Downhole Survey Services
Acoustic Televiewer Logging (ATV) is a type of downhole survey that uses both acoustic waves and imaging to measure the properties of the wellbore. It combines the capabilities of Full Waveform Sonic Logging (FWS) and Optical Televiewer Logging (OTV) to provide detailed information about the wellbore and the surrounding rock formation.
Acoustic Televiewer Overview?
The acoustic probe generates an image of the borehole wall by transmitting ultrasonic pulses from a fixed transducer with rotating mirror and recording the amplitude and travel time of the signals reflected at the interface between borehole fluid and the formation (borehole wall). A harder borehole surface translates to higher amplitude recorded by the tool, whereas softer surfaces, fractures, and void spaces are recorded at a lower relative amplitude.
Acoustic televiewers work best in boreholes that are smooth, circular, and have a high acoustic impedance contrast between the borehole fluid and borehole wall. A rough borehole wall with significant breakouts and vugs or an oval shaped borehole scatter the acoustic energy weakening the signal recorded by the televiewer’s transducer. Particles in heavier drilling muds, such as oil and some polymer-based muds, both scatter and absorb acoustic energy and cause loss of image resolution. Poor tool centralization can also degrade image quality.
Many modern acoustic televiewers like the QL40-ABI-2G also feature multi-echo capability. This is achieved by digitally recording the reflected acoustic wave train which is analyzed in real-time by the digital signal processor. Algorithms allow the system to detect the reflection from the acoustic window and to separate and classify all subsequent echoes.
Acoustic Televiewer Applications and Benefits:?
- Detailed and oriented structural information
- Reference for core orientation
- Fracture detection and evaluation
- Breakout analysis
- Detection of thin beds
- Determination of bedding dip
- Orientation of stress tensor
- Lithology and mineralogical characterization
- Casing inspection
- Repeatable and precise
- Continuous high resolution in-situ measurement
- Easy to confirm accuracy by comparing ATV & OTV logs
Rock Formation
ATV can be used to identify the type of rock formation, which is important for reservoir characterization and exploration.
Fractures
ATV can detect natural fractures in the rock formations that can affect the flow of fluids and production of oil and gas.
Vugs
ATV can detect the presence of vugs, which are large voids in the rock formation that can affect the well integrity and the production of oil and gas.
Cement And Drilling Mud Returns
ATV can detect the presence of drilling mud or cement returns, which can indicate a problem with the well integrity.
Corrosion And Erosion
ATV can detect signs of corrosion and erosion on the wellbore walls, which can indicate
What Is Acoustic Televiewer Logging Used For?
Some of the main uses include:
Reservoir Characterization
ATVs can be used to identify the presence, orientation and properties of hydrocarbon-bearing formations, which can help in the exploration and production of oil and gas. It can also be used to identify the type of rock formation, porosity, permeability, saturation, stress and strain, and natural fractures.
Completion Design
ATV is used to design the completion string and select the appropriate size of the casing and tubing, in order to ensure a proper fit and avoid wellbore collapse or other issues.
Well Integrity Check
ATV can be used to evaluate the condition of the well and detect any signs of damage or deformation, which can cause well integrity issues. It can also measure the stress and strain on the rock formation which is important for well integrity check and drilling optimization.
Fracture Detection
ATV can detect natural fractures in the rock formations that can affect the flow of fluids and production of oil and gas.
Production Optimization
ATV can be used to measure the porosity, permeability, saturation and fluid identification which are important for the production of oil and gas.
Drilling Optimization
ATV can be used to optimize drilling parameters such as weight on bit, rotary speed, mud flow and mud properties, to improve the drilling efficiency and reduce the risk of wellbore instability.
Mining And Geothermal Drilling
ATV can be used in mining drilling to identify the presence of mineral deposits and in geothermal drilling to identify the presence of hot water or steam.
Reservoir Monitoring
ATV can be used to monitor the changes of rock and fluid properties with time, to track the production of oil and gas and to identify the presence of changes in the reservoir that may affect the production.
