CA1207643A - Heat-treated steel alloy wireline drill rods, and method of making the same - Google Patents

Abstract

HEAT TREATED STEEL ALLOY WIRELINE
DRILL RODS, AND METHOD OF MAKING THE SAME

ABSTRACT

Unitary heat-treated steel alloy wireline drill rods are manufactured by heating the tubing therein at both ends and then quenching the same in order to obtain the desired hardness for the ends thereof.

Description

Background of the Invention It has been recognized that the hardening of rods and tubing used in oil well drilling is a desirable objective, becoming particularly importan~ as the depth S of oil and gas wells is increased. The process of heat-treating steel and hardening it by quenching has been employed in furtherance of this objective. For example, Canadian Patent No. 1,120,831 to Yamagata et al.
discloses a method of producing steel pipe material for oil wellswherein said steel pipe material possesses both high strength and a high resistance to sulphide stress corrosion. This method of manufacture comprises the steps of heating, at prescribed temperatures~ steel containing delimited percentages of C, Si, Mn, Al, B
and N ( and possibly Cr, Mo, and Nb ), quenching the steel, and thereafter tempering the material at certain other prescribed temperatures.
Canadian Patent No. 1,047,900 to Gondo et al. sets out a method for producing large diameter steel pipes, of improved toughness and tensile strength, for use in the petroleum and natur~1 gas indust~y. Heat treatment of the pipes is carried out by induction heating, locally applied successively from one end of the pipe to the other in order to avoid distortion of the pipes during the treatment. Forced cooling of the steel pipe is effected after each heating step at a specified cooling rate.
Canadian Patent No. 818,346 to Kruppert is directed to the distortion-free hardening of long pipes, such as those produced for oil-field use, by passing a cooling liquid through the interior of the pipe. The pipe that is to be hardened i5 placed in an elongated container and supported therein at a predetermined position. A nozzle assembly then introduces a cooling medium into the pipe in order to produce forced cooling.

2--Earlier patents, such as that of Canadian Patent ~o. 528,098 to ~larke, have more generally disclosed methods of producing heat-treated stainless steel, whereby the steel is heated and later quenched.

However, the use of heat-treated drill rod sections may necessitate that these treated sections be affixed to the othex parts of the drill rods by such means as welding or threading. This may result in the drill rod being damaged at the critical area of the junction during handling or manufacture. In addition, the junction area is prone to increased wear and decreased abrasion resistance when used in the demanding task of drilling earth formations.

Detailed Disclosure The steel alloy rods and tubing employed in the drilling of earth formations can be hardened by heat-treating the tubing. A section of the tubing about six inches from each end of the tube is heated and then quenched in order to obtain the desired hardnesc..
The heat treatment of the section of tubing that is to be hardened takes place in a cylindrical apparatus, the forward part of which contains induction coils for heating the tubing section and the latter part of which contains the quenching mechanism. The rod is placed in a fixture capable of rotating the rod at about 25~~0 revolutions per minute. The portion of the tubing that is to be treated is inserted into the cylindrical apparatus.
The heating of the section of tubing is by means of controlled induction heating. The rod is rotated as the end portion of the tuhing is heated by the induction coils to a maximum temperature withln some specified period of time. The maximum temperature and specified period depend upon the composition of the steel a~loy tubing; in one example, the tubing is heated to a maximum temperature of about 1600F in a period of about 28 seconds. The cylinder housing the induction coils is then moved about six inches so as to bring the quenching mechanism into position over the heated tubing section, a move that takes about five seconds.
As the rod continues to rotate in its fixture, the section of tubing that had been heated is now fully quenched b~ water or a quenching fluid consisting of a mixture of water and a quenching oil of 10% by volume. The quenching medium flows at a rate of 120 gallons per minute at a pressure of 30 PSI.
The orifice angle through which the quenching medium is forced forms an angle of 30 to the center of the tube. This con-trolled deluge quench takes about three minutes.
The cylinder apparatus is again moved about six inches so as to bring the induction coils into position around the section of tubing that had been heated. For the step of tempering, induction heating is applied at a controlled temperature again dependent upon the composition of thetubing;
for the above e~ample, the controlled temperature is about 750F.
The rod continues to rotate in order to minimize distortion during the second heating process. Once the desired degree of hardness has been achieved, the tubing is withdrawn from the heating Ullit and air cooled while still rotating. The cooling of the tubing continues on the discharge rack.
As a result of using this method, a wireline drill rod capable of greater drilling depths and having a longer life can be produced. Because the drill rod is a single unit rather than a composite rod having heat-treated sections welded or threaded thereupon,the rod posse~ses high S~I~U~, is more resistant to wear and abrasion at cri ical areasj and is not subject to thread damage during assembly or handling.

Claims (11)

1. A method of manufacturing a unitary steel alloy drill rod having tubing with heat-treated end sections therein, said method comprising the steps of:
heating said end section of said tubing of said rod to a maximum temperature in a specified period of time;
quenching the heated end section of said tubing;
heating said end section of said tubing again at a controlled temperature;
allowing the heated end section of said tubing to cool;
wherein said rod is continuously rotated during the heating and cooling operations.

2. The method of claim 1, wherein said heating of said end section of said tubing is by means of induction coils.

3. The method of claim 1, wherein said end section of said tubing is initially heated to a temperature of 1600°F
in a period of about 28 seconds.

4. The method of claim 3, wherein said heated end section of said tubing is quenched in about three minutes by a quenching medium.

5. The method of claim 4, wherein said quenching medium is comprised of water.

6. The method of claim 4, wherein said quenching medium is comprised of a mixture of water and a quenching oil of 10% by volume.

7. The method of claim 1 or 4 wherein said end section of said tubing is heated the second time to a temperature of 750°F.

8. The method of claim 1, 3 or 4 wherein said rod is continuously rotated during the heating and cooling operations at a rate of 24 to 40 revolutions per minute.

9. The method of claim 1, 3 or 4 wherein said tubing is treated at each of the two end sections.

10. The method of claim 1, 3 or 4 wherein said end section of said tubing that is heat-treated is the end section that extends a distance of six inches from the edge of said tubing.

11. A unitary heat-treated steel alloy drill rod made by the process of claim 1, 3 or 4.