Application of the fiber-optic distributed temperature sensing for monitoring the liquid level of producing oil wells

Peng, Gaoliang; He, Jun; Yang, Shengnan; Zhou, Weiyong

doi:10.1016/j.measurement.2014.08.012

Cited by 42 publications

(18 citation statements)

References 10 publications

(8 reference statements)

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“…It determines the depth of liquid level by counting the acoustic waves reflected from tubing collars or velocity-time products [14]. The advantages of this acoustic analysis include an inexpensive and non-intrusive process resulting in its wide applications across the world, compared to mechanical, capacitive and optical methods [15,16]. In a production gas/oil well, the gas/oil flows in the tubing and annular partial obstructions, poor surface connections or odd length of tubing joints are the main disturbing factors for annulus liquid level measurements [17].…”

Section: Introductionmentioning

confidence: 99%

A Novel Acoustic Liquid Level Determination Method for Coal Seam Gas Wells Based on Autocorrelation Analysis

Zhang

Fan

et al. 2017

Energies

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Abstract:In coal seam gas (CSG) wells, water is periodically removed from the wellbore in order to keep the bottom-hole flowing pressure at low levels, facilitating the desorption of methane gas from the coal bed. In order to calculate gas flow rate and further optimize well performance, it is necessary to accurately monitor the liquid level in real-time. This paper presents a novel method based on autocorrelation function (ACF) analysis for determining the liquid level in CSG wells under intense noise conditions. The method involves the calculation of the acoustic travel time in the annulus and processing the autocorrelation signal in order to extract the weak echo under high background noise. In contrast to previous works, the non-linear dependence of the acoustic velocity on temperature and pressure is taken into account. To locate the liquid level of a coal seam gas well the travel time is computed iteratively with the non-linear velocity model. Afterwards, the proposed method is validated using experimental laboratory investigations that have been developed for liquid level detection under two scenarios, representing the combination of low pressure, weak signal, and intense noise generated by gas flowing and leakage. By adopting an evaluation indicator called Crest Factor, the results have shown the superiority of the ACF-based method compared to Fourier filtering (FFT). In the two scenarios, the maximal measurement error from the proposed method was 0.34% and 0.50%, respectively. The latent periodic characteristic of the reflected signal can be extracted by the ACF-based method even when the noise is larger than 1.42 Pa, which is impossible for FFT-based de-noising. A case study focused on a specific CSG well is presented to illustrate the feasibility of the proposed approach, and also to demonstrate that signal processing with autocorrelation analysis can improve the sensitivity of the detection system.

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Section: Introductionmentioning

confidence: 99%

A Novel Acoustic Liquid Level Determination Method for Coal Seam Gas Wells Based on Autocorrelation Analysis

Zhang

Fan

et al. 2017

Energies

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“…Therefore, a high measurement resolution, a high level of safety, reduced need for infrequent maintenance, and cost-effectiveness are strongly demanded for liquid-level sensing in automobiles [ 4 , 5 , 6 ]. There are many methods that can be used to measure the liquid level, some of which are the float type, the electro-static type [ 7 , 8 ], the optical type [ 9 ], optical fiber sensors [ 10 , 11 , 12 , 13 ], the guide pulse type [ 14 ], and the ultrasonic type [ 11 , 12 , 13 ]. The float type detects the position of the float on a liquid surface combined with a resistive sensor, which has been used since early times because of its simple structure and reasonable cost.…”

Section: Introductionmentioning

confidence: 99%

“…Although it has a resolution of only 20 cm, because this technique depends on the entry of water into the fiber core through the grooves, it can be applied in large-scale structural health monitoring (SHM). The other fiber sensors utilize Fiber Bragg Grating (FBG) [ 11 ], the response of Raman fiber scattering between different heated mediums [ 12 ], and the self-imaging properties of the multimode interference (MMI) [ 13 ]. Those sensors offer numerous merits, such as resistance to corrosion, robustness against noises, high accuracy, and so on.…”

Section: Introductionmentioning

confidence: 99%

Measuring Liquid-Level Utilizing Wedge Wave

Matsuya

Honma

Mori

et al. 2017

Sensors

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A new technique for measuring liquid-level utilizing wedge wave is presented and demonstrated through FEM simulation and a corresponding experiment. The velocities of wedge waves in the air and the water, and the sensitivities for the measurement, are compared with the simulation and the results obtained in the experiments. Combining the simulation and the measurement theory, it is verified that the foundation framework for the methods is available. The liquid-level sensing is carried out using the aluminum waveguide with a 30° wedge in the water. The liquid-level is proportional to the traveling time of the mode 1 wedge wave. The standard deviations and the uncertainties of the measurement are 0.65 mm and 0.21 mm using interface echo, and 0.39 mm and 0.12 mm utilized by end echo, which are smaller than the industry standard of 1.5 mm. The measurement resolutions are 7.68 μm using the interface echo, which is the smallest among all the guided acoustic wave-based liquid-level sensing.

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“…Another recent application is the prediction of a liquid level through of a distributed sensing system based in temperature measurements, as mentioned by Peng at al. [11]. In Ref.…”

Section: Introductionmentioning

confidence: 99%

Groundwater level monitoring using a plastic optical fiber

Mesquita

Paixão

Antunes

et al. 2016

Sensors and Actuators A: Physical

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The present work describes the testing and application of a low cost plastic optical fiber sensor on the monitoring of groundwater levels. Two sensors with different grove depth (½ and ¼ of the core thickness) and a resolution of 20 cm along 2 m of the optical fiber were produced and tested. The sensors were tested under two experimental setups: water level variation (increasing and decreasing of the water level) and groundwater increase simulation, in a soil column. The analysis of the optical signal's amplitude and its variations due to the increasing or decreasing of water level showed that both tested sensors presented an appropriate performance and adequate sensibility to groundwater level variation and, therefore, can be used for in situ applications of monitoring.

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Application of the fiber-optic distributed temperature sensing for monitoring the liquid level of producing oil wells

Cited by 42 publications

References 10 publications

A Novel Acoustic Liquid Level Determination Method for Coal Seam Gas Wells Based on Autocorrelation Analysis

A Novel Acoustic Liquid Level Determination Method for Coal Seam Gas Wells Based on Autocorrelation Analysis

Measuring Liquid-Level Utilizing Wedge Wave

Groundwater level monitoring using a plastic optical fiber

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