Development and Application of an In-Situ Combustion Reservoir Simulator

1980 ◽  
Vol 20 (01) ◽  
pp. 39-51 ◽  
Author(s):  
Gary K. Youngren
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Solution Method ◽  
Oil And Gas ◽  
Three Dimensions ◽  
Volatile Components ◽  
In Situ Combustion ◽  
Gas Phases ◽  
Reservoir Simulator

Youngren, Gary K., SPE-AIME, ARCO Oil and Gas Co. Abstract This paper describes a three-dimensional, three-phase in-situ combustion reservoir simulator that rigorously models fluid flow, heat transfer, and vaporization/ condensation. It has five components: water, oxygen, nonvolatile oil, and two arbitrary volatile components. The volatile components partition between the oil and gas phases. The physical mechanisms modeled, the comprehensive mathematical solution method employed, and four applications of the simulator are presented. The applications demonstrate that the simulator can be used to interpret laboratory results and predict the effects of reservoir characteristics and operating strategy on field performance. Introduction Crookston et al. and Farouq Ali thoroughly reviewed previous developments in the mathematical simulation of in-situ combustion processes. Briefly, the earliest studies modeled certain aspects of the process using simple assumptions for the remaining process using simple assumptions for the remaining features in order to make the problem tractable. For example, Chu modeled one-dimensional thermal conduction, convection, and the thermal effects of vaporization and condensation, but multi phase fluid flow effects were simplified by assuming constant fluid saturations. Smith and Farouq Ali simulated conduction, convection, heat losses, and heat generation in two-dimensions, but assumed single-phase flow and constant fuel consumption. Recently, Farouq Ali and Crookston et al. described comprehensive three-phase, two-dimensional simulators that model the most essential features of in-situ combustion; however, results were presented only for hypothetical one- and two-dimensional examples with relatively few grid blocks.The objective of this work was to develop an in-situ combustion simulator that would rigorously model fluid flow, heat transfer, and vaporization/ condensation and still be efficient enough to allow simulation of realistic reservoir problems. Accordingly, the simulator employs a stable, efficient, highly implicit solution method. It is formulated to handle three dimensions, three phases, five components, gravity and capillary forces, heat transfer by convection and conduction within the reservoir and conductive heat loss to adjacent strata. Quantitative data on high-temperature combustion kinetics of crude oils in porous media is inadequate to allow rigorous treatment of reaction kinetics; thus, the combustion reaction is treated simply, yet realistically, by assuming that the combustion rate is limited only by the oxygen flux. This paper first describes the simulator, outlining the physical mechanisms modeled and the numerical solution method employed. It concludes by presenting analysis of real laboratory and field data in one, two, and three dimensions. Simulator Description Physical Properties Physical Properties The most significant features of the simulator are listed in Table l and detailed in Appendix A.The simulator has five components: water, nonvolatile (dead) oil, oxygen, and two arbitrary volatile components that partition between the oil and gas phases. The last four components are considered insoluble in water. The last two components are arbitrary and may be any one of the combinations: nitrogen (N2) and solution gas, N2 and carbon dioxide (CO2), N2 and a distillable hydrocarbon, CO2 and solution gas, or CO2 and a distillable hydrocarbon. SPEJ p. 39

In-Situ Combustion Model

1980 ◽  
Vol 20 (06) ◽  
pp. 533-554 ◽  
Author(s):  
Keith H. Coats
Keyword(s):  
Fluid Flow ◽  
Input Data ◽  
Computing Time ◽  
Three Dimensions ◽  
Maximum Efficiency ◽  
Combustion Model ◽  
Model Formulation ◽  
Time Step ◽  
In Situ Combustion

Abstract This paper describes a numerical model forsimulating wet or dry, forward or reverse combustionin one, two, or three dimensions. The formulation isconsiderably more general than any reported to date.The model allows any number and identities ofcomponents. Any component may be distributed inany or all of the four phases (water, oil, gas, andsolid or coke.The formulation allows any number of chemicalreactions. Any reaction may have any number ofreactants, products, and stoichiometry, identifiedthrough input data. The energy balance accounts forheat loss and conduction, conversion, and radiationwithin the reservoir.The model uses no assumptions regarding degreeof oxygen consumption. The oxygen concentration iscalculated throughout the reservoir in accordancewith the calculated fluid flow pattern and reactionkinetics. The model, therefore, simulates the effectsof oxygen bypassing caused by kinetic-limitedcombustion or conformance factors.We believe the implicit model formulation resultsin maximum efficiency (lowest computing cost), andrequired computing times are reported in the paper.The paper includes comparisons of model resultswith reported laboratory adiabatic-tube test results.In addition, the paper includes example field-scalecases, with a sensitivity study showing effects on oilrecovery of uncertainties in rock/fluid properties. Introduction Recent papers by Ali, Crookston et al., andYoungren provide a comprehensive review of earlierwork in numerical modeling of the in-situcombustion process.The trend in this modeling has been toward morerigorous treatment of the fluid flow and interphasemass transfer; inclusion of more components, morecomprehensive reaction kinetics, and stoichiometry;and more implicit treatment of the finite differencemodel equations.The purpose of this work was to extend thegenerality of previous models while preserving orreducing the associated computing-time requirement.The most comprehensive or sophisticated combustionmodels described to date appear to be thoseof Crookston et al. and Youngren. Therefore, wecompare our model formulation and results here withthose models.A common objective of different investigators'efforts in modeling in-situ combustion is developmentof more efficient formulations and methods ofsolution. This is especially important in thecombustion case because of the large number ofcomponents and equations involved. For a given numberof components and reactions, computing time pergrid block per time step will increase rapidly as theformulation is rendered more implicit. However, increasing implicitness tends to allow larger timesteps, which in turn reduces overall computingexpense. To pursue the above objective, then, authorsshould present as completely as possible the details oftheir formulations and the associatedcomputing-time requirements.The thermal model described here simulateswet or dry, forward or reverse combustion in one, two, or three dimensions. The formulation allowsany number and identities of components and anynumber of chemical reactions, with reactants, products, and stoichiometry specified through input products, and stoichiometry specified through input data. SPEJ P. 533

Reverse Combustion Instabilities in Tar Sands and Coal

1980 ◽  
Vol 20 (04) ◽  
pp. 267-277 ◽  
Author(s):  
Robert D. Gunn ◽  
William B. Krantz
Keyword(s):  
Reaction Zone ◽  
Combustion Front ◽  
Stability Theory ◽  
Coal Gasification ◽  
Gas Production ◽  
Volatile Components ◽  
In Situ Combustion ◽  
Tar Sands ◽  
Vertical Well

Abstract A linear stability analysis shows that reverse combustion in coal and tar sands is only conditionally stable for mobility ratios less than one. However, high air-flow rates and gas generation at the combustion front can be stabilizing influences. For unstable operation, an estimate of the size of the reverse combustion channel may be obtained from the curve for the most highly amplified wave length. This provides a method for calculating the air flux, combustion front velocity, and rate of progress of the burn front. Recently the U.S. DOE Laramie Energy Technology Center (LETC) and Sandia Laboratories obtained experimental data about reverse combustion from a field test of in-situ coal gasification at Hanna, WY. These data show that 9.7 days were required for the development of a reverse combustion path 68 to 70 ft in length. The stability theory developed in this work predicts a length of 64 ft for this same 9.7-day period. In addition to quantitative predictions, stability theory provides an explanation of certain puzzling qualitative observations concerning reverse combustion. Introduction In-situ combustion is a potentially useful method for recovering fossil fuels from underground deposits. A number of in-situ combustion field tests have been conducted in oil reservoirs, tar sands, oil shale deposits, and coal seams. In-situ combustion can be classified into two broad categories: reverse combustion, in which the reaction front travels countercurrent to the flow of air, and forward combustion, in which the reaction zone travels in the same direction as the flow of air. Reverse combustion is especially important for coal and tar sands. During forward combustion, tars vaporized at the flame front in either coal or tar sands travel by convection into cooler regions ahead of the reaction zone where they condense and subsequently reduce the natural permeability of the fuel bed. In reverse combustion, vaporized tars or other high-molecular-weight compounds generated in the reaction zone travel toward the production well through a heated area already contacted by the high temperatures of the combustion front. As an added advantage, reverse combustion in tar sands substantially increases the relative permeability to gas. In lignite and subbituminous coal, drying and partial combustion typically increase the effective permeability to gas by four orders of magnitude. However, bituminous coal frequently swells on heating, and the net effect of reverse combustion on the permeability of swelling coals has not been investigated thoroughly. In coal and tar sands, reverse combustion is primarily a coking or carbonization process - i.e., the volatile components of the tar or coal are partially combusted while most of the carbon or coke is left unburned. For these reasons, reverse combustion represents an important part of some in-situ combustion methods currently being investigated for tar sands and coal. In the linked vertical well process for in-situ coal gasification, reverse combustion is used first to develop a high-permeability path between the production and air injection wells, while in the second stage of the process forward gasification or combustion is used as the major gas production method. Both industrial companies and government laboratories have investigated the linked vertical well process. For tar sands, the LETC is considering the use of reverse combustion as a preparatory mechanism similar to that used in coal.

Simulation of Hydraulic Fracturing Processes

1980 ◽  
Vol 20 (06) ◽  
pp. 487-500 ◽  
Author(s):  
A. Settari
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Hydraulic Fracturing ◽  
Fracture Propagation ◽  
Thermal Recovery ◽  
Reservoir Rock ◽  
Flow And Heat Transfer ◽  
Fracture Closure ◽  
Fracturing Process

Abstract A mathematical model of the fracturing process, coupling the fracture mechanics and fracture propagation with reservoir flow and heat transfer, has been formulated. The model is applicable to fracturing treatments as well as to high leakoff applications such as fractured waterfloods and thermal fractures. The numerical technique developed is capable of simulating fracture extension for reasonably coarse grids, with truncation error being minimized for high leakoff applications when the grid next to the fracture is approximately square. With the aid of the model, a generalization of Carter's propagation formula has been developed that is also valid for high fluid-loss conditions. The capabilities of the model are illustrated by examples of heat transfer and massive-hydraulic-fracturing (MHF) treatment calculation. Introduction Induced fracturing of reservoir rock occurs under many different circumstances. Controlled hydraulic fracturing is an established method for increasing productivity of wells in low-permeability reservoirs. The technology of fracturing and the earlier design methods are reviewed by Howard and Fast.1 In waterflooding, injection pressures also often exceed fracturing pressures. This may result from poor operational practices, but it also could be intended to increase injectivity.2 In heavy oils, such as Alberta oil sands, most in-situ thermal recovery techniques rely on creating injectivity by fracturing the formation with steam.3 Fracturing also is being used as a method for deterining in-situ stresses4 and for establishing communication between wells for extraction of geothermal energy.5,6 Finally, fractures may be produced by explosive treatment or induced thermal stresses (such as in radioactive waste disposal). To date, most of the research has been directed toward the understanding and design of fracture stimulation treatments, with emphasis on predicting fracture geometry.7–11 The influence of fluid flow and heat transfer in the reservoir has been neglected or accounted for by various approximations in these methods. On the other hand, the need for reservoir engineering analysis of fractured wells led to the development of analytical techniques and numerical models for predicting postfracture performance.1 A common feature of all these methods is that they treat only stationary fractures, which therefore must be computed using some of the methods of the first category mentioned earlier. With the high costs associated with MHF,17–19 and with increasing complexity of the treatments, it is becoming important to be able to understand the interaction of the physical mechanisms involved and to improve the designs. This paper presents a numerical model of the fracturing process that simultaneously accounts for the rock mechanics, two-phase fluid flow, and heat transfer, both in the fracture and in the reservoir. The model is capable of predicting fracture propagation, fluid leakoff and heat transfer, fracture closure, cleanup, and postfracture performance. Although the detailed calculations of geometry, proppant transport, etc., have not been included, they can be integrated in a natural way within the present model. Because vertical fractures are prevalent except for very shallow depths, the discussion is limited to vertical fracturing. The paper focuses attention on the formulation of the basic model and the numerical techniques in general. Applications to fracturing treatments and the specific enhancements of the model are described in a more recent paper.20

A Computational Scheme for Fluid Flow and Heat Transfer Analysis in Porous Media for Recovery of Oil and Gas

2005 ◽  
Vol 23 (7-8) ◽  
pp. 843-862 ◽  
Author(s):  
David M. Scott ◽  
Debendra K. Das ◽  
Vijayagandeeban Subbaihaannadurai ◽  
Vidyadhar A. Kamath
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Fluid Flow ◽  
Oil And Gas ◽  
Computational Scheme ◽  
Heat Transfer Analysis ◽  
Flow And Heat Transfer

Canadian Operator Works To Transform an Oil Field Into a Hydrogen Factory

2021 ◽  
Vol 73 (03) ◽  
pp. 38-40
Author(s):  
Trent Jacobs
Keyword(s):  
Hydrogen Production ◽  
Heavy Oil ◽  
Oil And Gas ◽  
Hydrogen Generation ◽  
Combustion Process ◽  
Oil And Gas Industry ◽  
Oil Field ◽  
In Situ Combustion ◽  
Associated Gas

As the oil and gas industry scans the known universe for ways to diversify its portfolio with alternative forms of energy, it might want to look under its own feet, too. For inside every oil reservoir, there may be a hydrogen reservoir just waiting to get out. The concept comes courtesy of Calgary-based Proton Technologies. Founded in 2015, the young firm is the operator of an aging heavy oil field in Saskatchewan. There, on a small patch of flat farm-land, Proton has been producing oil to pay the bills. At the same time, it has been experimenting with injecting oxygen into its reservoir in a bid to produce exclusively hydrogen. Proton says its process is built on a technical foundation that includes years of research and works at the demonstration scale. Soon, the firm hopes to prove it is also profitable. While it produces its own hydrogen, Proton is licensing out the technology to others. In January, fellow Canadian operator Whitecap Resources secured a hydrogen production license of up to 500 metric tons/day from Proton. Whitecap produces about 48,000 B/D, and thanks to carbon sequestration, the operator has claimed a net negative emissions status since 2018. Proton says it has struck similar licensing deals with other Canadian operators but that these companies have not yet made public announcements. Where these projects go from here may end up representing the ultimate test for Proton’s innovative twist on the in-situ combustion process known so well to the heavy-oil sector. “In-situ combustion has been used in more than 500 projects worldwide over the last century. And, they have all produced hydrogen,” said Grant Strem, a cofounder and the CEO of Proton. Strem is a petroleum geologist by back-ground who spent the majority of his career working on heavy-oil projects for Canadian producers and research analysis with the banks that fund the upstream sector. While his new venture remains registered as an oil company, the self-described explorationist has come to look at oil fields very differently than he used to. “In an oil field, you have oil—hydrocarbons, which are made of hydrogen and carbon. The other fluid down there is H2O. So, an oil field is really a giant hydrogen-rich, energy-dense system that’s all conveniently accessible by wells,” Strem explained. But, in those past examples, the hundreds of other in-situ combustion projects, hydrogen production was merely a byproduct, an associated gas of sorts. It was the result of several reactions generated by air injections that producers use an oxidizer to heat up the heavy oil and get it flowing. What Proton wants to do is to super-charge the hydrogen-generating reactions by using the oil as fuel while leaving the carbon where it is. That ambition includes doing so at a price point that is roughly five times below that of Canadian natural gas prices and an even smaller fraction of what other hydrogen-generation methods cost.

Thermo-mechanical Effects on Fracture Growth and Apertures in Three-Dimensional Subsurface Fractured Rocks 

2021 ◽  
Author(s):  
Adriana Paluszny ◽  
Robin N. Thomas ◽  
M. Cristina Saceanu ◽  
Robert W. Zimmerman
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Three Dimensional ◽  
Growth Patterns ◽  
Three Dimensions ◽  
Interaction Patterns ◽  
Flow Equations ◽  
The Matrix ◽  
Model Equations ◽  
Fracture Growth

<p>A finite-element based, quasi-static growth algorithm models mixed mode concurrent fracture growth in three dimensions, leading to the formation of non-planar arrays and networks. To model the fully coupled THM model, equations describing mechanical deformation as well as heat transfer in the matrix and in the fractures are introduced in the formulation, simultaneously accounting for the effect of fluid flow and stress-strain response. This results in five separate, but two-way coupled model equations: a thermoporoelastic mechanical model; two fluid flow equations, one for the rock matrix and one for the fractures; two heat transfer equations, similarly for both the matrix and fractures. Fractures are represented explicitly as discrete surfaces embedded within a volumetric domain [1]. Growth is computed as a set of vectors that modify the geometry of a fracture by accruing new fracture surfaces in response to brittle deformation. Fracture tip stress intensity factors drive fracture growth. This growth methodology is validated against analytical solutions for fractures under compression and tension [2]. Thermal effects on the apertures and growth patterns will be presented. Isolated fracture geometries are compared with selected experimental results on brittle media. Accurate growth is demonstrated for domains discretised by refined and coarse volumetric meshes. Fracture and volume-based growth rates are shown to modify fracture interaction patterns. Two-dimensional cut-plane views of fracture networks show how fractures would appear on the surface of the studied volume.</p><p><strong>REFERENCES</strong></p><p>[1] N. Thomas, A. Paluszny and R. W. Zimmerman. Growth of three-dimensional fractures, arrays, and networks in brittle rocks under tension and compression. Computers and Geotechnics, 2020. doi: 10.1016/j.compgeo.2020.103447</p><p>[2] Paluszny and R. W. Zimmerman. Numerical fracture growth modeling using smooth surface geometric deformation. Eng. Fract. Mech., 108, 19-36, 2013. doi: 10.1016/j.engfracmech.2013.04.012</p>

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