US 2006/0067162 A1 · Ultrasonic cement scanner

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.

Claims57

Dependent claims

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.

10 more elements

A method for measuring a parameter of a borehole, the method comprising:

(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.

8 more elements

A tool for measuring a parameter of interest within 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;
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.

9 more elements

A method for measuring a parameter of interest within a borehole, the method comprising:

(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.

6 more elements

A logging system for measuring a parameter of environs of a borehole, the system comprising:

(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.

12 more elements

A method for measuring a parameter of environs of a borehole, the method comprising:

(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.

12 more elements

Dependencies are inferred from the claim text.

Ultrasonic cement scanner

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Ultrasonic cement scanner

Life of this patent

Abstract

Claims57