Provides high-resolution measurements that enable accurate analysis of cement, casing wear, casing thickness, corrosion, and fluid properties
The Weatherford UltraView tool provides high-resolution data for accurate evaluation of cement, casing wear, casing thickness, corrosion imaging, and fluid properties.
The UltraView tool uses two ultrasonic transducers. One transducer is dedicated to casing and cement inspection, and another is dedicated to fluid inspection. The transducer dedicated to casing and cement inspection is located in the rotating head and provides 360° coverage by capturing 72 samples per revolution. The transducer dedicated to fluid properties inspection is located in the tool body and provides real-time acoustic velocity, impedance, and density measurements of the wellbore fluid.
The tool incorporates an advanced, high-speed, measure-on-position DC motor that rotates the primary measurement transducer. This transducer fires upon arriving at a precise point in its rotation, which ensures accurate circumferential depiction of casing defects and cement distribution.
How Much Does the Borehole Fluid Affect the Cement Impedance Measurement in Ultrasonic Scanner Tools?
Lucio N. Tello, Dimas C. Azuaje, and Edwin K. Roberts Weatherford
Ultrasonic scanning tools measure the cement acoustic impedance at higher radial and vertical resolution than standard cement bond and sector tools. The impedance is affected by variations of the borehole fluid contained in the well. This is not problematic for most wells because the tool is typically calibrated in the same fluid as the main logging section. Also, small variations in the well fluid between the bottom and the top of the logging section can go undetected in the computed cement impedance because these variations are continuous and not abrupt. In the past, ultrasonic tools estimated the value of the fluid impedance by measuring the slowness and multiplying this value by the density, which is a constant reading at the surface. Sometimes the slowness measurement is done during a logging down pass. An error is introduced when the fluid changes from one type to another because both slowness and density changes; however, density changes in larger percentages than slowness, causing the fluid impedance to have a substantially different value than the estimated one. This difference in impedance causes the cement evaluation to be different also. In the present paper we introduce a newly developed mud chamber for the ultrasonic radial scanner tool that measures the fluid impedance directly, in situ, while logging and with greater accuracy. In addition, we present an algorithm to compute the influence of changes in the cement impedance due to variations of the impedance in the fluid column. Laboratory tests are presented using static logs and logs obtained during field testing corroborating the methodology and algorithm. Most of the time the tools give a correct reading; but in instances where stratigraphic fluid columns with vastly different densities are present, if no correction is applied, it can mean the difference in detecting the presence or absence of cement.
- Ultrasonic transducer in the rotating head
- Patented mud chamber design
- Two separate transducers: one dedicated to casing and cement inspection and another dedicated to fluid properties inspection
- Measure-on-position DC motor that rotates the primary measurement head
- Inspecting casing
- Monitoring internal wear and corrosion
- Locating internal and external casing defects
- Analyzing casing thickness
- Evaluating cement
- Producing high-resolution wellbore images
- Analyzing foam and lite cement
- The UltraView tool generates acoustic resonance within the casing and measures cement acoustic impedance while minimizing sensitivity to the microannulus, which eliminates the need to make an additional pass under increased well pressure.
- Real-time fluid velocity, impedance, and density measurements eliminate the need to use data gathered during the down pass, which may not represent conditions while logging up.
- Consistent transducer firing minimizes the chances of overlooking important features. The result is a more accurate depiction of cement distribution around the casing.
- High-resolution wellbore imaging provides detailed images of internal casing corrosion, defects, and perforation patterns.
- Use of data from each shot fired provides high-resolution real-time thickness measurement.
- The UltraView tool can be run on either single- or seven-conductor wireline.
- Combinability with the Weatherford SecureViewSM suite, including FluxView™ and BondView™ tools, enables diagnosis of multiple downhole threats in a single pass.
The UltraView tool simultaneously delivers data for cement inspection, internal and external casing inspection, and fluid properties analysis.
|Data||Acoustic impedance, fluid impedance, travel time, amplitude, casing ID, casing thickness|
|Logging speed||1,800 ft/hr (540 m/hr)|
Casing thickness: 0.200 to 0.800 in. (5 to 21 mm)*
Acoustic impedance: 0 to 10 Mrayl
Cement evaluation mode: 1.0 in. at 1800 ft/hr (540 m/hr)
Image mode: 0.5 in. at 1800 ft/hr (540 m/hr)
|Thickness resolution||±0.002 in. (0.051 mm)|
|Acoustic impedance resolution||0.2 Mrayl|
Internal radius ±1%
Acoustic impedance < 3.83 Mrayl ± 0.5 Mrayl
|Depth of investigation||Thickness of casing; casing-to-cement interface|
WBM up to 14 ppg maximum mud weight
OBM up to 11.5 ppg maximum mud weight and 8.5% maximum solids
|*The second harmonic is used for a thickness greater than 0.625 in. (15 mm).|
|Outer diameter*||3.38 in. (86.0 mm)|
|Length||18.66 ft (5.69 m)|
|Weight||315.00 lb (142.90 kg)|
|Maximum temperature||350ºF (177ºC)**|
|Maximum pressure||20,000 psi (138 MPa)**|
|Minimum casing size||4.5 in. (11.43 cm)|
|Maximum casing size||20.0 in. (50.8 cm)|
*Outer diameter depends on the head used.
**Temperature and pressure ratings are 175ºF (80ºC) and 5,000 psi (35 MPa) when logging casing of greater than 14-in. OD and less than 22-in. OD.