Session: 03-04-02 Inline Inspection Performance I

Paper Number: 133711

133711 - Evaluation of High-Resolution Downhole Tubular Inspection Tools by Full-Scale Field Testing 

Abstract: 

Downhole tubular corrosion poses a significant threat to underground gas storage (UGS) well integrity. Therefore, integrity management of UGS wells requires periodic inspection of tubular conditions using various inspection tools to properly identify and size corrosion anomalies. The corrosion inspection data are then used to estimate the remaining burst strength of the tubulars using various methods. However, the calculated remaining burst strength can have significant uncertainties due to the variations of the input parameters, including the reported corrosion feature sizes from the inspection tools, casing material property variations, in-situ load conditions, and prediction model uncertainties.

In an effort to improve the tubular corrosion management for UGS wells, this study focused on a quantitative performance evaluation of a few selected state-of-the-art downhole tubular corrosion inspection tools based on a full-scale field test program. The tools tested are based on principles of ultrasonic testing and magnetic flux leakage, which are two types of high-resolution tubular inspection technologies that can provide relatively accurate sizes of isolated corrosion induced metal-loss defects (including depth, length and width). The test well included a casing string and a tubing string with varying size, weight and grades. A combination of artificial and natural corrosion features were present on the external surface of the casing and tubing joints. These joints have been laser scanned to establish an accurate baseline for a comprehensive evaluation of the inspection tool performance. This paper presents the process and methodology of the field test and tool performance evaluation. Statistical approaches were employed to determine the quantitative tool performance metrics, including the probability of detection, probability of false call and feature sizing accuracy.

The outcome of this study provided a comprehensive understanding of the capabilities and performance of the tubular inspection tools, which allows UGS operators to make informed decisions regarding well intervention and operation. Moreover, the statistical performance results not only allow the determination of the feature sizing tolerances that can be used in a deterministic integrity assessment method but also provide valuable inputs for further development of a probability-based tubular integrity assessment workflow.

Presenting Author: Abrar Islam C-FER Technologies (1999) Inc.

Presenting Author Biography: Mr. Abrar Islam is a researcher in the Pipeline Integrity & Operations department at C-FER Technologies. He holds an MSc in Structural Engineering from the University of Alberta. His work has primarily focused on pipeline structural integrity analysis for strain demand and capacity modelling using analytical models, finite element method, and full-scale experimental data. Abrar has also been involved in statistical performance evaluation of downhole inspection tools for underground gas storage wells using field test data.

Authors:

Gang Tao C-FER Technologies (1999) Inc.
Quy Doan Southern California Gas Company
Abrar Islam C-FER Technologies (1999) Inc.
Diana Abdulhameed C-FER Technologies (1999) Inc.
Allen Scoging Southern California Gas Company
Steve Cardiff Southern California Gas Company