Search

To improve the oil recovery and economic efficiency in heavy oil reservoirs in late steam flooding, taking J6 Block of Xinjiang Oilfield as the research object, 3D physical modeling experiments of steam flooding, CO2-foam assisted steam flooding, and CO2 assisted steam flooding under different perforation conditions are conducted, and CO2-assisted steam flooding is proposed for reservoirs in the late stage of steam flooding. The experimental results show that after adjusting the perforation in late steam flooding, the CO2 assisted steam flooding formed a lateral expansion of the steam chamber in the middle and lower parts of the injection well and a development mode for the production of overriding gravity oil drainage in the top chamber of the production well; high temperature water, oil, and CO2 formed stable low-viscosity quasi-single-phase emulsified fluid; and CO2 acted as a thermal insulation in the steam chamber at the top, reduced the steam partial pressure inside the steam chamber, and effectively improved the heat efficiency of injected steam. Based on the three-dimensional physical experiments and the developed situation of the J6 block in Xinjiang Oilfield, the CO2 assisted steam flooding for the J6 block was designed. The application showed that the CO2 assisted steam flooding made the oil vapor ratio increase from 0.12 to 0.16 by 34.0%, the oil recovery increase from 16.1% to 21.5%, and the final oil recovery goes up to 66.5% compared to steam flooding after perforation adjustment. Key words: heavy oil reservoir, three-dimensional physical simulation experiment, steam flooding, CO2 assisted steam flooding, steam chamber, steam (CO2) chamber overriding gravity drainage

This study conducts a literature survey on the chemical steam additives tested in both lab and field settings from 1982 to present (2020). We summarize the major recovery mechanisms of both steam-based recovery process and steam-chemical-based recovery process. Next, we review the previous lab-scale/field-scale studies examining the applications of surfactants, alkali, and novel chemicals in the steam-based oil recovery process. Among the different surfactants studied, alpha-olefin sulfonate (AOS) and linear toluene sulfonate (LTS) are the recommended chemicals for their foam control/detergency effect. In particular, AOS was observed to perform especially well in residual oil saturation (ROS) reduction and sweep efficiency improvement when being co-injected with alkali. Application of organic alkali (alone or with a co-surfactant) has also drawn wide attention recently, but its efficacy in the field requires further investigation and the consumption of alkali by sands/clay is often an inevitable issue and, therefore, how to control the alkali loss requires further investigation. Novel chemical additives tested in the past five years include fatty acids (such as tail oil acid, TOA-Na+), Biodiesel (o/w emulsion), along with other types of chemical additives including switchable hydrophilicity tertiary amines (SHTA), chelating agents, Deep Eutectic Solvents (DES), graphite and SiO2 particles, ionic liquids and urea. High thermal stability of some of the novel chemicals and their potential in increasing displacement efficiency and ROS reduction efficiency in the lab studies require further investigation for their optimized application in the field settings to minimize the use of steam while improving the recovery effectively. This review reveals that when being properly applied, chemical additives can improve oil recovery via steam foam control, detergency effect (IFT reduction and wettability control), and viscosity reduction. In certain cases, microemulsion generation could be observed (o/w or w/o) with the addition of chemical additives at steam condition (which leads to recovery improvement), but the microemulsion effect on the conformance control (separate from the foamy effect), is lacking detailed investigation.

The steam-assisted gravity drainage (SAGD) process is a widely used thermal recovery technique for heavy oil reservoirs worldwide. In addition to numerical simulation methods, analytical models are alternative tools for the prediction and evaluation of heavy oil recovery by SAGD. In this study, a new analytical oil production rate prediction model for the entire SAGD process, including the rising, transition, expanding and depletion stages, is derived based on the movement rules of the steam chamber interface. The main improvements compared with existing analytical models in this work involve the introducing of a transition stage which is between the rising and the expansion stages, the modification of the depletion stage, the consideration of homogeneity with anisotropy, and the modification of the initial slope angle and shape factors which vary with reservoir parameters and steam injection parameters. Furthermore, the new analytical model is validated against with a relatively complete analytical model and numerical simulation models under field conditions. The results show that the new analytical model can predict the oil rate during the entire SAGD process more accurately than other available analytical models and with high agreement with numerical simulation results and field data. The results also show that the continuity of oil rate is improved by introducing the transition stage. The anisotropy of the permeability cannot be ignored, because it affects the peak oil rate and plateau time of the SAGD process. Moreover, the new model can quickly diagnose the phase of the steam chamber development, which provides guidance for the follow-up adjustment in heavy oil field application.

Steam-Assisted Gravity Drainage (SAGD) has been demonstrated as an effective process for recovering extra-heavy oil. However, large volumes of steam are required to heat the viscous oil, resulting in high consumption of natural gas and water, which affects its economic benefit. Therefore, research has long focused on improving the SAGD performance. In this study, a viscosity reducer (VR) assisted SAGD (VR-SAGD) process is systematically examined by experiment and numerical simulations based on an extra-heavy oil sample from a commercial SAGD block in Xinjiang oil fields, China. A scaled two-dimensional (2D) VR-SAGD experiment is carried out using a scale model to study the mechanisms of production dynamics and to observe the steam chamber development phases of the VR-SAGD process. A history match is conducted based on the 2D experimental data, and the recovery mechanisms of VR-SAGD are discussed. Heterogeneity in terms of barriers sandwiched in the pay zone is studied, and operational parameters are optimized based on the history match results. The 2D physical simulation results show that VR-SAGD accelerates the oil rate by a factor of 1.74 and reduces the instantaneous steam-to-oil-ratio by 49.7%. The VR co-injected with steam propagates in advance and accumulates at the front of the steam chamber and around the barriers to accelerate the effect of viscosity-reduction and reduce the heat loss to the overburden. Numerical simulation results indicate that the optimum time for VR injection is during and after the phase when the steam chamber expands sideways. The optimized VR/steam volume ratio and production/injection volume ratio are 1:9 and 1.2:1, respectively. The VR-SAGD process shows good potential to improve post-SAGD performance and reduces steam consumption in extra-heavy oil reservoirs.

It is challenging to enhance heavy oil recovery in the late stages of steam flooding. This challenge is due to reduced residual oil saturation, high steam-oil ratio, and lower profitability. A field test of the CO2-assisted steam flooding technique was carried out in the steam-flooded heavy oil reservoir in the J6 block of the Xinjiang oil field (China). In the field test, a positive response to the CO2-assisted steam flooding treatment was observed, including a gradually increasing heavy oil production, an increase in the formation pressure, and a decrease in the water cut. The production wells in the test area mainly exhibited four types of production dynamics, and some of the production wells exhibited production dynamics that were completely different from those during steam flooding. After being flooded via CO2-assisted steam flooding, these wells exhibited a gravity drainage pattern without steam channeling issues, and hence, they yielded stable oil production. In addition, emulsified oil and CO2 foam were produced from the production well, which agreed well with the results of laboratory-scale tests. The reservoir-simulation-based prediction for the test reservoir shows that the CO2-assisted steam flooding technique can reduce the steam-oil ratio from 12 m3 (CWE)/t to 6 m3 (CWE)/t and can yield a final recovery factor of 70%.

We evaluated the performance of a field-wide post-steam in-situ combustion (ISC) project conducted in a complex heavy oil reservoir in China using laboratory one-dimensional combustion experiments, reservoir simulation outputs, and data collected from the field application. The commercial ISC project showed vastly different production performances in different regions of the field and two types of representative well groups were identified. Type I group has a low oil viscosity (30%); after ISC treatment, these producers show a high initial water cut, while some experience channeling issues and hence produce a large quantity of flue gas. Type II group has a high oil viscosity (>20000 mPa.s) and a low cyclic steam stimulation (CSS) recovery factor (15-20%); these producers have a high air injection pressure exceeding the fracture pressure. Corresponding remedial methods were designed and applied to these two well groups. Presently, the evaluation methods described in this paper are being applied in the field, and initial results have been acquired.

Steam injection is the most popular used method in recovering heavy oil reservoirs. Many researchers were engaged in enhancing oil recovery (EOR) methods by using various well configurations. Laboratory experiments and field applications have verified the feasibility of extra-heavy oil recovery by steam injection using vertical injector -horizontal producer. It was also referred to as a steam assisted gravity drainage (SAGD) process. However, the characteristic of steam chamber growth and production performance during the vertical injector-horizontal producer steam injection process have not been fully understood. In this study, a 3D physical model was constructed to investigate the mechanisms of the steam injection process using vertical injector-horizonal producer. Numerical simulations were also conducted to verify the laboratory experiment and field application. In the aspect of steam chamber growth, the results revealed that three stages were included during the steam injection process. In the aspect of developing mechanisms, it can be divided into steam flooding and gravity drainage stages. Moreover, the results show that about 43.9% of original oil in place (OOIP) was produced in the gravity drainage stage. In addition, subcool showed significant difference in steam flooding and gravity drainage stages. The temperature distribution mode of the horizontal producer was analyzed and proved to be a significant factor that influences the production performance. Sensitivity analysis by using numerical simulation demonstrated that oil viscosity is the dominant factor that impact the production performance. The results guided the development of pilot test area in Xinjiang Oilfield, China. The study can provide a clearer understanding of the vertical injector-horizontal producer steam injection process in recovering heavy oil reservoirs.

An analytical model to predict the steam oil ratio (SOR) of the steam-assisted gravity drainage (SAGD) process, including the growing up, expanding and depletion of the steam chamber development, is proposed through the use of steam chamber development modes, energy balance, and mass balance. The calculated instantaneous steam oil ratio (ISOR) and cumulative steam oil ratio (ISOR) using the new analytical model are compared and validated with other analytical models results and numerical simulation results. The results showed that the new analytical model can predict the changing of SOR during the lifetime of the SAGD process more accurately than other analytical models. In addition, it had a high agreement with the numerical simulation results. Additionally, the new model could predict more parameters, including water cut, steam quality, heat proportion in different parts of a reservoir than previous models. This model could be a fast-effective guide for the design, prediction, and adjustment of field dual-horizontal SAGD well pairs.

Laboratory experiments and pilot applications have proved that urea is an efficient agent to enhance heavy oil recovery. Numerous studies have been conducted to investigate the mechanisms of urea co-injection process in steam flooding or cyclic steam stimulation. However, investigations of applying urea in steam assisted gravity drainage (SAGD) process are rarely published. The mechanism of enhanced oil recovery in the urea assisted SAGD process has not been fully understood. Laboratory experiments and numerical simulations were conducted to study the decomposition rate of urea, the effect of urea decomposition products on reservoirs and pipelines, and the distribution of effective decomposition products of urea in the steam chamber at conditions of different concentrations, temperatures, and injection rates. The results show that the solubility of the effective urea decomposition products affects their distribution in the formation because of the huge difference between the solubility in oil and water. In SAGD process, urea cannot be completely decomposed and will produce solid decomposition products, which could block the reservoir pores and production pipelines in certain conditions. Moreover, numerical simulation indicates that the use of low-concentration urea injection in SAGD can effectively enhance oil recovery and oil production rate, while high-concentration urea can reduce the oil recovery and oil production rate. In addition, it was proved that CO2 mainly exists at the edge of the steam chamber and NH3 is distributed in the irreducible water near the well-bore. CO2 is more effective than NH3 for enhancing oil recovery in urea assisted SAGD. Studies indicate that urea co-injection is a feasible method for enhancing oil recovery in the SAGD process.

The steam oil ratio (SOR) usually increases during the later steam-assisted gravity drainage (SAGD) process, resulting in a decrease in economic benefits and an increase of oil remaining in the wedge zones. To extract wedge zone oil efficiently and economically, this study proposed a method, namely infill wells assisted in-situ combustion (ISC) following SAGD, which takes advantages of SAGD and ISC in sequence by proper well patterns. The requirements for successful ISC following SAGD were discussed, including fuel supply, thermal communication, high temperature oxidation (HTO) kinetics, and the proper time to convert to ISC and the proper well patterns for ISC. The potential method was studied systematically by both physical and numerical simulations based on parameters of a typical extra-heavy oil reservoir in China. The results show that SAGD can be converted to ISC when the steam chamber extends to the edge of SAGD well pattern with infill wells in the middle of well pair as air injectors. It is shown that infill wells assisted ISC following SAGD method has great potential for enhancing oil recovery in extra-heavy oil reservoirs and also presents good economic benefit and operability due to its high oil efficiency. With the well pattern recommended, the oil recovery and economic benefit can be improved by 12.8% and 26.4%, respectively, compared to continued SAGD process. This will provide important guidance for the development in extra-heavy oil reservoirs worldwide.

Steam assisted gravity drainage (SAGD) technology by dual-parallel horizontal wells is matured commercial technology. In China SAGD was used commercially from 2012, current SAGD production rate is 17,000bbl/d. However, because of reservoir heterogeneity the production performance is not expected, oil rate per well is low, steam oil ratio (SOR) is higher. FC project in Xinjiang Oilfield has been operated for 6 years since 2012, however, the expected oil rate and SOR are still not gained. By analyzing various data about 168 dual-horizontal well patterns, three typical SAGD horizontal producer temperature modes are put forward. They are basically uniform mode (Type I), heel section tending to steam breakthrough mode (Type II), toe section non-start-up mode (Type III) respectively. Different temperature modes represent different recovery and producing characteristics, appropriated enhanced measures should be put forward. Basic uniform mode is 27% (45 well patterns), its characteristic is the temperature difference along the horizontal producer is about 30℃ and the whole well section is utilized basically. Heel section tending to steam breakthrough mode is 47% (79 well patterns), the temperature of heel section is 80℃ higher than that of toe section. There are hotspots near heel section, and steam is easy to break into producer in heel section. Liquid production intensity (t/d/m) of heel section is 5-10 times lower than that of toe section. Toe section non-start-up mode is 26% (44 well patterns), the temperature difference is more than 100℃ along horizontal producer, toe section cannot be start up efficiently. Different enhanced measures have been applied to these three types. For Type I, sub-cool is lowed from 30-40℃ to 8-15℃ to increase liquid production intensity, then the oil production and SOR are enhanced. For Type II, an appropriated length electric heater is placed in the toe section to increase its temperature and narrow temperature gap between heel and toe section. Liquid production intensity of toe section is increased by this measure. For Type III, assisted vertical injector wells are used to utilize the toe section and make the steam chamber develop uniformly in toe section.

Currently Block J6 is in the later stage of steam flooding after 27 years’ steam injection, its recovery factor is about 50%, and the water cut is more than 95%. Particularly, the present steam oil ratio is about 12 m3(CWE)/t which has reached the economic limit and is in ineffective development. Cores from four post steam flooding drilling wells show that only top 2-3m of the total 25-30m pay zone has a steam chamber which is the main steam channel and its residual oil saturation is about 20%, the other 22-27m pay zone is displaced by hot water and its oil saturation is 40-55%. A 3D physical simulation show the conventional steam flooding with full interval perforation quickly broke through from the top of reservoir, and the steam oil ratio rose rapidly from 5 m3(CWE)/t to 10 m3(CWE)/t. The recovery factor was only 20.1% at the time of steam breakthrough, and then it was in the phase of high steam oil ratio for a long time. During CO2 assisted steam flooding the whole perforated producer is switched into a low half perforated well, and the recovery factor increases from 20.1% to 81.1%, the steam oil ratio is 3.3m3(CWE)/t. There are three characteristics in CO2 assisted steam flooding stage, firstly there is a steam and CO2 assisted gravity drainage mode, steam chamber expands from the top 2-3cm to the total 20cm oil layer. Secondly, there is a stable emulsion foam oil, its water cut is 60-70%, CO2 liquid ratio is about 5:1 Sm3/t, CO2 is a kind of dispersed bubble so it is much more than the dissolved CO2 liquid ratio 2:1 Sm3/t. Thirdly, CO2 lows the heatloss to overburden and keeps the formation pressure. The calculation shows that the heat loss can be reduced by more than 10% in the top layer. A pilot test including 9 well patterns(49 wells) has been established, and its recovery factor will be up to 75%, and the steam oil ratio will up to 2 m3(CWE)/t, a good production performance is predicted optimistically.

Conventionally, the start-up method of dual-horizontal wells SAGD is steam circulation. During circulation phrase, the minimum circulation time and maximum heat communication uniform profile are expected to achieve high oil production. Generally, circulation phrase takes 2 to 3 months in Canada in high quality reservoir. For the poor quality reservoir, circulation time will be longer, for example, in China it takes 200-300 days. In order to solve the disadvantages about longer preheating time and preheating ununiformity of the conventional steam circulation method, the electric preheating method is researched, super-longer integrated coiled tubing electric heater is put down to the horizontal wells separately to heat oil formation uniformly. The heating mechanism of electric heating method is mainly based on the high temperature heat conduction. The method is less influenced by the permeability of reservoir and the viscosity of crude oil, and the heating efficiency is high. Studies show that the electric preheating method is uniform along the entire horizontal section, the effective heating inter-communication between two wells can reach to 100% theoretically, and the preheating time can greatly shortened. The optimizing results in Block Z1 of Xinjiang Oilfield indicate that the electric preheating time of SAGD is 90 days while the steam circulation time is more than 200 days and the inter-communication profile is 100%. The cost of preheating start is reduced from 420,000$ of steam circulation to 220,000$.

Background: In order to overcome the limitation of long scanning time, compressive sensing (CS) technology exploits the sparsity of image in some transform domain to reduce the amount of acquired data. Therefore, CS has been widely used in magnetic resonance imaging (MRI) reconstruction. Discussion: Blind compressed sensing enables to recover the image successfully from highly under- sampled measurements, because of the data-driven adaption of the unknown transform basis priori. Moreover, analysis-based blind compressed sensing often leads to more efficient signal reconstruction with less time than synthesis-based blind compressed sensing. Recently, some experiments have shown that nonlocal low-rank property has the ability to preserve the details of the image for MRI reconstruction. Methods: Here, we focus on analysis-based blind compressed sensing, and combine it with additional nonlocal low-rank constraint to achieve better MR images from fewer measurements. Instead of nuclear norm, we exploit non-convex Schatten p-functionals for the rank approximation. Results & Conclusion: Simulation results indicate that the proposed approach performs better than the previous state-of-the-art algorithms.

Dynamic magnetic resonance imaging (MRI) is an important auxiliary diagnostic method, and higher resolution of images is more conducive to the doctor to diagnose. In this paper, we extend a method which is referred to as robust principal component analysis (RPCA) to reconstruct dynamic magnetic resonance data from under-sampled measurements based on the low-rank plus sparse decomposition model. We consider the dynamic MRI as the sum of the background and the dynamic components, where the background is enforced low-rank by a non-convex function and a 3D sparsifying transform is used to enforce sparsity in the dynamic components. The proposed optimization problem is solved based on variable splitting and alternative optimization. The results of the in-vivo dynamic cardiac dataset show the proposed method achieves superior reconstruction quality, compared to the state-of-the-art reconstruction methods.

The propagating characteristics of combustion fronts and coke zones in the combustion assisted gravity drainage process were studied using 3D physical simulation experiments. The main mechanisms and factors affecting stable propagation of the combustion fronts were discussed. The experimental results show that the propagation of combustion front can be divided into startup stage, radial expands stage and moving forward stage. The top oil layer is ignited first at the startup stage. Ignition temperature, ignition time and air injection rate are the key parameters for successful ignition. At the radial expanding stage the combustion front grows in size and expands radically and downwards like a funnel, and the air injection rate should match the area of combustion front. After the combustion front propagates beyond the “toe” position, the burning zone would advance along the horizontal well at a certain angle. The controlled gas override and gas seal of the coke in the horizontal well contributes significantly to the overall stability of the process. In field pilot testing, well pattern, ignition parameters and regime of injection and production should be optimized to ensure the stable propagation of the combustion front. Key words: combustion assisted gravity drainage, horizontal well, combustion front, propagating characteristic, physical simulation

Sign language recognition (SLR) plays an important role in communication between deaf and hearing society. However, the recognition result is still worse for signer independent recognition. The reason is that there exists large variation between the signs from different subjects. In this paper, weighted hidden markov model (HMM) is proposed to deal with the variation. Unlike traditional HMM, WHMM assigns each sign samples with different weights. For the sign sample with big variation, the sample weight is big accordingly. Furthermore, we utilize Kinect to produce robust sign features to improve recognition rate. Our system is evaluated on one Chinese sign language dataset of 156 isolated sign words. Experimental result shows our proposed method outperforms other methods with a high recognition rate of 94.74%.

The mechanism and problems associated with development engineering of fire-flooding in post-steam-injected heavy oil reservoirs was studied using 1D & 3D physical simulation experiments and reservoir numerical simulation. The temperature of combustion zone decreased and high-temperature zone enlarged because there existed secondary water formed during steam injection, which could absorb and carry heat towards producers out of the combustion front during fire flooding, but high saturation of water in layers caused by secondary water had less influence on the quantity of fuel deposit and air consumption. In the process of 3D fire flooding experiment, air override was observed during the combustion front moving forward and resulted in a coke zone in the bottom of the layer, and the ultimate recovery factor reached 65% on fact that the remaining oil saturation within the coke zone was no more than 20%. The flooding model, well pattern, well spacing, and air injection rate were optimized according to the specific property and the existed well pattern in the post-steam-injected heavy oil reservoir, and the key techniques of ignition, lifting, and anticorrosion was also selected at the same time. The pilot of fire flooding in the H1 block in the Xinjiang Oilfield was carried out from 2009 based on these research works, and now begins to show better performance. 摘要: ：通过室内一维、三维物理模拟实验和油藏数值模拟，系统研究了稠油油藏注蒸汽后期转火驱开发的机理和相关油藏工程问题。研究表明：注蒸汽后期地层次生水体的存在会降低火驱燃烧带峰值温度、扩大热前缘波及范围，其干式注气过程同样具有湿式燃烧的机理。，由次生水体造成的高含水饱和度对单位体积地层燃料沉积量、氧气消耗量等燃烧指标影响不大。三维物理模拟物模实验火驱最终采收率可以达到65%，火驱过程中有明显的气体超覆现象，油层最底部存在未发生燃烧的结焦带，但结焦带中大部分原油已被驱扫，剩余油残余油饱和度低于20%。结合稠油油藏注蒸汽后期的储集层特征和现有井网条件，对火驱驱替模式、井网、井距和注气速度等进行了优化，并筛选了点火、举升、防腐等关键工艺技术。研究结果应用于新疆H1井区火驱矿场试验中，目前矿场试验初见成效。图1110表4参1720 Key words: heavy oil reservoir, fire flooding, steam injection, wet combustion, physical simulation, numerical simulation

Steam assisted gravity drainage (SAGD) enjoys great advantages in the development of extra heavy oil reservoir such as high oil rate and favarable oil steam ratio. However, there are also disadvantages, such as intensive energy consumption, produced water recycle and disposal, that have impacts on the economics of SAGD projects. Furthermore, oil steam ratio declines and water cut rises when the SAGD comes into its later stage while great residual oil existing in the wedge zone. This paper proposes a new method, turning to in situ combustion (ISC) in the later SAGD, to improve the performance of the later SAGD. The feasibility and performance are both studied systematically. Firstly, a numerical model is established on the basis of reservoir and fluid parameters from a block in Xinjiang oil field, China, and then the performance characteristics in different stages of SAGD in extra heavy oil are studied. Particularly, characteristics of performance, features of temperature, pressure, steam chamber, distribution of residual oil in the later SAGD in extra heavy oil reservoir are deeply characterized. Combining these features and using physical simulation method, the feasibility of ISC in later SAGD in extra heavy oil reservoir has been discussed in terms of the effects of the oxidation kinetics characteristics, the thermal connectivity, the fuel supply, the coke deposit and the combustion front shape of extra heavy oil. Furthermore, the time when or before the steam chamber spreads to the edge of the SAGD well pair pattern is determined to be the optimum time to turn to ISC for the typical reservoir. By adding vertical wells for air injection in the middle of SAGD well pairs is the appropriate well pattern for ISC in the later SAGD. And perforating in the middle and lower interval is demonstrated to be the better method to control injection and production. Four stages in the process of ISC performance are determined and dissected. The study results indicate that stable combustion front shape and high production rate can be achieved after turning to ISC. Another 50.7% of the OOIP can be obtained in the ISC stage, regardless of 30% oil recovery in the SAGD stage.

Abstract The barriers in oil reservoir have great effect on SAGD production. Due to wide existence of interlayers, steam chamber can not move upward freely in perspective of chamber development, and also leads to a longer SAGD production cycle so as to increase the investment risk. Firstly the author studied the distribution and formation reasons of muddy barriers in the Zhong 32 of Windy City oilfield. Steam chamber developing characteristics and steam breakthrough pattern are studied by temperature detection data, historical data and microseismic data fitting dynamic data binding static geologic data. Barriers have three relative position relation with SAGD horizontal well. The order sorted by barrier influence to production from high to low degree: injection well inside barriers, between injection and production wells, above injection well. The results showed that the barrier pattern of Zhong32 is physical barriers, with characteristics of high shale-sand ration, low permeability, poor blocking ability. The horizontal continuous barriers increased steam channeling risks thereby control vapor liquid interface more difficult. Double tubes steam injection and artificial lift can be beneficial for the stable steam chamber operation, increase oil production and decrease water cut. High pressure steam operation increases the opportunities of barriers breakthrough by steam and obtains high oil production per day. The pattern of steam breakthrough in muddy barriers can be divided into bypassing and traversing.

Non-Condensable Gasses (NCG) are gasses such as carbon dioxide, hydrogen sulphide, methane and nitrogen which can be present in a SAGD steam chamber but do not condense into the liquid phase to any large degree. Recent theoretical and laboratory work has shown that these gasses can enhance the thermal efficiency of SAGD without a significant reduction in productivity. There has been considerable discussion, both positive and negative, regarding the behavior of these gases in the steam chamber. Benefits to SAGD productivity have been suggested by some, while other authors have projected impacts on bitumen recovery. This paper highlights how numerical simulation can be used as a tool to analyze the impact of NCG in SAGD through modification of K-value based on thermodynamic theory. As the simulated bitumen production rates were much less than those found in the field. It is necessary to adjust physical properties so as to make the gas more soluble, e.g. by artificially modifying the K values. The author has developed a method of modeling the effects of NCG in a steam zone using the new modified K value table. This paper will present the results of these simulations with and without modification of K-value and predict impact of NCG on SAGD performance.