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Identifi cation of Rotational Torque and Power in HDD |
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Identifi cation of Rotational Torque and Power in HDD Authors: D. Niżnik, A. Gonet
The effi ciency and economics of directional drilling is infl uenced by drilling techniques and technology
as well as drilling devices, drill bits – so much different from the ones used for deep drilling. Identifi cation
of the torque and power needed for rotating the string and drilling of rocks are of special signifi cance.
The present works on drilling techniques and technology (Brouthers & Silverman, 1982; Dvorak,
2006; Finnsson, 2005; Frantzen, 2003; Gęborys, 1999; Iseley & Tanwani, 1992; Lubiński & Miska,
1988) do not provide a complex solution to the problems related to identifi cation of torque and power
in the drilling process, encountered during shallow HDD drilling at less than 30 m of depth in various
types of rocks. Drilling companies frequently do not make use of appropriate procedures and standards
systemizing the HDD processes.
The results of fi eld surveys made during performing a directional borehole in Rajsk, near the Soła
river are presented in the paper. A zone of macroscopically homogeneous rocks was distinguished in the
profi le. Two very important parameters (especially at large diameter boreholes) were registered at constant
values axial stress and rotational speed: torque and power needed for drilling rocks and rotating the string.
Additionally, the defl ection angle and azimuth of well along the string were measured. A pilot hole was
drilled with a single-nozzle bit 0.0762 m in diameter and enlarged with a reamer 0.4 m in diameter.
The above parameters were statistically analyzed and their infl uence on rotational torque and power
needed for drilling and rotation of the string investigated. The most favorable regression equations are
given in the paper. They account for the infl uence of the axial stress, rotational speed, length of the string
and accumulated intensity of axis defl ection on the torque (6 and 7) and power (11 and 12). |
2011