Method and apparatus for determining direction parameters of a continuously explored borehole

Apparatus for determining direction parameters of a borehole comprising:

• an elongated tool;
• means for centering said tool within a borehole;
• first means, comprised within said tool, for sensing accelerations to which said housing is subjected to during tool motion in the borehole and including gravitational acceleration;
• second means, comprised within said tool, for sensing the orientation of said housing with respect to a predetermined direction;
• and
• means for processing and combining the respective outputs of said first and second sensing means in a manner such as to provide direction parameters for the position of the tool at a given depth within said borehole, which parameters are substantially free from the effects of tool motion.

Apparatus for determining direction parameters of a borehole, comprising:

• an elongated tool;
• means for centering said tool within a borehole;
• first means, comprised within said tool, for sensing accelerations to which said housing is subjected to during tool motion in the borehole, including gravitational acceleration;
• second means, comprised within said tool, for sensing the orientation of said housing with respect to a predetermined direction;
• first means for combining the respective outputs of said first and second sensing means in a manner such as to provide a reduction of the tool motion effects present in the output of said first sensing means;
• and
• second means for combining the output of said second sensing means with the output of said first sensing means as reduced by said first combining means to provide direction parameters for the position of the tool at a given depth within said borehole, which parameters are substantially free from the effects of tool motion.

A machine implemented method of processing a well log made up of a multiplicity of acceleration components representing accelerations undergone by a device moving through a borehole in an earth formation, and a second well log made up of a multiplicity of reference components representing a nonvertical vector of fixed direction, the logs being derived as the device moves through the borehole, to generate an improved log of a directional parameter of the borehole, comprising the steps of:

• selecting one of said logs for to be stabilized and the other of said logs for stabilizing said log to be stabilized;
• modifying components at a selected depth level of said log to be stabilized with components at said selected depth level of said log for stabilizing to obtain stabilized components from which the effects of rotational movement of said device are substantially eliminated;
• and
• using the results of the preceding step to generate an improved tangible log of a directional parameter of the borehole.

A machine implemented method of processing an acceleration log made up of a multiplicity of acceleration components representing accelerations undergone by a device moving through a borehole in an earth formation, and a reference log made up of a multiplicity of reference components representing a nonvertical vector of fixed direction, the logs being derived as the device moves through the borehole, to generate an improved log of a directional parameter of the borehole, comprising the steps of:

• filtering acceleration components at a selected depth level of said acceleration log to reduce the effect of rotational movement of said device thereon;
• modifying transverse axial acceleration components at said selected depth level of said acceleration log with transverse axial reference components and a diagonal reference component at said selected depth level of said reference log to obtain stabilized transverse axial acceleration components from which the effects of rotational movement of said device are substantially eliminated;
• filtering said rotationally-stabilized transverse axial acceleration components and a longitudinal axial acceleration component at said selected depth level of said acceleration log to reduce the effect of acceleration of said device generally attributable to nongravitational effects;
• and
• using the results of the preceding step to generate an improved tangible log of a directional parameter of the borehole.