Importance

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Abstract

A method is presented for accurately surveying and determining the profile of the path of a subterranean wellbore containing a constant density fluid extending contiguously throughout. A first pressure sensor, associated with a downhole tool, is traversed station-by-station along the wellbore for measuring the pressure of the fluid within the wellbore at each station. A second pressure sensor is located within the wellbore fluid at a known elevation. The elevation of the first pressure sensor, at a station, is determined by adding the calculated differential height to the known absolute elevation of the second sensor. As each elevation is referenced to the second sensor, no cumulative errors are incurred. If the density of the fluid is unknown, a third pressure sensor within the wellbore fluid can be provided at a known elevation different from that of the second sensor. The areal position of each station is determined by conventional means associated with the downhole tool. The elevation for each of a plurality of stations is combined with the areal position determined at each station to determine the path of the wellbore.

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First Claim