A Basis for Automated Control of Steam Trap Subcool in SAGD

SPE Journal ◽  
2012 ◽  
Vol 17 (03) ◽  
pp. 680-686 ◽  
Author(s):  
Dharmeshkumar R. Gotawala ◽  
Ian D. Gates
Keyword(s):  
Temperature Difference ◽  
Oil Sands ◽  
Dynamic Control ◽  
Recovery Process ◽  
Steam Injection ◽  
Liquid Pool ◽  
Gravity Drainage ◽  
Approximate Theory ◽  
Smart Wells ◽  
The Difference

Summary Full steam conformance along the well pair of the steam-assisted gravity-drainage (SAGD) oil-sands-recovery process is essential for high thermal efficiency. Conformance can be improved by controlling injection and production strategies to ensure that steam is delivered to target regions in the reservoir. Smart wells use interval-control valves (ICVs) that, conceptually, can be dynamically controlled to yield uniform steam injectivity along the well pair. Dynamic control algorithms, such as proportional-integral-derivative (PID) control and their associated controller parameters, have not yet been developed for the SAGD processes that use ICVs. One control strategy would be to control the interwell subcool temperature difference—that is, the difference between the steam-injection temperature and the produced-fluids temperature. If this temperature difference is small, then the liquid pool above the production well is small and there is a likelihood of live steam production from the chamber. On the other hand, if the difference is large, the pool may rise above the injection well and gravity drainage is hindered because the chamber is largely filled with liquid. Here, the focus is on developing a simple, approximate theory for the behavior of the liquid pool at the base of the steam chamber to determine the ranges of values of control parameters to achieve a targeted interwell subcool temperature difference.

Numerical Simulation of Thermal Solvent Replacing Steam under Steam Assisted Gravity Drainage SAGD Process

2010 ◽  
Author(s):  
Weiqiang Li ◽  
Daulat D. Mamora
Keyword(s):  
High Temperature ◽  
Oil Recovery ◽  
Oil Sands ◽  
Steam Injection ◽  
Thermal Recovery ◽  
Production Performance ◽  
Gravity Drainage ◽  
Steam Assisted Gravity Drainage ◽  
Recovery Technique ◽  
Simulation Results

Abstract Steam Assisted Gravity Drainage (SAGD) is one successful thermal recovery technique applied in the Athabasca oil sands in Canada to produce the very viscous bitumen. Water for SAGD is limited in supply and expensive to treat and to generate steam. Consequently, we conducted a study into injecting high-temperature solvent instead of steam to recover Athabasca oil. In this study, hexane (C6) coinjection at condensing condition is simulated using CMG STARS to analyze the drainage mechanism inside the vapor-solvent chamber. The production performance is compared with an equivalent steam injection case based on the same Athabasca reservoir condition. Simulation results show that C6 is vaporized and transported into the vapor-solvent chamber. At the condensing condition, high temperature C6 reduces the viscosity of the bitumen more efficiently than steam and can displace out all the original oil. The oil production rate with C6 injection is about 1.5 to 2 times that of steam injection with oil recovery factor of about 100% oil initially-in-place. Most of the injected C6 can be recycled from the reservoir and from the produced oil, thus significantly reduce the solvent cost. Results of our study indicate that high-temperature solvent injection appears feasible although further technical and economic evaluation of the process is required.

Approximate Physics-Discrete Simulation of the Steam-Chamber Evolution in Steam-Assisted Gravity Drainage

SPE Journal ◽  
2018 ◽  
Vol 24 (02) ◽  
pp. 477-491 ◽  
Author(s):  
Enrique Gallardo ◽  
Clayton V. Deutsch
Keyword(s):  
Oil Sands ◽  
Recovery Process ◽  
Thermal Recovery ◽  
Porous Media Flow ◽  
Gravity Drainage ◽  
Discrete Simulation ◽  
Flow Equations ◽  
Integrity Assessment ◽  
Steam Chamber ◽  
Steam Assisted Gravity Drainage

Summary Steam-assisted gravity drainage (SAGD) is a thermal-recovery process to produce bitumen from oil sands. In this technology, steam injected in the reservoir creates a constantly evolving steam chamber while heated bitumen drains to a production well. Understanding the geometry and the rate of growth of the steam chamber is necessary to manage an economically successful SAGD project. This work introduces an approximate physics-discrete simulator (APDS) to model the steam-chamber evolution. The algorithm is formulated and implemented using graph theory, simplified porous-media flow equations, heat-transfer concepts, and ideas from discrete simulation. The APDS predicts the steam-chamber evolution in heterogeneous reservoirs and is computationally efficient enough to be applied over multiple geostatistical realizations to support decisions in the presence of geological uncertainty. The APDS is expected to be useful for selecting well-pair locations and operational strategies, 4D-seismic integration in SAGD-reservoir characterization, and caprock-integrity assessment.

scholarly journals Identifying Reservoir Features via iSOR Response Behaviour

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 427
Author(s):  
Jingyi Wang ◽  
Ian Gates
Keyword(s):  
Oil Sands ◽  
Gravity Drainage ◽  
Athabasca Oil Sands ◽  
Steam Chamber ◽  
Heterogeneous Reservoirs ◽  
Steam Assisted Gravity Drainage ◽  
Response Behaviour

To extract viscous bitumen from oil sands reservoirs, steam is injected into the formation to lower the bitumen’s viscosity enabling sufficient mobility for its production to the surface. Steam-assisted gravity drainage (SAGD) is the preferred process for Athabasca oil sands reservoirs but its performance suffers in heterogeneous reservoirs leading to an elevated steam-to-oil ratio (SOR) above that which would be observed in a clean oil sands reservoir. This implies that the SOR could be used as a signature to understand the nature of heterogeneities or other features in reservoirs. In the research reported here, the use of the SOR as a signal to provide information on the heterogeneity of the reservoir is explored. The analysis conducted on prototypical reservoirs reveals that the instantaneous SOR (iSOR) can be used to identify reservoir features. The results show that the iSOR profile exhibits specific signatures that can be used to identify when the steam chamber reaches the top of the formation, a lean zone, a top gas zone, and shale layers.

Remote monitoring of the steam‐flood enhanced oil recovery process

Geophysics ◽  
1987 ◽  
Vol 52 (11) ◽  
pp. 1457-1465 ◽  
Author(s):  
E. F. Laine
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
High Frequency ◽  
Oil Sands ◽  
Seismic Velocity ◽  
Color Image ◽  
Vertical Plane ◽  
Recovery Process ◽  
Steam Flood ◽  
Borehole Seismic

Cross‐borehole seismic velocity and high‐frequency electromagnetic (EM) attenuation data were obtained to construct tomographic images of heavy oil sands in a steam‐flood environment. First‐arrival seismic data were used to construct a tomographic color image of a 10 m by 8 m vertical plane between the two boreholes. Two high‐frequency (17 and 15 MHz) EM transmission tomographs were constructed of a 20 m by 8 m vertical plane. The velocity tomograph clearly shows a shale layer with oil sands above it and below it. The EM tomographs show a more complex geology of oil sands with shale inclusions. The deepest EM tomograph shows the upper part of an active steam zone and suggests steam chanelling just below the shale layer. These results show the detailed structure of the entire plane between boreholes and may provide a better means to understand the process for in situ heavy oil recovery in a steam‐flood environment.

scholarly journals Sex and death: from cell fate specification to dynamic control of X-chromosome structure and gene expression

2018 ◽  
Vol 29 (22) ◽  
pp. 2616-2621 ◽  
Author(s):  
Barbara J. Meyer
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
X Chromosome ◽  
Chromosome Structure ◽  
Dynamic Control ◽  
Three Dimensional ◽  
X Chromosomes ◽  
Meiotic Chromosomes ◽  
The Difference ◽  
Developmental Decision

Determining sex is a binary developmental decision that most metazoans must make. Like many organisms, Caenorhabditis elegans specifies sex (XO male or XX hermaphrodite) by tallying X-chromosome number. We dissected this precise counting mechanism to determine how tiny differences in concentrations of signals are translated into dramatically different developmental fates. Determining sex by counting chromosomes solved one problem but created another—an imbalance in X gene products. We found that nematodes compensate for the difference in X-chromosome dose between sexes by reducing transcription from both hermaphrodite X chromosomes. In a surprising feat of evolution, X-chromosome regulation is functionally related to a structural problem of all mitotic and meiotic chromosomes: achieving ordered compaction of chromosomes before segregation. We showed the dosage compensation complex is a condensin complex that imposes a specific three-­dimensional architecture onto hermaphrodite X chromosomes. It also triggers enrichment of histone modification H4K20me1. We discovered the machinery and mechanism underlying H4K20me1 enrichment and demonstrated its pivotal role in regulating higher-order X-chromosome structure and gene expression.

Modeling of the Vacuum Arc Remelting Process for Estimation and Control of the Liquid Pool Profile

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Joseph J. Beaman ◽  
Luis Felipe Lopez ◽  
Rodney L. Williamson
Keyword(s):  
Dynamic Control ◽  
Liquid Pool ◽  
Grain Structure ◽  
Vacuum Arc ◽  
Linear Quadratic ◽  
Vacuum Arc Remelting ◽  
Nonlinear Dynamic Equations ◽  
Pool Profile ◽  
Estimation And Control ◽  
Molten Liquid

Vacuum arc remelting (VAR) is an industrial metallurgical process widely used throughout the specialty metals industry to cast large alloy ingots. The final ingot grain structure is strongly influenced by the molten metal pool profile, which in turn depends on the temperature distribution in the ingot. A reduced-order model of the solidifying ingot was developed specifically for dynamic control and estimation of the depth of molten liquid pool atop the ingot in a VAR process. This model accounts only for the thermal aspects of the system ignoring other physical domains such as fluid flow and electromagnetic effects. Spectral methods were used to obtain a set of nonlinear dynamic equations which capture the transient characteristics of liquid pool profile variations around a quasi-steady operating condition. These nonlinear equations are then linearized and further simplified by suppressing fast modes. The resulting system was used to construct a linear-quadratic-gaussian (LQG) controller which was tested in a laboratory-scale furnace showing a good performance. A high-fidelity physics-based model is used in real-time to provide information about the solidifying ingot and potential solidification defects.

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