bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Scheme to Enhance Steam-Assisted Gravity Drainage Production
Authors: Holmes Michael , Gupta Subodh 
Published: May 2016

Abstract
Steam-assisted gravity drainage (SAGD) is the present method of choice to produce the initially immobile bitumen in oil sands. However, the unit cost of production and its energy intensity offer room for improvement through further development of the technology. Dissolved gas presents a challenge due to free gas formation upon heating. To establish equilibrium and due to local pressure gradients, this gas is pushed to the edges of the steam chamber, where temperatures are lower. The gas acts as a thermal insulator, reducing the efficiency of heat transfer between the steam and bitumen. Currently, injector wells create small axial pressure gradients which allow for gas to be swept to low pressure locations where it can accumulate and get produced.
This study presents a novel well configuration to increase gas production and reservoir sweep efficiency. By drilling the injector well shorter than the producer well and adding tubing to the toe in the producer, the gas will be swept towards the toe and produced. The hot emulsion flowing through the producer annulus will heat the toe region by conduction, allowing the steam chamber to spread progressively towards the toe.
A simulation study was conducted. Homogeneous reservoir simulations were performed and the proposed process was compared to several base cases with varying completions, fluid properties, and reservoir properties based on current oil sands projects. Heterogeneous simulations were performed with a non-porous shale baffle in varying locations. Results were compared to classical SAGD and an in-depth analysis was performed to understand the mechanisms behind the improvements and better optimize the process.
The homogeneous simulations indicate that the proposed process is very efficient at removing solution gas from the reservoir, which increases oil production rates. Steam to oil ratio (SOR), a measure of process energy efficiency, is reduced. The proposed process outperforms classical SAGD with conventional completion scheme in all heterogeneous simulations as well, both in terms of oil production rate and SOR. Simulations suggest startup can be performed the same as conventional SAGD. Overall, the proposed process is very easy to implement and offers significant benefits over classical SAGD with similar or reduced costs.
Adapting Extended-Reach, Float-in Tubular-Running Practices to SAGD Completions
Authors: Webb P. D. , MacPhail W. F. , Burke L. H. , Montero J. 
Published: May 2016

Abstract
High torque-and-drag (T&D) values can increase the difficulty of installing tubing in extended reach steam-assisted gravity drainage (SAGD) wells. Extra surface applied compressional force (tubing jacks) is often needed to land the tubing, leading to increased completion operation time and costs, and increased hazard potential. In many cases the likelihood of sinusoidal and helical buckling of the production tubing is also significant. A method of running tubing in extended-reach horizontal wells is presented which uses pipe floatation to reduce sliding friction in the lateral section. For SAGD wells in the subject area, the operator was able to eliminate the use of tubing jacks to run production tubing to the toe of the well. Data was acquired that allowed the comparison of tubing load conditions, both with and without the floatation method. This data was also compared with torque-and-drag (T&D) modeling results to illustrate the reduction in friction that was achieved and quantify the benefit of the method.
The method adapts principles used to float casing into wells to SAGD tubing installation, and moreover uses specifically designed floatation subs to increase the efficiency of the method. The floatation subs are used to trap air in sections of the tubing string in order to improve running forces. Once the tubing is landed, applied pressure is used to burst fragmentation domes within the floatation subs, leaving no obstructions in the tubing string.
In all trials of the float-in method, tubing was landed under its own weight, without using tubing jacks. In all of the conventional method wells, tubing jacks were needed to successfully land the tubing. Torque-and-drag models accurately predicted the point at which conventionally deployed tubing reached a neutral hookload.
New Data on The Behaviour of Asphaltenes in Thermal Heavy Oil and Bitumen Production Operations
Authors: Romanov G. V. , Ganeeva Yu. M. , Barskaya E. E. , Yusupova T. N. , Arbuzov A. E. 
Published: May 2016

Abstract
World heavy oil and bitumen deposits contain more than twice the amount of crude compared to conventional reservoirs. Thermal production operations are used worldwide for heavy oil and bitumen production. Because of their nature, heavy oil and bitumen have a higher asphaltene content than conventional hydrocarbons. Asphaltene behaviour is affected by changes in pressure, introduction of gas to a reservoir, acidizing and other factors, including temperature. The effect of temperature on asphaltenes in heavy oil is still not well understood.
The paper presents new data on asphaltene behaviour in thermal heavy oil and bitumen production operations. Liquid crystals in asphaltenes are detected when heat is applied. Temperature when liquid crystals appear in asphaltenes of heavy oil and bitumen is significantly lower than that for conventional oil. An assumption is made that this phenomenon is caused by the structure of asphaltenes, namely an enhanced amount of "archipelago" type molecules in asphaltenes. In situ combustion causes an increase of condensed aromatic compounds in asphaltenes, asphaltene transformation up to coke and deposition in porous media. The process changes the individual characteristics of the oil system. The individual characteristics of heavy oil do not change when steam injection technology is applied. The paper also provides data on viscosity of heavy oil and bitumen versus temperature as a function of heavy oil composition and the effect of ultrasound on heavy oil viscosity.
Unlocking Potential Of The Lower Grand Rapids Formation, Western Canada: The Role Of Sand Control and Operational Practices in SAGD Performance
Authors: Williamson H. , Babaganov A. , Romanova U. 
Published: May 2016

Abstract
Grand Rapids is one of the major oil sand formations in Western Canada. As in-situ production of bitumen using Steam Assisted Gravity Drainage (SAGD) continues to grow, oil sands in the Grand Rapids formation is beginning to attract more industry attention. This paper focuses on the performance of two well pairs at the Blackrod SAGD Pilot Project operated by BlackPearl Resources Inc. The geology of the Lower Grand Rapids formation, sand control selection, and operational practices will be discussed using both laboratory and field data. Petrographic data of oil sand core before and after steam injection and the potential thermal formation damage mechanisms are discussed. Differences in the performance and the key learnings of the two well pairs are presented.
The findings of the work are to be implemented during the next phase of the project and are thought to be useful to other operators developing oil sands located in the Grand Rapids formation or similar oil sand and heavy oil deposits.
A New Well Positioning Technique for SAGD Applications
Authors: Wu Hsu-Hsiang , Ahmadi Akram , Hinke Sean 
Published: May 2016

Abstract
The magnetic ranging method is used in many oil-field drilling applications, especially in heavy oil production. One typical example is used in the steam-assisted gravity drainage (SAGD) technique to enhance oil recovery of heavy crude oil and bitumen. Such SAGD applications require drilling two horizontal twin wells that are parallel and separated by a few meters. As a result of accumulated survey errors, it is very challenging to achieve a controlled separation and good relative well placement among wells using conventional logging-while-drilling (LWD) survey data. Current practice mainly relies on wireline technology to access one of the twin wells to generate an active ranging signal; however, this is costly and time consuming.
This paper presents a true access-independent magnetic ranging solution, designed around SAGD applications, that eliminates the need to access a target wellbore below the surface. A surface excitation is attached to a wellhead of a target well to introduce a current signal traveling along the entire target well. Concurrently, LWD gradient array sensors in a drilling well measure the induced field to determine the relative distance and direction between the two wells. This method permits operators to efficiently acquire access-independent active ranging measurements, enabling faster well placement optimization.
This paper discusses the fundamentals of the new ranging technique, including both the surface excitation and the gradient array systems. The paper also analyzes modeled responses, experimental data, and field trial results from a gradient discovery tool (GDT) to validate the proposed concept. Comparing the novel tool to the current industry standard tool, a magnetic guidance tool (MGT), the paper demonstrates that the GDT is capable of achieving accurate and valid ranging performance in SAGD applications. Furthermore, the described LWD system presents an alternative ranging tool to current wireline techniques and provides several advantages for well intersection and positioning applications that can help reduce overall time and costs.
Strain Based Design and Field Application of Thermal Well Casing String for Cyclic Steam Stimulation Production
Authors: Han Lihong , Wang Hang , Wang Jianjun , Zhu Lijuan , Xie Bin , Tian Zhihua 
Published: May 2016

Abstract
This paper focuses on the strain based design and field application of thermal well casing for cyclic steam stimulation process. The heavy oil is a main field of China petroleum industry, where the cyclic steam stimulation process has been widely used and playing the dominating role in production. Generally the casing damage rate is 15-30% under this process, which has resulted in a large economic cost. The high damage rate is mainly caused by the current strength design method, where both the room and elevated yield strength were considered not beyond anticipated field thermal stress. In fact the casing material will serve in cyclic thermal elastic-plastic deformation state and the single yield strength is not sufficient for long term thermal stimulation process.
This paper presented a new strain based design method for thermal casing string. New material parameters were proposed to build the safety evaluation principle throughout the service life. For thermal casing the material plasticly deforming limit, called as allowable strain, is determined by the homogeneous deforming capacity. For design strain, the material creep rate equation is introduced to evaluate the accumulative elevated strain in long term service together with initial install strain, thermal strain and soil strain. When the design strain is not more than the allowable strain the casing material will safely serve throughout the whole life. In addition the strain fatigue limit is measured to evaluate the material safety for thermal cycle life. According to the factual field engineering environment the gas tight thread joint was adopted to prevent steam leak which otherwise will cause a large transversal stress between different formations and result in slip deformation of casing string.
Before the engineering operation the full scale test procedure was proposed and finished to evaluate the string integrity in multiple thermal cycles. From 2011, this method was used in Xinjiang oil field for eight wells for more than 14 steam cycles and all the experiment wells served well without any damage. Several wells were cyclic measured through multi arms inspector and the data showed that all the casing deformation located in controlled scope except that only one has obvious deformation because poorer cementing quality. The field practice has showed that the new method has better fitness for thermal wells.
Probabilistic Analysis on the Caprock Integrity During SAGD Operations
Authors: Yang B. , Xu B. , Yuan Y. 
Published: May 2016

Abstract
Geomechanical simulations are often used to study the deformation and mechanical failure behaviour of caprock formations in a SAGD operation. Different assumptions are made when building the simulation models. Usually the overburden formations above the reservoir are described by a limited number of vertically separated layers with varying thickness. Each layer is assumed homogeneous with laterally uniform material properties. In many cases, these simplifications are not accurate. It is important that the simulations properly consider the vertical and lateral variations.
This paper presents a probabilistic analysis on caprock integrity using a randomized finite element simulation approach. Volume of shale (VSH) logs and X-ray Diffraction (XRD) analysis data are used to generate stochastic distribution of 3 major litho-facies: sands, shale with low illite/smectite (I/S) contents and shale with high I/S contents. The litho-facie distributions are then mapped onto the finite element discretization of simulation models. Mechanical properties of the 3 major litho-facies are measured in a geomechanical laboratory test program. The geomechanical finite element model is coupled with thermal reservoir simulation results to study the deformation behaviour of caprock during a SAGD operation. Following a number of simulations, the results are statistically analyzed to estimate the probability of the caprock to enter plastic yielding.
Experimental Evaluation of the Effect of Temperature on Wettability of the Grosmont Carbonate Reservoir in Alberta
Authors: Modaresghazani J. , Moore R. G. , Mehta S. A. , Ursenbach M. G. 
Published: May 2016

Abstract
A series of experiments were conducted to study the potential effect of temperature on wettability of a carbonate reservoir using contact angle measurement method. Natural core plugs which were originally drilled out of the formation, were further cut into disk-shaped core samples in order to mount them inside a custom made cell which was designed to run the high temperature and high pressure experiments. This proprietary cell was designed to hold a solid core wafers and equipped with an injection needle to create a droplet on the surface of the wafer. Having made a droplet of oil on the surface of the core sample, the temperature was ramped to elevated temperatures and the contact angles were measured continuously at certain time intervals. Experiments were conducted on both natural cores and toluene-extracted core samples.
Re-Examination of Fingering in SAGD and ES-SAGD
Authors: Ji Dongqi , Yang Sheng , Zhong He , Dong Mingzhe , Chen Zhangxin , Zhong Liguo 
Published: May 2016

Abstract
Steam-Assisted Gravity drainage (SAGD) is a popular approach for oil sands recovery, in which a steam chamber is developed inside reservoir with heated up bitumen flowing downwards along the edge of the steam chamber to production well by gravity. To improve the production performance of SAGD, solvent co-injection with steam (called ES-SAGD) is also proposed. In both SAGD and ES-SAGD, the penetration of low viscosity gas phase into viscous bitumen induces fingering at the steam chamber edge, resulting in non-uniform steam chamber. In this study, for the first time, the phenomenon of fingering is re-examined under the condition of mobile initial-water in oil sands through a newly designed reservoir simulation model. The effect of Solution Gas to Oil Ratio (GOR) on fingering in SAGD is also studied. In addition, the impact of solvent-water-bitumen phase behavior, which is critical to the amount of gas phase, on fingering is examined in ES-SAGD. The results reveal that fingering takes place at the oil zone on the top of steam chamber in SAGD, due to the ex-solution of solution gas under elevated temperature. The addition of solvent in ES-SAGD enhances the fingers by reducing the partial pressure of the solution gas and increasing the amount of solution gas at the top of steam chamber. It is found that the flow of the initial-water in oil sands mitigates the degree of fingering and helps stabilize steam chamber edge. This re-examination of fingering in SAGD and ES-SAGD demonstrates that the mobility of the initial water in oil sands has to be taken in account in the analysis of steam chamber instability.
Numerical Assessment of the Maximum Operating Pressure for SAGD Projects Considering the Effects of Anisotropy and Natural Fractures in the Caprock
Authors: Rahmati Ehsan , Nouri Alireza , Fattahpour Vahidoddin , Trivedi Japan 
Published: May 2016

Abstract
This paper presents a numerical assessment for the Maximum Operating Pressure (MOP) of a Steam Assisted Gravity Drainage (SAGD) project considering the effect of the Natural Fractures (NFs) and intrinsic anisotropy of the cap shale. Current numerical and heuristic assessments usually ignore the effect of the intrinsic and structural anisotropy of the cap shale in the caprock integrity studies.
A coupled Hydro-Thermo-Mechanical (HTM) model was developed to assess the MOP. The coupled model employed a novel constitutive model which was developed to investigate the effect of NFs and intrinsic anisotropy in the cap shale. The coupled model was validated against surface heave measurements, and later utilized in a sensitivity study to assess the MOP for cases with different number of NF sets, fracture density and fracture dip angle.
Results indicate that the MOP is highly sensitive to the fracture density and dip angle. According to the results, vertical fractures have minor effect on the MOP while oblique fractures with the dip angle between 25° to 65° significantly affect the MOP. Neglecting the NFs can lead to significant overestimation of the MOP. This highlights the necessity to include the NFs in the caprock integrity assessments.
The numerical model presented in this paper considers the intrinsic anisotropy and the presence of NFs in the cap shale, while existing mathematical tools for caprock integrity studies have not incorporated the intrinsic and structural anisotropy. Ignoring the anisotropy in caprock can potentially cause a considerable overestimation of the MOP.
Gravity Inflow Performance Relationship for SAGD Production Wells
Authors: Taubner S. P. , Lipsett M. G. , Keller A. , Kaiser T. M. 
Published: May 2016

Abstract
This paper presents the formulation and verification of a simple model for predicting the liquid level above steam-assisted gravity drainage (SAGD) production wells. Controlling the proximity of the liquid-vapour interface to the producer is paramount for maximizing the energy efficiency of SAGD, optimizing production, and reducing the risk of liner damage from steam breakthrough; and so a simple model can be used for quick approximation and potentially for decisions on wellbore design and operational control.
The formulation is based on continuity of mass flow and thermal behaviour. Darcy's law is the key phenomenon in formulating an analytical model of the flow through the liquid pool, or steam trap, around the production well, which is referred to in this work as a gravity inflow performance relationship (GIPR). The GIPR relates the liquid level above the producer to the inflow rate, system pressures, and reservoir and fluid properties. To validate our modelling assumptions, the liquid level predicted by the GIPR is compared to data generated from a commercial reservoir simulator for a wide range of operating conditions.
Based on data from 31 reservoir simulations, the GIPR predicts the liquid level with high accuracy. The liquid levels given by the GIPR and reservoir simulator differ by a root-mean-square error of only 0.23 m. The introduction of a correction factor in the GIPR reduces the root-mean-square error to just 0.17 m. Moreover, the GIPR reveals fundamental relationships between the liquid level and SAGD process variables, providing insight into the mechanics of steam trap control. The relationship between the liquid level and the inflow rate yields a criterion for the stability of the liquid-vapour interface above the production well. The criterion elucidates the conditions under which the position of the liquid-vapour interface will be unstable and, thus, the conditions under which steam breakthrough or injector flooding may be expected.
The GIPR provides a simple, efficient, and accurate way to predict the liquid level above SAGD production wells, enabling the optimization of well designs and control strategies to facilitate steam trap control. In addition, the GIPR reveals relationships between variables that are masked with more complex models, providing an enhanced understanding of the SAGD process.
Investigation of Post-Abandonment Surface Deformation in SAGD Operations
Authors: Hosseini Amir H. , Mostafavi Vahid , Bresee Don 
Published: May 2016

Abstract
Steam-Assisted-Gravity-Drainage (SAGD) has been extensively applied in thermal recovery from oilsands reservoirs in the Athabasca region of Northern Alberta. As the steam chambers associated with SAGD well pairs become mature, a form of abandonment is often applied for pressure maintenance in the depleted zone. Quantification of potential surface subsidence associated with SAGD abandonment becomes critical especially when the mature wells are in proximity of future developments. In addition, induced shear stresses should also be estimated to fulfill well integrity requirements. In this case study, a coupled reservoir – geomechanical simulation model is developed, calibrated and utilized to estimate the magnitude of post-abandonment subsidence and the induced shear stresses in Surmont SAGD Pilot Project. In the context of this study, first, the development of a simplified 2D static geomechanical model using an original geomodel realization as well as geomechanical properties and stress profiles is discussed, which forms the basis for the coupled simulation model. The calibration workflow of the coupled reservoir-geomechanical simulation model to historical heave data is then reviewed and the impacts of different parameters on calibration quality is investigated. Finally, the estimation of subsidence and the induced shear stresses in the nearby wells is discussed, and the magnitude of residual heave is quantified. The results of this study show that only a fraction (up to 40%) of surface heave is reversible (in form of subsidence) during the abandonment phase. Therefore, the magnitude of the surface subsidence and the associated shear stresses are quite small. The modeling study has also shown that a small magnitude of subsidence may be recorded even 10 years after abandonment. However, more than 50% of the surface subsidence is observed in the first two years post-abandonment. Other important findings of this study includes (1) documenting the effects of thief zone interaction as it relates to irreversibility of surface heave; (2) documenting the impacts of various geomechanical parameters on the quality of calibration against the historical heave data; (3) observation of the relative impacts of the pressure and temperature fields on the magnitude of heave; and (4) quantification of incremental, yet small, shear stresses along the nearby horizontal wells.