Distributed Fiber Optic Sensing for Real-Time Monitoring of Gas in Riser during Offshore Drilling

Abstract

Effective well control depends on the drilling teams’ knowledge of wellbore flow dynamics and their ability to predict and control influx. Unfortunately, detection of a gas influx in an offshore environment is particularly challenging, and there are no existing datasets that have been verified and validated for gas kick migration at full-scale annular conditions. This study bridges this gap and presents pioneering research in the application of fiber optic sensing for monitoring gas in riser. The proposed sensing paradigm was validated through well-scale experiments conducted at Petroleum Engineering Research & Technology Transfer lab (PERTT) facility at Louisiana State University (LSU), simulating an offshore marine riser environment with its larger than average annular space and mud circulation capability. The experimental setup instrumented with distributed fiber optic sensors and pressure/temperature gauges provides a physical model to study the dynamic gas migration in full-scale annular conditions. Current kick detection methods primarily utilize surface measurements and do not always reliably detect a gas influx. The proposed application of distributed fiber optic sensing overcomes this key limitation of conventional kick detection methods, by providing real-time distributed downhole data for accurate and reliable monitoring. The two-phase flow experiments conducted in this research provide critical insights for understanding the flow dynamics in offshore drilling riser conditions, and the results provide an indication of how quickly gas can migrate in a marine riser scenario, warranting further investigation for the sake of effective well control.

Low-Frequency Distributed Acoustic Sensing for Early Gas Detection in a Wellbore

“…PERTT lab provides a versatile research environment for performing multiphase flow experiments on field-scale wellbores up to 5800 ft. in depth. The facility has 15,000 gallon capacity water circulation system and the ability to inject gas up to 10,000 SCFM (million standard cubic feet per day) [23,6]. The gas monitoring experiments analyzed in this study were conducted in a 5163 ft. deep test-well at PERTT.…”

“…EAL-TIME downhole measurement and monitoring are essential for maintaining safe wellsite operation and effective reservoir management. Over the past few years, the oil and gas industry has seen a rapid increase in the deployment of optical fiber-based distributed acoustic sensors (DAS) and distributed temperature sensors (DTS) for real-time downhole monitoring in both onshore and offshore operations [1,2,3,4,5,6]. Optical fiber sensors offer many unique advantages over conventional techniques such as logging tools and gauges.…”

“…One major benefit is the ability to measure temperatures and strain along the length of the fiber with higher sensitivity, thus making it possible to monitor the entire well simultaneously [7]. With an inherent tolerance for high temperatures and pressures, chemical passivity, corrosion resistance, and electrical insulation, fiber optic systems have the potential to address many of the downhole monitoring challenges in the oil and gas industry [6].…”

Integrating Fiber Optic Data in Numerical Reservoir Simulation Using Intelligent Optimization Workflow

“…Optical fiber sensors can be installed in a wellbore in a permanent, semipermanent, or temporary or retrievable mode [8]. A permanent installation of fiber optics involves cementing the fiber behind the casing.…”

“…The temporary or retrievable method is deployed via slick line or coiled tubing [9,10], and is the method used for the CSS test well in this study. There are numerous field examples of successful deployment of distributed fiber optic sensors for injection and production flow profiling, temperature monitoring, seismic measurement, wellbore integrity monitoring, and others [8][9][10][11][12].…”