Downhole depth correlation and computation apparatus and methods for combining multiple borehole measurements
First Claim
1. A system for determining parameters of interest from within a borehole, comprising:
- (a) a downhole subassembly;
(b) apparatus for conveying the downhole subassembly along the borehole;
(c) a plurality of sensors positioned within the downhole subassembly;
(d) a correlation system within the downhole subassembly for correlating responses of a sensor in the plurality of sensors to a common depth reference point and a common vertical resolution to form a set of correlated sensor data, wherein parameters of a correlation model are adjusted based upon the responses of a sensor in the plurality of sensors so as to optimize the correlation to the common depth reference point;
(e) a computing apparatus within the downhole subassembly for determining the set of correlated sensor data and for transforming the correlated sensor data into the parameters of interest utilizing a sensor combination model; and
(f) apparatus for transferring the parameters of interest to the surface of the earth.
1 Assignment
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Accused Products
Abstract
The current invention is directed toward the use of a downhole computer and downhole storage within a measurement-while-drilling (MWD) downhole subassembly to process data from the response of a plurality of sensors of different classes or one or more sensors of the same class which exhibit different measure points and vertical resolutions. Classes or types of sensors applicable to the invention include, but are not limited to, electromagnetic, acoustic, and nuclear. Sensor measurements are made essentially simultaneously. In combining downhole responses from one or more sensors to obtain parameters of interest, a critical prerequisite is downhole depth correlation and vertical resolution matching of all sensor responses prior to combination. Methods and apparatus are disclosed for performing these critical functions within the limits of telemetry and downhole storage capacities of current MWD systems, Alternate embodiments of the invention include wireline operations in which telemetry band width is limited by components such as single conductor logging cables employed in logging wells under high pressure.
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Citations
29 Claims
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1. A system for determining parameters of interest from within a borehole, comprising:
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(a) a downhole subassembly; (b) apparatus for conveying the downhole subassembly along the borehole; (c) a plurality of sensors positioned within the downhole subassembly; (d) a correlation system within the downhole subassembly for correlating responses of a sensor in the plurality of sensors to a common depth reference point and a common vertical resolution to form a set of correlated sensor data, wherein parameters of a correlation model are adjusted based upon the responses of a sensor in the plurality of sensors so as to optimize the correlation to the common depth reference point; (e) a computing apparatus within the downhole subassembly for determining the set of correlated sensor data and for transforming the correlated sensor data into the parameters of interest utilizing a sensor combination model; and (f) apparatus for transferring the parameters of interest to the surface of the earth. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for determining parameters of interest from within a borehole, comprising:
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(a) conveying a downhole subassembly having a plurality of sensors along the borehole to obtain unprocessed response data from the sensors in the plurality of sensors; (b) correlating the unprocessed response data to a common reference point along an axis of the downhole subassembly and a common vertical resolution so as to form a set of correlated sensor response data, wherein the correlation is adjusted automatically based upon the unprocessed response data to optimize the correlation of the unprocessed response data to the common reference point; and (c) combining the correlated sensor response data with downhole stored combination models utilizing a downhole computing apparatus for determining the parameters of interest. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A system for determining parameters of interest from within a borehole, comprising:
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(a) a downhole subassembly; (b) apparatus for conveying the downhole subassembly along the borehole; (c) a plurality of sensors disposed in the downhole subassembly; (d) a computing apparatus within the downhole subassembly; (e) a correlation system within the downhole subassembly for correlating the responses of sensors in the plurality of sensors to a common depth reference point and a common vertical resolution so as to form a set of correlated sensor data, wherein the correlation system includes (i) a buffer for storing a limited amount of sensor response data for correlation, (ii) a correlation model stored in the computing apparatus wherein parameters of the correlation model are adjusted by correlating excursions in the responses of the sensors in the plurality of sensors to determine the time interval between passage of two of the sensors past a given point within the borehole, (iii) apparatus for dividing a predetermined axial distance between the two sensors by the time interval of passage to obtain a downhole velocity of the downhole subassembly over the time interval of the passage, (iv) apparatus for adjusting the parameters of the correlation model based upon measured downhole velocity, (v) a first storage device containing sensor response models for certain sensors in said plurality of sensors, and (vi) apparatus for combining the data stored in the buffer with the correlation model and the sensor response models utilizing the computing apparatus to form the set of correlated sensor data; (f) a sensor combination model associated within the computing apparats for transforming the correlated sensor data into the parameters of interest; and (g) apparatus for transferring the parameters of interest to the earth'"'"'s surface. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A method for determining parameters of interest from within a borehole, comprising:
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(a) conveying a plurality of sensors and a computing apparatus disposed in a downhole subassembly along the borehole for obtaining unprocessed response data from the sensors in the plurality of sensors; (b) correlating the unprocessed response data from the sensors in the plurality of sensors to a common reference point along an axis of the downhole subassembly and to a common vertical resolution to form a set of correlated sensor response data, wherein the correlation includes (i) storing in a downhole buffer a limited amount of the sensor response data for correlation, (ii) storing a correlation model in a computing apparatus, wherein parameters of the correlation model are adjusted by correlating excursions in the responses of the sensors in the plurality of the sensors to determine time interval between the passage of two of the sensors in the downhole assembly past a given point in the borehole, (iii) dividing a predetermined axial distance between the two sensors by the time interval between the passage of two of the sensors in the downhole assembly past a given point within the borehole, (iv) adjusting the parameters of the correlation model based upon a measured velocity; (v) storing a sensor response models in a first downhole storage means, and (vi) combining the limited amount of stored sensor response data with the correlation model and the sensor response models utilizing the computing apparatus to form the set of correlated sensor response data; (c) combining the correlated sensor response data with stored sensor combination models utilizing the computing apparatus to determine the parameters of interest; and (d) transferring the parameters of interest to the surface. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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28. Apparatus for use during drilling of a borehole, comprising:
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(a) a downhole subassembly; (b) a plurality of sensors disposed in the downhole subassembly; (c) a correlation model within the downhole subassembly for correlating responses of a sensor in the plurality of sensors to a common depth reference point and a common vertical resolution to form a set of correlated sensor data, wherein parameters of the correlation model are adjusted based upon the responses of a sensor in the plurality of sensors to optimize the correlation to the common depth reference point; and (d) a computing apparatus within the downhole subassembly for determining the set of correlated sensor data and for transforming the correlated sensor data into parameters of interest utilizing a sensor combination model during drilling of the borehole.
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29. A method for determining parameters of interest from within a borehole, comprising:
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(a) conveying a downhole subassembly having a plurality of sensors along the borehole to obtain unprocessed response data from the sensors in the plurality of sensors; (b) correlating the unprocessed response data to a common reference point along the axis of the downhole subassembly and a common vertical resolution to form a set of correlated sensor response data, and wherein the correlation is adjusted automatically based upon the unprocessed response data to optimize the correlation of the unprocessed response data to the common reference point; and (c) determining the set of correlated sensor response data and combining the correlated sensor response data with downhole stored combination models utilizing a downhole computing apparatus for determining the parameters of interest.
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Specification