Ultrasonic cement scanner
First Claim
1. A tool for measuring a parameter of a borehole, the tool comprising:
- (a) a scanning head that rotates a scanning transducer assembly radially within said borehole;
(b) a mechanical subassembly for rotating said scanning head;
(c) a reference transducer assembly comprising (i) a reference transducer, (ii) a first chamber, (iii) a second chamber, and (iv) a plate separating said first chamber from said second chamber; and
(d) a processor for recording and processing full wave acoustic responses of said scanning transducer and said reference transducer;
wherein (e) a measure of said parameter (i) is obtained in said processor from said response of said scanning transducer, and (ii) said measure is corrected for variations in acoustic impedance of fluid filling said borehole and for systematic variations in said scanning transducer response by using said response of said reference transducer.
4 Assignments
0 Petitions
Accused Products
Abstract
An acoustic borehole logging system for parameters of a well borehole environs. Full wave acoustic response of a scanning transducer is used to measure parameters indicative of condition of a tubular lining the well borehole, the bonding of the tubular to material filling an annulus formed by the outside surface of the tubular and the wall of the borehole, the distribution of the material filling the annulus, and thickness of the tubular. A reference transducer is used to correct measured parameters for variations in acoustic impedance of fluid filling the borehole, and for systematic variations in the response of the scanning transducer. Corrections are made in real time. The downhole tool portion of the logging system is operated essentially centralized in the borehole using a centralizer that can be adjusted for operation in a wide range of borehole sizes.
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Citations
57 Claims
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1. A tool for measuring a parameter of a borehole, the tool comprising:
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(a) a scanning head that rotates a scanning transducer assembly radially within said borehole;
(b) a mechanical subassembly for rotating said scanning head;
(c) a reference transducer assembly comprising (i) a reference transducer, (ii) a first chamber, (iii) a second chamber, and (iv) a plate separating said first chamber from said second chamber; and
(d) a processor for recording and processing full wave acoustic responses of said scanning transducer and said reference transducer;
wherein(e) a measure of said parameter (i) is obtained in said processor from said response of said scanning transducer, and (ii) said measure is corrected for variations in acoustic impedance of fluid filling said borehole and for systematic variations in said scanning transducer response by using said response of said reference transducer. - View Dependent Claims (2, 3)
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4. A method for measuring a parameter of a borehole, the method comprising:
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(a) rotating radially within said borehole a scanning transducer;
(b) providing a reference transducer assembly comprising (i) a reference transducer, (ii) a first chamber, (iii) a second chamber, and (iv) a plate separating said first chamber from said second chamber;
(c) recording and processing full wave acoustic responses of said scanning transducer and said reference transducer; and
(d) combining said full wave acoustic responses of said scanning transducer and said reference transducer to obtain a measure of said parameter;
wherein(e) said measure is corrected for variations in acoustic impedance of fluid filling said borehole and for systematic variations in said scanning transducer response by using said response of said reference transducer. - View Dependent Claims (5, 6, 7)
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8. A tool for measuring a parameter of interest within a borehole, the tool comprising:
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(a) a scanning head that rotates a scanning transducer assembly radially within said borehole;
(b) a mechanical subassembly for rotating said scanning head; and
(c) a centralizer subassembly which positions said scanning head essentially in the center of said borehole, and comprises (i) a mandrel, (ii) a plurality of centralizer arm sets, (iii) springs which urge said centralizer arm sets against a wall of said borehole within a given operating range, and (iv) an adjustment nut and mandrel shaft assembly cooperating with said plurality of centralizer arm sets;
wherein(d) said adjustment nut can be rotated to vary said operating range of said centralizer subassembly; and
(e) said parameter of interest is determined from a full wave response of said scanning transducer. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method for measuring a parameter of interest within a borehole, the method comprising:
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(a) rotating a scanning transducer assembly radially within said borehole;
(b) providing a centralizer subassembly which positions said scanning transducer essentially in the center of said borehole, and comprises (i) a mandrel, (ii) a plurality of centralizer arm sets, (iii) springs which urge said centralizer arm sets against a wall of said borehole within a given operating range, and (iv) an adjustment nut and shaft assembly;
(c) rotating said adjustment nut to vary said operating range of said centralizer subassembly; and
(d) determining said parameter of interest from a full wave response of said scanning transducer. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A tool for measuring a parameter of interest of a borehole, the tool comprising:
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(a) a scanning head that rotates a scanning transducer radially within said borehole, wherein said scanning transducer comprises a piezoelectric crystal disposed on a backing material, and wherein (i) said backing material comprises a large density material evenly dispersed in an elastic material, and (ii) composite density of said backing material is in the range of 10 grams per cubic centimeter (gm/cm3) to 19 gm/cm3 thereby matching acoustic impedance of said backing material to acoustic impedance of said piezoelectric crystal; and
(b) a mechanical subassembly for rotating said scanning head;
wherein(c) said parameter of interest is obtained from a full wave response of said scanning transducer. - View Dependent Claims (21)
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22. The tool of 21 further comprising:
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(a) a reference transducer assembly comprising (i) a reference transducer, (ii) a first chamber, (iii) a second chamber, and (iv) a plate separating said first chamber from said second chamber; and
(b) a processor for recording and processing full wave acoustic responses of said scanning transducer and said reference transducer;
wherein(c) a measure of said parameter of interest (i) is obtained in said processor from said response of said scanning transducer, and (ii) said measure is corrected for variations in acoustic impedance of fluid within said borehole and for systematic variations in said scanning transducer response using said response of said monitor transducer. - View Dependent Claims (23, 24)
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25. A method for measuring a parameter of interest in a borehole, the method comprising:
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(a) rotating a scanning transducer radially within said borehole, wherein said scanning transducer comprises a piezoelectric crystal disposed on a backing material; and
(b) fabricating said backing material with a large density material evenly dispersed in an elastic material;
wherein composite density of said backing material is in the range of 10 grams per cubic centimeter (gm/cm3) to 19 gm/cm3 thereby matching acoustic impedance of said backing material to acoustic impedance of said piezoelectric crystal; and
(c) obtaining said parameter of interest from a full wave response of said scanning transducer. - View Dependent Claims (26, 28, 29)
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27. The method of 25 further comprising the steps of:
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(a) providing a reference transducer assembly comprising (i) a reference transducer, (ii) a first chamber, (iii) a second chamber, and (iv) a plate separating said first chamber from said second chamber;
(b) determining acoustic slowness of fluid in said borehole, with said tool in said borehole, from the travel time in said first chamber of acoustic energy emitted by said reference transducer;
(c) determining free pipe response of said tool, with said tool in said borehole, from a full wave response of said reference transducer in said second chamber with said tool in said borehole; and
(d) using said acoustic slowness and said free pipe response to correct said measure of said parameter for said variations in acoustic impedance of said fluid and for said systematic variations in scanning transducer response.
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30. A logging system for measuring a parameter of environs of a borehole, the system comprising:
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(a) a tool;
(b) a conveyance means; and
(c) a data conduit connecting said tool and said conveyance means;
wherein(d) said tool comprises (i) a scanning head that rotates a scanning transducer assembly radially within said borehole, wherein said scanning transducer assembly comprises a piezoelectric crystal disposed upon a backing material fabricated with a large density material evenly dispersed in an elastic material, and composite density of said backing material is in the range of 10 gm/cm3 to 19 gm/cm3 thereby matching acoustic impedance of said backing material to acoustic impedance of said piezoelectric crystal, (ii) a mechanical subassembly comprising a motor for rotating said scanning head, (iii) a reference transducer assembly comprising a reference transducer, a first chamber, a second chamber, and a plate separating said first chamber from said second chamber, (iv) a centralizer subassembly which positions said tool essentially in the center of said borehole and comprises an adjustment nut and mandrel shaft assembly, wherein said adjustment nut can be rotated to vary the operating range of said centralizer subassembly, and (iv) an electronics assembly comprising a processor in which said measure of said parameter is determined from a full wave acoustic response of said scanning transducer assembly, and said measure of said parameter is corrected for variations in acoustic impedance of borehole fluid using response of said reference transducer in said first chamber, and corrected for systematic variations using response of said reference transducer in said second chamber. - View Dependent Claims (31, 32, 33, 34, 35, 36, 38, 39, 40, 41, 42, 43)
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37. The logging system of 36 wherein casing corrosion is determined from amplitude of said first reflection using a predetermined casing corrosion relationship.
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44. A method for measuring a parameter of environs of a borehole, the method comprising:
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(a) providing a tool;
(b) operationally connecting said tool to a conveyance means by means of a data conduit; and
(c) conveying said tool along said borehole via said conveyance means and data conduit to measure said parameter as a function of depth within said borehole;
wherein(d) said tool comprises (i) a scanning head that rotates a scanning transducer assembly radially within said borehole, wherein said scanning transducer assembly comprises a piezoelectric crystal disposed upon a backing material fabricated with a large density material evenly dispersed in an elastic material, and a composite density of said backing material is in the range of 10 gm/cm3 to 19 gm/cm3 thereby matching acoustic impedance of said backing material to acoustic impedance of said piezoelectric crystal, (ii) a mechanical subassembly comprising a motor for rotating said scanning head, (iii) a reference transducer assembly comprising a reference transducer, a first chamber, a second chamber, and a plate separating said first chamber from said second chamber, (iv) a centralizer subassembly which positions said tool essentially in the center of said borehole and comprises an adjustment nut and mandrel shaft assembly, wherein said adjustment nut can be rotated to vary an operating range of said centralizer subassembly, and (iv) an electronics assembly comprising a processor means in which said measure of said parameter is determined from a full wave acoustic response of said scanning transducer assembly, and said measure of said parameter is corrected for variations in acoustic impedance of borehole fluid using response of said reference transducer in said first chamber, and corrected for systematic variations using response of said reference transducer in said second chamber. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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Specification