Applied Ultrasonic Technology in Wellbore-Leak Detection and Case Histories in Alaska North Slope Wells

Abstract

Summary When operators are faced with well-integrity problems, a variety of methods may be used to detect the source of annular communication. Methods for detecting downhole leak points include spinners, temperature logs, downhole cameras, thermal-decay logs, and noise logs. However, many of these methods are ineffective when dealing with very small leaks and can result in collected data that require a significant amount of logging finesse to interpret. Ultrasonic listening devices have been used for a number of years to detect leak sources effectively in surface production equipment. Ultrasonic energy has some properties that, when compared to audible-frequency energy, make it ideal for accurate leak detection (Beranek 1972; Povey 1997; Evans and Bass 1972). Like audible-frequency energy, ultrasonic energy can pass through steel. However, ultrasonic energy propagates relatively short distances through fluids when compared to equal-energy audible-frequency sound. Thus, when an ultrasonic signal of this nature is detected, the detection tool will be in close proximity to the energy source. On this premise, an ultrasonic leak-detection tool was developed for downhole applications to take advantage of the unique properties of ultrasonic-energy propagation through various media. Data-acquisition equipment and filtering algorithms were developed to allow continuous logging conveyed on standard electric line at common logging speeds. Continuous logging has proved to be significantly more efficient in locating anomalies than static logging techniques commonly used in noise-logging operations. During development, the tool was shown to be effective in locating leaks as small as 0.026 gal/min with an accuracy of 3 ft in production tubing, casing, and other pressure-containing completion equipment. Leaks also have been detected through multiple strings of tubing and casing. The tool has proved to be effective in locating leaks that other diagnostic methods were unable to locate.

Water shutoff and conformance improvement: an introduction

“…Gels have been used at times to treat these small leaks (Creel and Crook 1997;Jia et al 2020;Jurinak and Summers 1991;Urdahl et al 1992). Leaks are commonly diagnosed with pressure tests, flow surveys (e.g., spin flowmeter), or wellbore televiewers (Johns et al 2009;Smith 1990;Ward et al 1994).…”

Acoustic Wave-Based Method of Locating Tubing Leakage for Offshore Gas Wells

“…In general, downhole leaks are detected by measuring and analyzing the abnormal signals that are generated as leak flow moves through holes in the tubing, e.g., temperature, flow rate, and acoustic signals. Traditional logging methods, including flowmeter logging [4], temperature logging, ultrasonic logging [5], noise logging [6], and the integrated approach [7], can be used to measure abnormal signals by placing logging tools in the tubing. The abnormal signals in the tubing are measured and recorded by the sensors installed on the logging tools during lifting.…”

Acoustic signal processing for well integrity monitoring systems

“…Ultrasonic energy analysis is widely used in leak detection because ultrasonic energy propagates through the steel structure of a wellbore [13]. For example, Farooqui et al [14] introduced an acoustic-based tool, Johns et al [15] illustrated an ultrasonic method of leak detection for casing repair, and Johns et al [16] studied the attributes of ultrasound and leaks in Alaskan north slope wells. Other approaches were later based on noise measurement [17] and more recent integrated approaches [18], [19] in which noise and temperature measurements are coupled with a turbine or spinner flowmeter information to correlate data, which are then used to infer the location of leaks.…”