Impact of Matrix Block Size on Oil Recovery Response Using Surfactants in Fractured Carbonates

2012 ◽  
Author(s):  
Ali Goudarzi ◽  
Mojdeh Delshad ◽  
Kishore K. Mohanty ◽  
Kamy Sepehrnoori
Keyword(s):  
Oil Recovery ◽  
Block Size ◽  
Matrix Block ◽  
Recovery Response ◽  
Fractured Carbonates

CO2 EOR Potential in Naturally Fractured Haft Kel Field, Iran

2010 ◽  
Vol 13 (04) ◽  
pp. 720-729 ◽  
Author(s):  
Sayyed Ahmad Alavian ◽  
Curtis H. Whitson
Keyword(s):  
Oil Recovery ◽  
Block Size ◽  
Co2 Injection ◽  
Model Parameters ◽  
Matrix Permeability ◽  
Matrix Block ◽  
Naturally Fractured ◽  
Oil Density ◽  
Single Matrix ◽  
Co2 Density

Summary We present results studying the enhanced-oil-recovery (EOR) potential for carbon dioxide (CO2) injection in the naturally fractured Haft Kel field, Iran, on the basis of detailed compositional simulations of a homogeneous single matrix block surrounded by fractures. Oil recoveries from CO2 injection in this idealized model approach 90% for reservoir pressures of 1,400 psia and higher (i.e., at and above current reservoir pressure of 1,500–1,800 psia). It is expected that heterogeneity will reduce recovery on the field scale. This compares with 15–25% recoveries reported for gas-cap expansion and/or injection of hydrocarbon (HC) gas. Fundamentally different recovery mechanisms develop above and below 2,000 psia, the pressure at which CO2 density equals the reservoir-oil density. At lower pressures, CO2 is less dense than reservoir oil and traditional gas/oil gravity segregation results, with a highly efficient process driven by gravity, compositional effects, and interfacial-tension (IFT) gradients that cause capillary-induced oil flow. At pressures greater than 2,000 psia, CO2 density is greater than reservoir-oil density, resulting in an unusual gravity-drainage mechanism whereby CO2 enters the bottom of a matrix block and pushes oil out the sides and top of the matrix block. The effect of several key parameters has been studied in detail—matrix permeability, matrix-block size, matrix/matrix capillary continuity (stacked blocks), and the use of mixtures of CO2 and HC gas. One of the key results is how the rate of recovery differs for combined injection of HC gas and CO2, and how it varies for CO2 injection for different model parameters. EOR results are affected by grid sensitivity. Grid effects have been quantified and compared for different model parameters. Final EOR assessment is made using models in which sufficient grid refinement is used to minimize grid sensitivity.

Matrix Refinement in Mass Transport Across Fracture-Matrix Interface: Application to Improved Oil Recovery in Fractured Reservoirs

2021 ◽  
Author(s):  
Sarah Abdullatif Alruwayi ◽  
Ozan Uzun ◽  
Hossein Kazemi
Keyword(s):  
Fractured Reservoirs ◽  
Block Size ◽  
Grid Cell ◽  
Matrix Interface ◽  
Unsteady State ◽  
Matrix Block ◽  
Matrix Blocks ◽  
The Matrix ◽  
Saturation Distribution ◽  
State Pressure

Abstract In this paper, we will show that it is highly beneficial to model dual-porosity reservoirs using matrix refinement (similar to the multiple interacting continua, MINC, of Preuss, 1985) for water displacing oil. Two practical situations are considered. The first is the effect of matrix refinement on the unsteady-state pressure solution, and the second situation is modeling water-oil, Buckley-Leverett (BL) displacement in waterflooding a fracture-dominated flow domain. The usefulness of matrix refinement will be illustrated using a three-node refinement of individual matrix blocks. Furthermore, this model was modified to account for matrix block size variability within each grid cell (in other words, statistical distribution of matrix size within each grid cell) using a discrete matrix-block-size distribution function. The paper will include two mathematical models, one unsteady-state pressure solution of the pressure diffusivity equation for use in rate transient analysis, and a second model, the Buckley-Leverett model to track saturation changes both in the reservoir fractures and within individual matrix blocks. To illustrate the effect of matrix heterogeneity on modeling results, we used three matrix bock sizes within each computation grid and one level of grid refinement for the individual matrix blocks. A critical issue in dual-porosity modeling is that much of the fluid interactions occur at the fracture-matrix interface. Therefore, refining the matrix block helps capture a more accurate transport of the fluid in-and-out of the matrix blocks. Our numerical results indicate that the none-refined matrix models provide only a poor approximation to saturation distribution within individual matrices. In other words, the saturation distribution is numerically dispersed; that is, no matrix refinement causes unwarranted large numerical dispersion in saturation distribution. Furthermore, matrix block size-distribution is more representative of fractured reservoirs.

Solvent Selection Criteria and Optimal Application Conditions for Heavy-Oil/Bitumen Recovery at Elevated Temperatures: A Review and Comparative Analysis

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Khosrow Naderi ◽  
Tayfun Babadagli
Keyword(s):  
Comparative Analysis ◽  
Oil Recovery ◽  
Heavy Oil ◽  
Selection Criteria ◽  
Elevated Temperatures ◽  
Fractured Reservoirs ◽  
Solvent Type ◽  
Wide Range ◽  
Cost Efficient ◽  
Fractured Carbonates

Sole thermal or solvent methods for heavy-oil recovery are not effective enough to deliver cost efficient processes. Hybrid applications of those two techniques have been proposed to take advantage of each and a wide range of investigations have been recently performed focusing on extreme conditions such as bitumen containing sands and carbonates, deep reservoirs, and oil-wet fractured carbonates. What is critically important in these applications is to determine the best performing solvent for a particular application and optimal application conditions for a given solvent at high temperature conditions. In this study, the results from various reported works on the hybrid applications of thermal (mainly steam) and solvent methods were complied, analyzed, and compared. Attention was given to a comparative analysis of steam-over-solvent injection in fractured reservoirs (SOS-FR) method. Steam/solvent methods show a promising outcome in general, while specific modifications must be taken into account for different application situations. These were discussed and specified, especially from proper solvent type and optimal application conditions for alternate injection of steam and solvent in different reservoir types.

Bivariate Log-Normal Distribution of Stimulated Matrix Permeability and Block Size in Fractured Reservoirs: Proposing New Multilinear-Flow Regime for Transient-State Production

SPE Journal ◽  
2018 ◽  
Vol 23 (04) ◽  
pp. 1316-1342 ◽  
Author(s):  
Salam Al-Rbeawi
Keyword(s):  
Normal Distribution ◽  
Flow Regime ◽  
Fractured Reservoirs ◽  
Block Size ◽  
Analytical Models ◽  
Matrix Permeability ◽  
Matrix Block ◽  
The Matrix ◽  
Log Normal ◽  
Log Normal Distribution

Summary This paper investigates the impacts of varied stimulated matrix permeability and matrix-block size on pressure behaviors and flow regimes of hydraulically fractured reservoirs using bivariate log-normal distribution. The main objective is assembling the variance in these two parameters to the analytical models of pressure and pressure derivative considering different porous-media petrophysical properties, reservoir configurations, and hydraulic-fracture (HF) characteristics. The motivation is eliminating the long-run discretization treatment in the porous media required by applying analytical models to describe the variance in the previously discussed parameters with the distance between HFs. Several analytical models for pressure response were generated in this study for hydraulically fractured reservoirs with rectangular-shaped drainage areas. These models take into account the change in stimulated matrix permeability from the maximum value close to the HF face to the minimum value at the so-called no-flow boundary between fractures. They also consider the change in the matrix-block size, corresponding to the change in the induced-fracture density (number of fractures per foot of length), from the minimum value close to the fracture face to the maximum value at the no-flow boundary. Bivariate log-normal distribution was used to describe the change in the stimulated matrix permeability and matrix-block size. The formations of interest are composed of stimulated reservoir volume (SRV), where the matrix is stimulated by the fracturing process, and unstimulated reservoir volume (USRV), where the stimulation process does not affect the matrix. The outcomes of this study can be summarized as Generating new analytical models for pressure and pressure derivative in hydraulically fractured reservoirs that consider the change in stimulated matrix-block size and permeability using bivariate log-normal distribution Understanding the effect of using the probability-density function (PDF) of matrix-block size and permeability in the pressure distribution of different reservoirs Observing the new multilinear-flow regime that develops at intermediate production time and represents several simultaneous linear-flow regimes inside HFs, SRV, and USRV Developing analytical models for the new multilinear-flow regime Studying the effects of petrophysical properties of HFs, induced fractures, and matrix as well as reservoir size and configuration on pressure behavior The most interesting points in this study are The applicability of bivariate log-normal distribution for describing the variance and nonuniform distribution of matrix-block size and permeability. The large variance in the matrix-block size and permeability causes significant decrease in wellbore-pressure drop. Small value of standard deviation of matrix-block size and permeability indicates the possibilities for significant decrease in wellbore pressure drop. The means of matrix-block size and permeability may not have significant effects on reservoir-pressure distribution. The new multilinear-flow regime is characterized by a one-eighth slope on the pressure-derivative curve and is seen always after HF linear flow and before boundary-dominated flow regime. Multilinear-flow regime develops to bilinear-flow regime with a one-quarter slope for uniform distribution of equal matrix-block size and permeability.

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