Page 95 - Air and Gas Drilling Manual

Chapter 3: Downhole Equipment 3-23
Since the magnetic single-shot instrument utilizes a simple compass for
directional information, the instrument must be placed in a nonmagnetic portion of
the drill string in order for the compass to give accurate azimuth readings. This is
why the nonmagnetic drill collars are placed at the bottom of the drill string. When
running the single-shot survey care must be taken to make sure that the single-shot
instrument is located approximately midway along the nonmagnetic drill collar
length section before the camera film is allowed to be exposed.
More details regarding directional drilling operations and surveys will be
discussed in Chapter 12.
3.4 Drill Pipe
There are four types of drill pipe that are used in air and gas drilling operations.
These are standard API drill pipe, heavy-weight drill pipe, drill rod, and dual wall
pipe.
3.4.1 Standard API Drill Pipe
Appendix B gives the dimensions and mechanical properties for standard API
drill pipe. This is the drill pipe used in most rotary drilling operations (shallow and
deep). API drill pipe are fabricated by various API certified manufacturers around
the world, principally for use in the drilling of deep wells for the recovery of oil and
natural gas. Table B-3 gives the drill pipe dimensions (outside diameter, inside
diameter, and weight per unit length) of the pipe body of various drill pipe sizes.
API drill pipe size is denoted by the outside diameter of the pipe body and its
associated nominal (pipe body) weight per unit length. The nominal weight per unit
length defines the wall thickness and the inside diameter. The lengths of drill pipe
elements (pipe body and tool joints) are defined in the API range designation of
Table 1-1. When tool joints (box and pin) are added to a pipe body the average
actual weight per unit length of the drill pipe element is increased above the pipe
body nominal weight per unit length. API drill pipe is also classified by API
material (steel) grade. Table 3-2 gives the API material grade designations and
respective standards for minimum yield, maximum yield, and minimum tensile
strength of the steel grade. The actual steel used to produce the various API grades
for drill pipe fabrication is one of the AISI grade classifications of steel produced in
US steel mills. For an AISI grade of steel to be used to fabricate drill pipe of a
particular API grade the AISI grade must satisfy the minimum and maximum
specification given in Table 3-2.
Table 3-2: API drill pipe steel grades minimum and maximum mechanical properties [1].

API Grade E 75 X 95 G 105 S135
Min. Yd. (psi) 75,000 95,000 105,000 135,000
Max. Yd. (psi) 105,000 125,000 135,000 165,000
Min. Ten. (psi) 100,000 105,000 115,000 145,000
Table 3-2 shows that for API E75 grade the minimum yield is 75,000 psi, the
maximum yield is 105,000 psi, and the minimum tensile (ultimate) strength is