CHEMICAL COMPOSITION OF WIRE FOR HARDFACING APPLIED ON DRILLING PIPE TOOL JOINTS

Abstract

The present invention refers to the chemical composition of a wire for hardfacing tool joints of oil drilling pipes, known in the industry as hardbanding. This wire has in its microstructure the formation of graphite to reduce the coefficient of friction and maintain hardness, aiming to protect the drilling pipe and the well casing pipe.

Description

FIELD OF THE INVENTION

The present invention refers to the chemical composition of a wire for hardfacing tool joints of oil drilling pipes, known in the industry as hardbanding. The hardbanding wire has a chemical composition that is intended to reduce the drilling pipe wear, but which causes the removal of steel from the casing tube wall placed in the well. As examples of application are Drilling and Completion of Oil Wells.

DESCRIPTION OF THE STATE OF THE ART

In oil well drilling, friction in the sliding between the drilling pipe connections, designated as tool joints (TJ), and the well casing pipes can lead to removal of wall material and consequently the well will lose structural integrity.

This is caused by the damage to the structural capacity due to the reduction in the thickness of the casing tube that acts as the well structure.

In order to minimize removal of material from the casing pipe thickness and reduce toll joint (TJ) wear, hard materials with an anti-wear chemical composition are deposited by means of electric arc deposition, which are designated as hardbanding (HB).

In the technical literature, core wires for welding are widely known in various segments of the market as well as in the petrochemical industry. Gas-shielded welding cored wires, cored wires for submerged arc welding and self-shielded cored wires are found with chemical compositions of from 3.0% - 12.0% by weight chromium; 5.0% - 1.5% by weight manganese; 0.0% - 5.0% by weight niobium and 0.5% - 2.5% by weight silicon.

Currently on the market there are several hardbanding wires with different compositions. Most of these hardbandings are ferrous based, that is, they can be classified as steels. The main microstructure of these steels is martensitic and they may have significant portions of retained austenite. Some other types of hardbandings have in their chemical composition additions of niobium (Nb) or titanium (Ti), resulting in a microstructure predominantly made up of a martensitic matrix with carbides of these elements (TiC or NbC).

Among the alloys currently known, the best results are found with a martensitic matrix with some retained austenite and niobium or titanium carbides (NbC and TiC). These carbides have an aspect ratio (elongation) close to 1 and are formed during solidification of the alloy (primary solidification carbides).

Document CA2779308 refers to glass forming chemistries which may be provided as feedstocks for weld overlay hardfacing and forming protective surfaces, which in particular, may be applied to the surface of a tool joint for protection of the tool joint in oil and gas drilling operations. The material described in this patent is a hardbanding alloy supplied in the form of a wire or cored wire having a chemical composition of carbon in the range of from 1.0% to 3.0% by weight and chromium in the range of from 3.0% to 12.0% by weight.

US2002054972 refers to the hardbanding of tool joints or steel pipe sections. More particularly those used for well drilling in the oil and gas industry to reduce joint wear and extend the life of well casing pipes. This hardbanding material is based on chromium with a low carbon content and contains tungsten.

None of the already existing hardbandings is provided with lubrication features. Thus, the present invention discloses a weld deposition wire having in its chemical composition elements that, after application, cause the formation of graphite.

BRIEF DESCRIPTION OF THE INVENTION

The present invention deals with a weld deposition wire having in its chemical composition iron, carbon, niobium, cerium, silicon and titanium and, after application, it produces a ferrous based hardbanding having martensitic microstructure, with the presence of NbC and/or TiC and graphite.

The advantages of the present invention are: maintenance of wear protection of the drill pipe tool joints through the required hardness for contact, reduction in the number of cycles of welding reapplication, and reduction in the coefficient of friction in the sliding of the tool joint on the coated well, causing mitigation in the rate of removal of material from the well hardbanding and operational drilling improvements in torque resulting from rock cutting.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1: Micrograph of typical hardbanding wire microstructure with the new chemical composition after application on the tool joint.

DETAILED DESCRIPTION OF THE INVENTION

The chemical composition of the hardbanding wire according to the present invention is comprised between:

• C: 1.0% to 4.5% by weight;
• Cr: 3.0% to 12.0% by weight;
• Nb: 0.0% to 5.0% by weight;
• Ti: 0.0% to 5.0% by weight;
• Ce: 0.0% to 1.0% by weight;
• Mg: 0.0% to 1.0% by weight;
• Mn: 0.5% to 1.5% by weight;
• Ni: 0.0% to 20% by weight;
• Mo: 0.0 to 3.0% by weight;
• Si: 0.5% to 3.5% by weight;
• W: 0.5% to 1.0% by weight.
• P: < 0.010% by weight;
• S: < 0.0710% by weight;

This chemical composition allows the formation of niobium and/or titanium carbides, a martensitic matrix with retained austenite and graphite.

The carbides contribute to the wear resistance of the tool joint and the graphite plays the role of reducing the coefficient of friction in the interaction between the drill pipe and the well casing pipe.

Claims

1. CHEMICAL COMPOSITION OF WIRE FOR HARDFACING APPLIED ON DRILLING PIPE TOOL JOINTS, characterized by having the following chemical composition:

a. C: 1.0% to 4.5% by weight;

b. Cr 3.0% to 12.0% by weight;

c. Nb: 0.0% to 5.0% by weight;

d. Ti: 0.0% to 5.0% by weight;

e. Ce: 0.0% to 1.0% by weight;

f. Mg: 0.0% to 1.0% by weight;

g. Mn: 0.5% to 1.5% by weight;

h. Ni: 0.0% to 20% by weight;

i. Mo: 0.0 to 3.0% by weight;

j. Si: 0.5% to 3.5% by weight;

k. W: 0.5% to 1.0% by weight;

l. P: < 0.010% by weight;

m. S: < 0.0710% by weight.

2. CHEMICAL COMPOSITION OF WIRE FOR HARDFACING APPLIED ON DRILLING PIPE TOOL JOINTS, according to claim 1, characterized by having a martensitic matrix with retained austenite.

3. CHEMICAL COMPOSITION OF WIRE FOR HARDFACING APPLIED ON DRILLING PIPE TOOL JOINTS, according to claim 1, characterized by having titanium carbides.

4. CHEMICAL COMPOSITION OF WIRE FOR HARDFACING APPLIED ON DRILLING PIPE TOOL JOINTS, according to claim 1, characterized by having niobium carbides.

5. CHEMICAL COMPOSITION OF WIRE FOR HARDFACING APPLIED ON DRILLING PIPE TOOL JOINTS, according to claim 1, characterized by having graphite.