Requirement for a new approach in pipeline leak detection

Although the risks of transporting hazardous hydrocarbons by pipeline are relatively low in comparison to other methods, there is a responsibility on the pipeline operator to ensure that the line’s integrity is maintained and the danger to the public and the environment is minimized. An essential component of any pipeline integrity maintenance system is the detection of leaks, as early as possible. In particular, smaller leaks can be very difficult to identify at the source and are a major safety concern. Recent studies have shown that more than 50% of pipeline leaks are from small holes (pinholes) rather than larger defects. The widely used Computational Pipeline Monitoring (CPM) systems are typically capable of detecting leaks down to a level of approximately 1.5% to 2% of pipeline flow rate (equivalent to several hundred gallons per day for larger oil transmission line). If left undetected, these leaks can easily increase in intensity or lead to full-bore rupture. Such leaks can cause significant damage to the environment, which can be very expensive and difficult to remediate. Early detection of leaks can greatly reduce the loss of product from the pipeline and avoid or minimize environmental damages.

There are a variety of methods that can detect leaks in natural gas and petroleum product pipelines, ranging from manual inspection to advanced satellite based hyper-spectral imaging. Typically, most operators opt for a combination of CPM where available, and direct observation methodologies which include aerial patrols, ground patrols and public and landowner awareness programs that are designed to encourage and facilitate the reporting of suspected leaks. Permanent monitoring sensors based on acoustic or other technologies are also available. These methods can be costly, and none can reliably detect small leaks regardless of their location in the line.

Most pipeline operators have in-line inspection (ILI) programs using “smart pigs” that detect cracking, wall thinning and other anomalies in pipelines. However, lines are typically only inspected at intervals of several years, and all ILI technologies have limits on the minimum cross-sectional area of the defects they can detect. Through-wall pinhole leaks typical of aggressive corrosion mechanisms such as MIC are not typically detected. Also many lines, particularly in the upstream and mid-stream sector, are never pigged. There is therefore a risk that leaks may go undetected for long periods resulting in shutdown and expensive clean-up operations when they are eventually discovered. Costs for a single leak in access if $10 million USD are not exceptional where leaks go undetected or lead to a more serious failure. Pure Technologies Ltd’s SmartBall is designed to reduce this risk and, perhaps, to allow the interval between pigging to be increased, thereby resulting in cost savings for operators.

SmartBall design

SmartBall is a leak detection pigging technology originally developed and successfully implemented for the water industry, and now refined to allow operation in oil and gas pipelines over 4-inches in diameter. SmartBall has been proven capable of detecting leaks in liquid lines of less than 0.5 gallons per minute where conventional CPM methods can detect leaks no smaller than 21 gpm. Development work is continuing to reduce the detection threshold still further.

Whereas traditional approaches utilizing acoustic monitoring techniques on pipelines have focused on longitudinal deployment and spacing of acoustic sensors, the SmartBall uses only a single acoustic sensor that is deployed inside the pipeline. Propelled by the flow of the liquid or gas being transported in the pipeline, the device will record all noise events as it traverses the length of the pipeline. This allows the acoustic sensor to pass in very close proximity to any leak whereby the sensor can detect very small leaks, whose noise signature can be clearly distinguished from any background noise.

The device consists of a spherical aluminum inner core containing the acoustic sensor and other instrumentation. The core is permanently sealed preventing any ingress of product into the electronics and ensuring the device is intrinsically safe for use in a potentially explosive environment. Other components and instruments inside the core include rechargeable batteries, microprocessor, solid-sate memory, temperature & pressure sensor, accelerometer, magnetometer, and an ultrasonic transmitter. The internal core is encased in a urethane shell for protection and to minimize noise generated as it passes through the pipe. The ball is manufactured in three sizes, 3.2inch OD for 4in lines, 5.4inch OD for 6in and 8in lines and 8.9inch OD for 10in lines and larger. Access for data download and recharging the internal batteries is by a small port eliminating the need to dismantle the ball.

SmartBall operation

Compared with conventional ILI operations, SmartBall is very straightforward to use. The ball can be deployed through existing pig-launching and retrieval stations or, in lines without pigging facilities, the ball can be introduced though an existing valve or through a “T” inserted in the line. The equipment is very portable regardless of the pipe size, as the ball is less than the diameter of the line. Pipe diameter changes, small radius bends, small-bore valves and other features that can render a pipeline ‘unpiggable’ are no obstacle to the SmartBall. An inspection pig for a 36” pipeline must be transported on a semi-trailer and loaded into the pig trap by crane, while SmartBall can be transported as checked baggage or in an SUV. Mobilization costs are low and the device can be easily operated by pipeline operations personnel. The associated analysis software will quickly identify any leaks detected by the system, so the pipeline owner can have the result of the inspection before the inspection teams leaves the site.

During the run, the ball can be tracked using conventional above-ground marker boxes that detect the passage of the ball’s on-board transponder. The ball also contains an acoustic ‘pinger’ than can be tracked by sensors mounted on the pipe. The SmartBall’s internal accelerometers also record the rotation of the ball to provide a third tracking mechanism. Using these indicators, it is possible to identify the location of any leak to within 1m. This is more than adequate to allow a field crew to locate and excavate the leak site.

SmartBall applications

SmartBall can be operated in both liquids and gas lines over a very wide range of pressures, flow speeds and temperatures. It is intended primarily for regular monitoring of operational pipelines to detect the early onset of leaks. Typically, the SmartBall inspection would be performed alongside the operator’s routine cleaning or batching pig runs. No special arrangements need to be made to run the SmartBall, so after some basic training the same field crew responsible for other pigging operations can run the ball and analyze the data.

If a leak is suspected, from SCADA, CPM or any other source, SmartBall can be used on an emergency basis to quickly identify the location of the leak. Similarly, locating a leak identified during a hydrotest can be a lengthy and costly operation. Provided conditions allow the test medium to be moved through the line, SmartBall offers a fast location method. If more than one leak exists, this approach is particularly beneficial.

Another use for SmartBall is to find where unauthorized tapping of pipelines is being done in order to steal product. This is a particular problem in some developing countries.

SmartBall can be used in main transmission lines, but is also well suited to gathering and distribution systems where facilities for smart pigs are not available or the costs of ILI are prohibitive.

Technical validation

SmartBall has been commercially deployed in water pipelines for since 2005 and has successfully identified leaks (natural and artificially induced for validation purposes) in all cases. The detection principle for liquid hydrocarbon lines is identical and initial field trails in an oil transmission line have shown the ball’s capability is as effective as for water pipelines. The generally higher pressures in hydrocarbon lines mean that the SmartBall’s leak detection threshold is enhanced. Leaks in gas pipelines generate a more distinct acoustic signature which further assists the SmartBall’s sensitivity.

Field trails are continuing in several oil pipelines in North and South America. Field trails are also scheduled for several gas pipelines.

Commercial arrangement

Pure Technologies Ltd offer pipeline operators two options for their SmartBall leak detection service. (1) An on-demand inspection and data analysis service performed by Pure personnel in the same manner as a conventional ILI inspection. (2) Provision of SmartBall equipment under license for use as required by the pipeline operator. The license arrangement will include equipment, software, on-site setup and calibration, baseline inspection of the pipeline section(s) to be included and training of the pipeline operator’s personnel. The SmartBall equipment may be used as often as required during the license period.

The technology is also being made available under license to service providers who are interested in adding SmartBall leak detection to their portfolio of oilfield services.

For further information, please contact:

Richard Fletcher
General Manager – Oil & Gas Division
Pure Technologies Group
705, 11th Ave. SW
Calgary, Alberta, Canada
T2R 0E3
Phone: +1 (403) 266 6794
Fax : +1 (403) 266 6570
Email: richard.fletcher@soundprint.com