Fiber Optic Pressure Transducer Research Articles

Novel insight into pressurization of the male and female urethra through application of a multi-channel fibre-optic pressure transducer: Proof of concept and validation.

PurposeTo confirm feasibility of recording pressure along the length of the urethra using a multi-sensor fibre-optic pressure catheter; to identify the spatial and temporal features of changes in pressure along the urethra at sites related to specific striated pelvic floor muscles; and to investigate the relationship between urethral pressures and activation of individual pelvic floor muscles estimated from ultrasound imaging.Materials and MethodsProof-of-concept study including one male (47 years old) and one female (33 years old). A multi-sensor fibre optic pressure catheter (10 mm sensor separation) was inserted into the urethra. Pressure data were recorded simultaneously with trans-perineal ultrasound imaging measures of pelvic floor muscle activity during sub-maximal and maximal voluntary contractions and evoked coughs.ResultsPressure changes along the urethra were recorded in all tasks in both participants. Face validity of interpretation of pressure measures with respect to individual muscles was supported by correlation with ultrasound-measured displacements induced by the relevant muscles. Onset of pressure increase occurred in a distal to proximal sequence in the urethra of the male but not the female during voluntary contraction. Peak urethral pressures varied in location, timing and amplitude between tasks. Evoked cough induced in the greatest urethral pressure increase across all tasks for both participants.ConclusionsThe high spatial resolution pressure catheter provide viable and valid recordings of urethral pressure in a male and female. Data provide preliminary evidence of sex differences in spatial and temporal distribution of urethral pressure changes.

A fiber-optic sensor-based device for the measurement of vaginal integrity in women.

Pelvic floor disorders (PFDs) in women are a major public health concern. Current clinical methods for assessing PFDs are either subjective or confounded by interference from intra-abdominal pressure (IAP). This study introduces an intravaginal probe that can determine distributed vaginal pressure during voluntary exercises and measures the degree of vaginal tissue support independent of IAP fluctuations. An intravaginal probe was fabricated with 18 independent fiber-optic pressure transducers positioned along its upper and lower blades. Continuous pressure measurement along the anterior and posterior vaginal walls during the automated expansion of the probe enabled the resistance of the tissue to be evaluated as a function of displacement, in a manner reflecting the elastic modulus of the tissue. After validation in a simulated vaginal phantom, in vivo measurements were conducted in the relaxed state and during a series of voluntary exercises to gauge the utility of the device in women. The probe reliably detected variations in the composition of sub-surface material in the vaginal phantom. During in-vivo measurements the probe detected distributed tissue elasticity in the absence of IAP change. In addition, the distribution of pressure along both anterior and posterior vaginal walls during cough, Valsalva and pelvic floor contraction was clearly resolved with a large variation observed between subjects. Our data highlight the potential for the probe to assess the integrity of the vagina wall and support structures as an integrated functional unit. Further in vivo trials are needed to correlate data with clinical findings to assist in the assessment of PFDs.

Intermuscular pressure between synergistic muscles correlates with muscle force.

The purpose of the study was to examine the relationship between muscle force generated during isometric contractions (i.e. at a constant muscle-tendon unit length) and the intermuscular (between adjacent muscles) pressure in synergistic muscles. Therefore, the pressure at the contact area of the gastrocnemius and plantaris muscle was measured synchronously to the force of the whole calf musculature in the rabbit species Oryctolagus cuniculus Similar results were obtained when using a conductive pressure sensor, or a fibre-optic pressure transducer connected to a water-filled balloon. Both methods revealed a strong linear relationship between force and pressure in the ascending limb of the force-length relationship. The shape of the measured force-time and pressure-time traces was almost identical for each contraction (r=0.97). Intermuscular pressure ranged between 100 and 700 mbar (70,000 Pa) for forces up to 287 N. These pressures are similar to previous (intramuscular) recordings within skeletal muscles of different vertebrate species. Furthermore, our results suggest that the rise in intermuscular pressure during contraction may reduce the force production in muscle packages (compartments).

Two Successive Shock Waves Generated by Underwater Pulse Electric Discharge for Medical Applications

This paper reports on analysis of two different types successive underwater shock waves generated by a device incorporating a compact shock-wave generator with a magnetic pulsed compression circuit. To generate shock waves, underwater pulsed electric discharges in high-impedance saline water were used. The saline water made possible underwater shock waves propagation in tissue with low reflection between the solution and tissue boundary, owing to their similar acoustic impedances. A cylindrical electrode holder and a semiellipsoidal shock-wave focusing reflector/generator were used in this paper. The diameter of the compact shock-wave reflector was 20 mm. Two kinds of successive underwater shock waves, one generated by electric discharge plasma expansion and the other by bubble collapse, were observed. The shock waves were studied by time-resolve high-speed visualization and direct pressure measurement using a fiber optic probe hydrophone pressure transducer. The former method elucidated propagation of underwater shock waves and behavior and collapse of the bubble near the electrodes, while the later measured two kinds of underwater shock waves pressures at different voltage amplitudes using the cylindrical electrode holder and the shock focusing generator. This paper clearly shows the importance of the secondary shock waves, their control, and damping, for effective and safe medical application of shock waves.

Signal analysis of a polarimetric fiber optic sensor for dynamic strain monitoring

Polarimetric fiber optic sensors have many advantages over other fiber optic sensors and strain gauges. As opposed to Fiber Bragg Grating sensors, polarimetric fiber sensors can be constructed with very simple, portable and robust experimental setup. In the paper we propose two methods of the polarimetric sensor output signal analyzing. First method is based on depolarization phenomena, and calculates degree of polarization (DOP), second one uses Fast Fourier Transform to analyze dynamic sensor response. Usefulness of both methods has been shown and experimentally proven. Full Text: PDF References K. Schroeder, W. Ecke, J. Apitz, E. Lembke, G. Lenschow, "A fibre Bragg grating sensor system monitors operational load in a wind turbine rotor blade," Meas. Sci. Technol. 17, 1167–1172 (2006). CrossRef G. Hegde, A. Asundi, "Performance analysis of all-fiber polarimetric strain sensor for composites structural health monitoring," NDT&E International 39, 320–327 (2006). CrossRef G. Wehrle, P. Nohama, H. J. Kalinowski, P. I. Torres, L. C. G.Valente, "A fibre optic Bragg grating strain sensor for monitoring ventilatory movements" Meas. Sci. Technol. 12, 805–809 (2001). CrossRef W. J. Bock, A. W. Domanski, T. R. Wolinski, "Influence of High Hydrostatic Pressure on Beat Length in Highly Birefringent Single-Mode Bow-Tie Fibers," Appl. Optics 29, 3484-3488 (1990). CrossRef A. W. Domański, M. Bieda, P. Lesiak, P. Makowski, M. Szeląg, T. Poczęsny, K. Prokopczuk, P. Sobotka, M. Chychłowski, M. Sierakowski, T. R. Woliński, "Polarimetric optical fiber sensors for dynamic strain measurement in composite materials," Acta Physica Polonica A. 124, 399-401 (2013). CrossRef P. Lesiak, G. Rajan, Y. Semenova, G. Farrell, A. Boczkowska, A. W. Domański, T. R. Woliński, "A hybrid highly birefringent fiber optic sensing system for simultaneous strain and temperature measurement," PLP 3, 140-142 (2010). CrossRef R. A. Chipman, "Depolarization in the Mueller Calculus," Proc. SPIE 5158, 184–192 (2003). CrossRef N. Furstenau, M. Schmidt, W. J. Bock, W. Urbanczyk, "Dynamic pressure sensing with a fiber-optic polarimetric pressure transducer with two-wavelength passive quadrature readout," App. Opt. 37, 663-671 (1998). CrossRef

Simultaneous magnetic resonance imaging and consolidation measurement of articular cartilage.

Magnetic resonance imaging (MRI) offers the opportunity to study biological tissues and processes in a non-disruptive manner. The technique shows promise for the study of the load-bearing performance (consolidation) of articular cartilage and changes in articular cartilage accompanying osteoarthritis. Consolidation of articular cartilage involves the recording of two transient characteristics: the change over time of strain and the hydrostatic excess pore pressure (HEPP). MRI study of cartilage consolidation under mechanical load is limited by difficulties in measuring the HEPP in the presence of the strong magnetic fields associated with the MRI technique. Here we describe the use of MRI to image and characterize bovine articular cartilage deforming under load in an MRI compatible consolidometer while monitoring pressure with a Fabry-Perot interferometer-based fiber-optic pressure transducer.

In Vivo Discography in Degenerate Porcine Spines Revealed Pressure Transfer to Adjacent Discs

In vivo experimental porcine study. To investigate if discography induced pressure increase in adjacent degenerate discs. Despite refinements in the past 2 decades, the validity of discography is debated. Discography in healthy pigs has shown that the pressure increase during disc injection transmits to adjacent discs, a potential source for false positive responses. Degeneration in 1 lumbar disc was induced in 10 pigs by drilling a hole through the endplate. Intradiscal pressure was recorded using a 0.36-mm fiber-optic pressure transducer inserted into nucleus pulposus through a 22-gauge needle. The pressure was measured simultaneously in 2 adjacent discs during slow (0.03 mL/s) automated contrast injection into 1 of the discs up to 8 bar (116 psi). Ten adjacent discs were prefilled with contrast from previous discogram. A pressure increase 2 psi or more above baseline was defined as increased pressure in adjacent discs. Pressure was recorded until 15 minutes after injection. A total of 28 discograms were successfully performed. A pressure increase during injection was detected in 57% (16) of the 28 adjacent discs with mean 3.2 psi (1.7-8.2; standard deviation, 1.8), corresponding to a mean increase above baseline of 11%. Of those 16 adjacent discs, 4 were nondegenerate and 12 degenerate, of which 7 were prefilled. Fifteen minutes after injection, 89% of adjacent discs displayed increase in pressure of mean 14% above baseline. Discography induced pressure increase in adjacent discs in a degenerate disc model, something not reported earlier. If present, also in human spine pressure transmission, may be a potential cause for false positive discography responses.

Development of a large-animal model to measure dynamic cerebrospinal fluid pressure during spinal cord injury

Spinal cord injury (SCI) often results in considerable permanent neurological impairment, and unfortunately, the successful translation of effective treatments from laboratory models to human patients is lacking. This may be partially attributed to differences in anatomy, physiology, and scale between humans and rodent models. One potentially important difference between the rodent and human spinal cord is the presence of a significant CSF volume within the intrathecal space around the human cord. While the CSF may "cushion" the spinal cord, pressure waves within the CSF at the time of injury may contribute to the extent and severity of the primary injury. The objective of this study was to develop a model of contusion SCI in a miniature pig and establish the feasibility of measuring spinal CSF pressure during injury. A custom weight-drop device was used to apply thoracic contusion SCI to 17 Yucatan miniature pigs. Impact load and velocity were measured. Using fiber optic pressure transducers implanted in the thecal sac, CSF pressures resulting from 2 injury severities (caused by 50-g and 100-g weights released from a 50-cm height) were measured. The median peak impact loads were 54 N and 132 N for the 50-g and 100-g injuries, respectively. At a nominal 100 mm from the injury epicenter, the authors observed a small negative pressure peak (median -4.6 mm Hg [cranial] and -5.8 mm Hg [caudal] for 50 g; -27.6 mm Hg [cranial] and -27.2 mm Hg [caudal] for 100 g) followed by a larger positive pressure peak (median 110.5 mm Hg [cranial] and 77.1 mm Hg [caudal] for 50 g; 88.4 mm Hg [cranial] and 67.2 mm Hg [caudal] for 100 g) relative to the preinjury pressure. There were no significant differences in peak pressure between the 2 injury severities or the caudal and cranial transducer locations. A new model of contusion SCI was developed to measure spinal CSF pressures during the SCI event. The results suggest that the Yucatan miniature pig is an appropriate model for studying CSF, spinal cord, and dura interactions during injury. With further development and characterization it may be an appropriate in vivo large-animal model of SCI to answer questions regarding pathological changes, therapeutic safety, or treatment efficacy, particularly where humanlike dimensions and physiology are important.

Novel ex-vivo mechanobiological intervertebral disc culture system

Intervertebral disc degeneration, a leading cause of low back pain, poses a significant socioeconomic burden with a broad array of costly treatment options. Mechanical loading is important in disease progression and treatment. Connecting mechanics and biology is critical for determining how loading parameters affect cellular response and matrix homeostasis. A novel ex-vivo experimental platform was developed to facilitate in-situ loading of rabbit functional spinal units (FSUs) with relevant biological outcome measures. The system was designed for motion outside of an incubator and validated for rigid fixation and physiologic environmental conditions. Specimen motion relative to novel fixtures was assessed using a digitizer; fixture stiffness exceeded specimen stiffness by an order of magnitude. Intradiscal pressure (IDP), measured using a fiber-optic pressure transducer, confirmed rigidity and compressive force selection. Surrounding media was controlled at 37°C, 5% O2/CO2 using a closed flow loop with an hypoxic incubator and was validated with probes in the specimen chamber. FSUs were subjected to cyclic compression (20 cycles) and four-hour creep at 1.0MPa. Disc tissue was analyzed for cell viability using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which showed high viability (>90%) regardless of loading. Conditioned media was assayed for type-II collagen degradation fragments (CTX-II) and an aggrecan epitope (CS-846) associated with new aggrecan synthesis. CTX-II concentrations were not associated with loading, but CS-846 concentrations appeared to be increased with loading. Preservation of the full FSU allows physiologic load transmission and future multi-axis motion and identification of load-responsive proteins, thereby forming a new niche in intervertebral disc organ culture.

Sonography for Determining the Optic Nerve Sheath Diameter With Increasing Intracranial Pressure in a Porcine Model

This study investigated whether it is feasible to use sonography to monitor changes in the optic nerve sheath diameter in a porcine model. A fiber-optic intracranial pressure transducer was surgically placed through the frontal sinus directly into the brain parenchyma of adult Yorkshire pigs (n = 5). A second bolt was placed on the contralateral side for intraparenchymal fluid infusion. Optic nerve sheath diameter measurements were acquired by each of 2 ultrasound operators around the leading edge of the nerve, 3 to 5 mm distal from the origin of the optic nerve. To induce a change in diameter, intracranial pressure was manipulated by injecting normal saline into the intraparenchymal infusion catheter located in the symmetric contralateral position as the pressure-monitoring probe. Data from 1 pig were unusable because of a cerebrospinal fluid leak into the sinus and orbital fissure. Saline aliquots of 1 to 10 mL were able to generate intracranial pressures typically starting from 10 to 15 mm Hg and increasing to 75 to 90 mm Hg, which eventually evoked a Cushing response. Fluid injection was controlled to increase pressures by 60 mm Hg over a 15- to 20-minute period. Regression analysis of all animals showed that the optic nerve sheath diameter increased by 0.0034 mm/mm Hg of intracranial pressure; however, this slope ranged from 0.0025 to 0.0046, depending on the animal measured. There was no discernible effect of the ultrasound operator on the slope; however, measurements made by 1 operator were consistently higher than the others by about 8% of the overall diameter range. These results suggest that the use of the optic nerve sheath diameter to noninvasively confirm acute changes in intracranial pressure over 1 hour is feasible in a porcine model. We recommend that this method be validated in humans using direct intracranial pressure measurement where possible to confirm it as a screening tool for acute and chronically increased diameters secondary to elevated pressure in clinical settings.

A structural-analytical model of differentiating transformation of the signals of fiber-optic pressure transducers

Studies on, and a new variant of, a structural-analytical model of differentiating transformation of optical signals in a fiber-optic transducer are presented.

The Transfer of Disc Pressure to Adjacent Discs in Discography

In vivo experimental study. The primary objective of the study was to investigate pressure transmission to adjacent discs during discography. A secondary objective was to quantify the transmitted pressure, both in contrast injected and noninjected porcine intervertebral discs. Discography is used to before surgery identify painful discs. A pain response during discography that is concordant with the patient's experienced back pain is regarded as an indication that the injected disc is the source of pain. However, the sensitivity and specificity of discography are matters of debate. Pressure-controlled discographies have been reported to reduce the number of false-positive discs using low pressure criteria. Preliminary data indicated a transfer of pressure from an injected to an adjacent disc during discography. Pressure transmission in vivo during lumbar discography, not reported before might, if clinically present, contribute to a false-positive diagnosis. Thirty-six lumbar discs in 9 adolescent pigs were investigated. Intradiscal pressure was recorded during contrast injection, using a 0.36/0.25 mm fiber-optic pressure transducer inserted into the nucleus pulposus via a 22 G needle. The pressure was measured simultaneously in 2 adjacent discs during contrast injection into 1 of the discs at pressures up to 8 bar. Transmitted pressure was recorded both in noninjected discs and in discs that were prefilled with contrast. Thirty-three discs were successfully examined. During contrast injection, there was an intradiscal pressure rise in the adjacent disc with a median value of 16.0% (range, 3.2-37.0) over baseline pressure. There was no significant difference in pressure increase between the noninjected and prefilled discs (P < 0.68). Discography of porcine discs induces a pressure increase in adjacent discs. A similar pressure transfer during human clinical discography might elicit false-positive pain reactions.

Pressure Generation from Micro-Bubble Collapse at Shock Wave Loading

This paper reports the result of a primary experimental and analytical study used to explore a reliable technology that is potentially applicable to the inactivation of micro-creatures contained in ship ballast water. A shock wave generated by the micro-explosion of a 10mg silver azide pellet in a 10mm wide parallel test section was used to interact with a bubble cloud consisting of bubbles with average diameter 10µm produced by a swirling flow type micro-bubble generator. Observations were carried out with a high-speed camera, IMACON200, and the corresponding rebound pressures of the collapsing bubbles were measured with a fiber optic probe pressure transducer that provides high spatial and temporal resolutions. We found that micro-bubbles collapse in several hundred nanoseconds after the shock exposure and the resulting peak pressure pulses that repeatedly occurred exceeded well over 200MPa measured at the 20mm distance from the explosion center. These continued for well over 20µs. The experimental pressure responses were explained by solving the one-dimensional bubble Rayleigh-Plesset equation. Such high peak pressures could be used effectively for the inactivation of micro-creatures contained in ship ballast water.

衝撃波作用による微小気泡群の崩壊と衝撃圧生成(流体工学,流体機械)

This paper reports the result of a primary experimental and analytical study used to explore a reliable technology that is potentially applicable to the inactivation of micro-creatures contained in ship ballast water. A shock wave generated by the micro-explosion of a 10mg silver azide pellet in a 10mm wide parallel test section was used to interact with a bubble cloud consisting of bubbles with average diameter 10µm produced by a swirling flow type micro-bubble generator. Observations were carried out with a high-speed camera, IMACON200, and the corresponding rebound pressures of the collapsing bubbles were measured with a fiber optic probe pressure transducer that provides high spatial and temporal resolutions. We found that micro-bubbles collapse in several hundred nanoseconds after the shock exposure and the resulting peak pressure pulses that repeatedly occurred exceeded well over 200MPa measured at the 20mm distance from the explosion center. These continued for well over 20µs. The experimental pressure responses were explained by solving the one-dimensional bubble Rayleigh-Plesset equation. Such high peak pressures could be used effectively for the inactivation of micro-creatures contained in ship ballast water.

Measuring interstitial fluid pressure with fiberoptic pressure transducers

In this report we describe a practical procedure for measuring interstitial fluid pressure (IFP) using fiberoptic pressure transducers based on optical interferometry. Eight mice were used for subcutaneous IFP measurements and four mice for intramuscular IFP measurements with a FOBPS-18 fiberoptic pressure transducer. We used four mice for subcutaneous IFP measurements with a SAMBA-420 MR fiberoptic pressure transducer. One measurement was made for each mouse simultaneously by using a fiberoptic system and an established approach, either transducer-tipped catheter or wick-in-needle technique. The mean IFP values obtained in subcutaneous tissues were − 3.00 mm Hg (SEM −/+ 0.462, n = 8), − 3.25 mm Hg (SEM −/+ 0.478, n = 4), − 3.34 mm Hg (SEM −/+ 0.312, n = 6), and − 2.85 (SEM −/+ 0.57, n = 6) for the FOBPS fiberoptic transducer, the SAMBA fiberoptic transducer, the transducer-tipped catheter, and the wick-in-needle technique, respectively. There was no difference between these techniques to measure IFP (Friedman test, p = 0.7997). The subcutaneous IFP measurements showed strong linear correlation between fiberoptic transducer and transducer-tipped catheter ( R 2 = 0.9950) and fiberoptic transducer and wick-in-needle technique ( R 2 = 0.9966). Fiberoptic pressure transducers measure the interstitial fluid pressure accurately, comparable to conventional techniques. The simplified IFP measurement procedures described in this report will allow investigators to easily measure IFP, and elucidate the unit pressure change per unit volume change (d P/d V) in normal or cancer tissues in the presence of strong electromagnetic fields encountered in MRI.

Measurement of blast wave by a miniature fiber optic pressure transducer in the rat brain

Exposure to blast wave that is generated during an explosion may result in brain damage and related neurological impairments. The aim of this study was to investigate pressure changes induced by exposure to blast inside the rat brain. For intracranial pressure measurement we used a miniature optic fiber sensor (o.d. 550 μm) with a computer recording system. The sensor was placed in the third cerebral ventricle of anesthetized rats exposed to 40 kPa blast wave in a pneumatic-pressure driven shock tube. Short pressure waves lasting several ms were detected inside the brain with the magnitude that might result in nervous tissue damage.

Change in canal pressure with cervical cerclage

KATHLEEN HUHN, WILLIAM WATSON, Mayo Clinic College of Medicine, Obstetrics and Gynecology, Rochester, Minnesota OBJECTIVE: To determine the pressure and temporal changes associated with cerclage placement. STUDY DESIGN: Models of a cervix were made using smooth and skeletal muscle tissue to a uniform width and central canal diameter. Different types of suture (0-Prolene and 5 mm Mersilene) and cerclage types (McDonald and Shirodkar) were loosely placed in each ‘‘cervix’’ model. A LuMax fiber optic pressure transducer catheter was placed in the canal at the level of the cerclage stitch and tightened with the initial pressure recorded. The catheter was than advanced past the cerclage site and serial measurements were taken at 0.5 cm intervals along the length of the model. Readings were reported at one minute intervals for a total of ten minutes for each cerclage. The percent change in pressure for each sample was recorded. RESULTS: The average initial canal pressures after securing the cerclage stitch was 174.6 cm H20 (SD 23.5). The average canal pressure at the 10 minute mark was significantly reduced (P ! .001) to 69.9 cm H20 (SD 25.4) resulting in a mean decrease in canal pressure of 62.3%. The average total zone of pressure recorded around the level of the cerlage stitch was 1.69 cm (SD 0.59). At the ten minute mark, this 1.56 cm (SD 0.56) zone of pressure had not signicantly decreased (P = .17). Two models were re-evaluated 24-hours after stitch placement and had canal pressures of 35-40 cm H20 and a zone of pressure which decreased from 2.5 cm to 1.0 cm. CONCLUSION: While the pressure within the canal decreased signficantly within the first ten minutes after cerclage placement, the zone of pressure generated by the cerclage placement remained constant. The initial canal and zone of pressure decreased to relatively low levels by the following day. SMFM Abstracts S155

Optical pressure measurement

The supersonic combustor of a hypersonic engine is a harsh environment in which to apply close-coupled sensors. While fiber optic sensors have some inherent advantages over conventional electronic sensors, the first challenge was to design a fiber optic connector that could support the application of fiber optic sensors. We have designed a high-temperature fiber optic connector that will allow the placement of a fiber optic sensor into the wall of a high-temperature pressure vessel such as the DCR combustor. This connector has proven versatile enough to support monitoring of the ignition status of the combustor via looking at the spectral content of the flame. Additional information about the combustion process can be obtained by using multiple fibers and multiple detectors with different wavelength sensitivities or by connecting the fiber to a spectrometer. We have also shown that two different fiber optic transducer manufacturers, using two different fiber optic sensing technologies, can produce fiber optic pressure transducers that can be installed inside of the high-temperature fiber optic connector. These pressure transducers were closely coupled to the combustor and have successfully monitored the combustor pressure during short ground tests. The transducers used for these tests were modifications of standard designs by Fiso Technologies and Optrand Inc. The small size of the fiber optic pressure transducers and their high-temperature capability allowed them to be applied in locations where the application of conventional strain gauge transducers is not possible. Such close coupling of the transducers allowed observation of phenomena not seen with prior existing instrumentation. Both of the transducers furnished useful data; however, optimization of the transducers was not possible under the scope of this program. It should be noted that the hypersonic DCR tests are short ground tests using heat sink model hardware. The optical sensors have not yet been proven in a flight environment, where the run times will be longer and the combustor temperatures will be higher. We must perform additional work to make them ready for flight tests.

Permanent Fiber-Optic Monitoring at Northstar: Pressure/Temperature System and Data Overview

Summary In-well fiber-optic sensing systems offer the potential for continuous, highly accurate, highly reliable, real-time data measurements. During the past 3 years, permanent downhole fiber-optic pressure and temperature (P/T) transducers have become an accepted new technology in the oil and gas industry. Northstar, on the North Slope of Alaska, represents the first multiwell, new field development to incorporate fiber-optic P/T gauges. Real-time downhole pressure data are critical to managing the miscible-gas injection enhanced-recovery process at Northstar. Fiber-optic gauges were selected because of their reliability at high temperatures and their ability survive the severe shock and vibration conditions associated with post-installation perforating operations. As of publication, optical P/T gauges have been installed in 15 wells at North-star. The data have proved valuable to the asset team in monitoring the perforating program, determining initial reservoir pressure, managing well drawdown, diagnosing completion problems, building wellbore-hydraulics and inflow-performance models, and providing pressure-buildup data, all without the need for well interventions and the resulting loss in production volume.

A Novel Fiber-Optic Pressure Sensor Operated at 1300-nm Wavelength

In this paper, we discuss a particular topology of a fiber-optic pressure transducer, developed recently at the Laboratory of the Photonics Research Center, University of Quebec en Outaouais. The sensor, which is an extension of our previous polarimetric configuration, was designed to operate using typical telecommunications components at the wavelength of 1300 nm. The pressure sensor is temperature compensated in an innovative way and has no polarizer between the LD and the sensor. The absolute accuracy of this sensor can be less than 1% in a wide range of temperatures, and including all types of metrological errors such as hysteresis and unrepeatability.