OA16254A - Threaded end of a tubular component for drilling or working hydrocarbon wells, and resulting connection. - Google Patents

Abstract

A threaded end (1; 2) of a tubular component for drilling or working hydrocarbon wells, said end comprising a threaded zone (3; 4) produced on its external or internal peripheral surface depending on whether the threaded end is male or female in type, at least a portion of the end (1; 2) being coated with a dry film comprising an organic matrix in which ion exchange pigments are dispersed in proportions in the range 3% to 30% by weight; and a connection resulting from connecting two corresponding ends by makeup.

Description

THREADED END OF A TUBULAR COMPONENT FOR DRILLING OR WORKING HYDROCARBON WELLS, AND RESULTING CONNECTION [01] The présent invention relates to a galling-résistant tubular component used for drilling and workîng hydrocarbon wells, and more precisely to the threaded end of such a component, said end being male or female in type and capable of being connected to a corresponding end of another component to form a connection. The invention also relates to a threaded connection resulting from joining two tubular components by makeup. The invention also relates to a process for coating such a galling-resistant tubular component.

[02] A component which is “used for drilling and workîng hydrocarbon wells” means any element that is substantially tubular in form intended to be connected to another element of the same type or otherwîse to fînally constîtute either a string for drilling a hydrocarbon well or a riser intended for maintenance, such as work-over risers, or for workîng, such as production risers, or for a casing string or tubing string used in workîng wells. The invention is also applicable to components used in a drill string, such as drill pipes, heavy weight drill pipes, drill collars and the portions of pipe connections and heavy weight pipes known as tool joints.

[03] Each tubular component comprises one end provided with a male threaded zone and/or one end provided with a female threaded zone each intended to be connected by makeup with the corresponding end of another component, the assembly defining a threaded tubular connection. [04] Threaded tubular components are connected under defined loads in order to satisfy the requirements for an interférence fit and seal imposed by the service conditions. The threaded tubular connection resulting therefrom is subjected to an optimum interférence fit at the end of makeup, which is the gage for an optimum mechanical strength of the threaded connection, for example as regards tensile forces, but also as regards accidentai break out in service, and for optimum sealing performances. The designer of the threaded connection is thus obliged to define, for a given type of connection, a value for the optimum makeup torque which must, for %

ail assemblies of that type of connection, be lower than the plastification torque CP (to avoid plastification of the abutments and the resulting disadvantages) and be higher than the shouldering torque, CAB. Completing makeup to a torque below CAB cannot guarantee a correct relative positioning of the male and female éléments and thus cannot guarantee a suitable interférence fit for their sealing surfaces. Thus, the optimum makeup torque should be substantially higher than the shouldering torque, CAB. As a conséquence, the greater the différence between the plastification torque CP and the shouldering torque CAB, the larger the margin for definîng the optimum makeup torque, and the stronger the threaded connection will be as regards loads in service. In order to satisfy this type of spécification, it is necessary to employ coatings that can obtaîn a différence between the plastification torque and the shouldering torque which is greater than or equal to that obtained with conventional normalized lubricants in accordance with the American Petroleum Institute’s API RP 5A3.

[05] Further, the coatings must provide the connection with good galling résistance and allow a certain number of makeup and breakout cycles to be completed without alteration to the surfaces which are brought into interfering contact. This means that the high pressure shear strength must be équivalent to or better than that of a grease conforming to API (American Petroleum Instîtute) standard RP 5 A3 for a contact pressure of more than 500 MPa and preferably more than 800 MPa.

[06] The threaded tubular components are connected then used under severe conditions in terms of corrosion. Again, the use of coatings that can as far as possible resist the appearance of corrosion is désirable. This corrosion dégradés the geometry of the threadings and of the sealing zones. The corrosion has many origins, frequently linked to transport and/or to storage of the tubular components in zones which are hot, humid, maritime, etc.

[07] More precisely, the invention is intended to address ail or some of the technical spécifications mentioned above.

W.

[08] The invention concems a threaded end of a tubular component for drilling or working hydrocarbon wells, comprising a threaded zone produced on its extemal or internai peripheral surface depending on whether the threaded end is male or female in type. At least a portion of the end is coated with a dry film comprising an organic matrix in which ion exchange pigments are dispersed in proportions in the range 3% to 30% by weight.

[09] Optional characteristics, which are complementary or substitutional, are defined below.

[10] The pigments may comprise cation exchange pigments selected from the class defined by calcium, zinc, cobalt, strontium, lithium, magnésium or yttrium ion exchange amorphous silicas, calcium, molybdenum or sodium ion exchange zeolites, and calcium or cérium ion exchange bentonites.

[11] The pigments may comprise anion exchange pigments such as vanadate ion exchange hydrotaicite.

[12] The organic matrix may hâve a shear strength under contact pressures of at least 500 MPa equal to or greater than that obtaîned for a grease in accordance with API standard RP 5A3. At the same time, the organic matrix may hâve a torque on shoulder résistance value which is greater than or equal to that obtaîned for a grease in accordance with API standard RP 5A3.

[13] The organic matrix may be a thermoplastic matrix.

[14] The organic matrix may be selected from the class defined by polyamides, polyethylene waxes, copolyamides based on an acid dimer, esterified colophanes, terpene resins, styreneterpene resins, polyether etherketones, polyfluoroalkyls, and polyethersulphones.

[ 15] The organic matrix may comprise a polyethylene wax.

[16] The organic matrix may comprise a copolyamide resin.

[ 17] The organic matrix may be a thermoset matrix.

[18] The organic matrix may comprise a polyuréthane.

[19] The polyuréthane matrix may be obtaîned by curing a fluorourethane polymer in aqueous dispersion or in a solvent base using a polyisocyanate type hardener.

L, [20] The polyuréthane matrix may be obtained by curing a soiid polyester poiyol using a polyisocyanate type hardener.

[21] The polyuréthane matrix may be obtained by UV curing then by wet polymerization of a hybrid acrylic-urethane copolymer, [22] The end portion may be pre-treated by a surface préparation step selected from the group constituted by sanding, conversion treatments and electrolytic déposition, before coating it with the dry film.

[23] The organic matrix may further comprise particles of solid lubricants.

[24] The organic matrix may further comprise corrosion inhibitors.

[25] The threaded zone may be at least partially coated with a dry film.

[26] The threaded end may comprise a metal/metal sealing surface, saîd sealing surface being coated with dry film.

[27] The invention also pertains to a threaded tubular connection comprising a male threaded end and a female threaded end made up one into the other, at least one of the threaded ends being coated with a dry film in accordance with the invention.

[28] The end coated with a dry film may be the female threaded end.

[29] The features and advantages of the invention will be described in more detail in the description which follows, made with reference to the accompanying drawings.

[30] Figure 1 is a diagrammatic view of a connection resulting from connecting two tubular components by makeup;

[31 ] Figure 2 is a diagrammatic view of a makeup curve for two threaded tubular components;

[32] Figure 3 is a diagrammatic view of the chemical mechanisms involved at the surface of a tubular coated component in accordance with the invention;

[33] Figure 4 is a diagrammatic view of a test set-up.

[34] The threaded connection shown in Figure 1 comprises a first tubular component with an axis of révolution 10 provided with a male end 1 and a second tubular component with an axis of révolution 10 provided with a female end 2. The two ends 1 and 2 each finish in a terminal surface which is orientated radially with respect to the axis 10 of the threaded connection and are respectively provided with threaded zones 3 and 4 which cooperate mutually for mutua! connection of the two components by æakeup. The threaded zones 3 and 4 may be of the trapézoïdal, self-lockîng, etc thread type. Furthermore, metal/metal sealing surfaces 5, 6 intended to corne into interférence contact against each other after connecting the two threaded components by makeup are provided respectively on the male and female ends close to the threaded zones 3, 4. Finally, the male end 1 ends in a terminal surface 7 which cornes into abutment against a correspondîng surface 8 provided on the female end 2 when the two ends are made up one into the other. The Applicant has also developed another embodiment wherein the abutment formed in the présent case by the two contact surfaces 7 and 8 is replaced by selflocking interférence coopération of the threaded zones 3, 4 - see U S-4 822 081, US RE 30 467 and US RE 34467.

[35] As can be seen in Figures 1 and 3, at least one of the threaded tubular connections is coated over at least a portion of one of its ends, termed the substrate 11, with a dry film 12 comprising an organic matrix containing the ion exchange pigments. The dry film 12 may at least partially cover the threaded zone 3, 4. The dry film 12 may at least partially cover the metal/metal sealîng surface 5, 6. In the embodiment iilustrated in Figure 1, the dry film 12 is formed on the central zone of the threaded zone 4.

[36] Using ion exchange pigments as corrosion inhibitors in paint type coatings is recent and is actively contributing to the graduai replacement of traditïonal corrosion inhibitors such as zinc chromâtes which are known to be extremely toxic. The protection mechanism of ion exchange pigments has been preferentially studied in organic coatings with an aqueous and/or solvent base.

[37] The action mechanism of ion exchange pigments can be described as an electrochemical process based on two distinct steps, leading to:

• adsorptîon of aggressive ions présent in the coating 12;

• the formation of an insoluble protective layer on the surface leading to passivation of the interface 13 between the substrate 11 and the coating 12.

[38] The Applicant has paid particular attention to cation exchange silica and more particularly to calcium ion exchange silica which has produced very good results. The protection mechanistn is detailed in Figure 3 in the case of a steel substrate 11 and for a moist environment containing water, oxygen and hydroxide ions. Metallic iron atoms are generally oxidized into ferrous ions, Fe²⁺, by an electrochemical mechanism la and in a second step may be oxidized into ferrie ions, Fe^ï+, at the anodic corrosion site at zone A.

[39] Due to the permeability of organic coatings 12, oxygen and water can be présent at the interface 13 between the coating 12 and the substrate 11 where oxygen is reduced into hydroxide ions, OH', by an electrochemical mechanism lb by means of a cathodic reaction at zone C.

[40] The silica can be dissolved into silicate ions by an electrochemical mechanism 2a as a functîon of the alkalinîty of the coating 12. This soluble part of the ion exchange pigment may react with ferrie ions by an electrochemical mechanism 3a at the interface 13 between the coating 12 and the substrate 11, forming a protective layer of ferrie silicate 4a.

[41] At the same time as this reaction, calcium ions présent at the surface of the silica pigment are reieased following adsorptîon of aggressive H⁺ ions at the silica surface by an electrochemical mechanism 2b, which on reaction by an electrochemical mechanism 3b reacts with silicate ions to form a film of calcium silicate in the alkaline zones at the surface of the métal 4b.

[42] Calcium silicate particles may precipitate with those of ferrie silicate to reinfoTcé the insoluble protective layer by formation of a layer of mixed oxides at the métal surface.

[43] This proposed mechanism is also valid for métal atoms other than iron, such as zinc, by the formation of a protective layer of ZnSiO} at the sacrificial anodic corrosion site. Zinc is involved when phosphatation type surface préparation or electrolytic déposition has been carried out with the aîm of accentuatïng the conosion résistance.

[44] Because of their structure, cation exchange silîcas also offer other benefits:

• the highly basic nature of the surface of the pigment means that acid compounds in the coating are neutral ized (a low alkalinity coating is not favourable to the protection mechanism);

• the low density and high spécifie surface area compared with conventional înorganic corrosion inhibitor pigments offers better efficiency for smaller quantifies;

• their versatility means that a wide variety of bînders, such as thermoplastic resins or thermoset resins, can be used in an aqueous, solvent or hot melt base.

[45] Cation exchange pigments which can be used are synthetic calcium, zinc, cobalt, strontium, lithium, magnésium or yttrium ion exchange amorphous silica pigments, calcium, molybdenum or sodium ion exchange zeolites, or calcium or cérium ion exchange bentonites.

[46] Regarding the anion exchange pigments, the anion exchange reaction more particularly occurs with an aggressive electrolyte containing chioride ions, such as vanadate anion exchange hydrotalcîte.

[47] The choice of organic matrix is preferably orientated towards organic matrixes having a shear strength at a contact pressure of at least 500 MPa which is greater than or equal to that obtained for a grease conforming to API standard RP 5A3 and having a torque on shoulder value that is greater than or equal to that obtained for a grease conforming to API standard RP 5A3. The shear strength at a contact pressure of at least 500 MPa is linked to the value for the torque on shoulder, The large high pressure shear strength is obtained fforn the value for the torque on shoulder, this latter being determined with respect to a reference torque for an API grease using tests on a Bridgman type machine. The tests are described in detail below in the présent application.

W [48] A first class of organic matrixes has been studied, namely thermoplastics and more particularly polyamides, polyethylene waxes, copolyamides based on an acid dimer, esterified colophanes, terpene resins, styrene-terpene resîns, polycther etherketones, polyfluoroalkyls and polyethersulphones.

[49] A second class of organic matrixes has been studied, namely thermosets and more particularly polyuréthanes. Several methods for obtaining polyuréthanes have been envisaged:

• curing a fluorourethane polymer in aqueous dispersion or în a solvent base using a polyisocyanate type hardener;

• curing a solid polyester polyol using a polyisocyanate type hardener;

• curing a hybrid acrylic-urethane copolymer in aqueous dispersion or in a solvent base by UV polymerization then wet polymerization.

[50] The Applicant initially carried out corrosion tests on calcium ion exchange silica and more particularly on a synthetic calcium ion exchange amorphous silica sold by the supplier GRACE DAVISON under the trade name SHIELDEX AC5.

[51] The Applicant determined the corrosion protection supplied by the calcium ion exchange silica in various thermoplastic matrixes, said matrixes also possibly comprising supplémentai additives such as solid lubricants or corrosion inhibitors.

[52] Similarly, in some cases the test spécimens initially underwent a step for surface préparation selected from the group constituted by sanding, conversion treatments such as phosphatation, or eiectrolytic déposition such as Cu-Sn-Zn, before they received the dry film coating.

[53] The corrosion tests consisted of a sait spray test carried out in a clîmatic chamber under the following conditions: 35’C with a 50 g/L saline solution with a density in the range 1.029 to 1.036 at 25^<IC, with a pH in the range 6,5 to 7.2 at 25°C and recovered at a mean rate of 1.5 mL/h.

[54] Specimens that were intact without rusting then had to correspond to the ReO class of ISO standard 9227 after exposure. The method provides a means of verifying that the comparative quality of a metallic material with or without a corrosion protective coating is maintained.

[55] The water résistance tests consisted of subjecting the specimens to an accelerated corrosion test in accordance with DIN standard 50017 carried out in a climatic chamber, This test, comprising one cycle per day, consisted of depositing water vapour by condensation under the following conditions: 35°C, 90% relative humidity for 8 hours, then allowing the specimen to dry. After 7 cycles, a check is made to see whether the substrate protected by the coating has corroded.

[56] Excellent résistance must correspond to the classifications in ISO standard 4628: no corrosion, no blistering, no cracking, nor flaking of a carbon steel plate treated by zinc phosphatation (8 to 20 g/m² deposit of phosphate) or treated by an electrolytic deposit of a temary Cu-Sn-Zn alloy with an intermediate layer of Ni.

[57] The results obtained were compared with those obtained with conventional organic or inorganic corrosion inhibîtors, namely overalkalinized calcium sulphonate dérivatives and hydrated zinc calcium strontium orthophosphosîlicates.

[58] Firstly, the Applicant determined the corrosion protection of a carbon steel surface treated with an electrolytic Cu-Sn-Zn deposit then coated with a viscoplastic type monocomponent matrix such as polyethylene wax (homopolymer) comprising various traditional inorganic corrosion inhibitor pigments (specimens A, B, D) and SHIELDEX (specimen C).

Table l below shows that the use of calcium ion exchange silica can increase the corrosion résistance by at least 50% compared with known pigment or wax corrosion inhibîtors.

ΙΟ

Product name	Chemical nature	Specîmen A(%)	Specîmen B (%)	Specîmen C(%)	Specîmen D (%)
Licowax PE52O	Polyethylene wax	85	70	85	85
Nasul CA W1935	Overalkalinized calcium sulphonate and oxidate	15
Arcot 785	Overalkalinized calcium sulphonate and calcinate		30
Shieldex AC5	Calcium ion exchange amorphous silica			15
Halox SZP391	Strontium zinc calcium orthophosphosilicate				15
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	48	72	216	144

Table 1 [59] From these first results, the Applicant then sought to détermine a lirniting concentration that could provide satîsfactory corrosion protection.

Product name	Chemical nature	Specîmen A (%)	Specîmen B(%)	Specîmen D(%)
Licowax PE520	Polyethylene wax	95	90	85
Shieldex AC5	Calcium ion exchange amorphous silica	5	10	15
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	72	204	216

Table 2 [60] Table 2 shows that the corrosion protection becomes effective from a lirniting concentration of 10% by weight of calcium ion exchange silîca. For higher concentrations, the corrosion protection is slightly increased but a large quantity of pigments could cause heterogeneity in the film, causing unwanted porosity.

[61] Based on an optimum concentration of 10% by weight of calcium ion exchange silica, the

Applicant compared the corrosion protection of several thermoplastic matrixes with different adhesion properties for a carbon steel surface which had undergone a prior surface préparation step. In this case, it was an electrolytîc Cu-Sn-Zn deposit.

[62] The results are shown in Table 3:

Product name	Chemical nature	Specimen A(%)	Specimen B(%)	Specimen C (%)	Specimen D(%)
Licowax PE520	Poiyethylene wax	90		-	-
Licowax FP371	Ethylene oxidevînyl acetate copolymer wax		90
Thermelt 105	Pure copolyamide resin (Tg = +23°C)	-	-	90	-
Thermelt 200	Pure copolyamide resin (Tg = -26°C)	*	*	-	90
Shieldex AC5	Calcium ion exchange amorphous silica	10	10	10	10
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	204	144	408	792

Table 3 [63] Compared with the results obtained (Table 4) with other inorganic pigments such as 10% strontium zinc calcium orthophosphosilicates and 10% zinc phosphate, the calcium ion exchange 5 silica offers relative versatility in terms of corrosion protection whatever the thermoplastic matrixes employed, and especially with the pure copolyamide resin. In other words, the protection mechanism of the ion exchange silica means that traditional cathodic and/or anodic type mechanisms can no longer apply.

Vit—'

Product name	Chemical nature	Specîmen A (%)	Specîmen B (%)	Specîmen C (%)	Specîmen D(%)
Licowax PE520	Polyethylene wax	90		90
Licowax FP371	Ethylene oxidevinyl acetate copolymer wax		90		90
Halox SZP391	Strontium zinc calcium orthophosphosilicate	10	10
PZW2	Dihydrated zinc phosphate	-	-	10	10
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	186	54	114	72

Table 4 [64] As can be seen in Table 5, the Applicant verified the importance of particle size on anticorrosion protection performance. It is désirable to use calcium ion exchange silicas with a small mean particle size for sub-Iayer type coatings not exceeding 20 pm. The Applicant also 5 verified that a small particle size means that the coating thickness can be lower.

Product name	Chemical nature	Specîmen A* (%)	Specîmen B* (%)	Specîmen C* (%)	Specîmen D** (%)
Licowax PE520	Polyethylene wax	90	90
Thermelt 105	Pure copolyamide resin (Tg = +23°C)	-	-	90	90
Shieldex AC5	Calcium ion exchange amorphous silica (mean particle size 5 pm)	10		10
Shieldex AC3	Calcium ion exchange amorphous silica (mean particle size 3 Pm)		10		10
Sait spray test (ÏSO 9227)	Appearance of corrosion following exposure (hours):	204	96	408	816

Table 5: * Mean coating thickness « 35-40 pm; **: mean thickness = - 25 pm.

[65] The Applicant then observed that a réduction in the thickness of the dry coating proportional to that of the particle size of the calcium ion exchange silica produces very interesting sait spray test performances with corrosion protection multiplied by two. This resuit opens up the prospect of a lubricating coating on a thinner thermoplastic matrix which interfères less during the shouldering phase, (luis producing manageable shouldering torque values.

[66] Regarding the tribologîcal results conceming films, the Applicant determined the behaviour of coatings incorporating ion exchange pigments during a makeup operation spécifie for “premium” connections. More precisely, the torque on shoulder résistance CSB, also ToSR (Torque on Shoulder Résistance), was simulated and determined. This torque anses during makeup operations spécifie for premium connections used in the oil industry and represented in Figure 2. The curve in Figure 2 expresses the makeup torque (or interférence) as a function of the number of rotational tums made.

[67] As can be seen, a profile for the makeup torque of “premium” connections breaks down into four portions. In a first portion PI, the extemal threads of the male threaded element (or pin) of a first component of a threaded tubular connection as yet hâve no radial interférence with the internai threads of the corresponding female threaded element (or box) of a second component of the same threaded tubular connection.

[68] In a second portion P2, the geometrical interférence of the threads of the male and female threaded éléments generates a radial interférence which increases as makeup continues (generating a small but increasing makeup torque).

[69] In a third portion P3, a sealîng surface at the extemal periphery of the end portion of the male threaded element interfères radially with a conesponding sealing surface of the female threaded element to produce a metal/metal seah [70] In a fourth portion P4, the front end surface of the male threaded element is in axial abutment with the annular surface of a makeup abutment of the female threaded element. This fourth portion P4 corresponds to the terminal phase of makeup. The makeup torque CAB which corresponds to the end of the third portion P3 and to the start of the fourth portion P4 is termed the shouldering torque. The makeup torque CP which corresponds to the end of the fourth portion P4 is termed the plastification torque.

I4 [71] Beyond this plastification torque CP, it is assumed that the male makeup abutment (end portion of the male threaded element) and/or the female makeup abutment (zone located behind the annular abutment surface of the female threaded element) is subjected to plastic deformation, which may dégradé performance as regards the tîghtness of the contact between the sealing surfaces by plastification of the sealing surfaces too. The différence between the values for the plastification torque CP and the shouldering torque CAB is termed the torque on shoulder résistance CSB (CSB = CP - CAB).

[72] A threaded tubular connection is subjected to an optimum interférence fit at the end of makeup, which is the gauge for an optimum mechanical strength of the threaded connection, for example as regards tensîle forces, but also as regards accidentai break-out in service, and for optimum sealing performances. The designer of a threaded connection is thus obliged to define, for a given type of threaded connection, a value for the optimum makeup torque which, for ali connections of this type of connection, must be lower than the plastification torque CP (in order to avoid plastification of the abutments and the resulting disadvantages) and be higher than the shouldering torque, CAB.

[73] Endîng makeup with a torque which is less than CAB cannot guarantee correct relative positioning of the male and female éléments and thus of an effective seal between their sealing surfaces. Furthermore, there is a risk of break-out. The effective value of the shouldering torque CAB fluctuâtes greatly from one connection to another for the same type of connection as it dépends on the diamétral and axial machining tolérances of the male and female threads and sealing surface(s); the optimized makeup torque should be substantîally higher than the shouldering torque CAB. As a conséquence, the higher the value of the torque on shoulder résistance CSB, the larger the margin for defming the optimized makeup torque, and the more the threaded connection will be résistant to operational stresses.

I5 [74] Friction tests were carried out using a Bridgman type machine. This type of machine has in particular been described in the article by D Kuhlmann-Wilsdorf et al, “Plastic flow between Bridgman anvils under high pressures”, J. Mater. Res., vol 6, no 12, Dec 1991.

[75] A diagrammatic and functional example of a Bridgman machine is illustrated in Figure 4. This machine comprises:

• a disk DQ which can be driven in rotation at selected speeds;

• a first anvil EC1, preferably conical in type, permanently attached to a first face of the disk DQ;

• a second anvil EC2, preferably conical in type, permanently attached to a second face of the disk DQ, opposite its first face;

• first EPI and second EP2 pressure éléments, such as pistons, for example, which can exert the selected axial pressures P;

• a third anvil EC3, preferably cylindrical in type, which is permanently attached to one face of the first pressure élément EP1 ;

• a fourth anvil EC4, preferably cylindrical in type, which is permanently attached to one face of the second pressure element EP2.

[76] To test a lubricant composition, two pièces of a material identical to that constituting a threaded element are covered with said composition in order to form the first S1 and second S2 specimens. Next, the first specimen SI is interposed between the free faces of the first EC1 and third EC3 anvils, and the second specimen S2 between the free faces of the second EC2 and fourth EC4 anvils. Next, the disk DQ is rotated at a selected speed whîle applying a selected axial pressure P (for example of the order of 1 GPa) with each of the first EP 1 and second EP2 pressure éléments, and the makeup torque to which each specimen SI, S2 is subjected is measured.

[77] The axial pressure, the rotation speed and the angle of rotation are selected in the Bridgman test in order to simulate the Hertz pressure and the relative speed of the abutment surfaces at the end of makeup.

[78] Using such a machine, it is possible to fix scveral different paîrings of parameters (makeup torque, rotation speed) in order to impose predetermined makeup torques on specimens

SI and S2, and thus to check whether these specimens SI and S2 closely followa given makeup torque profile, and in particular whether they can reach a number of completed tums before gallîng which is at least equal to a threshold value selected with respect to the selected makeup torques.

[79] In the présent case, the selected contact pressure was l GPa and the rotation speed was rpm. The test specimens were formed from carbon steel, machined then coated with different formulations of dry coatings, listed in the table below along with the détermination of the torque on shoulder résistance (CSB or ToSR).

[80] The Applicant therefore determined the tribo-rheologîcal behaviour for various thermoplastic matrixes without an ion exchange silica pigment then with an ion exchange silica pigment using a Bridgman test. Table 6 summarizes the ToSR and the sait spray test performances for a représentative portion of the thermoplastic matrixes which were studied.

Product name	Chemical nature	Specimen A(%)	Specimen B(%)	Specimen C(%)	Specimen D(%)	Specimen E (%)
Dertoline PLS	Colophane esterified with pentaerythritol	60	60
Sylvares ZT 105L	Terpene phenolic resin			60
Thermelt 105	Pure copolyamide resin (Tg - +23 °C)				100
Thermelt 200	Pure copolyamide resin (Tg = -26°C)					90
Hydrogenated castor oil	Hydrogenated castor oil	25
Vestowax AV5012	Ethylene-vinyl acetate copolymer wax		25	25
Waxso N	Ethylene bisstearamide wax					10
Viscoplex 6- 950	Polyalkylmethacrylate in minerai oil	15
Evathane 28800	Ethylene-vinyl acetate copolymer		12
Lotryi 35BA320	Ethylene-butyl acrylate copolymer			15
Benzoflex 352	1,4-cycIohexanedimethanol, dibenzoate		3
Bridgman ToSR	ToSR:	92%	85%	94%	114%	108%
sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	276	264	288	144	456
Table 6: Mean	thickness of coating = 3(	D to 40 pm

[81] The results after incorporation of calcium ion exchange silica are given in Table 7:

	Specimen Al (%)	Specimen B1 (%)	Specimen Cl (%)	Specimen DI (%)	Specimen El (%)
Formulation A	90	-	-	-	-
Formulation B	-	90	-	-	-
Formulation C	-	-	90	*	*
Formulation D	-	-	-	90	-
Formulation E	-	-	-	-	90
Shieldex AC5	10	10	10	10	10
ToSR:	101%	91%	101%	123%	122%
Gain:	+ 10%	+7%	+7.5%	+8%	+13%
Appearance of corrosion (hours):	960	936	952(*)	756	816
Gain:	x 2.5	x 2.5	x 2.3	x 4.2	x 0.8

Table 7 [82] The Applicant observed that corrosion protection was remarkably reinforced by using calcium ion exchange silica as a corrosion inhîbitor pigment, which means that exposures of 750

IS hours or more can be achieved in a sait spray test without rusting. Passivation of the surface préparation is also very good; for al) of the specimens studied, less than 10% of the surface was corroded or non-passivated after 1000 hours of exposure.

[83] At the same time, the use of calcium ion exchange silica as a corrosion inhibitor in the various thermoplastic matrixes, having exhibited only a torque on shoulder résistance in the range 80% to 110%, contributes greatly to the increase in this value for various matrixes. The relative increase is in the range 7% to 13%.

[84] In the light of these good performances, the Applicant sought to check whether the efficiency of calcium ion exchange silica was maintained in several formulations încorporating solid lubricants recognized in particular for their négative influence on the torque on shoulder résistance and the homogeneîty of the coating. The compositions and performances of the formulations are given in Table 8.

Product name	Chemîcal nature	Specimen A* (%)	Specimen B** (%)	Specimen C* (%)	Specimen D»« (%)
Thermelt 105	Pure copolyamide resin (Tg = +23 °C)	75	75	-	-
Thermelt 200	Pure copolyamide resin (Tg = -26°C)		-	67.5	67.5
Waxso N	Ethylene bisstearamide wax	-		7.5	7.5
Rhodorsil 47 V1000	Dimethylpolysiloxane (oil)	5	5	5	5
Carbofluor 3000	Carbon fluoride	8	8	8	8
Timrex KS4	Synthetic graphite	2	2	2	2
Shieldex AC5	Calcium ion exchange amorphous silica	10	10	10	10
Bridgman ToSR	ToSR:	140%	•	114%	-
sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	636	> 1200	> 1200	> 1200

Table 8: (*: carbon steel specimen with electrolytic Cu-Sn-Zn deposit; **: carbon steel specimen with zinc phosphatation).

[85] Solid lubricants are generaliy incorporated into such matrixes to the détriment of corrosion protection because the rigidity of the coating is increased. The Applicant observed cracks and prématuré detachments with sample A.

[86] In contrast, the corrosion protection performances proved to be excellent especially with sufficiently flexible thermoplastic matrixes, reinforcing adhesion by mechanical coupling even with different surface préparations.

[87] The torque on shoulder résistance values remained unchanged, demonstrating the importance of the sélection of the thermoplastic matrix for the additives (solid lubricants, rheology modification additives, corrosion inhibitors) and above ail the considération of the idea of entirely unforeseeable general rheological behaviour under very high pressure.

[88] In order to validate the calcium ion exchange silica in a definitive manner, the Applicant elected to compare different corrosion inhibitor pigments with different protection mechanisms for the same thermoplastic matrix, namely:

• zinc stéarate, which reduces ion permeability and increases wet adhesion;

• lamellar aluminium, which increases the electrical résistance of the surface and acts as a sacrificial anode.

Product name	Chemical nature	Rcf	Specimen A (%)	Specimen B(%)	Specimen C(%)
Dertoline PLS	Colophane esterified with pentaerythritol	60	54	57	54
Hydrogenated castor oil	Hydrogenated castor oil	25	22.5	24	22.5
Viscoplex 6- 950	Polyalkylmethacrylate in minerai oil	15	13.5	14	13.5
Lîgastab Zn70	Zinc distearate	-	10	•	•
Stapa PA	Lamellar aluminium (pigment paste)	•	-	5	-
Shieldex AC5	Calcium ion exchange amorphous silica	-	•		10
Bridgman ToSR	ToSR:	92%	86%	87%	101%
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	276	504	504	960

Table 9: Carbon steel specimen with electrolytic Cu-Sn-Zn deposit [89] The Applicant came to the same conclusion when testing other thermoplastic matrixes with another corrosion inhibitor, namely calcium modified aluminium triphosphate. The very good results are shown in Table 10 below.

Product name	Chemical nature	Ref(%)	Specimen A (%)
Thcrmelt 200	Pure copolyamide resin (Tgm-26®C)	67.5	67.5
Waxso N	Ethylene bîsstearamide wax	7.5	7.5
Rhodorsil 47V1000	Dimethylpolysiloxane (oil)	5	5
Carbo fluor 3000	Carbon fluoride	8	8
Timrex KS4	Synthetic graphite	2	2
Shieldex AC5	Calcium ion exchange amorphous silica	10	-
K-White Ca650	Modified aluminium triphosphate	-	10
Bridgman ToSR	ToSR:	101%	100%
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	960	264

Table 10: Carbon steel specimen with electrolytic Cu-Sn-Zn deposit [90] Finally, the performances of the ion exchange silica obtained in thermoplastic matrixes could be considerably improved, namely by reinforcing the matrix with nanometric pigments. Table 12 summarizes the results obtained.

Product name	Chemical nature	Ref(%)	Specimen A (%)	Specimen B (%)
Thermelt 200	Pure copolyamide resîn (Tg = -26“C)	67.5	37.5	67.5
Thermelt 105	Pure copolyamide resin (Tg = +23°C)	-	37.5
WaxsoN	Ethylene bisstearamide wax	7.5	-	7.5
Rhodorsil 47V1000	Dimethylpolysiloxane (oil)	5	5	-
Carbofluor 3000	Carbon fluoride	8	8	-
Timrex KS4	Synthetic graphite	2	2	-
Shieldex AC5	Calcium ion exchange amorphous silica	10	10	10
Baikalox CR125	Nanometric alumina		-	10
Bridgman ToSR	ToSR:	101%	126%	119%
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	960	> 1000	1776
Table 11: Car	ion steel specimen with electrolytic Cu-Sn-Zn deposît

[91] The Applicant has observed that replacing solid lubricants with a nanometric alumina with a gamma crystalline structure can considerably augment corrosion protection beyond 1500 hours exposure in a sait spray test with no rust spots, without modifying the mechanical performances as regards friction and torque on shoulder résistance. In addition, it should be noted that the synergistic combination of the ion exchange silica and the nanometric alumina also contributes to reinforcing passivation of a surface préparation of the electrolytic Cu-Sn-Zn type for sait spray test exposure times of more than 1500 hours.

[92] The Applicant also evaluated the corrosion protection provided by calcium ion exchange 10 silica in various thermoset matrixes, said matrixes possibly also comprising supplémentai addîtives such as solid lubricants or corrosion inhibitors.

[93] More particularly, the Applicant studied the corrosion protection of a carbon steel initially treated with an electrolytic Cu-Sn-Zn deposit and then coated with a fluorourethane coating. The fluorourethane coating was obtained from an aqueous dispersion of curable fluoro ethylene vinyl ether. The results obtained are shown in Table 12.

t

Product naine	Chemîcal nature	Ref (%)	Specimen A(%)	Specimen B (%)	Specimen C(%)
LUMIFLON FD9I6	FEVE	87	81.5	84	82
BAYHYDUR 3100	Aliphatic polyisocyanate HDI (hardener)	13	12	12.5	12
Halox CW491	Calcium phosphosilicate	-	6.5	-	-
Shieldex AC5	Calcium ion exchange amorphous silica	-	-	3.5	-
Halox SZP391	Strontium zinc calcium orthophosphosilicate			•	6
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	168	1008	504	1008

Table 12 [94] In order to improve the corrosion protection of ion exchange silica, the researchers combined calcium ion exchange silica with phosphosilicate type corrosion inhibitor pigments with the aim of obtaining synergistic effects. The results are shown in Table 13. The synergistic 5 effects between calcium ion exchange silica and corrosion inhibitors such as Halox® 750 meant that corrosion protection of 1200 hours or more in accordance with ISO standard 9227 were obtained with no rust spots, blistering or detachment and with major passivation of the surface préparation. The weight ratio between the two corrosion inhibitors was preferably 1.

Product name	Chemical nature	Specimen A (%)	Specimen B (%)	Specimen C(%)	Specimen D (%)
LUMIFLON FD916	FEVE	84	81	8!	81
BAYHYDUR 3100	Aliphatic polyisocyanate HDI (hardener)	12.5	12	12	12
Halox 750	Inorganic/organic phosphosilîcate	-	3.5	*	-
Halox CW491	Calcium phosphosilîcate	-	-	4.5	-
Shieldex AC5	Calcium ion exchange amorphous silica	3.5	3.5	2.5	3.5
Halox SZP391	Strontium zinc calcium orthophosphosîlicate				3.5
Sait spray test (ISO 9227)	Appearance of corrosion following exposure (hours):	504	1176	816 (biistering)	> 1200

Table 13 [95] In conclusion, the calcium ion exchange silica can produce remarkable corrosion protection, especially compared with known corrosion inhibitors, whether they be overalkaîinized calcium sulphonates or inorganic strontium zinc calcium orthophosphate type pigments or even of the lamellar aluminium type, and for the various thermoplastic matrixes employed.

[96] Furthermore, the rheological behaviour of the matrix is positively influenced by the use of calcium ion exchange silica.

[97] The use of calcium ion exchange silica can satisfy two aims, namely:

· provîding corrosion protection beyond an exposure period in a hostile environment of more than 750 hours using the sait spray test;

• preserving or improving the value of the torque on shoulder résistance of the thermoplastic matrix.

[98] At the same time, by incorporating a single pigment constituent into the matrix, the invention simultaneously provides corrosion résistance properties and properties that can stabilize the value of the torque on shoulder résistance at a high value wîthout modifying the lubrication performance under low and high Hertz loads.

'K [99] In the context of accentuated protection, the use of anion exchange pigments either in synergy with cation exchange pigments such as calcium ion exchange silica or replacing them should provide an even more general response to corrosion protection under humid conditions regardless of the surface or surface préparation. In fact, because their protective mechanism is particularly adapted to moist media containing chioride ions, and because of the respective electrochemical potentials of the pigments and the métal atoms on the surface, the association between the anion or cation exchange pigments could be particularly suitable, especially as a plurality of insoluble protective layers could be formed by this mechanism for different métal atoms on the surface or for different surface préparations.

[100] As an example, the association between a calcium ion exchange silica and a vanadate ion exchange hydrotalcite should improve aggressive ion adsorption (H⁺ and chlorides) and should in particular reînforce passivation of an electrolytic Cu-Sn-Zn deposit at the interface by an electronic interaction or physical adsorption of the ionic species présent.

[101] In terms of application, the dry films comprising an organic matrix in which the ion exchange pigments are dispersed are preferably applied to the threaded zones of tubular components used for drilling or working hydrocarbon wells. More particularly, said dry films may be deposited on the female threaded zones, said threaded zones being provided to cooperate by makeup with male threaded zones which are themselves coated with a dry film which may be of a different nature.

[102] In a non limiting manner, the dry films comprising an organic matrix in which ion exchange pigments are dispersed may also be applied to the sealing surfaces 5, 6 described in Figure 1 and intended to cooperate by an interférence fit, and/or to the abutment surfaces 7, 8.

5 NOV. 2012

CABI

té nd

Cameroun

AOUN

B.P 50 Tél. 2 E«

Claims (20)

1. A threaded end (l ; 2) of a tubular component for drilling or working hydrocarbon wells, said end comprising a threaded zone (3; 4) produced on its extemal or internai peripheral surface depending on whether the threaded end is male or female in type, characterized in that at Ieast a portion of the end (1; 2) is coated with a dry film comprising an organic matrix in which ion exchange pigments are dispersed in proportions in the range 3% to 30% by weight.

2. A threaded end of a tubular component according to claim 1, characterized in that the pigments comprise cation exchange pigments selected from the class deftned by calcium, zinc, cobalt, strontium, lithium, magnésium and/or yttrium ion exchange amorphous silicas, calcium, moiybdenum and/or sodium ion exchange zeolites, and calcium and/or cérium ion exchange bentonites.

3. A threaded end of a tubular component according to claim 1 or claim 2, characterized in that the pigments comprise anion exchange pigments constituted by vanadate ion exchange hydrotalcite.

4. A threaded end of a tubular component according to any one of the precedîng daims, characterized in that the organic matrix has a shear strength under contact pressures of at Ieast 500 MPa and a torque on shoulder résistance value which is greater than or equal to those obtained for a grease conforming to API standard RP 5A3.

5. A threaded end of a tubular component according to any one of claims 1 to 4, characterized in that the organic matrix is a thermoplastic matrix.

6. A threaded end of a tubular component according to daim 5, characterized in that the organic matrix is selected from the class defined by polyamides, polyethylene waxes, copolyamides based on an acid dimer, esterified colophanes, terpene resins, styreneterpene resins, polyether etherketones, polyfluoroalkyls and polyethersulphones.

7. A threaded end of a tubular component according to claim 5, characterized in that the organic matrix comprises a polyethylene wax.

8. A threaded end of a tubular component according to claim 5, characterized in that the organic matrix comprises a copolyamide resin.

5

9. A threaded end of a tubular component according to any one of claims 1 to 4, characterized in that the organic matrix is a thermoset matrix.

10. A threaded end of a tubular component according to claim 9, characterized in that the organic matrix comprises a polyuréthane.

11. A threaded end of a tubular component according to claim 10, characterized in that the

10 polyuréthane matrix is obtained by curing a fluorourethane polymer in aqueous dispersion or in a solvent base using a polyisocyanate type hardener.

12. A threaded end of a tubular component according to claim 10, characterized in that the polyuréthane matrix is obtained by curing a solid polyester polyol using a polyisocyanate type hardener.

15

13. A threaded end of a tubular component according to claim 10, characterized in that the polyuréthane matrix is obtained by UV curing then by wet polymerization of a hybrid acrylic-urethane copolymer.

14. A threaded end of a tubular component according to any one of the preceding claims, characterized in that the end portion (I; 2) is pre-treated by a surface préparation step

20 selected from the group constituted by sanding, conversion treatments and electrolytic déposition, before coating it with the dry film.

15. A threaded end of a tubular component according to any one of the preceding claims, characterized in that the organic matrix further comprises particles of solid lubricants.

16. A threaded end of a tubular component according to any one of the preceding claims,

25 characterized in that the organic matrix further comprises corrosion inhibîtors.

17.

17.

18.

18.

19.

19.

20.

20.

A threaded end of a tubular component according to any one of the preceding ciaims, characterized in that the threaded zone (3; 4) is at least partially coated with dry film.

A threaded end of a tubular component according to any one of the preceding ciaims, characterized in that it comprises a metal/metal sealing surface, said sealîng surface being coated with dry film.

A threaded tubular connection comprising a male threaded end and a female threaded end of a tubular component made up one into the other, characterized în that at least one of the threaded ends is in accordance with one of the preceding ciaims.

A threaded tubular connection according to claim 19, characterized in that the end coated with dry film is the female threaded end.

27 pages

ORIGINAL

1- VALLOUREC MANNESMANN OIL & GAS FRANCE

2- NIPPON STEEL & SUBIΤΟΜΟ METAL CORPORATION

PAR PROCURATION

0 5 NOV. 2012