Abstract

The oil and gas production industry continually strives to adopt new technologies and operating practices. Driven by the need of the operator to optimize production and reduce costs, this goal is further fueled by the emerging acceptance of the digital oil field. One of the technologies currently enhancing the management of production assets is optical in-well permanent monitoring.

Optical in-well permanent monitoring has matured over the years. Initial systems were expensive, complicated to install, and able to support only limited applications. Today, optical permanent monitoring systems are comparable to electrical gauge systems in terms of performance, cost and installation complexity. With the added benefit of long-term reliability, operators can rely on quality measurements throughout the life of the well. In addition, optical permanent monitoring systems have demonstrated no measurable drift or error. This capability provides the reservoir and production engineer with a reliable, stable, high-quality data stream throughout the life of the well.

Optical in-well permanent monitoring systems are gaining an ever-widening acceptance in upstream oil and gas production operations. Early interest was based on the promise of high reliability and stability coupled with unique measurement capabilities. Since the first installation of an optical pressure gauge in 1993, the industry now has more than 60 permanent optical installations comprising a total of 72 pressure/temperature gauges, 10 in-well flowmeters, and 41 distributed temperature sensors. Drawing on global field installation successes and failures-from simple single-gauge installations to multi-zone intelligent wells with integrated pressure sensing, in-well flow measurements and remote flow control-this paper assesses the degree to which optical permanent monitoring technology has delivered on its initial promise. In short, has the potential of this technology become a reality?

Introduction

Optical sensing has had potential in the oil field for the past 20 years. To manage and optimize well production, operators needed a monitoring system that delivered high-performance, stable measurements throughout the life of the well, and reliability without the need for routine maintenance or intervention.

Since its inception in the 1980s, optical sensing was focused on unique monitoring applications that included extreme operating environments, physical limitations, and unique measurement requirements. Existing electrical sensing technology did not readily meet these requirements. Though initial applications for optical sensing targeted military and space applications, it was apparent that the same challenges applied to the monitoring of oil and gas wells. Early development of sensing technologies and the application of these technologies to production monitoring began in the mid-1980s. By the early 1990s, field-testing was implemented to validate the technology. The success of the field trials led to significant investment by service companies and operators in the development of sensor systems, and the introduction of commercial fiber-optic sensing products and services.

Over the past five years, the optical production-monitoring business has grown from the technology demonstration phase to mainstream fit-for-purpose systems used by operators worldwide. Initially, fiber-optic sensing was limited to simple reservoir pressure monitoring and distributed temperature-measurement applications.

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