Lined casing inspection method
First Claim
1. A method for in-situ determining the thickness of a subsurface pipe wall having an outer surface and having an inner surface covered by a lining, said determining method using a sonic signal produced from a wire line logging instrument, said signal capable of being reflected wherein a reflected signal is capable of being detected by said instrument, said reflected signal having indicators of said wall surfaces each of said indicators having a discrete arrival time, wherein said indicators are also affected by said lining, which method comprises the steps of:
- a) placing said instrument proximate to the center of said pipe;
b) generating said sonic signal, wherein said sonic signal is reflected by said pipe wall surfaces;
c) detecting said reflected signal from said placed instrument;
d) detecting said wall surface indicators affected by a property of said lining; and
e) calculating said thickness from a calculation dependent upon a difference between said arrival times of said detected indicators.
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Accused Products
Abstract
A log analysis method can be used to determine a relative condition of a lined casing within a geothermal well from logged instrument data. Uncertain conditions, such as an unknown scale layer thickness, may perturb the indicators of a casing condition within the logged signals. The method can be used to detect the perturbed signals, discern a perturbed reference interfacial indicator in the data, searches for an adjacent interfacial indicator within a window, and axially aligns the adjacent indicator by shifting the data signal towards the reference indicator. The baseline indicator may be an arbitrarily selected signal indicator or a prior (non-scaled/non-eroded) condition indicator. A prior condition indicator can also be used to determine a second window for detecting an adjacent surface signal indicators. The computations used in the present invention are based upon a theoretical model of signal(s) traversing first outward then back across the conducted fluid, scale (if present), liner, casing structure (pipe), cement (or borehole fluid, subsequent casing and cement), and subsurface formation/fluids. The arbitrary or prior condition baseline avoids the need to "know" the actual properties of intervening materials currently required for analysis of casing conditions and some of the extrapolation limitations inherent in current analysis methods. The method can also achieve accurate results by iterating on the baseline indicator.
39 Citations
22 Claims
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1. A method for in-situ determining the thickness of a subsurface pipe wall having an outer surface and having an inner surface covered by a lining, said determining method using a sonic signal produced from a wire line logging instrument, said signal capable of being reflected wherein a reflected signal is capable of being detected by said instrument, said reflected signal having indicators of said wall surfaces each of said indicators having a discrete arrival time, wherein said indicators are also affected by said lining, which method comprises the steps of:
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a) placing said instrument proximate to the center of said pipe; b) generating said sonic signal, wherein said sonic signal is reflected by said pipe wall surfaces; c) detecting said reflected signal from said placed instrument; d) detecting said wall surface indicators affected by a property of said lining; and e) calculating said thickness from a calculation dependent upon a difference between said arrival times of said detected indicators.
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2. A method for determining a generally uncertain property of at least a portion of a layered fluid conduit comprising first and second layers, wherein said generally uncertain property is related to said first layer and a generally uncertain condition is related to said second layer, said method using an instrument capable of detecting a fluid conduit affected signal having indicators of at least two fluid conduit properties wherein said generally uncertain condition also affects said indicators, which method comprises the steps of:
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a) placing said instrument in the vicinity of said fluid conduit where said affected signal can be detected; b) detecting said affected signal from said placed instrument; c) detecting said indicators within said detected affected signal, said detected indicators constituting discerned indicators; and d) calculating said generally uncertain property from a calculation dependent at least in part upon a comparison of said detected indicators to a reference indicator. - View Dependent Claims (3, 4, 5, 6)
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7. An inspection method for determining an otherwise uncertain condition of at least a portion of one layer of a multi-layered material using a signal generator capable of producing a distinct signal directed towards said material, wherein said directed signal is affected by at least two conditions of said multi-layer material to form a data signal, said method also using at least one detector capable of detecting said data signal having an indicator of a first layer condition, said indicator being affected by a second generally uncertain condition, which method comprises the steps of:
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a) placing said signal generator and said signal detector at locations in signal communication and generating said distinct signal, said signal detector being placed at a distance from the closest one of said layers; b) traversing said detector in a direction which generally maintains said distance to said closest one layer; c) producing a series of said data signals from said traversing detector; d) selecting a baseline indicator of said first layer condition; e) detecting said first layer condition indicator within said series of data signals; and f) calculating a relative shift of at least a portion of said series of data signals based upon a comparison to said baseline indicator, wherein said relative shift produces a series of shifted data signals. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for determining a property of a geothermal fluid conduit from a conduit affected signal, said method comprising:
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a) placing an instrument inside said conduit, said instrument being capable of detecting a conduit affected signal having indicators of at least two fluid conduit properties and wherein a generally uncertain condition also affects said indicators; b) detecting said conduit affected signal with said placed instrument; c) detecting said affected indicators within said conduit detected signal; and d) calculating said property from a calculation dependent at least in part upon a comparison of at least one of said detected indicators to a reference indicator.
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Specification