Leak Detection for Oil & Gas a Safety Necessity

Overview

Leak detection for oil & gas continue to evolve, with an increasing number of end user organizations now viewing leak detection systems (LDS) as a positive investment in safety. Many countries have also developed regulatory requirements for leak detection, making these types of systems vital. The bottom line is that these systems can provide owner-operators with added insurance against undetected leaks or ruptures that could cause significant financial, operational, and/or environmental harm.

These types of investments can also reduce risk by maintaining operational integrity to help reduce the frequency of accidents or other abnormal events and help mitigate their negative impact on safety, environment, and profitability of the pipeline or relevant oil & gas facility.  This applies whether it’s an offshore, subsea, or onshore oil or gas facility.

According to industry sources, there are more than 2.5 million miles of operating pipelines; enough to circle the Earth at the equator almost ten times over.  Over the next five years, industry sources forecast the need to install over 60,000 miles of new transmission pipelines globally to keep up with the demand from increased production from both unconventional and conventional oil and gas projects.  ARC believes leak detection technology would be needed for a good percentage of these pipelines.

Leak Detection for Oil & Gas Snapshot

An increasing number of pipeline operating companies and related stakeholders are beginning to realize that investments in LDS solutions not only will mitigate risk by helping prevent catastrophic leaks and the associated financial and operational implications, but also should help reduce fines, regulatory oversight, and damage to a company’s reputation.

American Petroleum Institute (API) document, API 1130, stipulates that an ideal LDS should be able to:

• Detect even small leaks quickly
• Reliably alarm real leaks while minimizing false alarms
• Accurately detect and report leak location and flow
• Operate robustly in non-ideal circumstances
• Detect liquids and gas in single- or multiphase pipelines
• Have a wide operating range that includes both steady-state and transient states, including startup and shutdown and flow adjustments

ARC Advisory Group sees an increasing trend among pipeline operators and related stakeholders to view investments in LDS as an additional layer of insurance that can help reduce operational losses and financial liabilities from persons and property, enhance pipeline integrity, and extend the life of the asset.  Joint industry projects (JIP) such as those being conducted by DNV GL will no doubt help raise awareness of the importance of LDS and likely provide best practices and industry standards for other companies to follow and deploy in their own brownfield and/or greenfield pipeline projects.

Deploying LDS is critical to help owner-operators, pipeline operators, and other relevant stakeholders maximize their transportation operations, mitigate losses, and reduce the chances that undetected leaks could escalate into major problems and/or cause an explosion.  The greatest future potential likely resides in serving onshore transmission pipeline applications; given the large number of producing wells and increasing need to transport oil and gas with greater safety and more cost-effectively than by rail, trucks, or (in some cases) marine vessels.  ARC believes that an increasing number of existing pipelines and relevant oil & gas industry facilities will incorporate LDS through retrofits and/or network upgrades, especially in high- consequence areas and in countries in which increased regulatory oversight is anticipated.

Two Major Types of Leak Detection Systems

ARC (and others) typically segment the LDS market into two major types: external-based LDS and internal-based (software) LDS.

External-based Systems

External-based LDS relies primarily on dedicated sensors (hardware), with software required to compute leak detection-related analytics. Acoustic/ultrasonic LDS, which fall in the external category, are more responsive in detecting leaks and minimally affected by multi-component flow. Also, these systems can be used on new pipelines or retrofitted to existing pipelines, and operate with low false alarm rates.

Another external-based system, fiber optic systems, employs two main sensing methods for leak detection: distributed temperature sensing (DTS) and distributed acoustic sensing (DAS). This fiber optic technology is not sensitive to fluid changes, accurate for leak localization, not affected by pipeline transients, sensitive to small leaks, if leak signal is present, and typically, fast to alarm leaks. 

Internal-based Systems

Internal software-based LDS rely primarily on existing SCADA systems and measurement data to determine leaks.  Some suppliers provide a primarily software-based leak detection solution that leverages measurements from pressure, temperature, and flow transmitters that are not associated with the software sale. Among the software-based LDS solutions, ARC has grouped together balancing methods (volume balance, line balance, and modified volume balance) within the of mass/volume balance category. Additional computational pipeline monitoring (CPM)-based leak detection software systems include negative pressure wave, statistical analysis, RTTM, and E-RTTM systems and rely on real-time data provided by a SCADA system. 

Leak Localization Methods

Leak detection systems are equipped with accurate leak localization technologies to identify leaks or ruptures in different conditions.  This enables users to take swift containing action to minimize harm to people and the environment. Localized repairs can then be carried out cost effectively.

The gradient intersection method provides relatively high accuracy, even on smaller leaks.  This technology is based upon the pressure profiles of the two points of inspection (inlet & outlet). This approach is most suitable for detecting gradual or continuous leaks.

The wave propagation method is useful for relatively large and/or sudden leaks, but doesn’t work well locating small and/or gradual leaks. In practical use, it is limited to steady-state conditions. It is able to locate leaks in pumping or in paused flow conditions.

Major LDS Applications

ARC research shows the major applications for LDS have been for onshore liquid and gas transmission pipelines.  The next largest applications are for gathering lines and flowlines, both onshore and offshore/subsea. These are closest to the wellhead and critical components in getting the oil and gas to the transmission pipeline. Well-to-FPSO (floating production, storage, and offloading) and subsea/offshore transmission pipelines are additional application areas.   

Recommendations

Today’s LDS offers significant potential operational and risk management benefits for pipeline operators and other end users who would be well advised to develop tactics and strategies to leverage these potential benefits.  Users should take the time to understand their specific pipeline operational requirements to select the LDS that will best meet the requirements of their respective projects.

ARC recommends that operators and users consider several different technical and commercial factors before deciding on an LDS and related LDS supplier. These include:

• Age of pipeline
• Pressure requirements (i.e., low, high, etc.)
• Composition of medium (i.e., multiphase, oil, gas, etc.)
• Accuracy of system – localization, volume detection, etc.
• Responsiveness of system – how quickly leak is detected
• Ease of use, training
• False alarm management/mitigation
• Reliability of system

• Slack condition during transient/s

ARC has developed an LDS technology evaluation and selection guide to help pipeline operators and other owner-operators determine the most important aspects of the technology needed for their specific applications.

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Keywords: Leak Detection Systems (LDS), Oil, Gas, Safety, Selection Criteria, ARC Advisory Group.