The Experts below are selected from a list of 4752 Experts worldwide ranked by ideXlab platform
Serhat Akin - One of the best experts on this subject based on the ideXlab platform.
-
Mathematical modeling of Steam-assisted gravity drainage
Computers & Geosciences, 2006Co-Authors: Serhat AkinAbstract:A mathematical model for gravity drainage in heavy-oil reservoirs and tar sands during Steam injection in linear geometry is proposed. The mathematical model is based on experimental observations that the Steam Zone shape is an inverted triangle with the vertex fixed at the bottom production well. Both temperature and asphaltene content dependence of viscosity of the drained heavy oil and their impact on heavy oil production are considered. The developed model has been validated using experimental data presented in the literature. It is seen that the oil production rate is affected as the asphaltene content of the crude oil changes as a function of temperature. The oil production rate conforms well to previously published data covering a wide range of heavy oils and sands for gravity drainage.
Warren Mannington - One of the best experts on this subject based on the ideXlab platform.
-
Numerical modelling of production from the Poihipi dry Steam Zone: Wairakei geothermal system, New Zealand
Geothermics, 2007Co-Authors: Sadiq J. Zarrouk, Michael J. O'sullivan, Adrian Croucher, Warren ManningtonAbstract:Abstract The Poihipi power station utilizes dry Steam from a shallow Zone near the margin of the Wairakei geothermal reservoir. The station has been in operation for several years, with daily variations in the fluid production rate following variations in time-of-day pricing of electricity. The corresponding varying pressure history provides a good database for testing models of the geothermal reservoir. Three different types of model were calibrated, namely, uniform porous medium, dual-porosity, fractured medium, and fractional dimension. The best match to the pressure data was achieved with the fractional dimension model.
Duncan Graham - One of the best experts on this subject based on the ideXlab platform.
-
Gravity changes in the Tauhara sector of the Wairakei–Tauhara geothermal field, New Zealand
Geothermics, 2009Co-Authors: Trevor M. Hunt, Duncan GrahamAbstract:Abstract Five microgravity surveys, done between 1972 and 2006, show that in the northern part of the Tauhara geothermal field there were large gravity decreases prior to 1985 associated with the expansion of Steam Zones resulting from pressure drawdown caused by fluid extraction at Wairakei. Since 1985 there have been gravity increases of up to 240 μgal in the northern part of Tauhara, corresponding to a mass increase of about 20 Mt. The gravity increases are centred near the unused deep well TH4, and are inferred to result mainly from resaturation of a deep Steam Zone due to a downflow of water in the well. We suggest that the water entered the well from a confined groundwater aquifer at a known casing break at 393 m depth and exited in the region of slotted casing at about 900–1000 m depth causing displacement of single-phase liquid upwards into the overlying Steam Zone. The average downflow rate is estimated to be about 110 t/h (30 kg/s); however, no downhole measurements in the well have been possible due to casing breaks. Simple modelling of the gravity data suggests the region of resaturation had the form of a cone of impression 150–250 m high and extending laterally for 1–2 km. Since 1985, gravity changes in the central and southern parts of the Tauhara field have been less than 50 μgal, indicating little net mass loss (
Karsten Høgh Jensen - One of the best experts on this subject based on the ideXlab platform.
-
Three-dimensional numerical modeling of Steam override observed at a full-scale remediation of an unconfined aquifer
Ground Water Monitoring and Remediation, 2005Co-Authors: Jakob Gudbjerg, Tom Heron, Torben O. Sonnenborg, Karsten Høgh JensenAbstract:Steam injected below the water table tends to move upward because of buoyancy. This limits the horizontal Steam Zone development, which determines the optimal spacing between injection wells. In this study, observations indicating Steam override at a full-scale remediation of an unconfined aquifer are analyzed by numerical modeling using the code T2VOC. A simplified three-dimensional (3D) numerical model is set up, which qualitatively shows the same mechanisms as observed at the site. By means of the model, it is found that it will be possible to achieve a larger horizontal extent of the Steam Zone in a layered geology compared to the homogeneous case. In the homogeneous case, the Steam injection rate increases dramatically when the injection pressure is increased, which is necessary to achieve a larger horizontal development. The development of the Steam Zone under unconfined conditions is found to be a complex function of the geologic layering, the water table at steady-state extraction, and the injection/extraction system. Because of this complexity, it will be difficult to predict Steam behavior without site-specific 3D numerical modeling.
-
On spurious water flow during numerical simulation of Steam injection into water-saturated soil.
Journal of Contaminant Hydrology, 2004Co-Authors: Jacob Gudbjerg, Torben O. Sonnenborg, O. Trötschler, A. Färber, Karsten Høgh JensenAbstract:Numerical simulation of Steam injection into a water-saturated porous medium may be hindered by unphysical behavior causing the model to slow down. We show how spurious water flow may arise on the boundary between a Steam Zone and a saturated Zone, giving rise to dramatic pressure drops. This is caused by the discretization of the temperature gradient coupled with the direct relation between pressure and temperature in the Steam Zone. The problem may be a severe limitation to numerical modeling. A solution is presented where the spurious water flow is blocked and this widely enhances the performance of the model. This new method is applied to a previously reported example exhibiting numerical problems. Furthermore, it is applied to the simulation of 2-D sandbox experiments where LNAPL is remediated from a smearing Zone by Steam injection. These experiments would have been difficult to analyze numerically without the adjustment to prevent spurious flow.
Sadiq J. Zarrouk - One of the best experts on this subject based on the ideXlab platform.
-
Numerical modelling of production from the Poihipi dry Steam Zone: Wairakei geothermal system, New Zealand
Geothermics, 2007Co-Authors: Sadiq J. Zarrouk, Michael J. O'sullivan, Adrian Croucher, Warren ManningtonAbstract:Abstract The Poihipi power station utilizes dry Steam from a shallow Zone near the margin of the Wairakei geothermal reservoir. The station has been in operation for several years, with daily variations in the fluid production rate following variations in time-of-day pricing of electricity. The corresponding varying pressure history provides a good database for testing models of the geothermal reservoir. Three different types of model were calibrated, namely, uniform porous medium, dual-porosity, fractured medium, and fractional dimension. The best match to the pressure data was achieved with the fractional dimension model.