Optimal Amount of Solvent in Solvent Aided Process

Gupta, Suraj; Gittins, Simon; Sood, Arun K.; Zeidani, Khalil

doi:10.2118/137543-ms

Cited by 18 publications

(7 citation statements)

References 8 publications

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“…With artificially enhanced values of D mimicking the doublelayer effect of the diffuse layer combined with drainage from beyond the S g ¼ 0 front without actual consideration of the diffuse layer in this work, the profiles for SOR and oil rates obtained against the SSR are similar to those obtained numerically and presented by Gupta et al (2010), even if they do not match exactly.…”

Section: Discussionsupporting

confidence: 54%

“…The SOR and oil-rate profiles are of similar nature, as obtained by Gupta et al (2010). Higher oil rates are achieved with butane and pentane (-like) solvents compared with propane and hexane.…”

Section: Estimation Of Steam-injection Rates To Maintain the Oil Ratesupporting

confidence: 62%

“…In preference to the black-box approach of GAs, Gupta et al (2010) explored ways of optimizing the solvent addition on the basis of a mechanistic understanding of the process using comprehensive numerical simulations. They started with a view to relate performance of the SAP with the solvent concentration at the interface.…”

Section: Introductionmentioning

confidence: 99%

“…The current work attempts to explore the optimal solvent using the concept of interface concentration of the solvent from Gupta et al (2010) with the help of the extended analytical formulation of SAGD from Butler (1985Butler ( , 1988.…”

Section: Introductionmentioning

confidence: 99%

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An Investigation Into Optimal Solvent Use and the Nature of Vapor/Liquid Interface in Solvent-Aided SAGD Process With a Semianalytical Approach

Gupta

Gittins

2012

SPE Journal

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The steam-assisted gravity-drainage (SAGD) process is used widely to recover heavy oil and bitumen from formations in which no other recovery method has proved to be economical. It is an energy-intensive process, and because of economic and environmental reasons, solvents as additives to the injected steam are being explored currently to reduce the energy and emissions intensity of SAGD. The solvent-aided process (SAP), tested in the field and described in the literature, is one such attempt.In the SAP, a small amount of hydrocarbon solvent is introduced as an additive to the injected steam. Thus, the viscosity of the oil is also reduced because of solvent dilution in addition to heating. The SAP can improve the energy efficiency of SAGD significantly, thus reducing the heat requirement, as shown in field trials discussed elsewhere. However, on the use of the right amount of solvent that can result in best overall performance, there is very little discussion in the literature. Because of the high cost of such solvents, there is incentive to optimize their use in SAGD. Recently, various authors have attempted to address the subject with, for example, arbitrary time-dependent schemes of solvent injections, assessing their impact on results or by treating the internal reservoir dynamics as a black box and using optimization methods, such as genetic algorithms (GAs), to estimate the optimal amount of solvent. While these approaches orient us to the problem in a context-specific manner, it is believed a generalized treatment to estimate optimal use of solvent requires a mechanism-based understanding.The approach presented in this paper is aimed at estimating the optimal solvent in the context of SAGD. It combines the existing Butler's oil-drainage analytical models (Butler 1985(Butler , 1988(Butler , 1994 for SAGD and vapor extraction (VAPEX), which deal with heating effect and solvent-dilution effect one at a time, into one. Then, it calculates the time-dependent steam rates to maintain the predicted oil rates in conjuction with solvent rates and, thus, estimates the solvent/steam ratio (SSR) and the steam/oil ratio (SOR). The results are discussed for a few light-alkane solvents. In the process of this exercise, it is discovered that to obtain reasonable SSR and SOR, a significant amount of oil has to drain from a diffuse layer, which has a varying temperature, solvent concentration, and gas saturation (from maximaum gas saturation at the injection end to zero at the vapor/liquid interface). Gravity Drainage of Oil Under the Influence of Both Heating and Solvent DilutionThe following mathematical framework is developed with the aim of tabulating SORs and oil rates for a given reservoir, a given

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Section: Discussionsupporting

confidence: 54%

Section: Estimation Of Steam-injection Rates To Maintain the Oil Ratesupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Investigation Into Optimal Solvent Use and the Nature of Vapor/Liquid Interface in Solvent-Aided SAGD Process With a Semianalytical Approach

Gupta

Gittins

2012

SPE Journal

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“…The semi-analytical model was developed by combining Butler's oil drainage analytical models (Butler et al, 1981(Butler et al, , 1985 and VAPEX solvent dilution effect (Gupta et al, 2010). In this paper, some modifications to this approach are suggested and the results from this approach are validated against 2D reservoir simulation.…”

Section: Es-sagd Initially Conceived Bymentioning

confidence: 99%

Analyzing the Reservoir Performance of an Expanding Solvent - Steam Assisted Gravity Drainage (ES-SAGD) Process Using a Semi-Analytical Approach

Kannan

Srinivasan

2014

SPE Improved Oil Recovery Symposium

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Steam Assisted Gravity Drainage (SAGD), through many successful field projects, has proven to be an effective process for improved recovery of heavy oil and bitumen from subsurface reservoirs. However, the continued search for a more energy efficient method has led to the development of an improved process called Expanding Solvent (ES)-SAGD that has the potential to accelerate recovery with less steam requirement per barrel of oil produced. Understanding the physics associated with this process is key for making robust predictions regarding the process performance. In this paper, a semi-analytical model is discussed, which can be used to determine the performance of the ES-SAGD process. The results of the semianalytical model are compared to 2D numerical simulation results in order to validate the model.The semi-analytical model, an extension to the model by Gupta et al. (2012) is developed by combining Butler's (Butler et al., 1981(Butler et al., , 1985 oil drainage analytical expression for SAGD and VAPEX (Gupta el., 2010) solvent dilution effects. This approach, with some modifications, is validated by the use of a 2D simulation. Numerical simulation of a short length-scale process like solvent dilution in oil sometimes may yield less accurate result prediction due to inherent numerical dispersion issues. Dynamic gridding based on both temperature and concentration change criterion is demonstrated to be one of the viable options to obviate this issue.Trends for bitumen production rate and some key operation parameters obtained using the semi-analytical model are in good agreement with the numerical simulation results, rendering this model suitable for performing solvents-screening studies. However, there are some differences in magnitude of the results between the simulation and semi-analytical method that can be attributed to grid orientation effects. Modifications to the semi-anlayitcal approach and reservoir model used in 2D simulations have been made to minimize the observed differences.It can be concluded that the approach discussed in this paper could give a preliminary estimate of the key parameters that affect the recovery using the ES-SAGD process. The paper also presents some useful guidelines for simulating the process performance using current commercial simulators.

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Pore-Scale Performance Evaluation and Mechanistic Studies of the Solvent-Aided SAGD (SA-SAGD) Process Using Visualization Experiments

2015

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Optimal Amount of Solvent in Solvent Aided Process

Cited by 18 publications

References 8 publications

An Investigation Into Optimal Solvent Use and the Nature of Vapor/Liquid Interface in Solvent-Aided SAGD Process With a Semianalytical Approach

An Investigation Into Optimal Solvent Use and the Nature of Vapor/Liquid Interface in Solvent-Aided SAGD Process With a Semianalytical Approach

Analyzing the Reservoir Performance of an Expanding Solvent - Steam Assisted Gravity Drainage (ES-SAGD) Process Using a Semi-Analytical Approach

Pore-Scale Performance Evaluation and Mechanistic Studies of the Solvent-Aided SAGD (SA-SAGD) Process Using Visualization Experiments

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