IAEA International Atomic Energy Agency Gauges and well logging Overview Day 6 – Lecture 3.
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Transcript of IAEA International Atomic Energy Agency Gauges and well logging Overview Day 6 – Lecture 3.
IAEAInternational Atomic Energy Agency
Gauges and well logging
Overview
Day 6 – Lecture 3
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Objectives
• To give an awareness of the use of radioactive sources in gauging equipment
• To gain a basic understanding of how these gauges work
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Content
• What is a nuclear gauge ?• Applications of gauges in industry• Gamma gauges
• transmission
• Beta gauges• transmission and backscatter
• Neutron gauges• Well logging
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What is a Nuclear Gauge?
• Device used in numerous industries, mostly in process control and quality control.
• Consists basically of a shielded radiation source and a radiation detector
• The radiation interacts with the examined material before reaching the detector, supplying real-time data.
Detector
Material Flow
Shutter Control
ShieldingSource
Shutter(Closed)
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Applications of gauges in industry
Quality Control• Density: rubber, oils, fabric, paper, etc• Thickness: paper, glass, steel, plastic films• Level: beverages, cooking oil
Process Control• Density: cement, mud, liquids, chemical products• Level: vessels, silos, chemical products, minerals• Moisture: glass, cement, minerals
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Applications of gauges in industry
Film Thickness Paper Thickness
Beverage Level Oil Level
Quality control
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Applications of gauges in industry
Process Control
Mineral Weight
Liquid FlowMud Flow
Mineral Level
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Types of nuclear gauge
Gauges can be categorised by their mode of • operation
• transmission• backscatter
• type of radioactive source used• Gamma• Beta• Neutron
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Types of nuclear gauge
Transmission: the detector measures the amount of radiation that passes through the examined material
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Types of nuclear gauge
Backscatter: the detector is placed on the same side as the source, measuring the amount of scattered radiation
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Types of nuclear gauge
• Gamma• Beta• Neutron
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Gamma gauges
• Density gauge• Level gauge• All operate in transmission mode• Sources used
• caesium-137• cobalt-60• americium-241
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Density gauge
Detector
Typical source:1 GBq Cs-137
Source
For a known thickness of material, the density can be deduced by comparing the radiation signal at the detector with and without the material in the beam
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Point level gauge
High level alarm
Low level alarm
Typical source:10 GBq Cs-137
Sources Detectors
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Point level gauges
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Liquid fill height gauge
Typical source:3.7 GBq Am-241
Source Detector
Accept
Reject
Drinks can or bottle
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Liquid fill height gauge
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Beta gauges
• thickness gauge (transmission)• coating thickness gauge (transmission)• film thickness gauge (backscatter)• Sources used
• krypton-85 (encapsulated gas)• strontium-90 (foil source)• promethium-147 (foil source)
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Beta thickness gauge
detector
source
web
Typical sources:3.7 GBq Pm-14711.1 GBq Kr-85
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Beta thickness gauge
Can be used to measure: paint, oil, lubricating films, plastic, enamel, ceramic and phosphate coatings on metals and some non-metals
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Beta thickness gauge
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Beta coating thickness gauge
Detector 1
Source 1
web
Typical source:37 GBq Kr-85
coating
Source 2
Detector 2
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Beta backscatter gauge
GM counter
SourceMetal coating
Substrate
Typical sources:200 MBq Pm-147, Tl-204
Thicker the coating, the more backscatter
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Beta backscatter gauge
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Neutron gauges
• hydrocarbon detection gauge• moisture content gauge• usually operate in backscatter mode• Sources used
americium-241/berylliumplutonium-238/beryllium
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Moisture Gauging using Neutrons
Detector
Neutron shield
Neutron sourceHigh hydrogenconcentration
Low hydrogenconcentration
Typical source1.85 GBq Am/Be
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Neutron soil moisture gauge
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Nuclear Density Gauge
Am-241/Be
Cs-137
Typical sources:1.85 GBq Am-241/Be370 MBq Cs-137Neutron source
moisture measurement
gamma sourcedensity measurement
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Nuclear density gauge
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Well Logging Operations and Equipment
• Well logging• Drill to Stop• Measurement or Logging While Drilling
• Borehole logging• Sources used
• caesium-137 (gamma), typically 40 GBq• americium-241 / beryllium (neutron), typically
110 GBq
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Drill-to-Stop Well Logging Operation
Well Logging operation that requires all drilling operations to cease and requires that parts of the drilling apparatus are removed to provide access to the well bore. The well logging tool is then lowered into the well bore to obtain information.
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Drill-to-Stop Well Logging Operation
Well Logging tools without sources stored in transport vehicle
Well Logging tools without sources at storage facility
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Measurement While Drilling (MWD)
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Measurement while Drilling (MWD)
Well Logging operations that occur during the drilling of the well bore and do not require that the drill stem or other equipment be removed from the well. This type of operation requires that the well logging tool contains one or more sealed sources and be located above the drilling stem to obtain information through mud telemetry communications.
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MWD - Neutron Sub
Radioactive Source Port
Detectors
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MWD – Gamma Sub
Radioactive Source Port
Detectors
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Geological borehole logging
Geological logging is used to investigate the geological make-up of an area by lowering test tools into a borehole. The picture shows a logging tool containing a neutron source.
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Summary
• Overview of the types of nuclear gauges found in the workplace
• Brief description of well logging equipment and process