Pore-Scale Experimental Investigation of the Residual Oil Formation in Carbonate Sample from the Middle East

Liu, Yongjie; Pi, Jian; Tong, Kaijun

doi:10.3390/pr11082289

Cited by 3 publications

References 32 publications

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Quantitative Characterization Method for Remaining Oil Distribution in Heavy Oil After Multi-Cycle Steam Huff and Puff Based on CT Scanning

Zheng,

Hou,

2024

Day 3 Wed, April 24, 2024

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Steam huff and puff is an important development method for heavy oil reservoirs. An accurate description of the remaining oil distribution after steam huff and puff is crucial for reservoir development. In this study, an experimental setup is used to simulate the multi-cycle steam huff and puff process more realistically. The occurrence state and distribution of remaining oil after different cycles of steam huff and puff are investigated. CT scanning is conducted after the first, fourth, and seventh cycles. Based on characterization parameters such as shape factor, contact ratio, and Euler number, the microscopic remaining oil is classified into network remaining oil, cluster remaining oil, film remaining oil, and isolated droplet remaining oil. The volume proportions of different types of remaining oil of different cycles of steam huff and puff are compared. The viscosity of the heavy oil used in the experiment is 560 mPa·s (25°C). The results indicate that as the number of cycles increases, the volume proportion of network remaining oil decreases, while the volume proportions of cluster, film, and isolated droplet remaining oil increase. From the first to the seventh cycle, the volume proportion of network remaining oil decreases by 34.11%, while the volume proportions of cluster, film, and isolated droplet remaining oil increase by 12.87%, 14.48%, and 6.76% respectively. The oil phase transitions from a continuous distribution to a discontinuous distribution. With an increase in the number of cycles, the water saturation increases, and the distribution of remaining oil becomes more dispersed. The results of this research guide the subsequent production of heavy oil.

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Quantitative Characterization Method for Remaining Oil Distribution in Heavy Oil After Multi-Cycle Steam Huff and Puff Based on CT Scanning

Zheng,

Hou,

2024

Day 3 Wed, April 24, 2024

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Estimating Residual Oil Saturation in Carbonate Rocks: A Combined Approach of Direct Simulation and Data-Driven Analysis

Rizk,

Tembely,

AlAmeri

et al. 2024

SPE Journal

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Summary Estimating residual oil saturation (Sor) post-waterflooding is critical for selecting enhanced oil recovery strategies, further field development, and production prediction. We established a data-driven workflow for evaluating Sor in carbonate samples using microcomputed tomography (μ-CT) images. The two-phase lattice Boltzmann method (LBM) facilitated the flooding simulation on 7,192 μ-CT samples. Petrophysical parameters (features) obtained from pore network modeling (PNM) and feature extraction from μ-CT images were utilized to develop tree-based regression models for predicting Sor. Petrophysical features include porosity, absolute permeability, initial water saturation (Swi), pore size distribution (PSD), throat size distributions (TSD), and surface roughness (Ra) distribution. Our method excludes vugs and macro/nanoporosity, which complicates multiscale simulations—a recognized challenge in modeling carbonate rocks. When subdividing the image into numerous subvolumes, certain subvolumes may contain vugs exceeding the dimensions of the subvolume itself. Hence, these vugs were omitted given the entirety of the image constitutes a vug. Conversely, vugs with dimensions smaller than those of the subvolume were not excluded. Despite scale limitations, our subsampling, supported by substantial data volume, ensures our microscale porosity predictions are statistically reliable, setting a foundation for future studies on vugs and nanoporosity’s impact on simulations. The results show that features obtained from dry-sample images can be used for data-driven Sor prediction. We tested three regression models: gradient boosting (GB), random forest (RF), and extreme gradient boosting (XGBoost). Among these, the optimized GB-based model demonstrated the highest predictive capacity for Sor prediction [R2 = 0.87, mean absolute error (MAE) = 1.87%, mean squared error (MSE) = 0.12%]. Increasing the data set size is anticipated to enhance the models’ ability to capture a broader spectrum of rock properties, thereby improving their prediction accuracy. The proposed predictive modeling framework for estimating Sor in heterogeneous carbonate formations aims to supplement conventional coreflooding tests or serve as a tool for rapid Sor evaluation of the reservoir.

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Study on the Mobilization Mechanisms of Microscopic Residual Oil in High-Water-Cut Sandstone Reservoirs

Sun,

Wang,

Zhao

et al. 2024

Processes

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As mature oilfields enter the high-water-cut development stage, significant amounts of residual oil remain trapped underground. To enhance the effectiveness of tertiary oil recovery, it is crucial to understand the distribution and mobilization patterns of this residual oil. In this study, polydimethylsiloxane (PDMS) was used to create a microscopic oil displacement model, which was observed and recorded using a stereomicroscope. The experimental images were extracted, analyzed, and quantitatively evaluated, categorizing the microscopic residual oil in the high-water-cut sandstone reservoirs of Dagang Oilfield into cluster-like, pore surface film-like, corner-like, and slit-like types. Polymer–surfactant composite flooding (abbreviated as SP flooding) effectively mobilized 47.16% of cluster-like residual oil and 43.74% of pore surface film-like residual oil, with some mobilization of corner-like and slit-like residual oil as well. Building on SP flooding, dual-mobility flooding further increased the mobilization of cluster-like residual oil by 12.37% and pore surface film-like residual oil by 3.52%. With the same slug size, dual-mobility flooding can reduce development costs by 16.43%. Overall, dual-mobility flooding offers better development prospects.

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Pore-Scale Experimental Investigation of the Residual Oil Formation in Carbonate Sample from the Middle East

Cited by 3 publications

References 32 publications

Quantitative Characterization Method for Remaining Oil Distribution in Heavy Oil After Multi-Cycle Steam Huff and Puff Based on CT Scanning

Quantitative Characterization Method for Remaining Oil Distribution in Heavy Oil After Multi-Cycle Steam Huff and Puff Based on CT Scanning

Estimating Residual Oil Saturation in Carbonate Rocks: A Combined Approach of Direct Simulation and Data-Driven Analysis

Study on the Mobilization Mechanisms of Microscopic Residual Oil in High-Water-Cut Sandstone Reservoirs

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