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Pressure Prediction (pressure + prediction)

Distribution by Scientific Domains

Earth and Environmental Science	60%

Selected Abstracts

Pressure Prediction for High-Temperature and High-Pressure Formation and Its Application to Drilling in the Northern South China Sea

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2004
WANG Zhenfeng
Abstract, There are plentiful potential hydrocarbon resources in the Yinggehai and Qiongdongnan basins in the northern South China Sea. However, the special petrol-geological condition with high formation temperature and pressure greatly blocked hydrocarbon exploration. The conventional means of drills, including methods in the prediction and monitoring of underground strata pressure, can no longer meet the requirements in this area. The China National Offshore Oil Corporation has allocated one well with a designed depth of 3200 m and pressure coefficient of 2.3 in the Yinggehai Basin (called test well in the paper) in order to find gas reservoirs in middle-deep section in the Miocene Huangliu and Meishan formations at the depth below 3000 m. Therefore, combined with the "863" national high-tech project, the authors analyzed the distribution of overpressure in the Yinggehai and Qiongdongnan basins, and set up a series of key technologies and methods to predict and monitor formation pressure, and then apply the results to pressure prediction of the test well. Because of the exact pressure prediction before and during drilling, associated procedure design of casing and their allocation in test well has been ensured to be more rational. This well is successfully drilled to the depth of 3485 m (nearly 300 m deeper than the designed depth) under the formation pressure about 2.3 SG (EMW), which indicate that a new step in the technology of drilling in higher temperature and pressure has been reached in the China National Offshore Oil Corporation. [source]

Geological constraints of pore pressure detection in shales from seismic data

BASIN RESEARCH, Issue 1 2007
Gunn M. G. Teige
ABSTRACT Methods for detection of pore fluid overpressures in shales from seismic data have become widespread in the oil industry. Such methods are largely based on the identification of anomalous seismic velocities, and on subsequent determination of pore pressures through relationships between seismic velocities and the vertical effective stress (VES). Although it is well known that lithology variations and compaction mechanisms should be accounted for in pore pressure evaluation, a systematic approach to evaluation of these factors in seismic pore pressure prediction seems to be absent. We have investigated the influence of lithology variations and compaction mechanism on shale velocities from acoustic logs. This was performed by analyses of 80 wells from the northern North Sea and 24 wells from the Haltenbanken area. The analyses involved identification of large-scale density and velocity variations that were unrelated to overpressure variations, which served as a basis for the analyses of the resolution of overpressure variations from well log data. The analyses demonstrated that the overpressures in neither area were associated with compaction disequilibrium. A significant correlation between acoustic velocity and fluid overpressure nevertheless exists in the Haltenbanken data, whereas the correlation between these two parameters is weak to non-existing in the North Sea shales. We do not presently know why acoustic velocities in the two areas respond differently to fluid overpressuring. Smectitic rocks often have low permeabilities, and define the top of overpressures in the northern North Sea when they are buried below 2 km. As smectitic rocks are characterized by low densities and low acoustic velocities, their presence may be identified from seismic data. Smectite identification from seismic data may thus serve as an indirect overpressure indicator in some areas. Our investigations demonstrate the importance of including geological work and process understanding in pore pressure evaluation work. As a response to the lack of documented practice within this area, we suggest a workflow for geological analyses that should be performed and integrated with seismic pore pressure prediction. [source]

Pressure Prediction for High-Temperature and High-Pressure Formation and Its Application to Drilling in the Northern South China Sea

Surrogate model-based strategy for cryogenic cavitation model validation and sensitivity evaluation

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9 2008
Tushar Goel
Abstract The study of cavitation dynamics in cryogenic environment has critical implications for the performance and safety of liquid rocket engines, but there is no established method to estimate cavitation-induced loads. To help develop such a computational capability, we employ a multiple-surrogate model-based approach to aid in the model validation and calibration process of a transport-based, homogeneous cryogenic cavitation model. We assess the role of empirical parameters in the cavitation model and uncertainties in material properties via global sensitivity analysis coupled with multiple surrogates including polynomial response surface, radial basis neural network, kriging, and a predicted residual sum of squares-based weighted average surrogate model. The global sensitivity analysis results indicate that the performance of cavitation model is more sensitive to the changes in model parameters than to uncertainties in material properties. Although the impact of uncertainty in temperature-dependent vapor pressure on the predictions seems significant, uncertainty in latent heat influences only temperature field. The influence of wall heat transfer on pressure load is insignificant. We find that slower onset of vapor condensation leads to deviation of the predictions from the experiments. The recalibrated model parameters rectify the importance of evaporation source terms, resulting in significant improvements in pressure predictions. The model parameters need to be adjusted for different fluids, but for a given fluid, they help capture the essential fluid physics with different geometry and operating conditions. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Phonation threshold pressure predictions using viscoelastic properties up to 1,400 Hz of injectables intended for Reinke's space,

THE LARYNGOSCOPE, Issue 5 2010
Sarah A. Klemuk PhD
Abstract Objectives/Hypothesis: Viscoelastic properties of numerous vocal fold injectables have been reported but not at speaking frequencies. For materials intended for Reinke's space, ramifications of property values are of great concern because of their impact on ease of voice onset. Our objectives were: 1) to measure viscoelastic properties of a new nonresorbing carbomer and well-known vocal fold injectables at vocalization frequencies using established and new instrumentation, and 2) to predict phonation threshold pressures using a computer model with intended placement in Reinke's space. Study Design: Rheology and phonation threshold pressure calculations. Methods: Injectables were evaluated with a traditional rotational rheometer and a new piezo-rotary vibrator. Using these data at vocalization frequencies, phonation threshold pressures (PTP) were calculated for each biomaterial, assuming a low dimensional model with supraglottic coupling and adjusted vocal fold length and thickness at each frequency. Results were normalized to a nominal PTP value. Results: Viscoelastic data were acquired at vocalization frequencies as high as 363 to 1,400 Hz for six new carbomer hydrogels, Hylan B, and Extracel intended for vocal fold Reinke's space injection and for Cymetra (lateral injection). Reliability was confirmed with good data overlap when measuring with either rheometer. PTP predictions ranged from 0.001 to 16 times the nominal PTP value of 0.283 kPa. Conclusions: Accurate viscoelastic measurements of vocal fold injectables are now possible at physiologic frequencies. Hylan B, Extracel, and the new carbomer hydrogels should generate easy vocal onset and sustainable vocalization based on their rheologic properties if injected into Reinke's space. Applications may vary depending on desired longevity of implant. Laryngoscope, 2010 [source]