scholarly journals Determining gas rate distribution from temperature and pressure profiles in gas well

2012 ◽  
Vol 16 (5) ◽  
pp. 1339-1343 ◽  
Author(s):  
Emile Barrett ◽  
Imran Abbasy ◽  
Chii-Rong Wu ◽  
Zhenjiang You ◽  
Pavel Bedrikovetsky
Keyword(s):  
Inverse Problem ◽  
Flow Rate ◽  
Field Data ◽  
Pressure Data ◽  
Gas Well ◽  
Temperature Distributions ◽  
Pressure Profiles ◽  
Temperature And Pressure ◽  
Good Agreement

A simple and effective method of the gas rate prediction from temperature and pressure data is discussed in this paper. Solving the inverse problem allows determination of the flow rate by matching the gas pressure and temperature distributions with measured profiles. Results of field data treatment show good agreement with the model prediction.

HPLC METHOD DEVELOPMENT FOR ESTIMATION OF RAMELTEON IN TABLET DOSAGE FORM

INDIAN DRUGS ◽  
2013 ◽  
Vol 50 (06) ◽  
pp. 20-23
Author(s):  
S Sahoo ◽  
◽  
P. K. Panda ◽  
S. K. Mishra
Keyword(s):  
Flow Rate ◽  
Dosage Form ◽  
Method Development ◽  
Hplc Method ◽  
Reverse Phase Hplc ◽  
Ich Guidelines ◽  
Hplc Method Development ◽  
Tablet Dosage ◽  
Good Agreement

A simple, fast, accurate and precise reverse phase HPLC method is developed and described for the determination of ramelteon in tablet dosage form. Chromatography was carried on an ODS column using a mixture of acetonitrile and phosphate buffer pH 7.0 (35:65 V/V) as the mobile phase at a flow rate of 1.0 mL/min with detection at 286 nm. The retention time of the drug was 7.7 min. The procedure was validated for linearity, precision, accuracy, and robustness. The developed method was validated for linearity from 50 to 150% which shows the method is quite linear with a correlation coefficient of 0.999, for precision which includes system precision, method precision, intraday and by another analyst on another day, and accuracy. The %RSD for system precision was observed to be 1.1, whereas the method precision was observed to be 0.2. The % recovery from ‘accuracy’ studies yielded the recovery of 99.7-101.5% which indicates the capability of the method, and finally for robustness that includes studies w.r.t. change in flow rate, the percentage of organic modifier and pH. As per ICH guidelines, method validation results are in good agreement. The proposed method was simple, sensitive, precise and accurate.

Mitigation of Annulus Pressure Buildup in Offshore Gas Wells by Determination of Top of Cement

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Alex W. Mwang’ande ◽  
Hualin Liao ◽  
Long Zeng
Keyword(s):  
Field Data ◽  
Gas Wells ◽  
Gas Well ◽  
Pressure Buildup ◽  
Cheap Method ◽  
Calculation Results ◽  
Sustained Casing Pressure ◽  
Casing Pressure ◽  
Mitigation Methods

Annulus pressure buildup (APB) is still a serious problem in offshore gas wells, which threatens the safety of wells for the entire phases of drilling, completion, and production. The existing methods for mitigating APB are technically complex and highly costly. Setting top of cement (TOC) below the outer casing shoe to mitigate APB is easy to implement and can significantly reduce costs. However, there are no unified methods of determining TOC for this purpose. Nevertheless, existing petroleum standards give ambiguous regulations on the setting of TOC. This article brings a new and cheap method of mitigating APB by determining best TOC settings using a mathematical model for calculating APB from both annulus fluid expansion (AFE) and sustained casing pressure (SCP). Field data from gas well X are inputted to the model to describe how it serves this purpose. Calculation results for well X show that setting TOC's above and below the upper casing shoes for production and intermediate casings annuli, respectively, can greatly avoid the problem of APB and the costs associated with the existing mitigation methods. This technique can be used to other wells following the same procedures. The developed model reduced greatly the ambiguity of TOC determination as it helps to get the clear TOC combinations that control APB at the lowest cost of well construction while maintaining good and safe well operation.

Low-cost flow-rate estimate in separate layers along gas wells from temperature and pressure profiles

2013 ◽  
Vol 53 (1) ◽  
pp. 285
Author(s):  
Emile Barrett ◽  
Imran Abbasy ◽  
Chii-Rong Wu ◽  
Zhenjiang You ◽  
Pavel Bedrikovetsky
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Flow Rate ◽  
Low Cost ◽  
Pressure Sensors ◽  
Gas Wells ◽  
Production Rates ◽  
Pressure Profiles ◽  
Temperature And Pressure ◽  
The Mathematical Model

Estimation of rate profile along the well is important information for reservoir characterisation since it allows distinction of the production rates from different layers. The temperature and pressure sensors in a well are small and inexpensive; while flow meters are cumbersome and expensive, and affect the flow in the well. The method presented in this peer-reviewed paper shows its significance in predicting the gas rate from temperature and pressure data. A mathematical model for pressure and temperature distributions along a gas well has been developed. Temperature and pressure profiles from nine well intervals in field A (Cooper Basin, Australia) have been matched with the mathematical model to determine the flow rates from different layers in the well. The presented model considers the variables as functions of thermal properties at each location, which is more accurate and robust than previous methods. The results of tuning the mathematical model to the field data show good agreement with the model prediction. Simple and robust explicit formulae are derived for the effective estimation of flow rate and thermal conductivity in gas wells. The proposed approach has been applied to determine the well gas rate and formation thermal conductivity from the acquired well pressure and temperature data in field A. It allows for recommending well stimulation of layers with low production rates.

CALCULATION OF THE MAGNETOTELLURIC TENSOR IMPEDANCE: ANALYSIS OF BAND‐LIMITED MT SIGNAL PAIRS

Geophysics ◽  
1975 ◽  
Vol 40 (5) ◽  
pp. 790-797 ◽  
Author(s):  
Larry R. Grillot
Keyword(s):  
Field Data ◽  
Fourier Coefficients ◽  
Impedance Analysis ◽  
Impedance Tensor ◽  
Period Range ◽  
Tensor Impedance ◽  
Band Limited ◽  
Good Agreement ◽  
Least Squares Approach

A method of analyzing the tensor nature of magnetotelluric fields from short independent sections of filtered MT data is presented in which: (1) horizontal field components are filtered at chosen periods; (2) short sections which show a well defined signal over 3–4 cycles are selected from the records; (3) the polarizations of these short record sections are plotted; and (4) Fourier coefficients calculated for section pairs showing differing magnetic field polarizations are then used to calculate the elements of the impedance tensor. Results of this analysis performed on MT field data show that the use of MT signal pairs yields uniform principal resistivities for calculations using several different section pairs of the same period. These results also illustrate internal consistency of the resistivity estimates over the complete period range of the data (30–7500 sec). A brief comparison of the MT pairs calculations and results derived from a least‐squares approach at a selected period shows good agreement between the two methods. The overall results suggest that the use of independent signal pairs in the determination of the tensor impedance could complement more traditional methods in some cases.

STUDIES IN THE SYSTEM CALCIUM-OXIDE–SULPHUR-DIOXIDE–WATER: II. CALCULATION OF IONIC CONCENTRATIONS

1935 ◽  
Vol 13b (5) ◽  
pp. 308-322
Author(s):  
P. E. Gishler ◽  
O. Maass
Keyword(s):  
Vapor Pressure ◽  
Calcium Oxide ◽  
Sulphur Dioxide ◽  
Conductivity Data ◽  
Pressure Data ◽  
Vapor Pressure Data ◽  
Ionic Concentrations ◽  
Methods Of Calculation ◽  
Temperature And Pressure ◽  
Good Agreement

The conductivity and vapor pressure data of the system calcium-oxide–sulphur-dioxide–water presented in an earlier paper have been used to calculate ionic concentrations existing in this system, in the temperature and pressure range investigated. Two methods of calculation have been employed, one depending on the combination of vapor pressure and conductivity data, and the other, on conductivity data. For both, recourse was had to the data of Campbell and Maass on the system sulphur-dioxide–water. These methods gave results that are in good agreement with each other. The existence of a complex CaSO3.Ca(HSO3)2 was deduced.Hydrogen ion concentrations over the concentration and temperature range investigated have been calculated and extrapolations made to higher temperatures. These are presented in tabular form. Apart from the theoretical interest, it is pointed out that these results are of value in connection with studies of the delignification of wood by calcium-oxide–sulphur-dioxide–water solutions.

An Experimental Study of Vortex Chamber Flow

1961 ◽  
Vol 83 (4) ◽  
pp. 632-636 ◽  
Author(s):  
J. P. Holman ◽  
G. D. Moore
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Vortex Chamber ◽  
Simple Analysis ◽  
Functional Variation ◽  
Flow Area ◽  
Inlet Velocity ◽  
Fluid Properties ◽  
Temperature And Pressure ◽  
Good Agreement

It is shown that a relatively simple analysis predicts the functional variation of temperature and pressure in a vortex chamber with radius and inlet velocity. The predicted variation is in good agreement with experimental observations. By assuming that the flow at the outside of the chamber occupies some effective flow area, which is essentially independent of flow rate, the inlet velocity may be expressed in terms of the chamber dimensions and the fluid properties at entrance. The effective flow area assumption is verified experimentally for two chamber exit configurations using air.

Mechanisms of the HF/H2O Vapor Phase Etching of SiO2

1992 ◽  
Vol 35 (3) ◽  
pp. 21-26
Author(s):  
C. Helms ◽  
B. Deal
Keyword(s):  
Vapor Phase ◽  
Etch Rate ◽  
Pressure Data ◽  
Detailed Model ◽  
Wafer Temperature ◽  
Partial Pressures ◽  
Aqueous Etching ◽  
Good Agreement

In this paper we report on studies of the mechanisms responsible for HF/H2O etching and cleaning of Si surfaces. From these studies we have clearly established that the role of water is to provide a condensed solvent medium for the HF on the surface. Our results, as well as those in the literature, show that if the partial pressures of HF and H2O are too low (or sample temperature too high), condensation does not occur and little or no etching is observed. Based on these ideas, and pressure data from the literature, we have developed a detailed model that provides for the calculation of the onset of condensation as a function of wafer temperature and reactant partial pressures. In addition, the model allows determination of the HF concentration in the condensed H2O film. Comparison of etch rates obtained for aqueous etching as a function of HF concentration, and vapor phase etching as a function of calculated HF concentration, show good agreement. The vapor phase etch rate data, as a function of wafer temperature, total HF + H2O pressure, and partial pressure ratios, will be presented in detail along with information on the model.

scholarly journals Modeling of pure components high pressures densities using CK-SAFT and PC-SAFT equations

2018 ◽  
Vol 83 (3) ◽  
pp. 331-343
Author(s):  
Jovana Ilic-Pajic ◽  
Mirko Stijepovic ◽  
Gorica Ivanis ◽  
Ivona Radovic ◽  
Jasna Stajic-Trosic ◽  
...  
Keyword(s):  
High Pressures ◽  
Equations Of State ◽  
Model Parameters ◽  
Calculated Density ◽  
Average Percentage ◽  
Pure Compounds ◽  
Density Values ◽  
Temperature And Pressure ◽  
Good Agreement

SAFT equations of state have been widely used for the determination of different thermo-physical and phase equilibria properties. In order to use these equations as predictive models it is necessary to calculate the model parameters. In this work CK-SAFT and PC-SAFT equations of state were applied for the correlation of pure compounds densities in the wide ranges of temperature and pressure (288.15?413.15 K and 0.1?60 MPa, respectively). The calculations of densities for n-hexane, n-heptane, n-octane, toluene, dichloromethane and ethanol, under high pressure conditions, were performed with the new sets of parameters determined in this paper by CK-SAFT and PC-SAFT. Very good agreement between experimental and calculated density values was achieved, having absolute average percentage deviations lower than 0.5 %.

A Sensitivity Study of some Parameters on the Efficiency of a Passive Ventilation System Based on Solar Chimney

2013 ◽  
Vol 393 ◽  
pp. 815-820
Author(s):  
Hichem Hamdad ◽  
Salah Larbi ◽  
Abdelkader Kessouri
Keyword(s):  
System Analysis ◽  
Ventilation System ◽  
Environmental Parameters ◽  
Energy Performance ◽  
Sensitivity Study ◽  
Solar Chimney ◽  
Air Mass ◽  
Temperature Distributions ◽  
Good Agreement

The purpose of this work is related to passive ventilation system analysis based on solar chimney. It consists in the determination of the temperature distributions of the wall, the glazing, and along the airflow in the chimney. The air mass flow rate and the instantaneous efficiency of the solar chimney were also determined. The energy performance of the solar chimney has been studied versus some geometrical and environmental parameters. The sensitivity study of the influence of some parameters on the efficiency of the system is also analysed. It is shown that the incident solar radiation has an important role on the energy performance of the solar chimney. Obtained results are compared to those of the literature. Good agreement is observed between the different results.

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