Method Of Pressure Determination Research Articles

Well Shut-In Pressure Determination Method for Deepwater Drilling Considering Fluid-Solid-Heat Coupling

Blowout is one of the most serious safety threats in deepwater drilling. Considering the characteristics of gas invasion in complex formations, gas migration and distribution, and dynamic changes in temperature inside a wellbore, a deepwater well-closing pressure determination method considering thermal-fluid-solid coupling was proposed. The model was verified using actual data, and the average error in the increase in casing pressure during the closing process was found to be 5.42%. The shut-in pressure of oil and gas wells under a transient shut-in process was analyzed. The results showed that the fluid thermal expansion caused by temperature recovery had a significant impact on the change in wellhead backpressure after well closure. Furthermore, the time required for the wellbore pressure to recover to the formation pressure varies nonlinearly with factors such as geothermal gradients, pit gains, bottom-hole pressure, and gas production indices. A pressure calculation chart was developed for deepwater drilling. The shut-in time for deepwater drilling should not be less than 15 min, and in cases where the gas production index is small and the bottomhole pressure difference is large, the shut-in time should exceed 90 min. The results can provide theoretical guidance and technical support for well shut-in processes during deepwater drilling.

Optimizing Tourniquet Pressure in Upper Extremity Surgery.

Background: Pneumatic tourniquet is an effective tool to achieve hemostatic control of the surgical field in upper extremity (UE) operations. Elevated pressures have been associated with adverse effects despite various methods of pressure determination. We aim to demonstrate the usage of reduced tourniquet pressures and examine factors associated with achieving reduced pressures. Methods: A prospective study was conducted (2016-2018) at a Level 1 Trauma Center and an Outpatient Surgical Center, totaling 226 operations, involving a reduction of cuff pressures over time from a standard baseline of limb occlusion pressure for UE operations. Results: A gradual reduction of pressures was successfully achieved with a mean pressure of 187 mmHg and average time of tourniquet application being 25 minutes. We found chronological surgical number and patient BMI to be significantly associated with tourniquet pressure (p < 0.05). 4.5% of cases resulted in breakthrough bleeding, but did not reliably occur with any pressure thresholds, patient demographics, or operative factors (p > 0.05, for all). Conclusions: Reduced tourniquet pressures can mitigate complications associated with tourniquet use. Our research shows reduced pressures are successful in maintaining field visibility and we encourage an adoption of pressures below 200 mm Hg in most procedures that require a tourniquet.

Data preservation in pressure measurement

Suggestions concerning practical pressure scales are largely focused on the selection of primary calibrants, criteria for candidate reference points and choice of the equations of state. Meanwhile, preserving and archiving data related to pressure measurements need also considerable attention. These data, as well as metadata items, corresponding to the pressure determination method are often missing in publications, making it difficult to assess the soundness of the applied approach and validate the reliability of the results. Even if the relevant information is reported, it can be difficult to track down if buried in the article text or supplementary material. Therefore, only using a consistent standardized format one can conform to the requirements of modern science research data being FAIR, i.e. Findable, Accessible, Interoperable and Reusable. Existing data structures can serve as a good starting point, if properly adapted to host specific information related to the pressure measurement. In particular, essential high-pressure data and metadata can be encompassed within Crystallographic Information Framework (CIF), a widely accepted and robust standard file structure for the archiving and distribution of crystallographic information. This review is thus intended to indicate recommendations for data items to be preserved along with the associated measured pressure values.

Instantaneous pressure determination from unsteady velocity fields using adjoint-based sequential data assimilation

A sequential data assimilation (DA) method is developed for pressure determination of turbulent velocity fields measured by particle image velocimetry (PIV), based on the unsteady adjoint formulation. A forcing term F, which is optimized using the adjoint system, is added to the primary Navier–Stokes (N–S) equations to drive the assimilated flow toward the observations at each time step. Compared with the conventional unsteady adjoint method, which requires the forward integration of the primary system and the backward integration of the adjoint system, the present approach integrates the primary-adjoint system all the way forward, discarding the requirement of data storage at every time step, being less computationally resource-consuming, and saving space. The pressure determination method of integration from eight paths [J. O. Dabiri et al., “An algorithm to estimate unsteady and quasi-steady pressure fields from velocity field measurements,” J. Exp. Biol. 217, 331 (2014)] is also evaluated for comparison. Using synthetic PIV data of a turbulent jet as the observational data, the present DA method is able to determine the instantaneous pressure field precisely using the three-dimensional velocity fields, regardless of the observational noise. For the two-dimensional three-component (3C) or two-component (2C) velocity fields, which are not sufficient for pressure determination by the integration method due to the lack of off-plane derivatives, the present DA method is able to reproduce pressure fields whose statistics agree reasonably well with those of the referential results. The 3C and 2C velocity fields yield quite similar results, indicating the possibility of pressure determination from only planar-PIV measurements in turbulent flows. The tomography PIV measurements are also used as observational data, and a clear pressure pattern is obtained with the present DA method.

Reconstruction of surface-pressure fluctuations using deflectometry and the virtual fields method

This study presents an approach for obtaining full-field dynamic surface-pressure reconstructions with low differential amplitudes. The method is demonstrated in a setup where an air jet is impinging on a flat plate. Deformations of the flat plate under dynamic loading of the impinging jet were obtained using a deflectometry setup that allows measurement of surface slopes with high accuracy and sensitivity. The measured slope information was then used as input for the virtual fields method to reconstruct pressure. Pressure fluctuations with amplitudes of down to {mathcal {O}}(1)~text {Pa} were extracted from time-resolved deflectometry data using temporal band-pass filters. Pressure transducer measurements allowed comparisons of the results with an established measurement technique. Even though the identified uncertainties in fluctuations were found to be as large as 50%, the spatial distributions of dynamic pressure events were captured well. Dynamic mode decomposition was used to identify relevant spatial information that correspond to specific frequencies. These dynamically important spatio-temporal events could be observed despite their low differential amplitudes. Finally, the limitations of the proposed pressure determination method and strategies for future improvements are discussed.Graphic abstract

Determination of pressure in aqueo-carbonic fluid inclusions at high temperatures from measured Raman frequency shifts of CO2

Due to the presence of additional volatiles and/or electrolytes in CO 2 -H 2 O fluids, the total pressure of many natural aqueo-carbonic fluid inclusions at high temperatures as determined using microthermometry is usually made with considerable uncertainty. In this paper, we present the results of our high P - T in situ Raman scattering study of high-density aqueo-carbonic fluids, with and without a small amount of CH 4 and NaCl, whose objective is to derive a new method for pressure determination in aqueo-carbonic fluid inclusions at high temperatures. The measurement of the Fermi dyad bands at temperatures up to 400 °C and pressures up to 1200 MPa is described. The manner in which the frequency shifts and intensity of Raman bands are governed by pressure, temperature, presence of CH 4 in carbonic and NaCl in aqueous fluids is discussed. From the monotonic dependence of the frequency shifts of the lower Fermi dyad band ν − and the Fermi resonant splitting D ( D = ν + − ν − ) with pressure and temperature, the pressure (in MPa) in aqueo-carbonic fluid inclusions at elevated temperatures can be determined directly by using the following two polynomial equations: P ( MPa ) = − 16 + 1 . 232 × T − 53 . 72 × ( Δ ν − ) − 1 . 83 × 10 − 3 × T 2 + 24 . 46 × ( Δ ν − ) 2 − 0 . 292 × T × ( Δ ν − ) , P ( MPa ) = − 26 + 1 . 501 × T + 193 . 24 × ( Δ D ) − 1 . 61 × 10 − 3 × T 2 + 5 . 436 × ( Δ D ) 2 + 0 . 158 × T × ( Δ D ) , where T is in °C, Δ ν − and Δ D represent frequency shifts (in cm −1 ) of the lower band and the resonant splitting relative to the reference values measured at 23 °C and 6 MPa, respectively. Based on the attainable accuracy of the fitted peak positions and the results from fitting of Raman frequency shifts’ dependence with pressure and temperature, the uncertainty in pressure determination is about 50 MPa for pressures determined from ν − and 40 MPa from that determined from D .

HYDRODYNAMIC LOADS IN WATER CHANNEL OF SAYANO-SHUSHENSKAYA HYDROPOWER PLANT AT CLOSING REGULATOR DEVICE AND HYDRAULIC IMPACT

This paper presents a shock pressure determination method in a penstock at regulator devices closing. A system of resolving equations that describe a nonsteady motion of liquid in water channel of hydropower plant is described in the paper. Hydrodynamic loads are determined based on the example of Sayano-Shushenskaya hydropower plant water channel. For minimum pressure excess, the authors recommend the time of emergency-repair gate closure at simultaneous closing of a guide vane.

Study of Top Dead Center Measurement and Correction Method in a Diesel Engine

The thermal loss angle error analysis and maximum pressure determination method analysis were conducted first. Then the polytropic exponent method, the inflection point analysis, the loss function method and the symmetry method were utilized under different rotating speed, load and cooling water temperature, to calculate TDC in D6114 diesel engine and the results were compared with TDC position measured under the same condition with direct method of measurement. The study proved that (1) thermal loss angle of the diesel engine ranges from -1.0 ~ -0.6°CA; (2) Thermal loss angle is mainly affected by rotating speed and is reducing when rotate speed increases;(3) the symmetry method is generally the optimum for calculating the thermal loss angle of automotive diesel engines, with an error within 0.2°CA.

Pressure calibration of diamond anvil Raman gauge to 410 GPa

The first-order Raman band of diamond anvils has been investigated at pressure up to 410 GPa in order to develop an optical pressure determination method. The high-frequency edge of the band was calibrated by the pressure scale of the equation of state of Pt. A unique relationship between the edge-frequency and the sample pressure was confirmed up to the highest pressure, while the edge frequency reaches to 1907 cm−1 at 410 GPa. Usefulness of the diamond anvil Raman gauge as a laboratory-based pressure determination method in the multimegabar pressure range has been discussed.

Recent Advances in Ultra-High Pressure Generation Technology Using Diamond Anvil Cell: Challenge to the Frontier of Static High-Pressure Generation

Recently, we have succeeded to extend the attainable static pressure to 410 GPa using a diamond anvil cell (DAC). In this article, our recent advances in the ultra-high pressure generation technique of the DAC are reviewed, and the key factors for the high-pressure generation beyond 300 GPa were discussed. In addition, in such extremely high-pressures range, an optical pressure determination method and a direct observation method of the stress-state by the diamond anvil Raman spectroscopy have been presented.

Deviatoric stress and mean pressure in MgO compressed in a Kawai-type apparatus above 30 GPa: Evidence for reduction of deviatoric stress by annealing

By applying the numerical tensor analysis proposed by Yoneda and Kubo [Simultaneous determination of mean pressure and deviatoric stress based on numerical tensor analysis: a case study for polycrystalline X-ray diffraction of gold enclosed in a methanol–ethanol mixture. J. Phys.: Condens. Matter 18(2006)S979], we have determined deviatoric stress and mean pressure of polycrystalline MgO compressed in the Kawai-type apparatus. After the compression at room temperature, the mean pressure and the deviatoric stress in MgO were determined as 34.5 and 3.2 GPa, respectively. The mean pressure is significantly lower than the nominal pressure of 37.2 GPa determined by the conventional pressure determination method. By heating the sample to 1850 K with the constant press load, the deviatoric stress dramatically decreased to 0.1 GPa with a mean pressure of 34.2 GPa at room temperature after the heating. These results show both the importance of stress analysis to determine pressure more accurately and the effectiveness of annealing to reduce deviatoric stress in the sample.

Guidelines for Clinical Studies with Compression Devices in Patients with Venous Disorders of the Lower Limb

The scientific quality of published clinical trials is generally poor in studies where compression devices have been assessed in the management of venous disease. The authors' aim was to establish a set of guidelines which could be used in the design of future clinical trials of compression treatments for venous diseases. Consensus conference leading to a consensus statement. The authors form a expert consensus group known as the International Compression Club (ICC). This group obtained published medical literature in the field of compression treatment in venous disease by searching medical literature databases. The literature was studied by the group which attended a consensus meeting. A draft document was circulated to ICC members and revised until agreement between contributors was reached. The authors have prepared a set of guidelines which should be given consideration when conducting studies to assess the efficacy of compression in venous disease. The form of compression therapy including the comparators used in the clinical study must be clearly characterised. In future studies the characteristics of the material provided by the manufacturer should be described including in vivo data on pressure and stiffness of the final compression system. The pressure exerted on the distal lower leg should be stated in mmHg and the method of pressure determination must be quoted.

Diamond anvil Raman gauge in multimegabar pressure range

The first-order Raman band of diamond anvils has been investigated at pressure up to 380 GPa in order to develop an optical pressure determination method. The high frequency edge of the band was calibrated by the pressure scale of the equation of state of Pt. The universality of the relationship between the sample pressure and the edge-frequency was confirmed up to 370 GPa and the usefulness of the diamond anvil Raman gauge was demonstrated. Using the diamond anvil Raman spectroscopy, the stress-state of the anvil culet was directly observed in the multimegabar pressure range. Obtained pressure dependence of the shear stress suggested further extension of feasible pressure beyond 400 GPa.

Pressure calibration of diamond anvil Raman gauge to 310GPa

In order to develop an optical method for pressure determination in the multimegabar region, the first-order Raman spectra of diamond anvils were investigated at pressures up to 310GPa. The high-frequency edge of the Raman band, which corresponds to the Raman shift of the anvil culet due to the normal stress, was calibrated against the sample pressure derived from the equation of state of Pt. The obtained pressure dependence of the edge frequency demonstrates the reliability of this diamond anvil Raman gauge. Up to the maximum pressure of this study, the relation between Raman frequency and normal stress at the diamond anvil culet is formally similar to the equation of state of a hydrostatically compressed isotropic elastic body having a bulk modulus of K0=547(11)GPa and a pressure derivative of the bulk modulus K0′=3.75(20).

High-pressure Raman spectroscopy of diamond anvils to 250GPa: Method for pressure determination in the multimegabar pressure range

The first-order Raman spectra of diamond anvils used in a gasketed high-pressure cell have been measured at pressure up to 250GPa. The high-frequency edge of the Raman band, which corresponds to the Raman shift of the culet face, is represented by a function of pressure in the sample chamber up to 250GPa. The dependence is almost independent on loading conditions. The application of the pressure dependence for pressure determination up to the multimegabars pressure region is proposed.

Notes on the origin of formation fluid pressure: well-logging methods aspect

Current methods of pressure determination using well-log data are mostly based on porosity vs. pressure correlation and on the concept of pressure dependence on compaction processes due to overburden weight. However, natural compaction is a complex process, and many geologic and physical phenomena and processes other than compaction are known to generate pressure abnormalities. For these cases, pressure—porosity correlation may not be definitive, other parameters may correlate better, or no correlation may exist. For example in basins with no compaction or any other geologic activity, distribution of pressure deviations from hydrostatic pressure is solely determined by surface relief and by the 3-D distribution of water density and rock permeability. If a consolidated formation has fracture permeability and vertical fluid migration is a mechanism of abnormal pressure generation, usually no correlation exists between the vertical distribution of pressure and rock properties. All abnormal and subnormal pressure scenarios should be differentiated. Criteria to recognize each case and sets of parameters for indirect determination and/or prediction of formation pressure should be developed separately for each scenario. This will allow the maximum use of information pertinent to pressure distribution in each particular region or field and, therefore, more accurate pressure determination and prediction. In this paper, we formulate this problem and describe ways to develop new accurate methods of pressure determination using well-logs with other geologic information.

Deviatoric stress measurement under uniaxial compression by a powder x-ray diffraction method

The complete stress field in a polycrystalline sample compressed in a modified Drickamer-type apparatus was determined from x-ray diffraction data. The incident x rays, from a synchrotron source, were perpendicular to the compression axis, and the diffracted energy-dispersive signals were simultaneously determined for two directions relative to the compression axis. The two sets of d values measured by this system were analyzed by making use of a new equation derived by Singh, and the uniaxial stress component σ1−σ3 and the parameter α, which describes the stress and strain conditions across the grain boundaries of the sample, were obtained. This method was applied to NaCl and the results give the important information on the stress state and the pressure determination method under direct compression of a solid sample.

Variability of Indirect Methods Used to Determine Blood Pressure

Blood pressure is a cardiovascular measurement with dynamic characteristics that can be influenced by a number of internal and external factors. The preferred blood pressure determination method would be one that reduces variability between measurements and that reflects the true blood pressure level. In this article, we present the variability of, and agreement between, the blood pressures collected by two indirect methods on the same patients during a hypertensive research project. Data obtained on patients in a typical clinical setting are also provided. Twenty-four-hour diastolic pressures obtained by the automated method demonstrated no regression to a lower mean, while blood pressures obtained casually in the office exhibited such regression. The 95% confidence interval of repeated measures for casual office blood pressure on a patient in a research setting (35/17 mm Hg) or in typical clinic practice (26/19 mm Hg) were similar, while the range of the mean 24-hour automated blood pressure monitoring (21/11 mm Hg) was smaller and demonstrated less variability. The magnitudes of the differences in blood pressures obtained on separate occasions in the same subjects were significantly lower with automated vs casual blood pressure determination methods (7.9/4.6 vs 13.7/7.4 mm Hg for both systolic and diastolic pressures). The agreement (95% confidence interval) between blood pressures obtained by the two methods (19/12 mm Hg) was found to be similar to the repeatability of automated blood pressure monitoring alone, and superior to that for data recorded casually in the office (35/17 mm Hg). Thus, the variability in mean 24-hour automated blood pressures is less than that for casual office blood pressures. The clinician should understand that the variability of blood pressures measured on an individual may be much greater than that reported for populations of hypertensive patients, and must be considered when applying epidemiologic group data to a specific patient. Moreover, any methodology of indirect blood pressure measurement that may reduce the variability and improve repeatability of casual office blood pressures deserves further consideration.

Methods of pressure determination at the charge-rock boundary

Methods of pressure determination at the charge-rock boundary

4892. A simple graphical method of pressure determination in a McLeod gauge.: J K N Sharma et al, Vacuum, 31 (4/5), 1981, 195–197

4892. A simple graphical method of pressure determination in a McLeod gauge.: J K N Sharma et al, Vacuum, 31 (4/5), 1981, 195–197