Fuel Formation and Conversion During In-Situ Combustion of Crude Oil

SPE Journal ◽  
2013 ◽  
Vol 18 (06) ◽  
pp. 1217-1228 ◽  
Author(s):  
Hascakir Berna ◽  
Cynthia M. Ross ◽  
Louis M. Castanier ◽  
Anthony R. Kovscek
Keyword(s):  
Oil Recovery ◽  
Photoelectron Spectroscopy ◽  
Combustion Front ◽  
Combustion Products ◽  
Combustion Tube ◽  
Cross Sectional ◽  
In Situ Combustion ◽  
X Ray ◽  
Study Results

Summary In-situ combustion (ISC) is a successful method with great potential for thermal enhanced oil recovery. Field applications of ISC are limited, however, because the process is complex and not well-understood. A significant open question for ISC is the formation of coke or "fuel" in correct quantities that is sufficiently reactive to sustain combustion. We study ISC from a laboratory perspective in 1 m long combustion tubes that allow the monitoring of the progress of the combustion front by use of X-ray computed tomography (CT) and temperature profiles. Two crude oils—12°API (986 kg/m3) and 9°API (1007 kg/m3)—are studied. Cross-sectional images of oil movement and banking in situ are obtained through the appropriate analysis of the spatially and temporally varying CT numbers. Combustion-tube runs are quenched before front breakthrough at the production end, thereby permitting a post-mortem analysis of combustion products and, in particular, the fuel (coke and coke-like residues) just downstream of the combustion front. Fuel is analyzed with both scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). XPS and SEM results are used to identify the shape, texture, and elemental composition of fuel in the X-ray CT images. The SEM and XPS results aid efforts to differentiate among combustion-tube results with significant and negligible amounts of clay minerals. Initial results indicate that clays increase the surface area of fuel deposits formed, and this aids combustion. In addition, comparisons are made of coke-like residues formed during experiments under an inert nitrogen atmosphere and from in-situ combustion. Study results contribute to an improved mechanistic understanding of ISC, fuel formation, and the role of mineral substrates in either aiding or impeding combustion. CT imaging permits inference of the width and movement of the fuel zone in situ.

In-Situ Combustion Dynamics Visualized With X-Ray Computed Tomography

SPE Journal ◽  
2011 ◽  
Vol 16 (03) ◽  
pp. 524-536 ◽  
Author(s):  
B.. Hasçakir ◽  
G.. Glatz ◽  
L.M.. M. Castanier ◽  
A.R.. R. Kovscek
Keyword(s):  
Computed Tomography ◽  
Combustion Front ◽  
Combustion Tube ◽  
Data Set ◽  
In Situ Combustion ◽  
Combustion Dynamics ◽  
X Ray ◽  
Uniform Sample ◽  
X Ray Computed

Summary One method to access unconventional, heavy-oil resources is to apply in-situ combustion (ISC) to oxidize in place a small fraction of the hydrocarbon, thereby providing heat and pressure that enhances recovery. ISC is also attractive because it provides the opportunity to upgrade oil in situ by increasing the API gravity and decreasing, for instance, sulfur content. Despite a considerable literature on ISC dynamics, the propagation of a combustion front through porous media has never been visualized directly. We use X-ray computed tomography (CT) to monitor ISC movement, displacement-front shape, and thickness in a 1-m-long "combustion" tube. Temperature-profile history, liquid production, and effluent gas data are also obtained. Tests employ an 8.65°API heavy crude oil and representative sand. The general trend of saturation profiles is defined through spatially and temporally varying CT numbers. The role of initial oil and water saturations is examined by packing the combustion tube with either multiple samples with different saturations or by filling it with a uniform sample. Our work quantifies that ISC fronts display instabilities on a fine scale (cm). ISC reactions appear to add to front instability in comparison to inert gas advance. The pressure gradients during ISC appear to influence grain arrangement for loose packing. These grain arrangements cause combustion-front fingering, suggesting that the geomechanical state is relevant to combustion. These new data advance the knowledge base significantly by providing a data set for benchmarking of ISC simulations.

An Experimental Investigation of In Situ Combustion in High Permeability Contrast Systems

2021 ◽  
pp. 1-13
Author(s):  
Melek Deniz Paker ◽  
Murat Cinar
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
Combustion Front ◽  
Fractured Reservoirs ◽  
Front Propagation ◽  
High Permeability ◽  
Vertical Orientation ◽  
In Situ Combustion ◽  
Horizontal Orientation

Abstract A significant portion of world oil reserves reside in naturally fractured reservoirs and a considerable amount of these resources includes heavy oil and bitumen. Thermal enhanced oil recovery methods (EOR) are mostly applied in heavy oil reservoirs to improve oil recovery. In situ combustion (/SC) is one of the thermal EOR methods that could be applicable in a variety of reservoirs. Unlike steam, heat is generated in situ due to the injection of air or oxygen enriched air into a reservoir. Energy is provided by multi-step reactions between oxygen and the fuel at particular temperatures underground. This method upgrades the oil in situ while the heaviest fraction of the oil is burned during the process. The application of /SC in fractured reservoirs is challenging since the injected air would flow through the fracture and a small portion of oil in the/near fracture would react with the injected air. Only a few researchers have studied /SC in fractured or high permeability contrast systems experimentally. For in situ combustion to be applied in fractured systems in an efficient way, the underlying mechanism needs to be understood. In this study, the major focus is permeability variation that is the most prominent feature of fractured systems. The effect of orientation and width of the region with higher permeability on the sustainability of front propagation are studied. The contrast in permeability was experimentally simulated with sand of different particle size. These higher permeability regions are analogous to fractures within a naturally fractured rock. Several /SC tests with sand-pack were carried out to obtain a better understanding of the effect of horizontal vertical, and combined (both vertical and horizontal) orientation of the high permeability region with respect to airflow to investigate the conditions that are required for a self-sustained front propagation and to understand the fundamental behavior. Within the experimental conditions of the study, the test results showed that combustion front propagated faster in the higher permeability region. In addition, horizontal orientation almost had no effect on the sustainability of the front; however, it affected oxygen consumption, temperature, and velocity of the front. On the contrary, the vertical orientation of the higher permeability region had a profound effect on the sustainability of the combustion front. The combustion behavior was poorer for the tests with vertical orientation, yet the produced oil AP/ gravity was higher. Based on the experimental results a mechanism has been proposed to explain the behavior of combustion front in systems with high permeability contrast.

Predictability of Crude Oil In-Situ Combustion by the Isoconversional Kinetic Approach

SPE Journal ◽  
2011 ◽  
Vol 16 (03) ◽  
pp. 537-547 ◽  
Author(s):  
Murat Cinar ◽  
Berna Hasçakir ◽  
Louis M. Castanier ◽  
Anthony R. Kovscek
Keyword(s):  
Crude Oil ◽  
Combustion Front ◽  
Front Propagation ◽  
Combustion Tube ◽  
Complex Nature ◽  
Oil Viscosity ◽  
In Situ Combustion ◽  
Temperature Oxidation ◽  
Isoconversional Analysis

Summary One method to access unconventional heavy-crude-oil resources as well as residual oil after conventional recovery operations is to apply in-situ combustion (ISC) enhanced oil recovery. ISC oxidizes in place a small fraction of the hydrocarbon, thereby providing heat to reduce oil viscosity and increase reservoir pressure. Both effects serve to enhance recovery. The complex nature of petroleum as a multicomponent mixture and the multistep character of combustion reactions substantially complicate analysis of crude-oil oxidation and the identification of settings where ISC could be successful. In this study, isoconversional analysis of ramped temperature-oxidation (RTO) kinetic data was applied to eight different crude-oil samples. In addition, combustion-tube runs that explore ignition and combustion-front propagation were carried out. By using experimentally determined combustion kinetics of eight crude-oil samples along with combustion-tube results, we show that isoconversional analysis of RTO data is useful to predict combustion-front propagation. Isoconversional analysis also provides new insight into the nature of the reactions occurring during ISC. Additionally, five of the 10 crude-oil/rock systems studied employed a carbonate rock. No system displayed excessive oxygen consumption resulting from carbonate decomposition at combustion temperatures. This result is encouraging as it contributes to widening of the applicability of ISC.

Oxygen In-Situ Combustion for Oil Recovery: Combustion Tube Tests

1984 ◽  
Vol 36 (07) ◽  
pp. 1139-1144 ◽  
Author(s):  
James Gordon Hansel ◽  
Michael Arthur Benning ◽  
John Matthew Fernbacher
Keyword(s):  
Oil Recovery ◽  
Combustion Tube ◽  
In Situ Combustion

Experimental and Numerical Analysis of In-Situ Combustion in a Fractured Core

SPE Journal ◽  
2011 ◽  
Vol 16 (02) ◽  
pp. 358-373 ◽  
Author(s):  
H.. Fadaei ◽  
L.. Castanier ◽  
A.M.. M. Kamp ◽  
G.. Debenest ◽  
M.. Quintard ◽  
...  
Keyword(s):  
Combustion Front ◽  
Fractured Reservoirs ◽  
Experimental Studies ◽  
Steam Injection ◽  
Combustion Tube ◽  
Fractured Reservoir ◽  
In Situ Combustion ◽  
Matrix Permeability ◽  
The Matrix

Summary Approximately one-third of global heavy-oil resources can be found in fractured reservoirs. In spite of its strategic importance, recovery of heavy crudes from fractured reservoirs has found few applications because of the complexity of such reservoirs. In-situ combustion (ISC) is a candidate process for such reservoirs, especially for those where steam injection is not feasible. Experimental studies reported in the literature on this topic mentioned a cone-shaped combustion front, indicating that the process was governed by diffusion of oxygen into the matrix. The main oil-production mechanisms were found to be thermal expansion of oil and evaporation of light components (Schulte and de Vries 1985; Greaves et al. 1991). In order to confirm these results, we carried out reservoir-simulation studies presented in Fadaei et al. (2010). We have shown that the front has the shape of a cone, and we have performed a combustion/extinction analysis representing the results in a diagram of cumulative production vs. diffusion coefficient and matrix permeability. Before obtaining quantitative and qualitative comparisons, we need to characterize the systems we want to study. Therefore, we also carried out laboratory experiments using kinetic cells and combustion tubes. The kinetic-cell studies showed that the presence of carbonates has a significant effect on combustion kinetics. Our combustion-tube studies confirmed the previously observed coneshaped front. Previous studies reported in literature used heating elements along the combustion tube to regulate the temperature, which may have caused some undue heating of the core. To avoid that, we chose to use efficient insulation to minimize heat losses. Combustion advanced faster in nonconsolidated matrix, in which the permeability was higher than in consolidated matrix. The results showed that the presence of severe heterogeneities may prevent the combustion front from propagating. Several runs were performed for different air-injection rates and pressures and for different permeability contrasts between the matrix and the fracture. The next step of our work is the upscaling of ISC in the fractured reservoir at interwell scale on the basis of knowledge provided by simulation and experimental studies.

Effects of Steam on Heavy Oil Combustion

2009 ◽  
Vol 12 (04) ◽  
pp. 508-517 ◽  
Author(s):  
Alexandre Lapene ◽  
Louis Castanier ◽  
Gerald Debenest ◽  
Michel Yves Quintard ◽  
Arjan Matheus Kamp ◽  
...  
Keyword(s):  
Crude Oil ◽  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Heavy Oil ◽  
Combustion Front ◽  
Oil Viscosity ◽  
In Situ Combustion ◽  
Temperature Oxidation ◽  
Recovery Method

Summary In-Situ Combustion. In-situ combustion (ISC) is an enhanced oil-recovery method. Enhanced oil recovery is broadly described as a group of techniques used to extract crude oil from the subsurface by the injection of substances not originally present in the reservoir with or without the introduction of extraneous energy (Lake 1996). During ISC, a combustion front is propagated through the reservoir by injected air. The heat generated results in higher temperatures leading to a reduction in oil viscosity and an increase of oil mobility. There are two types of ISC processes, dry and wet combustion. In the dry-combustion process, a large part of the heat generated is left unused downstream of the combustion front in the burned-out region. During the wet-injection process, water is co-injected with the air to recover some of the heat remaining behind the combustion zone. ISC is a very complex process. From a physical point of view, it is a problem coupling transport in porous media, chemistry, and thermodynamics. It has been studied for several decades, and the technique has been applied in the field since the 1950s. The complexity was not well understood earlier by ISC operators. This resulted in a high rate of project failures in the 1960s, and contributed to the misconception that ISC is a problem-prone process with low probability of success. However, ISC is an attractive oil-recovery process and capable of recovering a high percentage of oil-in-place, if the process is designed correctly and implemented in the right type of reservoir (Sarathi 1999). This paper investigates the effect of water on the reaction kinetics of a heavy oil by way of ramped temperature oxidation under various conditions. Reactions. Earlier studies about reaction kinetic were conducted by Bousaid and Ramey (1968), Weijdema (1968), Dabbous and Fulton (1974), and Thomas et al. (1979). In these experiments, temperature of a sample of crude oil and solid matrix was increased over time or kept constant. The produced gas was analyzed to determine the concentrations of outlet gases, such as carbon dioxide, carbon monoxide, and oxygen. This kind of studies shows two types of oxidation reactions, the Low-Temperature Oxidation (LTO) and the High-Temperature Oxidation (HTO) (Burger and Sahuquet 1973; Fassihi et al. 1984a; Mamora et al. 1993). In 1984, Fassihi et al. (1984b) presented an analytical method to obtain kinetics parameters. His method requires several assumptions.

scholarly journals Use of two vertical injectors in place of a horizontal injector to improve the efficiency and stability of THAI in situ combustion process for producing heavy oils

2021 ◽  
Author(s):  
Muhammad Rabiu Ado
Keyword(s):  
Oil Recovery ◽  
Combustion Front ◽  
Combustion Process ◽  
Oil Production ◽  
Steam Injection ◽  
Electrical Heating ◽  
Heavy Oils ◽  
In Situ Combustion ◽  
Start Up

AbstractThe current commercial technologies used to produce heavy oils and bitumen are carbon-, energy-, and wastewater-intensive. These make them to be out of line with the global efforts of decarbonisation. Alternative processes such as the toe-to-heel air injection (THAI) that works as an in situ combustion process that uses horizontal producer well to recover partially upgraded oil from heavy oils and bitumen reservoirs are needed. However, THAI is yet to be technically and economically well proven despite pilot and semi-commercial operations. Some studies concluded using field data that THAI is a low-oil-production-rate process. However, no study has thoroughly investigated the simultaneous effects of start-up methods and wells configuration on both the short and long terms stability, sustainability, and profitability of the process. Using THAI validated model, three models having a horizontal producer well arranged in staggered line drive with the injector wells are simulated using CMG STARS. Model A has two vertical injectors via which steam was used for pre-ignition heating, and models B and C each has a horizontal injector via which electrical heater and steam were respectively used for pre-ignition heating. It is found that during start-up, ultimately, steam injection instead of electrical heating should be used for the pre-ignition heating. Clearly, it is shown that model A has higher oil production rates after the increase in air flux and also has a higher cumulative oil recovery of 2350 cm3 which is greater than those of models B and C by 9.6% and 4.3% respectively. Thus, it can be concluded that for long-term projects, model A settings and wells configuration should be used. Although it is now discovered that the peak temperature cannot in all settings tell how healthy a combustion front is, it has revealed that model A does indeed have far more stable, safer, and efficient combustion front burning quality and propagation due to the maintenance of very high peak temperatures of mostly greater than 600 °C and very low concentrations of produced oxygen of lower than 0.4 mol% compared to up to 2.75 mol% in model C and 1 mol% in model B. Conclusively, since drilling of, and achieving uniform air distribution in horizontal injector (HI) well in actual field reservoir are costly and impracticable at the moment, and that electrical heating will require unphysically long time before mobilised fluids reach the HP well as heat transfer is mainly by conduction, these findings have shown decisively that the easy-and-cheaper-to-drill two vertical injector wells configured in a staggered line drive pattern with the horizontal producer should be used, and steam is thus to be used for pre-ignition heating.

In-situ combustion front monitoring and tracking using InSAR

2020 ◽  
Vol 39 (4) ◽  
pp. 272-278
Author(s):  
Mohammad Bazargan ◽  
Pieter Bas Leezenberg ◽  
Anthony R. Kovscek
Keyword(s):  
Oil Recovery ◽  
Combustion Front ◽  
Surface Deformation ◽  
Time Derivative ◽  
Local Maximum ◽  
Recovery Process ◽  
Field Application ◽  
Surface Velocity ◽  
In Situ Combustion

Interferometric synthetic aperture radar (InSAR) is used to locate the combustion front during field application of the in-situ combustion (ISC) enhanced oil recovery process. As the combustion front propagates through the reservoir during ISC, lateral surface deformation occurs on the order of 1–100 mm/year, depending on the reservoir depth and overlying strata, with a unique time derivative signature. Monitoring using InSAR benefits from the existence of a thin (tens of centimeters) high-temperature (600°C) combustion front to accurately determine the front position. This can inform reservoir and production engineering design decisions. Analytical and numerical examples of a homogeneous, isotropic, and horizontal reservoir show that regardless of the depth of the reservoir, the combustion front is positioned at the local maximum of the rate of surface deformation. These results are consistent with analytical solutions for distribution of point stress in the earth. This result is applied to the field case of Suplacu de Barcau, Romania, that has a long history of ISC. For the Suplacu Field, surface deformation rate data were generated using InSAR for the time periods of 12 March 2003 to 28 July 2010 and 29 October 2014 to 19 June 2017. The time derivative of surface deformation (surface velocity) suggests the advancement of the combustion front, consistent with reservoir engineering analyses in the literature. Importantly, the predicted positions of the combustion front match the available historical data for Suplacu in 2006 and 2010. We have also predicted the position of the combustion front in 2017 using the most recent InSAR data.

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