In-Well Optical Sensing—State-of-the-Art Applications and Future Direction for Increasing Value in Production-Optimization Systems

Abstract

For any production optimisation system to function effectively it must reliably receive quality data on demand. Over the past decade the reservoir monitoring industry has been addressing the issue of reliability including implimentation of a step-change technology - Passive Optical Sensing Systems. Since the first installation of an in-well optical pressure gauge over 10 years ago, the industry has built a substantial track record with over 85 installations of P&T gauges and hundreds of DTS installations - acceptance is growing! Initially Optical Sensing systems were expensive, complicated to install, and could only support limited applications. Today, they are on a par with electronic gauges with respect to performance, cost and installation simplicity. The state- of-the-art in optical sensing technology includes Bragg-grating based Pressure and Temperature sensors, permanent Distributed Temperature Sensing (DTS), Single- and Multiphase Flowmeters, and Seismic sensors. This paper describes the operation of each of the sensing systems mentioned above, the data/information provided, together with details of application case histories. These range from simple single-gauge installations to complex wells with integrated pressure sensing, flow measurements and remotely activated zonal flow control - true Smart or Intelligent Wells. The future direction includes even more complex intelligent completions and subsea deployments. Also high accuracy distributed array temperature sensing, optical distributed pressure sensing, sand detection, and distributed strain (e.g. for riser monitoring), are just a few of the new generation of sensing systems that are described in the paper. As subsea continues to play an important role in our industry, the presentation (not included in this paper) will also include a synopsis from the SPE ATW "In-well Optical Sensing - Subsea Well Applications - Are We Ready"? held February 7th and 8th, 2006 in Galveston. Introduction To manage and optimize well production, operators need in-well monitoring systems that deliver high-performance measurements throughout the life of the well, and reliability without the need for routine maintenance or intervention. In the 1980's, the initial applications for optical sensing were focused on the military and areospace industries. The requirements that drove early development of optical sensing systems were not readily available in comparable electrical systems. These requirements included:Small physical size, allowing simple integration into small locations and embedding in composite structural systems.Multiple sensing point and measurement types on a single fiber, replacing multiple electrical sensors, instrument types and associated electrical wiring. This reduced system complexity and weight is critical in aerospace systems.Silica with high temperature fiber coatings, enabling the development of sensing systems for applications with operating temperatures in excess of 1,000°C.High reliability, maintained by having simple sensing elements at the measurement point and the sensor's instrument in a readily accessible location for servicing or repair.Immunity to interference from local radio or electrical transmission sources.No spark hazard, reducing the risk of fire. Also optical communication systems significantly improve signal performance, data density and transmission distance. These requirements also fit the needs of oil and gas in-well monitoring applications. Subsequently the first in-well optical Pressure and Temperature gauge was installed in a producing land well in the Netherlands in 1993. This initial system operated successfully for a period of more than 5 years. And so began the journey to broader acceptance of the technology in our industry. Through significant investment by service companies and operators in the development of sensor systems, a wider range of commercial optical sensing products and services has been brought to the oil and gas market.

Guidelines on Composite Flexible Risers: Monitoring Techniques and Design Approaches

“…Due to their application, marine risers are usually insulated to resist seabed temperatures. Different researchers have presented different studies on monitoring of marine risers, such as fatigue monitoring using shape-sensing devices [53,[66][67][68][69], fibre-optic monitoring [54,[70][71][72][73], intelligent systems [74][75][76], optical sensing [51,[77][78][79][80][81], Riser Integrity Management (RIM) [82,83], flexible pipe integrity assurance [36,69,84], pipeline condition monitoring [85][86][87], vibration monitoring for armour failure [63,67,68,86], pipeline surveillance monitoring [88], and leak detection systems [76,86,[89][90][91].…”

Sensors and the Way Forward for Sensing Efficiently and Effectively

“…At the beginning, like PDGs and PDMSs, these optical sensing applications were expensive, complicated to install and could only support limited applications. However the below listed specifications alongside the vast improvements in signal performance, data density and transmission distance, have drawn the way forward for their today's immense applications in the industry [1].…”

Depth Distribution of Gas Rates From Temperature and Pressure Profiles in Unconventional Gas Wells

“…Nowadays, continuous temperature and pressure profiling in complex wells can be obtained accurately and economically, with the aid of distributed pressure sensors (DPSs) and distributed temperature sensors (DTSs) (Bryant et al, 2004;Drakeley et al, 2006;Nath et al, 2007;Pinzo et al, 2007;Hernández and Haney, 2010;Overton, 2011). While the direct flow rate measurement is still a challenging job for those traditional single-point measurement tools.…”