Hevi-Wate drill pipe is an intermediateweight drill stem member. It consists of heavy-wall tubes attached to special extra-length tool joints. It has drill pipe dimensions for ease of handling. Because of its weight and construction, Hevi-Wate drill pipe can be run in compression the same as drill collars in small diameter holes and in highly deviated and horizontal wells.
Although special lengths are available, the pipe is normally furnished in 301 /2 ft (9.3 m) lengths in six sizes from 31 /2 to 65 /8 in. (88.9 to 168.3 mm) OD. One outstanding feature is the integral center wear pad which protects the tube from abrasive wear. This wear pad acts as a stabilizer and is a factor in the overall stiffness and rigidity of one or more joints of Hevi-Wate drill pipe.
An example of Hevi-Wate drill pipe as an intermediate-weight drill stem member follows:
Example: An approximate weight of 41 /2 in. OD drill pipe is 16.60 lb/ft; 41 /2 in. Hevi-Wate drill pipe weighs approximately 41 lb/ft. As another comparison, 61 /2 in. OD, 21 /4 in. ID drill collars weigh 100 lb/ft.
Example: An approximate weight of 114.3 mm OD drill pipe is 24.7 kg/m; 114.3 mm Hevi-Wate drill pipe weighs approximately 61.1 kg/m. As another comparison, 165.1 mm OD, 57.2 mm ID drill collars weigh 148.8 kg/m.
When a number of drill collars are used in directional drilling, they produce a great amount of contact area with the low side of the hole. As the collars are rotated, this high friction contact with the hole wall causes the collars to climb the side of the wall. Many people feel this rotation climbing action of the bottom collar causes the bit to turn hole direction to the right.
Hevi-Wate drill pipe provides stability and much less wall contact. This results in the directional driller being able to “lock-in” and better control both hole angle and direction.
Fig: #1
Using Hevi-Wate Drill Pipe for Bit Weight on Small Rigs
Hevi-Wate drill pipe, run in compression for bit weight, can reduce the hook load of the drill stem, making it ideal for smaller rigs drilling deeper holes. In shallow drilling areas, where regular drill pipe is run in compression, the more rigid Hevi-Wate drill pipe will allow more bit weight to be run with less likelihood of fatigue damage.
Hevi-Wate drill pipe should not be used for bit weight in vertical holes larger than those listed below:
· 5 in. Hevi-Wate pipe — maximum vertical hole 101 /16 in.
·41 /2 in. Hevi-Wate pipe — maximum vertical hole 91 /16 in.
· 4 in. Hevi-Wate pipe — maximum vertical hole 81 /8 in.
·31 /2 in. Hevi-Wate pipe — maximum vertical hole 7 in.
The ease in handling saves both rig time and trip time (see Figure Nos. 1 and 2). A long string of Hevi-Wate drill pipe will eliminate many of the problems associated with drill collars normally used on the smaller rigs.
Fig#2
