Modeling and Designing Improved Oil Recovery by Steam Injection in Naturally Fractured Reservoirs

Cicek, O.

doi:10.2118/93574-ms

Cited by 4 publications

(1 citation statement)

References 17 publications

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“…The investigation is conducted using a problem of steam injection operation in a naturally fractured reservoir with an inverted nine-spot pattern. The compositional problem is described in detail in an earlier work 20 . A complete set of data for the studied system is presented in Tables 1 through 4 and in Figs.…”

Section: Resultsmentioning

confidence: 99%

A Parametric Study of the Effects of Reservoir and Operational Properties on the Performance of Steam Displacement of Heavy Oil in Naturally Fractured Reservoirs

Cicek¹

2005

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fax 01-972-952-9435. AbstractThis research effort discusses the effects of a comprehensive range of fluid, rock-fluid and operational properties on the efficiency of steam injection in naturally fractured reservoirs with heavy oil. For this purpose, a fully implicit dualporosity/dual-permeability simulator is developed, and the model is applied to an inverted nine-spot pattern in a naturally fractured reservoir with heavy oil. The effects of the reservoir and operational properties on the steam displacement of heavy oil are studied comparatively in naturally fractured reservoirs with and without interacting matrix blocks and in approximate single porosity realizations of these naturally fractured reservoirs.The field scale numerical model is three-dimensional and three phase accounting for capillary, gravitational and viscous forces. The model solves for (n HC +5) primary variables simultaneously, where n HC is the number of hydrocarbon components. The fully implicit model formulates all reservoir and operational parameters as functions of all the primary variables. The model is linearized using the Newton-Raphson method. A direct and an iterative solver is used in the solution of the system of linear equations.The simulations of steam injection in naturally fractured systems are carried out for long periods of time in order to test the features of the model under strained conditions. The model is verified against the Fourth and Sixth SPE Comparative Solution Projects.This study should help in screening naturally fractured reservoirs for steam injection, and in designing steam injection operations in these reservoirs.The comparative analysis of the effects of reservoir and the operational parameters in naturally fractured reservoirs should provide insight into the range of confidence of heavy oil recovery from naturally fractured reservoirs by steam injection.

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Section: Resultsmentioning

confidence: 99%

A Parametric Study of the Effects of Reservoir and Operational Properties on the Performance of Steam Displacement of Heavy Oil in Naturally Fractured Reservoirs

Cicek¹

2005

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Evaluation of Steam Injection in a Fractured Heavy-Oil Carbonate Reservoir in Iran

et al. 2007

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Steam injection in naturally fractured heavy oil reservoirs provides an extremely challenging problem as well as a potentially effective and efficient improved oil recovery method. Coupling of the two distinct and contrasting matrix and fracture systems results in a highly non-linear problem, and it gets even more complicated as a result of steep changes in fluid properties due to the thermal effects of steam injection. Modeling and designing an optimum steam injection operation in such systems requires an accurate characterization and representation of a naturally fractured heavy oil reservoir and steam injection operation parameters and dynamics1. In this communication, the results of a feasibility study of steam injection in a highly fractured carbonate reservoir are discussed. The field is a giant structure located in south west of Iran at the coast of Persian Gulf. It is a symmetrical anticline with 56 mile length and 10 mile width in the surface with about 3.6 billion barrels of initial oil in place. The initial pressure is 927 psi at 1700 ft depth. The gravity of the oil is 7.24 °API with viscosity of about 2700 cp. The Geological model was constructed based on the available 2D and 3D seismic investigation and conventional core data from different samples. Extensive fracture characterization has been conducted using core data as well as the petrophysical interpretation using imaging logs. Dynamic reservoir simulation model with thermal option has been developed and used for optimization of different parameters for steam injection and their effect on reservoir performance and recovery factor. Reservoir simulation of the field showed that steam injection could improve oil recovery from zero up to nearly 12 %. Furthermore, the results illustrated that the important parameters for designing the steam injection are different strategies for perforating, well spacing, well type, pattern type and size. Additionally, the effect of other parameters such as injected steam quality, oil-water capillary pressure in matrix blocks, steam injection and oil production rate have been studied. Introduction The K Field is a highly fractured carbonate reservoir with about 3.6 billion barrels of initial oil in place. The two important formations in this field for oil production are Jahrum and Sarvak formations. Therefore, the field has been considered as the first developing extra heavy oil reservoir in Iran. Different scenarios were suggested for this field to put it on production among which steamflooding, cyclic steam stimulation and in situ combustion are the most promising methods because of their thermal nature. Sarvak formation with the average thickness of 985 ft is one of the main formations in this field. Initial oil in place of Sarvak reservoir based on Montecarlo calculations program is estimated at 2.7 billion barrels of oil. Therefore, the reservoir simulation study was focused on this formation. Steamflooding method is much like a waterflooding method since it is injected on a pattern basis. Full potential of Steamflooding method was not realized until commercial steamfloods were started in California2. After that many successful field test were reported in literature for both conventional and fracture reservoirs4, 5, 6. Additionally, it was successful both in light and heavy/ extra heavy oil reservoirs7. This is why we did reservoir simulation study based on this method. The objective of this study is to apply all the available data to construct the most reliable model and then determine if the steamflooding method is a suitable candidate to be implemented in this reservoir. CMG thermal simulator (STARS module) with dual porosity option was chosen for our simulation study and the PVT was tuned by the WinProp module. After construction of the model, we attempted to optimize the most significant field operational parameters. Geography and Geology of the Field K Field is a giant structure located in the southwestern part of Iran in the coast of Persian Gulf. Exploration of the field occurred in 1959 in Jahrum and Sarvak formations as extra heavy oil reservoir.

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Calculation of a Critical Steam Injection Rate for Thermally-Assisted Gas-Oil Gravity Drainage

2008

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Heavy oil contained in naturally fractured reservoirs is becoming an important resource as conventional oil reserves are depleted. However, maximizing recovery from such reservoirs is problematic due to the low flow rate of oil and the poor understanding of recovery mechanisms. One EOR method that is of particular interest is Thermally Assisted Gas-Oil Gravity Drainage (TA-GOGD). In this process, steam is injected into the reservoir. This heats the rock matrix blocks through the higher permeability fracture network and improves oil recovery principally by reducing the oil viscosity and thus increasing the rate of gravity drainage through the matrix. This paper shows that there is a critical steam injection rate for TA-GOGD in fractured reservoirs. If the injection rate is below this critical rate, the time to heat the matrix will increase and oil recovery increases with the square of steam velocity in the fracture. If the steam injection rate is greater than the critical rate then there is no significant increase in oil recovery with rate. A simple formula for calculating the critical steam rate in the fractures is derived analytically. We show that it correctly predicts the critical injection rate for detailed simulations of steam injection into an element of a fractured reservoir containing live oil. The predictions are shown to be correct for all fluid and rock properties investigated.

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Modeling and Designing Improved Oil Recovery by Steam Injection in Naturally Fractured Reservoirs

Cited by 4 publications

References 17 publications

A Parametric Study of the Effects of Reservoir and Operational Properties on the Performance of Steam Displacement of Heavy Oil in Naturally Fractured Reservoirs

A Parametric Study of the Effects of Reservoir and Operational Properties on the Performance of Steam Displacement of Heavy Oil in Naturally Fractured Reservoirs

Evaluation of Steam Injection in a Fractured Heavy-Oil Carbonate Reservoir in Iran

Calculation of a Critical Steam Injection Rate for Thermally-Assisted Gas-Oil Gravity Drainage

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