F Lannuzel

V Burklé-Vitzthum

R Bounaceur

P-M Marquaire

R Michels

REACTION MECHANISMS IN PETROLEUM: FROM EXPERIMENTATION TO UPGRADING AND GEOLOGICAL CONDITIONS

Keywords: kinetic models, reaction mechanisms, mixing effects, pressure effects, hydrocarbons evolution, upgrading

Among the numerous questions that arise concerning the exploitation of petroleum from unconventional reservoirs, lie the questions of the composition of hydrocarbons present in deep seated HP-HT reservoirs or produced during in-situ upgrading steps of heavy oils and oil shales. Our research shows that experimental hydrocarbon cracking results obtained in the laboratory cannot be extrapolated to geological reservoir conditions in a simple manner. Our demonstration is based on two examples: 1) the role of the hydrocarbon mixture composition on reaction kinetics (the "mixing effect") and the effects of pressure (both in relationship to temperature and time). The extrapolation of experimental data to geological conditions requires investigation of the free-radical reaction mechanisms through a computed kinetic model. We propose a model that takes into account 52 reactants as of today, and which can be continuously improved by addition of new reactants as research proceeds. This model is complete and detailed enough to be simulated in large ranges of temperature (150-500°C) and pressures (1-1500 bar). It is thus adapted to predict the hydrocarbons evolution from upgrading conditions to geological reservoirs.

INTRODUCTION

The perspective of a shortening of petroleum reserves raises the challenge of developing new exploitation strategies concerning unconventional reservoirs, like for instance deep seated, high pressure-high temperature reservoirs, tar sands or oil shales. In deep seated reservoirs, the challenge concerns our capacity to be able to reconstruct properly the evolution of hydrocarbons composition during basin evolution in order to predict the fluid quality. Concerning heavy oils and oil shales rise for instance the questions of the composition of hydrocarbons after in-situ upgrading steps and the prediction of the formation of acid gases.

The proposed presentation deals with the difficulty to extrapolate experimental results outside of the range of conditions at which they were obtained. The examples of the role of the hydrocarbon fluid composition (the "mixing effects", i.e the kinetic effect induced by a hydrocarbon on a mixture) and of pressure on the kinetics of cracking are taken. We are presenting our methodology to answer some of these questions by combining experimentation, construction of reaction networks and kinetic modelling.

EXPERIMENTAL CONDITIONS AND CONSTRUCTION OF THE KINETIC MODEL

Reactants are chosen among the most representative compounds of the aliphatic and the aromatic fractions of a crude oil, typically normal and branched alkanes, naphtenes, toluene and other alkylaromatics, hydroaromatics and PAH. Reactants are however chosen and classified based on their kinetic properties (i.e. their capacity to modify the kinetics of cracking of the mixture) rather than on their structure. For instance, benzene, toluene and decylbenzene belong to the same structural family of the monoaromatics. Yet, the kinetic influence of each molecule on hydrocarbon mixtures cracking is fundamentally different: benzene has no kinetic effect, toluene can be a strong inhibitor [START_REF] Razafinarivo | Etude de la pyrolyse d'un alcane induite par un hydroperoxyde à basse température[END_REF], long chain alkylbenzenes are inhibitors [START_REF] Burklé-Vitzthum | Kinetic effect of alkylaromatics on the thermal stability of hydrocarbons under geological conditions[END_REF] but act differently than toluene. On this basis, we also consider that a specific compound can be representative of the behavior of several other molecules having the same kinetic effect. Thus, the behavior of noctane in the hydrocarbon mixture is representative of all n-alkanes; toluene is representative of all methylaromatics and decylbenzene of all alkylaromatics bearing a side chain containing more that 4 carbon atoms. Of course, all of our assertings are verified by experimentation and chemical mechanisms construction [START_REF] Burklé-Vitzthum | Mechanistic modeling of the thermal cracking of decylbenzene. Application to the prediction of its thermal stability at geological temperatures[END_REF][START_REF] Burklé-Vitzthum | Kinetic effect of alkylaromatics on the thermal stability of hydrocarbons under geological conditions[END_REF][START_REF] Lannuzel | Influence des aromatiques sur la stabilité thermique des pétroles dans les gisements[END_REF].

The model compounds are pyrolysed pure or in mixtures, typically at 350-450°C under 100-1000 bars. The experimental setting used is that of confined pyrolysis [START_REF] Landais | Closed system pyrolysis: an efficient technique for simulating natural coal maturation[END_REF][START_REF] Landais | Pyrolysis of organic matter in cold-seal autoclaves. Experimental approach and application[END_REF]. Reactants are loaded into gold cells under controlled neutral atmosphere. After sealing, the gold cells are loaded into stainless steel reactors and heated under controlled pressure. The choice of the reactor design is mainly argumented by its capacity to reproduce reaction results on kerogen, oils and model compounds compatible with those observed in sedimentary basins [START_REF] Monthioux | Comparison between natural and artificial maturation series of humic coals from the Mahakam delta, Indonesia[END_REF][START_REF] Landais | Are temperature and time the only constrains to the simulation of organic matter maturation? Proceedings of the 16th EAOG[END_REF]. After the experiments, a complete mass balance of the reaction products is made using thermodesorption -multidimensional gas chromatography [START_REF] Gérard | Analysis of confined pyrolysis effluents by thermodesorption multidimensional gas chromatography[END_REF]. Compounds are identified using GC-MS.

After collection of the experimental data, the first step of reaction mechanisms writing is performed on the pyrolysis results of the pure compounds. Mechanisms are composed of elemental free-radical reactions with their corresponding rate constants that are not adjustable parameters. Second step concerns the binary mixtures, for which the mechanisms of both pure compounds are combined and the relevant cross reactions added. Other species can then be added incrementally to the mixture, adding their own reactions and cross reactions with the other species to the mechanism. The reaction model can thus be increased in size as research progresses.

When the model describes correctly the experiments, we consider that the most important reactions are very likely taken into account and the mechanism is thus validated. This model, based on the specific properties of elemental free-radical reactions can then be extrapolated to other pressure-temperature-time conditions, without empirical adjustment of rate constants by the user, as it is the case for simplistic kinetic models.

APPLICATION TO THE "MIXING EFFECTS"

In this section, we will show that "mixing effects" (co-reactions between compounds) can not be correctly extrapolated from experimental to reservoir conditions without a detailed kinetic model. We will compare the effect of an alkylaromatic with a long side-chain (decylbenzene) on n-alkanes cracking, to the effect of toluene. Then we will study the effect of toluene as a function of temperature and pressure.

Effects of decylbenzene on n-hexadecane cracking

An experimental study [START_REF] Burklé-Vitzthum | Kinetic effect of alkylaromatics on the thermal stability of hydrocarbons under geological conditions[END_REF] showed that n-hexadecane cracking rate is divided by a factor 2 when it is mixed with 20% of decylbenzene at 330°C and 700 bars. This effect has been explained by considering reaction mechanisms (1066 elemental reactions). The corresponding kinetic model allowed to extrapolate the results to the geological reservoirs time-temperature conditions (200°C-10 million years) and showed that decylbenzene indeed inhibits the n-hexadecane cracking, but by about a factor 50 to 3000, depending on temperature and on conversion. Inhibition can be measured by the Inhibition Factor (IF) that is defined by the ratio: conversion of pure alkane/conversion of alkane in mixture. If the IF = 1, no inhibition effect is observed. Figure 1 shows the evolution of the IF values vs temperature for the mixture hexadecanedecylbenzene (conversion = 1%). The kinetic role of long-chain aromatics at geological time-temperature conditions is thus much stronger than what could be inferred from the experimental conditions.

Effects of toluene on n-octane cracking at 350°C

Because of the similarity of structure between decylbenzene and toluene, we may think that they behave in a similar manner. At very low pressure (1mbar), toluene inhibits n-octane by about a factor 3 [START_REF] Razafinarivo | Etude de la pyrolyse d'un alcane induite par un hydroperoxyde à basse température[END_REF]), but at 700 bar, this inhibition becomes negligible (about a factor 1.1; [START_REF] Lannuzel | Influence des aromatiques sur la stabilité thermique des pétroles dans les gisements[END_REF]. So, at high pressure, toluene does not seem to be an interesting compound from a kinetic point of view.

The corresponding mechanism has been constructed [START_REF] Lannuzel | Influence des aromatiques sur la stabilité thermique des pétroles dans les gisements[END_REF]. It is composed of the mechanisms of pure toluene (30 elemental reactions), of pure octane and of the cross reactions (51 processes). In a general manner, the inhibition appears when a radical that is particularly stable is formed during the reaction. That is the case of the benzyl radical that is stabilized by resonance. But a kinetic analysis of the mechanism shows that the benzyl radical is consumed by addition on alkenes and so the inhibition effect does not appear at 350°C under 700 bar.

At very low pressures, the addition processes are negligible and so the accumulation of benzyl radicals in the medium causes the inhibition. Concerning decylbenzene, it has been shown that the addition reactions of decylbenzene radicals on alkenes are less important (the rate constant is about 100 times lower than the corresponding reaction with the benzyl radical) because of steric reasons. So decylbenzene acts as a better inhibitor than toluene.

Effects of toluene on n-octane cracking at low temperatures

The mechanism of the mixture toluene-octane has been simulated at 200°C under various pressures. Under high pressure (and in the contrary to what has been observed in our experiments at 350°C), toluene acts as a good inhibitor on the n-alkanes cracking (Figure 2): the conversion of octane is divided by about 10-20, and its half life is more than 2 times greater.

At lower pressures, the inhibition is weaker. Figure 3 shows the variation of the IF values vs temperature (200-450°C) for several pressures. Without a detailed and robust mechanism, the variation of the IF value appears totally unpredictable. The example of toluene has been chosen to demonstrate that the kinetic effect of a compound on the cracking of another reactant can not be easily predicted: the results of experiments can not be extrapolated outside the experimental temperature and pressure ranges without the mechanism. This conclusion is valid for secondary cracking in geological reservoirs as well as in-situ upgrading.

APPLICATION TO PRESSURE EFFECTS

Pressure is an important parameter to take into account, since its value changes considerably from deep seated petroleum reservoirs (several hundred to more than thousand bars) to in-situ upgrading of oil shales or heavy oils (few tens to more than hundred bars). Changing the pressure changes the concentrations of the compounds and so the importance of the bimolecular reactions compared to the unimolecular reactions. If the mechanism is detailed enough and takes into account all unimolecular and bimolecular processes, it is valid from very low pressures (1 bar) to very high pressures (about 1500 bar). Let us investigate the effect of pressure on the distribution of products and on the conversion obtained by alkanes cracking.

Distribution of products

Three types of products are obtained after n-alkane cracking: alkanes-minus (molecular weight less than the reactant), alkanes-plus (M.W greater than the reactant) and alkenes. The distribution between these three types is modified by temperature in a negligible manner, but pressure has a very strong effect (Figures 4). At low pressures, unimolecular processes, particularly decomposition by -scission, are dominant; so alkenes are the most abundant products and no alkanes-plus are formed. At high pressures, bimolecular processes and particularly additions become important: no alkenes can be detected because they are consumed to form alkanesplus.

Conversion

The simulated evolution of the n-octane conversion vs pressure is presented Figure 5. A maximum is obtained whatever the temperature but, when the cracking temperature increases, a greater pressure is needed to obtain this maximum. So at very low and very high pressures, the n-octane cracking seems to be inhibited by pressure.

A precise analysis of the mechanism reveals that the predominant free-radicals are different at low and high pressures and so the predominant processes are different too. The maximum occurs when no specific type of radicals is predominant but when all of them are present. The understanding of the effects of pressure on the reaction mechanisms of a given hydrocarbon mixture composition can thus be evaluated by our kinetic model considering geological reservoir conditions. While no pressure effect is observed at 350°C, the influence of pressure could be quantitated at 200°C. This is, to our knowledge, the first quantitative modelling of the effects of pressure on the cracking at geological conditions.

CONCLUSION

Through the examples of the mixing effects (co-reactions) and of the pressure effects on hydrocarbon cracking, we have shown that any extrapolation of results outside of the range of experimental conditions can lead to severe errors when detailed kinetic model based on reaction mechanisms are not considered. Our model comprises 52 reactants for the moment [START_REF] Dominé | Up to what temperature is petroleum stable? New insights from a 5200 free radical reactions model[END_REF] and it has been validated by correctly predicting the stability of some HP-HT reservoirs. Its construction principle permits to add more reactants to the model in a rigorous and relatively simple manner, thus allowing to investigate increasingly complex fluids. Such a model can represent correctly the aliphatic and the aromatic fractions of most crude oils, but the polar fractions are not explicitly taken into account. Nevertheless the asphaltenes can be treated as sources of hydrocarbons that constantly feed the model with reactants.

Our model is complete and detailed enough to be simulated in large ranges of temperature (150-500°C) and pressure (1-1500 bar). So it can be useful to predict the hydrocarbons evolution in various conditions: 1) secondary cracking of crude oils in geological reservoirs, 2) in-situ and ex-situ upgrading during the assisted recuperation of heavy oils and oil shales by heating or 3) by addition of gases or solvents. The next steps of this study will focus on H 2 S and hydrocarbons containing sulphur. Indeed one of the challenges of the assisted recuperation is to predict the formation of H 2 S and its effect on the upgrading of oil. Among the questions that arise: How is H 2 S formed? H 2 S leads to a stabilised free-radical; so, does H 2 S limit the upgrading of oil? How does it react with hydrocarbons? Most of the C-S bonds are relatively weak; are oils rich in sulphur more sensitive to cracking? Can we quantitate the induction effects due to C-S and S-S bonds breakage?

Fig. 1 .

 1 Fig. 1. Evolution of the Inhibition Factor as a function of the temperature for the mixture 80% n-hexadecane -20% decylbenzene (conversion of hexadecane = 1%).

Fig. 2 .

 2 Fig.2. Conversion of octane, as a pure compound (continuous line) and in mixture with toluene (10 %) (dashed line) at 200°C, as a function of time.

Fig. 3 .

 3 Fig.3. Evolution of the Inhibition Factor as a function of the temperature, for several pressures, in the case of the mixture 90% octane -10% toluene (conversion of octane = 1 %).

Fig. 4 .

 4 Fig.4. Distribution of the products obtained by a n-alkane cracking as a function of pressure, for two temperatures.

Fig. 5 .

 5 Fig.5. Conversion of a n-alkane as a function of pressure for two temperatures.

Acknowledgment: The authors would like to thank Total for funding this work, and especially D. Dessort for his interest and support.


Shlomo Barak
email: shlomo@tagapro.com

Entanglement -a Realistic Resolution of the Riddle No need to attribute non-locality in spacetime to Quantum Mechanics

Keywords: Photon, Photom, Entanglement, Polarizer

research documents, whether they are published or not. The documents may come

Entanglement -a Realistic Resolution of the Riddle

Introduction The Puzzling Entanglement

The entanglement of photons and other particles has been puzzling us since the year 1935, when the famous EPR paper [1] appeared. A summary of the subject appears in [START_REF] Rae | Quantum physics: Illusion or reality[END_REF]. In this paper we relate, without losing the generality in our argumentation, only to photons.

"Entanglement Between Photons that have Never Coexisted"

In a recent paper [START_REF] Megidish | Entanglement Between Photons that have Never Coexisted[END_REF], titled above, the puzzling is going even deeper:

Using entanglement swapping between two temporally separated photon pairs we entangle one photon from the first pair with another photon from the second pair. The first photon was detected even before the other was created. The observed quantum correlations manifest the non-locality of quantum mechanics in spacetime.

2

The Photon in the Quantum Field Theory -QFT [START_REF] Loudon | The Quantum Theory of Light[END_REF] The fields of QFT, one for every Elementary Particle, reside in space and follow its topology.

These fundamental fields, according to QFT, are all there is. The particles themselves are merely quantized excitations of these fields. As such they are point-like and structureless, and their masses cannot be derived and calculated. Necessarily and wrongly these masses are considered constants of nature. The ground state photon (photom as we call it) has the smallest discrete amount of electromagnetic field energy, which is 1/2hυ. The next level of excitation, with the energy hυ, is the photon. Thus, it is wrong to consider, in various situations, photons just by themselves without relating to their relevant photoms. The calculation of the density in space of photoms, which is very large compered to a single photon, appears in appendix A.

Stimulated and "spontaneous" Emission [5]

Fig. (1) shows on the left an atom on a high energy level (upper line) above the lower energy level (bottom line-ground state). If a photon, with the same energy as that of the difference in the energy levels of the atom, arrives it can induce the emission of an identical photon by the atom fall to the ground state. This process is termed Stimulated Emission.

Fig. (1) Stimulated and Spontaneous Emission

However, the atom can also emit a photon without an inducing photon from outside. This kind of emission is termed Spontaneous Emission. However, physicists [START_REF] Milonni | The Quantum Vacuum[END_REF], myself included, are convinced that in this case it is a photom (ground state photon) that induces the emission.

Below is evidence in support of this "Spontaneous" Emission idea. 2) shows a beam of excited atoms running through a narrow tube. The rate of emission of photons from these atoms is reduced drastically compared to their rate outside the tubemore than ten times [START_REF] Ballentine | Quantum Mechanics Prentice Hall[END_REF]. The explanation is simple: In this tube, modes of vibrations, namely photoms, perpendicular to the tube axis and with a wavelength twice the inner diameter of the tube, cannot exist. Hence the number of photoms is drastically reduced and so is the spontaneous emission. In another experiment a mirror is placed close and parallel to a beam of excited atoms. This time the emission rate is doubled, since the mirror reflects incoming photoms back towards the beam, thus doubling their number per unit volume.

4

The Probability of a single Photon to Go Through a Wire-Grid

Polarizer -to be Transmitted or to be Reflected

A single Photon is never traveling by itself; it should, at-least, be followed by a single photom, with the same wavelength, that induced its emission (spontaneous emission) [START_REF] Milonni | The Quantum Vacuum[END_REF] and it usually travels with an ensemble of photoms moving in phase like a semiclassical wave.

Hence, we must first understand the interaction of photoms with the polarizer.

Fig (3). Wire-grid Polarize

For our discussion we picked the wire-grid polarizer, see Fig. [START_REF] Megidish | Entanglement Between Photons that have Never Coexisted[END_REF]. In this case the mechanism by which the photons and photoms interact with the polarizer is much clearer than for the other polarizers. The Wire-grid Polarize explained in the Wikipedia:

Electromagnetic waves which have a component of their electric fields aligned parallel to the wires will induce the movement of electrons along the length of the wires. Since the electrons are free to move in this direction, the polarizer behaves in a similar manner to the surface of a metal when reflecting light, and the wave is reflected backwards along the incident beam.

For waves with electric fields perpendicular to the wires, the electrons cannot move very far across the width of each wire. Therefore, little energy is reflected and the incident wave is able to pass through the grid. In this case the grid behaves like a dielectric material.

Overall, this causes the transmitted wave to be linearly polarized with an electric field that is completely perpendicular to the wires.

The Transmitted wave goes through the port designated T (The Horizontal port H)

The Reflected wave goes through the port designated R (The Vertical port V)

We contend that in contrast to current understanding the going of an "individual" photon through a polarizer's port is pre-determined.

Our contention:

A photon with a given linear polarization oriented 0 to 45 degrees to that of the polarizer axis will be reflected -will "go through" port R (The Vertical port V).

A photon with a given linear polarization oriented 45 to 90 degrees to that of the polarizer axis will be transmitted -will go through port T (The Horizontal port H).

The "probabilistic nature" of the photon -Malus Law, as we show in the next chapter, is related, not to the photon nature alone, but to it entering the polarizer with an ensemble of photoms.

Malus Law

Fig. [START_REF] Loudon | The Quantum Theory of Light[END_REF] shows the well-known passage of photons through a polarizer and a following analyzer.

(If both the polarizer and analyzer are of the wire grid type, we can redirect the reflected beam in the forward direction. In this case we can relate to the orthogonal axes as the ports R and T.) We now consider (first step), only the passage of photoms and not that of photons.

Say n identical photoms, in phase, enter the analyzer at an angle ϑ. We can assume (a classical argument) that n cos 2 ϑ of them go through the analyzer port R (the vertical port V). And nsin 2 ϑ of them go through the other analyzer's port T (the horizontal port H).

A photon that leaves the polarizer (second step of our consideration), arrives with its polarization at an angle ϑ to the analyzer. This photon follows one of the ncos 2 ϑ photoms to go through port R of the analyzer OR one of the nsin 2 ϑ photoms to go through port T of the analyzer. Hence the "probabilistic" nature of the photon -Malus Law.

Entanglement

In an Entanglement experiment the successive exited atomic emissions, of two perpendicularly or parallel polarized photons, is induced by two different photoms.

Our contention, if valid, explains without additional arguments the Entanglementthe going of these two photons always through different or the same portsfull correlation.

Summary

We reveal the nature of the interaction of light with polarizers based on standard QFT and the known fact that spontaneous emission is an induced emission by ground state photons

Fig. (

  Fig. (2) shows a beam of excited atoms running through a narrow tube. The rate of emission

Fig. ( 2 )

 2 Fig. (2) Damping Spontaneous Emission

Fig. ( 4 )

 4 Fig. (4) Malus Law

(photoms). This enables us to resolve the entanglement riddle. Our resolution dispels the need to attribute non-locality in spacetime to Quantum Mechanics.

Appendix A Spatial Density of Photoms [5]

The spatial density of an ensemble of photoms of a given λ and a bandwidth dλ, see [START_REF] Milonni | The Quantum Vacuum[END_REF], is: n(ν) = 8πν 2 /c 3 •dν but ν=c/λ and dν=c/λ 2 •dλ hence: n(λ)=8π/λ 4 •dλ For photoms of λ = 500nm and a bandwidth dλ = 0.5nm the spatial density is: n(λ) ~2•10 11 photoms per cubic centimeter.


-Elle permet de formulerun savoir qui s'appuie sur l'explicitation les implications personnelles des sujets.

-Rapport au savoir vu comme un« processus » ausens de J. Beillerot, 1989. « On ne peut parler d'un homme qu'en leconsidérant avec l'accumulation de ses expériences culturelles. Le tout forme une unité. » (Winnicott, 1971)

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  is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come     Choisir la démarche clinique d'orientation psychanalytique pour faire de la recherche en sciences de l'éducation, regards croisés Esther Czuk Vel Ciuk, Laura Dose To cite this version: Esther Czuk Vel Ciuk, Laura Dose. Choisir la démarche clinique d'orientation psychanalytique pour faire de la recherche en sciences de l'éducation, regards croisés. Journée de la recherche EPN-R, Jun 2021, Nanterre, France. hal-03388637 Choisir la démarche clinique d'orientation psychanalytique pour faire de la recherche en sciences de l'éducation, regards croisés Journée de la Recherche de l'EPN-R 4 juin 2021 -ED139 Ecole langage et modélisation -ED1589 : CREF -Equipe « Savoir, rapport au savoir et processus de transmission » BIBLIOGRAPHIE Beillerot, J., Blanchard-Laville, C., & Mosconi, N. (1996). Pour une clinique du rapport au savoir. L'Harmattan. Blanchard-Lav ill e, C., Chaussecourt e, P., Hatchu el, F., & P echbert y, B . (2005). Rech erches cliniques d 'ori entat ion psychanalytique dans le champ de l'éducat ion et delafo rmation. Revue française de pédagogie, 151(1), 111-162. Cifali M. (2007). Exigenc es d'une position clinique. Chemins de formation, n°10/11, La démarche Travail de notre subjectivi té.pdf en éducation et recherche. Nant es, 68-75 de Gaulejac, V., Giust-Desprairies, F. & Massa, A. (2013). La recherche clinique en sciences sociales. Toulouse, France: Érès. Devereux, G., De l'angoisse à la méthode dans les sciences du comportement, Paris, Flammarion, 1980 [1967 pour l'édition originale en anglais], 474 p Revault d'Allones C. (1989). La Démarche clinique en sciences humaines, Dunod, 220 p. Yelnik Catherine. (2005). L''entretien clinique de recherche en sciences de l'éducation. Recherche et formation, 50, p133 à 146. Esther Czuk Vel Ciuk (esther.c.prof@gmail.com) sous la direction de Françoise Bréant, professeure des Universités émérite en Sciences de l'éducation. L'enseignant spécialisé et l'acte d'écriture -Approche clinique et création d'un espace potentiel de travail -Laura Dose (lauradose.uni@gmail.com) sous la direction de Françoise Hatchuel, professeure des Universités en Sciences de l'éducation Le sujet et son rapport à la subjectivité -Les trajectoires de resubjectivation - La démarche clinique en sciences sociales Approche multi-référentielle Visée non thérapeutique La démarche clinique s'intéresse […] à la personne totale, en situation. Elle se veut "au plus près de lPostulat de l'inconscient -Appui sur les concepts, notions et théories psychanalytiques (diversité) -Il existe une réalité psychique qui n'est pas directement accessible, elle échappe à la conscience (Roussillon, 2014). -Cet inconscient est à l'oeuvre dans les pratiques professionnelles. -« Le moi n'est pas le maître dans sa propre maison » (Freud, 1916) → Travailler dans une démarche en lien avec son objet de recherche  Prise en compte de implication du chercheur -Le chercheur ne peut s'abstraire de la relation aux objets qu'il étudie » « cette relation fait elle-même partie de la recherche» (Blanchard-Laville, 1999) -« Le chercheur est le premier objet de sa recherche » (Barus-Michel, 2011) -Etude du lien avec l'objet de recherche/biais/vigilance/distance : éthique -Elaboration des mouvements psychiques provoqués par la recherche et la personne qui la mène : contre-transfert du chercheur  Méthodes et outils : l'entretien, l'observation, l'écriture clinique, travail groupal Notre choix : entretiens non directif, individuels, enregistré et retranscrit -« Susciter une parole dans une relation » (Yelnik, 2005) -> Cadre méthodologique et éthique : confiance, anonymat, « portiers » -Consigne ouverte -Effacement du chercheur pour être à l'écoute de l'autre (Castarède, 1983) -Principe de « la libre association » : déroulement du fil de la pensée de l'interlocuteur -Principe de la non-sélection des propos (on prend ce qui est dit, comme cela est dit). -Analyse du contenu : considérer le langage comme résultat processus de pensée (Bardin) + « On ne parle pas toujours directement » (Kerbrat-Orecchioni) -Analyse manifeste du discours et hypothèses d'analyse d'un contenu latent à l'éclairage de concepts psychanalytiques. Rendre compte d'une analyse « en contexte ». Ex : pour la recherche à l'école : 5 rencontres singulières traitées comme des monographies, des portraits Conclusion -La démarche clinique d'orientation psychanalytique s'intéresse au singulier etauparticulier. Le.a chercheur.se y adopte position qui accompagne le sujet -Sa valeur heuristique n'est pas liée à la quantité de matériau recueilli mais plutôt sur une analyse en profondeur qui reconnaît la singularité des situations et leur complexité.