Study on the Flow Mechanism of Shale Oil with Different Injection Media

Chinese shale oil has high recoverable resources and great development potential. However, due to the limitation of development technology, the recovery rate of shale oil is not high. In this paper, the effects of different injection media on the development of shale oil reservoirs in Dongying forma...

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Main Authors: Lanlan Yao, Zhengming Yang, Haibo Li, Bo Cai, Chunming He, Debin Xia
Format: Article
Language:English
Published: Wiley 2021-01-01
Series:Advances in Civil Engineering
Online Access:http://dx.doi.org/10.1155/2021/6668563
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author Lanlan Yao
Zhengming Yang
Haibo Li
Bo Cai
Chunming He
Debin Xia
author_facet Lanlan Yao
Zhengming Yang
Haibo Li
Bo Cai
Chunming He
Debin Xia
author_sort Lanlan Yao
collection DOAJ
description Chinese shale oil has high recoverable resources and great development potential. However, due to the limitation of development technology, the recovery rate of shale oil is not high. In this paper, the effects of different injection media on the development of shale oil reservoirs in Dongying formation, Qikou depression, Huanghua depression, and Bohai bay basin, were studied by means of imbibition and nitrogen flooding. Combining nuclear magnetic resonance (NMR) technology with imbibition and gas displacement experiments, the mechanism of shale injected formation water, active water (surfactant), and nitrogen was reproduced. The displacement process of crude oil under different injection media and injection conditions was truly demonstrated, and the relationship between different development methods and the pore boundaries used was clarified. A theoretical basis for the effective development of shale oil was provided. At the same time, Changqing tight oil cores with similar permeability to Dagang shale oil cores were selected for comparison. The results showed that, as the imbibition time of shale samples increased, the imbibition efficiency increased. Pores with T2 < 10 ms contributed the most to imbibition efficiency, with an average contribution greater than 90%. 10 ms < T2 < 100 ms and more than 100 ms pores contributed less to imbibition efficiency. Active water can change the wettability of shale, increase its hydrophilicity, and improve the efficiency of imbibition. The imbibition recovery ratio of injected active water was 17.56% higher than that of injected formation water. Compared with tight sandstone with similar permeability, the imbibition efficiency of shale was lower. As the nitrogen displacement pressure increased, the oil displacement efficiency also increased. The higher the shale permeability was, the greater the displacement efficiency would be. T2 > 100 ms pore throat of shale contributed to the main oil displacement efficiency, with an average oil displacement efficiency contribution of 63.16%. And the relaxation interval 10 < T2 < 100 ms pore throat displacement efficiency contributed to 28.27%. T2 < 10 ms pore throat contributed the least to the oil displacement efficiency, with an average oil displacement efficiency contribution of 8.58%. Compared with tight sandstone with similar permeability, shale had lower oil displacement efficiency. The findings of this study can help for better understanding of the influence of different injection media on shale oil recovery effect.
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spelling doaj-art-8016f59b4b3240fea817828301ccc8962025-08-20T03:35:14ZengWileyAdvances in Civil Engineering1687-80861687-80942021-01-01202110.1155/2021/66685636668563Study on the Flow Mechanism of Shale Oil with Different Injection MediaLanlan Yao0Zhengming Yang1Haibo Li2Bo Cai3Chunming He4Debin Xia5College of Engineering Science, University of Chinese Academy of Sciences, Beijing 101400, ChinaCollege of Engineering Science, University of Chinese Academy of Sciences, Beijing 101400, ChinaInstitute of Percolation and Fluid Mechanics, China Petroleum Exploration and Development Research Institute, Langfang 065007, ChinaFracture Acidification Center of China Petroleum Exploration and Development Research Institute, Langfang 065007, ChinaFracture Acidification Center of China Petroleum Exploration and Development Research Institute, Langfang 065007, ChinaCollege of Engineering Science, University of Chinese Academy of Sciences, Beijing 101400, ChinaChinese shale oil has high recoverable resources and great development potential. However, due to the limitation of development technology, the recovery rate of shale oil is not high. In this paper, the effects of different injection media on the development of shale oil reservoirs in Dongying formation, Qikou depression, Huanghua depression, and Bohai bay basin, were studied by means of imbibition and nitrogen flooding. Combining nuclear magnetic resonance (NMR) technology with imbibition and gas displacement experiments, the mechanism of shale injected formation water, active water (surfactant), and nitrogen was reproduced. The displacement process of crude oil under different injection media and injection conditions was truly demonstrated, and the relationship between different development methods and the pore boundaries used was clarified. A theoretical basis for the effective development of shale oil was provided. At the same time, Changqing tight oil cores with similar permeability to Dagang shale oil cores were selected for comparison. The results showed that, as the imbibition time of shale samples increased, the imbibition efficiency increased. Pores with T2 < 10 ms contributed the most to imbibition efficiency, with an average contribution greater than 90%. 10 ms < T2 < 100 ms and more than 100 ms pores contributed less to imbibition efficiency. Active water can change the wettability of shale, increase its hydrophilicity, and improve the efficiency of imbibition. The imbibition recovery ratio of injected active water was 17.56% higher than that of injected formation water. Compared with tight sandstone with similar permeability, the imbibition efficiency of shale was lower. As the nitrogen displacement pressure increased, the oil displacement efficiency also increased. The higher the shale permeability was, the greater the displacement efficiency would be. T2 > 100 ms pore throat of shale contributed to the main oil displacement efficiency, with an average oil displacement efficiency contribution of 63.16%. And the relaxation interval 10 < T2 < 100 ms pore throat displacement efficiency contributed to 28.27%. T2 < 10 ms pore throat contributed the least to the oil displacement efficiency, with an average oil displacement efficiency contribution of 8.58%. Compared with tight sandstone with similar permeability, shale had lower oil displacement efficiency. The findings of this study can help for better understanding of the influence of different injection media on shale oil recovery effect.http://dx.doi.org/10.1155/2021/6668563
spellingShingle Lanlan Yao
Zhengming Yang
Haibo Li
Bo Cai
Chunming He
Debin Xia
Study on the Flow Mechanism of Shale Oil with Different Injection Media
Advances in Civil Engineering
title Study on the Flow Mechanism of Shale Oil with Different Injection Media
title_full Study on the Flow Mechanism of Shale Oil with Different Injection Media
title_fullStr Study on the Flow Mechanism of Shale Oil with Different Injection Media
title_full_unstemmed Study on the Flow Mechanism of Shale Oil with Different Injection Media
title_short Study on the Flow Mechanism of Shale Oil with Different Injection Media
title_sort study on the flow mechanism of shale oil with different injection media
url http://dx.doi.org/10.1155/2021/6668563
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