheology and electrical stability (API 13B-2 standard) and HP / HT static filtration. The static filtration test is performed with a pressure difference of 35.68 kg / cm² (35 bars) at a temperature of 180 ° C.

An important determination is the quantity and quality of the filtrate before and after the sludge aging. Indeed, the collected filtrate needs to be free of water. If the presence of free water or emulsion is detected, this means that the emulsion was broken during the filtration process.

In the muds considered in a first series of determinations, the base oil was Ultidrill® mineral oil (Hl) and the emulsifying systems used were TAI, TA3, TA4 and TA5.

The results are represented in the table below.

Table 3

<td></td><td colspan="4">Before the aging</td><td colspan="3">After aging 16 hours at 180 ° C</td>

<td>Emulsifier</td><td>TAI</td><td>TA3</td><td>TA4</td><td>TA5</td><td>TAI</td><td>TA3</td><td>TA4</td>

<td>VA (CP)</td><td> 35</td><td> 34</td><td> 44</td><td> 53</td><td> 45</td><td> 52</td><td> 86</td>

<td>VP (cP)</td><td> 24</td><td> 23</td><td> 30</td><td> 36</td><td> 37</td><td> 30</td><td> 55</td>

<td>YP (lb / 100ft²)</td><td> 22</td><td> 22</td><td> 28</td><td> 14</td><td> 16</td><td> 44</td><td> 62</td>

<td>Gel 0/10 (lb / 100ft²)</td><td> 11/16</td><td> 10/10</td><td> 17/21</td><td> 7/24</td><td> 2/3</td><td> 10/16</td><td> 47/77</td>

<td>SE (V) -</td><td> 1345</td><td> 1060</td><td> 750</td><td> 1060</td><td> 55</td><td> 255</td><td> 397</td>

<td>Filtered at 30 '(g)</td><td> 3.3</td><td> 4.5</td><td> 3.6</td><td> -</td><td> 54.2</td><td> 47.8</td><td> 4.3</td>

<td>Presence of water in the filtering</td><td>no</td><td>no</td><td>no</td><td></td><td>yes</td><td>yes</td><td>yes</td>

VA: apparent viscosity

VP: plastic viscosity

YP: yield point (constriction threshold)

Gel 0/10: gel values ​​at 10 s and 10 min

SE: electrical stability

It is found that in the case of the comparative formulation (TAI), the electrical stability drops after the aging step at 180 ° C and the filtration results are poor (presence of water in the filtrate). In the case of the systems according to the invention, the drop in electrical stability is much less brutal, and the filtration results are better, even excellent with the TA4 system.

The same determinations were made as previously on complete muds having the same composition, but in which Ultidrill® mineral oil was replaced by EDC 95-11® mineral oil (H2).

In the muds considered in this second series, the emulsifying systems used were TAI, ΤΆ4, TA6, TA7 and TA8.

The results are represented in the table below.

Table 4

<td></td><td colspan="5"></td><td colspan="5"></td>

<td>Emulating</td><td>TAI</td><td>TA4</td><td> TA6</td><td>TA7</td><td>TA8</td><td>TAI</td><td>TA4</td><td>TA6 *</td><td>TA7</td><td>TA8</td>

<td>VA (cP)</td><td> 55</td><td> 69</td><td> 57</td><td> 35</td><td> 44</td><td> 48</td><td> 70</td><td> 24</td><td> 62</td><td> 42</td>

<td>VP (cP)</td><td> 42</td><td> 50</td><td> 48</td><td> 28</td><td> 35</td><td> 43</td><td> 50</td><td> 16</td><td> 49</td><td> 89</td>

<td>YP (lb / 100 ft²)</td><td> 26</td><td> 38</td><td> 18</td><td> 14</td><td> 18</td><td> 10</td><td> 40</td><td> 16</td><td> 26</td><td> 9</td>

<td>Gel 0/10 (lb / 100ft²)</td><td> 14/20</td><td> 18/26</td><td> 22/16</td><td> 8/11</td><td> 8/10</td><td> 3/4</td><td> 27/45</td><td> 22/22</td><td> 5/7</td><td> 4/6 +</td>

<td>SE (V)</td><td> 1307</td><td> 751</td><td> - .</td><td> 590</td><td> 840</td><td> 232</td><td> 505</td><td> —</td><td> 280</td><td> 300</td>

<td>Filtered at 30 '(g)</td><td> 2.0</td><td> 2.1</td><td> —</td><td> 3.0</td><td> 3.5</td><td> 13.6</td><td> 2.2</td><td> —</td><td> 4.0</td><td> 4.5</td>

<td>Presence of water in the filtrate</td><td>no</td><td>no</td><td></td><td>no</td><td>no</td><td>yes</td><td>no</td><td></td><td>no</td><td>no</td>

<td>GOES:</td><td>apparent viscosity</td>

<td>VP:</td><td>plastic viscosity</td>

<td>AND P:</td><td>yield point (constriction threshold)</td>

<td>Gel</td><td>0/10: gel values ​​at 10 s and 10 min</td>

<td>I KNOW:</td><td>electrical stability</td>

With the base oil H2, it is still found that the stability of the emulsion manufactured with the systems according to the invention is much higher than that manufactured with the aid of the comparative system (TAI).

Example 4: DSC study

It was shown by a DSC calorimetric analysis technique that the size of the water droplets contained in the complete sludge made with the superamides was less affected by aging at 180 ° C. Indeed, it is difficult to measure the size of the water droplets in an oily sludge, mainly because of the significant amount of solids contained in this type of fluid. DSC allows you to analyze a complete mud sample, without diluting it. This sample is subjected to cooling until the crystallization of the water droplets is observed. The lower the observed crystallization temperature, the smaller the droplets (Clausse, D., "Research Techniques Utilizing Emulsions." In Encyclopedia of Emulsion Technology, Becher, P., Ed. Dekker: New-York, 1985; Vol. 2 , p. 77).

Two sludges formed with the base oil H2 were compared, one made with the commercial emulsifying system TAI and the other with the system of the invention TA4. These two sludges have been studied by DSC before aging (figures 1 and 2) and after aging for 16 hours at 180 ° C (figures 3 and 4). It is perceived by comparing the two types of sludge before aging (BHR), that their crystallization temperature is similar (approximately -93 ° C). In this way it can be thought that after manufacturing at room temperature, the two sludge possess a population of water droplets of comparable size, consequently a comparable stability. During the analysis of the sludge after aging (AHR), you realize that this is no longer the case. For TAI-based muds, the crystallization temperature is above the order of -55 ° C. This produces a coalescence of the drops. Therefore, the stability of the sludge after 16 hours is no longer very good. In contrast, for TA4-based muds, the results after aging are better. The presence of two crystallization peaks is observed. Therefore there is the presence of droplets of different size. The first peak is around -59 ° C, the second around -77 ° C, indicating that the average size of the water droplets of the mud made with TA4 is much smaller than the average size of the droplets of water from the mud made with TAI.

The stability of the sludge manufactured with the system according to the invention is therefore better after aging than that of the comparative system.

Example 5: toxicity and biodegradability of a system used in the invention.

The study has been carried out by an independent Norwegian NIVA laboratory, specialized in the evaluation of the toxicity of oil-based fluids used in the North Sea.

These tests linked biodegradability in seawater and toxicity.

The biodegradability test in seawater was carried out on the emulsifier superamid SA3, according to the standard protocol OECD 306 ("Closed Bottle Test" "Closed Bottle Test"). A biodegradability of 65% (62.6-66.4%) was obtained, which constitutes a more than acceptable result.

Toxicity was followed with a formulation containing 125 ml of Ultidrill® oil, 125 ml of brine at 20% by weight of CaCl₂, 12.5 g Ca (OH)₂, 6.5 g of emulsifier consisting of 1.25 g of SA3 and 5 g of tall oil fatty acid (Résinoline BD2 @), and 0.42 g of glycerol, on three species present in the North Sea.

A seaweed growth inhibition test was performed on Skeletonema costatum, according to the ISO 10253 standard, and an acute toxicity test on Arcadia tensa and on Corophium Volutator according to the ISO / FDIS 14669 protocol.

The results are given in the table below.

Table 5

<td>Species</td><td>Skeletonema costatum</td><td>Arcatia tonsa</td><td>Corophium Scroll Cor</td>

<td></td><td>ErC_5th= 29OO mg / 1 (*)</td><td>LC₅₀&gt; 10,000 mg / 1 (**)</td><td>LC_5th= 2O56 mg / 1 (**)</td>

The results given here show the good biodegradability and the absence of toxicity of the products used.

It is noted that in relation to this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.