Method and apparatus for determining direction parameters of a continuously explored borehole
First Claim
1. Method for determining at least two direction parameters of a borehole as a function of depth, comprising the steps of:
- producing an acceleration signal with three components representing a set of accelerations undergone by a tool travelling through the borehole, said components being detected along three reference axes related to this tool;
producing a reference signal with three components representing a vector of fixed direction different from the vertical, in relation with said three reference axes;
combining the components of said signals, measured at a given depth of the borehole, so as to eliminate the effects of tool movement in the components of one of said signals, constituting a signal to be stabilized, by means of the components of the other signal, constituting a stabilizing signal; and
combining the resulting components with components of said signals in a manner so as to derive parameters related to the position of the tool in the borehole and therefore related to direction parameters of the borehole.
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Accused Products
Abstract
Method and apparatus for continuously determining direction parameters of a borehole from the position of a well logging tool in the borehole during tool movement in the borehole, comprise a well logging tool including an accelerometer and a direction indicator, such as a magnetometer, with three sensitive axes respectively. Output signals derived from the accelerometer are prefiltered and then combined with respective output signals derived from the direction indicator in a manner so as to reduce to negligible proportions the effects of tool motion on respective ones of the output signals. The resulting signal is then subjected to a selective low-pass filtering, and the components thereof are thereafter, respectively combined with corresponding, suitable components of the original output signals in a manner such as to derive direction parameters for the borehole.
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Citations
22 Claims
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1. Method for determining at least two direction parameters of a borehole as a function of depth, comprising the steps of:
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producing an acceleration signal with three components representing a set of accelerations undergone by a tool travelling through the borehole, said components being detected along three reference axes related to this tool; producing a reference signal with three components representing a vector of fixed direction different from the vertical, in relation with said three reference axes; combining the components of said signals, measured at a given depth of the borehole, so as to eliminate the effects of tool movement in the components of one of said signals, constituting a signal to be stabilized, by means of the components of the other signal, constituting a stabilizing signal; and combining the resulting components with components of said signals in a manner so as to derive parameters related to the position of the tool in the borehole and therefore related to direction parameters of the borehole. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Apparatus for determining direction parameters of a borehole comprising:
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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. - View Dependent Claims (11, 12)
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13. Apparatus for determining direction parameters of a borehole, comprising:
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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.
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14. 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:
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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. - View Dependent Claims (15, 16, 17, 18)
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19. 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:
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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. - View Dependent Claims (20, 21, 22)
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Specification