Reservoir Heating Research Articles

Techno-economic optimization of enhanced geothermal systems with multi-well fractured reservoirs via geothermal economic ratio

Enhanced Geothermal System (EGS) shows vast potential for exploiting deep geothermal energy sources, although its techno-economic feasibility remains uncertain. The current research challenge lies in the absence of a reliable tool to rapidly evaluate the economic gains associated with the design of geothermal reservoirs. This study aims to develop an evaluation metric to assess the geothermal economic ratio of EGS. The efficacy, practicality, and simplicity of the proposed metric were demonstrated through its application to reservoir cases involving six fracture structures and four influencing parameters. The geothermal economic ratio of the system was enhanced through the augmentation of injection mass and the expansion of production well spacing. However, it was reduced by higher injection temperatures and wider primary fracture apertures. Using response surface design, the optimal parameters were found to be an injection temperature of 24 °C, an injection mass of 30 kg/s, a primary fracture aperture of 6.192 mm, and a production well spacing of 200 m. These parameters facilitated a reservoir heating efficiency of 0.322, a reservoir flow efficiency of 0.514, and a geothermal economic ratio of 1.026 × 10−20. The proposed metric and results would offer a concise and informative analysis of the market potential of EGS.

Using benzonaphthothiophenes to trace paleo-oil migration directions in the Ediacaran-Cambrian reservoirs of the central Sichuan Basin

Benzonaphthothiophenes (BNTs) are important organosulfur compounds in oil, and their concentrations and [2,1]/([2,1] + [1,2])BNT ratio have been used as migration tracers. Here we focus on the applicability of BNTs as migration tracers for abnormally heat-altered paleo-oil reservoirs. For this purpose, 57 pyrobitumen samples from the Ediacaran to Cambrian dolomite reservoirs in the central Sichuan Basin were collected and detected by gas chromatography-mass spectrometry. The results showed that most pyrobitumens of the studied samples are characterized by high concentrations of unsubstituted polycyclic aromatic hydrocarbons (PAHs), high values of fluoranthene/PAHs, pyrene/PAHs, fluoranthene/(fluoranthene + pyrene), benzofluoranthene/(benzofluoranthene + benzopyrene), and unsubstituted-to-methylated aromatic ratios due to the alteration by abnormal heating. These pyrobitumens have high concentrations of BNTs, and their three isomers show a pattern of [2,1] > [1,2] > [2,3]BNT. The BNTs concentrations display a good positive relationship with the concentrations of the abnormal heating-related PAH, while [2,1]/([2,1] + [1,2])BNT ratio has no correlation with the abnormal heating-related indices, suggesting that abnormal heating of the paleo-oil reservoirs lead to the enrichment of BNTs but has a limited effect on [2,1]/([2,1] + [1,2])BNT ratio. Moreover, [2,1]/([2,1] + [1,2])BNT ratio seem to be not affected by kerogen type and depositional environment, but increases with source rock maturity. Therefore, the [2,1]/([2,1]+[1,2])BNT is still an effective migration tracer for abnormally heated reservoirs. This ratio was applied as migration tracer in the studied area. The result suggests that the paleo-oil primarily migrated from west depression to east bulges, followed by the direction from northwest to southeast, which is congruent with the geological setting and exploration practice, demonstrating the applicability of this parameter for abnormally heat-altered oil reservoirs.

The study of core and particle model of Fushun oil shale based on microwave field

As an unconventional oil and gas resource, oil shale can alleviate the shortage of oil and gas resources. As a new heating process for oil shale retorting and in-situ mining, microwave can effectively exploit and utilize oil shale. In this paper, the Fushun oil shale and particle model under microwave field are studied by means of experiment and numerical simulation. Based on the measurement of the basic physical properties of oil shale, the effects of microwave power and absorbent (semi-coke and graphite) on the pyrolysis of oil shale were investigated. The experimental results show that the heating rate is the fastest when the maximum microwave power is 700 W without adding absorbent or adding the same absorbent. At the same power, the effect of graphite is slightly better than that of semi-coke. In the aspect of numerical simulation, COMSOL simulation software is used to simulate the oil shale core and particles based on the three-dimensional electromagnetic thermal model. The experimental conclusion is verified. At the same time, it is found in the simulation results that microwave heating has better temperature distribution gradient and electric field distribution. Furthermore, the microwave port is extended to the underground for the simulation of microwave in-situ mining. It is found that the reservoir temperature reaches 450 °C after 1000 days of reservoir heating.

Risk of surface movements and reservoir deformation for high-temperature aquifer thermal energy storage (HT-ATES)

High-temperature aquifer thermal energy storage (HT-ATES) systems are designed for seasonal storage of large amounts of thermal energy to meet the demand of industrial processes or district heating systems at high temperatures (> 100 °C). The resulting high injection temperatures or pressures induce thermo- and poroelastic stress changes around the injection well. This study estimates the impact of stress changes in the reservoir on ground surface deformation and evaluates the corresponding risk. Using a simplified coupled thermo-hydraulic-mechanical (THM) model of the planned DeepStor demonstrator in the depleted Leopoldshafen oil field (Upper Rhine Graben, Germany), we show that reservoir heating is associated with stress changes of up to 6 MPa, which can cause vertical displacements at reservoir depth in the order of 10–3 m in the immediate vicinity of the hot injection well. Both the stress changes and the resulting displacements in the reservoir are dominated by thermoelasticity, which is responsible for up to 90% of the latter. Uplift at the surface, on the contrary, is primarily controlled by poroelasticity with by two orders of magnitude attenuated displacements of << 10–3 m. Our calculations further show that the reservoir depth, elastic modulus, and injection/production rates are the dominant controlling parameters for the uplift, showing variations of up to two order of magnitudes between shallower reservoirs with low elastic moduli and deeper and more competent reservoirs. In addition, our findings demonstrate that the cyclic operation of HT-ATES systems reduces the potential for uplift compared to the continuous injection and production of conventional geothermal doublets, hydrocarbon production, or CO2 storage. Consequently, at realistic production and injection rates and targeting reservoirs at depths of at least several hundred meters, the risk of ground surface movement associated with HT-ATES operations in depleted oil fields in, e.g., the Upper Rhine Graben is negligible.

Combined gas effect on the oil reservoir in a dual-well system

Nowadays, high-viscosity oil reservoirs are located in a sphere of extra attention with the demands of special technologies. To maximize high-viscosity oil production advanced action technologies are used involving thermal and many other chemical methods. The article describes the results of a laboratory experiment to determine the rheological properties of high-viscosity oil, which determine the optimal temperature of the reservoir heating. A new method of thermobaric layer treatment; including heat transfer agent injection by a dual-well system; is suggested (injection to a vertical shaft and a heated oil production from a side shaft). A new steam injection steam-gas injection is proposed. The optimal layer warming temperature was 50 °C. The results of the calculations of the radius of the reservoir heating to the target temperature, which allowed for optimizing oil production are also discussed. Efficiency and warming area dependence on a heat-transfer agent to a layer injection time are also identified and presented. It was observed that thermo-physical calculations using the data of a laboratory experiment are useful in the well-design, as it allowed to determine the parameters of the technology and the position of the bottom hole about the source of heating. The optimal bottom hole spacing between the production side shaft and the vertical shaft was found to be 76.0 m. The optimal temperature of 50 °C was reached 10 days after the warning started.

THE EFFECT OF FLUID VARIATIONS IN THE RESERVOIR ON AIR PRESSURE IN KNIFE TOOL HEATING FURNACES

The stainless steel material reservoir tube can produce combustion steam from the heating furnace. The research objective was to determine the effect of variations in the type of liquid and air pressure efficiently used in the reservoir tube. The type of research used is pure experimental research. The medium used is mineral water, 10%, 20%, and 30% brine, and the Manufacturer's coolant is heated using a heating furnace at 110° C for 42 minutes and measured by a pressure gauge. The results of the tests carried out have the effect of differences in mineral water 1.50 bar or 1.48 atmosphere, 10% brine 1.50 bar or 1.48 atmosphere, 20% brine 2.40 bar or 2.36 atmosphere, 30% brine 3, 50bar or 3.45 atmospheres, factory coolant 1.75bar or 1.72 atmospheres. 30% salt water is more efficient and suitable for the stainless steel material reservoir heating process in producing steam under pressure, which is used in knife tools.

Modeling of the thermal-hydrodynamic and chemical regime of Geyser reservoir (Valley of Geyser, Kamchatka)

The thermal-hydrodynamic and chemical eight-decade history of the Geysers production reservoir in the Valley of Geysers (Kamchatka) shows either linear multiyear trends, seasonal cycles, or stepwise changes synchronized with geological catastrophes. Recent changes, apparently caused by surface meteoric water inflow into the productive Geysers reservoir as a result of caprock erosion from the 2007 catastrophic landslide and 2014 mud-flow, include: (1) seasonality of deep component discharge, (2) a drop in CO2 fraction of the gas content of geysers followed by a decrease in geyser eruption capacity, (3) increases in standard geothermometers (Na/K and SiO2) and (4) increases in the sulfate component. 2D numerical thermal-hydrodynamic (TH) model was developed and applied to explain the seasonal decrease in deep component discharge as an effect of gas phase condensation and upflows capture caused by cold water infiltration from the surface during flood periods. Thermo-hydrodynamic-chemical (THC) models and total chemical discharge/recharge balances were used to explain CO2 sequestration, increased sulfate component, and increased standard geothermometers due to gypsum/calcite transformation in surface water infiltration pathways rather than reservoir heating.

Calculation of temperature distribution in heavy oil reservoirs by electromagnetic heating

The introduction of heat into a reservoir has proven to be an effective way to reduce the viscosity of heavy oils by increasing the temperature in the formation. The use of electromagnetic energy has proven to be particularly attractive because of its advantages vis-à-vis conventional heat recovery techniques. While extensive research has been conducted on this radiofrequency recovery method over the years, numerical simulation with reservoir industry applications has been rarely used for electromagnetic heating with heavy oil reservoirs when connected to strong-bottom aquifers. We propose a numerical scheme to estimate temperature variations in the reservoir by electromagnetic absorption, based on the calculation of the electro- magnetic wavefield amplitude and radiation heat diffusion coupling. The electrical and thermal properties of the reservoir were calculated considering the fractions and saturation of its phases. The results obtained from this RF heating simulation show a radially distributed temperature profile within the reservoir. The power and frequency of the incident wave were considered for an antenna located in the center of the formation. This allows to determine the required energy in kWh, and its influence on the antenna power, as well as the thermal and electrical properties of the medium such as aquifers. Numerical modelling allows reaching a stable temperature inside the reservoir, in days or months, despite the strong presence of water-saturated zones. The simulation shows that the presence of aquifers at bottom and partially saturated media affects reservoir heating. To make the numerical experiment reproducible and verifiable, the workflow is provided in code form.

Modeling of the reservoirs heating with the aim of oil recovery increasing

The object of the research is optimal installation of the heat injection wells for reservoirs heating in order to increase oil recovery and, accordingly, support oil production in the hard-reaching heterogeneous reservoirs. One of the most problematic areas in modern oil production is the difficulty of extracting high-viscosity oil from the reservoirs. So far, the most effective method to overcome this problem is the thermal method. However, the possibilities of this method are limited by its high energy consumption and the cost of relevant practice research. Thus, less expensive corresponding methods of mathematical modeling become more important. This investigation uses a combined finite-element-difference method for the non-stationary thermal conductivity problem. Numerical modeling of the temperature distribution around heat injection wells are carried out, taking into account the heterogeneity of the thermal properties of the oil reservoir and the conditions of convective heat exchange at the reservoir’s boundaries. The proposed method, due to its high accuracy and convergence of the solutions, allows to obtain reliable practical results and has a number of advantages in comparison with the same research methods. It is established that the process of heating of oil reservoirs is slow and energy consuming, so to increase profitability, it is obviously necessary to use associated production products, such as associated gas. It is shown that less wet layers heat up better and there is no sense to heat the layer for more than two weeks, because the radius of the effective heating area (with a temperature exceeding 80 °C required for outcome of high-viscosity oil from the rock) in this case is sufficient. It is also found that the operation of heat-injection wells is more profitable with their joint interaction, in that case the effective heating area of the oil reservoir and, accordingly, the number of production wells will be the largest. Another hand, the main factor in the location of heat-injection wells is defined by special characteristics of the oil-bearing section of the reservoir in each case. The configurations of the location of heat-injection wells, which were presented in this paper, cover the most optimal cases of the installations of considered oil-bearing section of the reservoirs and can be used in practice.

Numerical Simulation Analysis of Heating Effect of Downhole Methane Catalytic Combustion Heater under High Pressure

The hot exhaust gas generated by a downhole combustion heater directly heats the formation, which can avoid the heat loss caused by the injection of high-temperature fluid on the ground. However, if the temperature of the exhaust gas is too high, it may lead to the carbonization of organic matter in the formation, which is not conducive to oil production. This paper proposes the use of low-temperature catalytic combustion of a mixture of methane and air to produce a suitable exhaust gas temperature. The simulation studies the influence of different parameters on the catalytic combustion characteristics of methane and the influence of downhole high-pressure conditions. The results show that under high-pressure conditions, using a smaller concentration of methane (4%) for catalytic combustion can obtain a higher conversion efficiency (88.75%), and the exhaust temperature is 1097 K. It is found that the high-pressure conditions in the well can promote the catalytic combustion process of the heater, which proves the feasibility of the downhole combustion heater for in situ heating of unconventional oil and gas reservoirs.

Study of thermally-induced enhancement in nanopores, microcracks, porosity and permeability of rocks from different ultra-low permeability reservoirs

Improving permeability is the crucial mechanism for further enhancing oil and gas recovery of ultra-low permeability reservoirs. To investigate the temperature sensitivity and stress sensitivity of permeability under an actual reservoir condition, heating treatment and real-time measurement of pulse-decay gas permeability (PDP) of cores collected from three different ultra-low permeability reservoirs were conducted in our self-developed high-temperature pseudo-triaxial core holder. To clarify the intrinsic relationship between the microstructure development and porosity-permeability enhancement, stereo light microscope (SLM) observation, computerized tomography (CT) scan and nuclear magnetic resonance (NMR) test were used to quantitatively characterize the dynamic variations in thermal cracks, nanopores and porosity. Based on the lithology analysis and thermal analysis, the primary mechanisms of nanopore evolution and thermal cracking for different ultra-low permeability rocks were analyzed in detail. The experimental results show that the permeability of Chang 8 ultra-low permeability sandstone and Longmaxi shale cores only increased by about one order of magnitude above the threshold temperature of 500 °C, while the permeability of Jimsar shale cores increased significantly by two orders of magnitude above the threshold temperature of 300 °C. Above their threshold temperatures, the permeability showed stronger stress sensitivity. The SLM observation and CT scan revealed that thermal cracks propagated rapidly above the threshold temperatures, which resulted in a substantial increase in temperature sensitivity and stress sensitivity of permeability. NMR test shows that the porosity of ultra-low permeability cores performed an increasing trend as the temperature rose. However, the nanopore structure in Chang 8 ultra-low permeability sandstone monotonously developed toward larger micron-sized pores, while the Longmaxi shale and Jimsar shale eventually re-evolved into smaller nanopores. We found that kerogen pyrolysis was the most critical mechanism leading to the microstructure, porosity and permeability enhancement in organic-rich shale. For organic-poor ultra-low permeability sandstone and shale, the quartz phase transition from α to β was considered as the key reaction for the thermal cracking and permeability improvement. By comparison, heating treatment has a higher thermal stimulation potential in shale cores from medium-to-low maturity shale oil reservoirs.

A coupled model for predicting thermophysical properties of saturated steam in dual-tubing SAGD horizontal wells with toe-point injection technique

In this paper, a coupled numerical model to simulate dual-tubing steam-assisted gravity drainage (SAGD) process with toe-point injection technique was developed, specially, a more rigorous approach was used to calculate the steam pressure. Based on the model, the distribution of thermophysical properties of steam along the wellbore is investigated. The results indicate that improving the annulus steam temperature uniformity in circulation stage and the annulus steam quality uniformity in production stage is the key to enhancing the reservoir heating uniformity. The influence of the heat transfer from the wellbore to the reservoir on reservoir heating is significant with a low steam injection rate, but the influence is weak with a high steam injection rate. The reservoir temperature nonuniformity is more likely to occur during production stage than during circulation stage, and more attention needs to be paid to optimizing the reservoir temperature uniformity during production stage. A “toe-good” heating effect can be observed with toe-point injection technique, and simultaneous dual-tubing injection technology is a suitable method for solving this problem. The findings of this study can help to better understand the relationship between the distribution of thermophysical properties of saturated steam along the wellbore and reservoir nonuniform heating.

Technology Focus: EOR Modeling (January 2021)

The enhanced-oil-recovery (EOR) literature produced in the past several months was dominated by reservoir modeling and characterization; flood enhancements; machine learning; and, more notably, relative permeability estimation. This last one needs to be under-stood further. Relative permeability characterizes flow in porous media, the understanding and manipulating of which is key to the success of EOR. Our fascination with the topic during the last 75 years, therefore, is understandable. Starting with a seminal paper from W.R. Purcell in 1949, we have more than 12,000 articles in the SPE collection alone on relative permeability estimation, of which more than 400 were published in the last year. Mechanics of motion is also important to mankind, but we do not have literature piling up on Newton’s laws of motion. Is it that we haven’t understood flow in porous media yet, or is it because the subject matter is so complex? The truth, perhaps, lies somewhere in between. Flow in pores that are randomly sized, randomly connected, and have variable chemical makeup is, by nature, complex and mathematically unmanageable. Relative permeability has been our attempt to lend its aggregate behavior some sense of manageability. This has always been done in a fit-for-purpose manner. What is fit for one context, however, may not be so for the others, and this uncertainty continues to churn out theses, antitheses, and syntheses. Expectedly, even more such activity arises with every improvement in computing capabilities, as is once again evident with advances in machine learning—new tools to handle old problems. That is where my first pick is for you, with some additional suggested readings in references that follow. Data analytics does much more than estimate relative permeability, and the second paper abridged here uses it to predict a flood performance. To allow a break from data science, the third paper chosen deals with the important topic of electromagnetics as applied to reservoir characterization and heating. I hope you find these to be useful and interesting reads.

Revising the effectiveness of thermal method application for unconventional bitumen oil production stimulation

A theoretical model of petroleum reservoir engineering process with high viscosity oil using the technology of double horizontal wells is proposed. Numerical solutions of the problem in a two-dimensional formulation are obtained. With this method of producing high viscosity oil the efficiency of oil reservoir development can be increased by ensuring uniform heating of the developed zone of the field. The proposed model allows us to trace the two-dimensional picture of oil filtration in the reservoir and investigate the main regularities of the process. The costs for oil reservoir heating, flow rate development and changes in the mass of pumped oil in the initial period of well operation are determined. The obtained solutions for a long stretch of time were extrapolated.

Optimization of the slotted liners parameters during dual tubing steam injection process

To study the distribution of steam parameters along the wellbore and the influence of slotted liners parameters on the effect of reservoir uniform preheating during the dual tubing steam injection process. Based on the structural characteristics of screen pipe completion and the simultaneous steam injection technology of long and short tubing, a coupled numerical model of fluid flow and heat transfer in reservoir and wellbore was established, and the model was solved by full implicit finite difference method and iterative technique. The results show that when the density, width and length of the slotted liners increase from 350 to 550/m, 0.20 to 0.40 mm and 35 to 75 mm, respectively, the difference of steam quality at the two ends of steam convergence position in the annuli increases by 0.41%, 2.26% and 1.71%, and the reservoir heating uniformity decreases by 1.49%, 2.68% and 2.08%, respectively. Optimizing the slotted liners parameters and reducing the steam quality difference at the convergence position of annuli can improve the uniform heating degree of reservoir along the horizontal wellbore.

Термогазохимическое воздействие на залежь высоковязкой нефти в скважине с дуальной системой стволов

The prospect of producing high-viscosity oil based on the thermal-gas-chemical formation treatment of exposure using binary composition in a well with a dual-well system is considered. The theoretical, computational, and experimental justification of the depth of reservoir heating, the distance between the vertical and side shafts, and the parameters of the technological mode of oil rate is given.

Applicability of heat-exchanger theory to estimate heat losses to surrounding formations in a thermal flood

Heat losses to cap and base rocks undermine the performance of a thermal flood. As a contribution to this subject, this paper investigates the applicability of the principles of heat exchanger to characterise heat losses between a petroleum reservoir and the adjacent geologic systems. The reservoir-boundary interface is conceptualised as a conductive wall through which the reservoir and adjacent formations exchange heat, but not mass. For a conduction-dominated process, the heat-transport equations are formulated and solved for both adiabatic and non-adiabatic conditions. Simulations performed on a field-scale example show that the rate of heating a petroleum reservoir is sensitive to the type of fluids saturating the adjoining geologic systems, as well as the characteristics of the cap and base rocks of the subject reservoir. Adiabatic and semi-infinite reservoir assumptions are found to be poor approximations for the examples presented. Validation of the proposed model against an existing model was satisfactory; however, remaining differences in performances are rationalised. Besides demonstrating the applicability of heat-exchanger theory to describe thermal losses in petroleum reservoirs, a novelty of this work is that it explicitly accounts for the effects of the reservoir-overburden and reservoir-underburden interfaces, as well as the characteristics of the fluid in the adjacent strata on reservoir heating. These and other findings should aid the design and management of thermal floods.

Improving Temperature-Logging Accuracy in Steamfloods

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 191539, “Temperature-Logging Guidelines and Factors That Affect Measurement Accuracy,” by Gede Adnyana (retired, former Chevron), Jyotsna Sharma, SPE, Don•Mims, SPE, David Barnes, and Ron Behrens, SPE, Chevron, prepared for the 2018 SPE Annual Technical Conference and Exhibition, Dallas, 24–26. The paper has not been peer reviewed. A robust reservoir surveillance program is key to managing a steamflooding operation successfully. Time-lapse temperature surveys are a primary data type collected from the observation wells to evaluate reservoir heating and to monitor the steamchest. The objective of this study was to look at factors that can affect a temperature log and steps that can be taken to improve temperature-measurement accuracy. Field data and analytical assessment show that several factors can affect the accuracy of a temperature log, which can subsequently affect interpretation and operational decisions. Temperature-Logging-Tool Overview Temperature-logging tools are among the most common used in thermal projects. These tools are accurate, reliable, and relatively inexpensive. Fig. 1 shows a schematic of a typical temperature tool. It includes a casing-collar locator (CCL), a temperature sensor, and tool electronics. Temperature logs can also be obtained in conjunction with data from other logs such as the cement-bond, carbon/oxygen, pulse-neutron, and openhole logs. However, it is recommended that temperature surveys from these tools be used for quantitative analysis because the other logs are recorded normally by first lowering the logging tool to the bottom of the well and then logging up to the surface. These log measurements may also be taken at a higher logging speed. But temperature tools, by comparison, are logged down-ward, therefore avoiding wellbore-fluid-churning issues. Additionally, depth control is maintained by monitoring tension on the line and by correlating to the CCL. Temperature sensors in the logging tool measure the temperature of the fluid in the wellbore, which is in thermal equilibrium with the adjacent formations. A resistance temperature detector (RTD) is the preferred sensor for temperature measurements. An RTD is a device that senses temperature by measuring the change in resistance of a material in a known and repeatable manner. Platinum thermistors are also used as temperature sensors; however, an RTD has better repeatability, long-term stability, and accuracy, and features greater sensitivity to small temperature changes than does a platinum thermistor. Additionally, platinum thermistors have lower maximum temperature limits typically and require more-frequent calibration, although their response can be faster than that of an RTD. The sensor requires a certain minimum time to reach thermal equilibrium with the measured fluid, which is a function of its response time, defined as the time unit required for a sensor to reach 63.2% of the total output signal when subjected to a step change in input. The step change can be an increase or decrease in the parameter being measured, such as temperature. Response time is affected by the type of sensor, the medium in the wellbore (typically water), and the change in temperature. Response time in air is much slower than in water, a state that exists even for newer RTD sensors. If the logging speeds are too fast, the sensor may not have sufficient time to equilibrate with the medium, resulting in an inaccurate temperature reading. However, higher or varying logging speeds often represent an operational decision to save time.

Simulations of In-Situ Upgrading Process: Interpretation of Laboratory Experiments and Study of Field-Scale Test

Summary In–situ upgrading (IU) is a promising method of improved viscous– and heavy–oil recovery. The IU process implies a reservoir heating up and exposure to a temperature higher than 300°C for a time period long enough to promote a series of chemical reactions. The pyrolysis reactions produce lighter oleic and gaseous components, while a solid residue remains underground. In this work, we developed a numerical model of IU using laboratory experience (kinetics measurements and core experiments) and validated the results by applying our model to an IU field–scale test published in the literature. Finally, we studied different operational conditions in a search for energy–efficient configurations. In this work, two types of IU experimental data are used from two vertical–tube experiments with Canadian bitumen cores (0.15 and 0.69 m). A general IU numerical model for the different experimental setups has been developed and compared with experimental data, using a commercial reservoir–simulator framework. This model is capable of representing the phase distribution of pseudocomponents, the thermal decomposition reactions of bitumen fractions, and the generation of gases and residue (solid) under thermal cracking conditions. Simulation results for the cores exposed to a temperature of 380°C and production pressure of 15 bar have shown that oil production (per pseudocomponent) and oil–sample quality were well–predicted by the model. Some differences in gas production and total solid residue were observed with respect to laboratory measurements. Computer–assisted history matching was performed using an uncertainty–analysis tool with the most–important model parameters. To better understand IU field–scale test results, the Shell Viking pilot (Peace River) was modeled and analyzed with the proposed IU model. The appropriate gridblock size was determined and the calculation time was reduced using the adaptive mesh–refinement (AMR) technique. The quality of products, the recovery efficiency, and the energy expenses obtained with our model were in good agreement with the field test results. In addition, the conversion results (upgraded oil, gas, and solid residue) from the experiments were compared with those obtained in the field test. Additional analysis was performed to identify energy–efficient configurations and to understand the role of some key variables (e.g., heating period and rate and the production pressure) in the global IU upgrading performance. We discuss these results, which illustrate and quantify the interplay between energy efficiency and productivity indicators.

Area of Reservoir Heating during Steam Cyclic Treatment of Oil Wells

To develop difficult-to-recover high-viscosity oils, thermal well treatment methods are applied ensuring the reduction of oil viscosity and the increase of oil recovery, thus decreasing the time of development. Among such methods is steam cyclic well treatment. Steam cyclic method of treatment involves three consecutive stages forming a cycle that can be repeated many times: steam injection stage, steam treatment stage, and oil production stage. The displacement of fluid from reservoir by steam occurs in three stages. The first stage is the formation of the area of the so-called “steam plateau”, which is the region of saturated vapor and water filtration at saturation temperature and reservoir pressure. In this case, the condensation of steam with the heat release takes place, which is sent to reservoir, increasing the temperature in it. The second stage is the displacement of the liquid from reservoir by hot water formed as a result of steam condensation. In the third stage of heat treatment, a stationary temperature field in the reservoir is formed. The whole process of steam cycling is affected by several factors, while the area of reservoir heating is difficult to determine. The integral method proposed in this paper makes it possible to make a preliminary assessment of the heating area of oil reservoir.