HWDP is an intermediate-weight drill string member with drill pipe dimensions for easier handling. Its heavy wall tube is attached to special extra-length tool joints. These provide ample space for recutting the connections and reduce the rate of wear on the OD.
A joint of HWDP has a greater wall thickness and longer tool joints than normal drill pipe. Midway between the tool joints is an integral wear pad which acts as a stabilizer.
HWDP is less rigid than DCs and has much less wall contact. Chances of differential sticking are reduced.
Its three-point wall contact feature solves two serious problems in directional drilling :
It permits high-RPM drilling with reduced torque. HWDP can be run through hole angle and direction changes with less connection and fatigue problems.
Today, the trend in BHA design is to minimize the number of DCs in the BHA and use HWDP to comprise a major portion of available weight on bit.
Note: Heavy Weight Drill Pipe should not be used as bit weight in vertical holes larger than those listed in the table below.
The BHA in a directional well may have 20 or more joints of HWDP between the drill collars and drill pipe.
Figure below shows the HWDP Dimensional Data Range :
(All dimensions are given in inches)
|Spiral Heavy Weight Drill Pipe|
Processing of Heavy Weight Drill Pipes :
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Heavy Weight Drill Pipe Material :