Numerical modeling of molecular diffusion and convection effects during gas injection into naturally fractured oil reservoirs

IF 1.8 4区工程技术 Q4 ENERGY & FUELS

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles Pub Date : 2021-01-01 DOI:10.2516/ogst/2021065

Hossein Gholamian, M. Ehsani, M. Nikookar, A. Mohammadi

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Abstract

Gas injection into a naturally fractured oil reservoir keeps the reservoir pressure and increments the initial recovery from the reservoir. The main aim of this work was to develop a numerical model to calculate the mass transfer (molecular diffusion and convection) between a gas injected in the fracture and residual fluid (gas and oil) in a matrix block. The dual continuum model is applied to describe flow behaviour and fluid recovery in porous media. Finally, the model is validated by comparing the outcomes with the results of two experimental works available in the literature. The mathematical model results are in agreement with the laboratory data including recovery of each component, saturation profile, and the pressure gradient between matrix and fracture. Modeling results show that after 25 days of N2 injection, the lighter and heavier components (C1 and C5) are recovered about 51% and 39%, respectively. These amounts for CO2 injection are 49% and 27%. It is found that the convection mechanism has a great effect on preventing the pressure drop of the reservoir during injection operations. In the nitrogen injection, without considering the convection, after 30 days, the matrix pressure reaches 1320 Psi from 1479 Psi but after 30 days, considering the convection, the pressure reaches 1473 Psi from 1479 Psi.

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天然裂缝性油藏注气过程中分子扩散和对流效应的数值模拟

对天然裂缝油藏进行注气可以保持油藏压力，提高油藏的初始采收率。这项工作的主要目的是建立一个数值模型来计算注入裂缝中的气体与基质块中的残余流体(气和油)之间的传质(分子扩散和对流)。采用双连续介质模型来描述多孔介质的流动特性和流体采收率。最后，通过与文献中已有的两项实验结果进行比较，对模型进行了验证。数学模型的结果与实验室数据吻合，包括各组分的采收率、饱和度曲线以及基质与裂缝之间的压力梯度。模拟结果表明，N2注入25天后，较轻组分(C1)和较重组分(C5)的回收率分别约为51%和39%。二氧化碳注入量分别为49%和27%。研究发现，对流机制对防止注油过程中储层压降有很大的作用。注氮时，不考虑对流，30天后，基质压力从1479 Psi达到1320 Psi, 30天后，考虑对流，压力从1479 Psi达到1473 Psi。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 工程技术-工程：化工

CiteScore

2.70

自引率

0.00%

发文量

审稿时长

2.7 months

期刊介绍： OGST - Revue d''IFP Energies nouvelles is a journal concerning all disciplines and fields relevant to exploration, production, refining, petrochemicals, and the use and economics of petroleum, natural gas, and other sources of energy, in particular alternative energies with in view of the energy transition. OGST - Revue d''IFP Energies nouvelles has an Editorial Committee made up of 15 leading European personalities from universities and from industry, and is indexed in the major international bibliographical databases. The journal publishes review articles, in English or in French, and topical issues, giving an overview of the contributions of complementary disciplines in tackling contemporary problems. Each article includes a detailed abstract in English. However, a French translation of the summaries can be provided to readers on request. Summaries of all papers published in the revue from 1974 can be consulted on this site. Over 1 000 papers that have been published since 1997 are freely available in full text form (as pdf files). Currently, over 10 000 downloads are recorded per month. Researchers in the above fields are invited to submit an article. Rigorous selection of the articles is ensured by a review process that involves IFPEN and external experts as well as the members of the editorial committee. It is preferable to submit the articles in English, either as independent papers or in association with one of the upcoming topical issues.