Downhole Oil Well Casing Integrity and In-Line Inspection Solutions

Dexon’s advanced well-casing inspection fleet provides rapid comprehensive analysis and reporting of anomalies. Dexon’s onsite in-line inspection testing facility includes well casing test spools allowing for client inspection verification and testing. Clients are welcome to visit Dexon’s RD&E department and test facilities in Thailand for technology demonstrations and inspection verifications. 

Dexon’s Production Well Casing In-line Inspection (ILI) fleet utilizes ultrasonic technology to offer comprehensive anomaly detection and sizing capabilities. Advanced ultrasonic sensors provide direct wall thickness data for the precise measurement of geometric and metal loss anomalies to ± 0.3 mm of actual wall thickness with axial and circumferential sampling distance of 1 mm.  

Bi-directional inspection provides multiple data sets increasing data coverage and ensuring the detection of critical defects. Rapid on-site field reporting is provided in as little as 2 hours, while final reporting is delivered within 24-72 hours. Allowing for immediate decision-making for repair or immediate redeployment of the asset, reducing downtime and maximizing production.  

Well Casing Fleet – Key Features

• Field reporting is delivered in as little as 2 hours. 

• Final reporting is provided in as little as 24 hours. 

• Bi-directional inspection capabilities provide multiple data sets per inspection. 

• Providing 400,000 raw direct measurement data samples per m2. 

• Lightweight construction and design allow for easy mobility and handloading on wirelines and slicklines. 

• Providing accurate wall thickness measurements down to 1.0 mm remaining wall thickness. 

• Highly accurate wall thickness measurements to within ± 0.3 mm. 

• Dexon’s 1,228 m2 R&D department includes 90+ personnel for the continual development and customization of inspection services to meet client requirements. 

Key Tool Specifications

Reliability: Specially designed to withstand extreme pressures and temperatures present in downhole wells providing consistent reliable inspection results. 

Accuracy: High sampling density of over 400,000 direct measurements per m2, provide inspection data with 1 mm axial and circumferential sampling distance and ± 0.3 mm wall thickness accuracy. 

Rapid assessment and turnaround: Rapid reporting times of 2 hours for onsite reporting and 24 hours for final reporting allow for actionable informed decision-making. 

Inspection speed: Maximum tool inspection speeds of 80 meters per minute. 

Minimal disruption to operating schedules: Inspection can be performed in line with planned logging runs eliminating disruption to operating schedules and maximizing production.  

Defect Detection Verification

Ultrasonic inspection data provides direct measurement of defects including defect size, 

location, remaining wall thickness, and metal loss percentage. Data is used to 

accurately determine pipeline condition and ensure asset integrity. Probability of detection (POD) 

figures based on defect size can be seen below. 

Dexon’s well casing fleet is able to accurately detect, locate, and quantify a full range of defects, including: 

• General and localized metal loss/corrosion (internal & external).

• Acute corrosion such as pinholes (internal & external).

• Ovality and geometric anomalies.

• Axial and circumferential cracking and crack-like defects.

Inspection Data Verification  

Accompanying Dexon’s 1,228 square meter R&D facility is a 7-acre test yard featuring pump-through, pull-through, and infinity test loops. The onsite testing facility allows for inspection data verification and rigorous tool testing. Pulsed echo and angle beam tip diffraction ultrasound allow for the detection and sizing of a range of defect types including metal loss, through-wall holes, cracking, and geometric deformations. Inspection data verification is performed demonstrating the fleet’s defect detection and sizing capabilities. A range of simulated internal and external defects have been added to pipe spools at Dexon’s onsite test yard. Actual defect dimensions are compared to measured defect dimensions using unity plotting, generating in–field probability of detection (POD) and probability of identification (POI) figures.  

Simulated Test Yard Metal Loss Inspection Data 

An arrangement of internal metal loss defects of varying depths and lengths can be seen in the inspection data below from Dexon’s onsite test yard. Both internal and external man-made defects are used to verify inspection data and tool capabilities prior to an inspection. 

Simulated internal metal loss defects in test yard inspection data. 

Six simulated defects can be seen in the ultrasonic C-scan and B-scan inspection data above. With A-scan data on the left showing the amplitude of individual ultrasonic signals chosen from the center of the first defect from the left, displaying a highly precise remaining wall thickness measurement of 2.54 mm to within ± 0.3 mm. 

A unity plot can be seen below comparing actual defect depth vs measured defect depth during smart pigging verification testing. Artificial defects were manufactured ranging from 1 mm to 9 mm in depth. Measurements can be seen to be within tolerance of ± 0.3 mm in greater than 90% of indications. 

Metal loss depth unity plotting compares actual defect depth vs measured defect depth during smart pigging verification testing. 

In–field Metal Loss Inspection Data  

In-field wall thickness inspection data shows general corrosion detected on the external surface of the production casing at a depth of 827 m. Maximum defect depth was recorded at 78% of nominal wall thickness with a remaining wall thickness of 1.54 mm. While defect length, width, and depth were measured at 192 mm, 149 mm, and 5.50 mm.

In-field metal loss inspection data shows general corrosion detected in a production well at a depth of 827 m. 

In–field Through Wall Hole Inspection Data 

The inspection data below shows a through-wall hole in a well-casing. Corrosion can be seen around the circumference of the pipe with a white area in the center of the defect. This white area signifies a hole in the pipe wall due to a loss of ultrasonic signal as the sound waves dissipate out of the pipe not returning an ultrasonic signal from the internal pipe wall surface.  

In-field inspection data shows the detection of a through-wall hole in a well-casing. 

Immediate Comprehensive Two-Tiered Reporting

Dexon’s production well-casing in-line inspection (ILI) program includes a two-tiered reporting structure ensuring asset integrity. The system provides rapid and actionable inspection results, allowing for immediate assessment of the well’s integrity. Providing prompt decision-making on repair requirements eliminating asset failure and ensuring maximum profitability and production capabilities.  

Immediate 2-Hour On-Site Field Reporting 

• Summary of all inspection operating details. 

• Issued within as little as 2 hours after the completion of the inspection allowing service teams to return the well to production. 

• Analysis and assessment of all critical defects. 

24-72 Hour Final Reporting

• Issued within 24-72 hours of completion of the inspection. 

• Featuring detailed assessment and analysis of all detected anomalies. 

• Utilizing mass quantities of inspection data providing detailed corrosion mapping, including over 400,000 individual direct wall thickness measurements per m2 of pipe wall.  

• A-Scan data recorder for each individual measurement. 

• Additional reporting criteria available upon request to meet client reporting needs. 

• Integrity assessment and calculations in accordance with API 579 and ASME FFS-1.