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Article

A Fractal Permeability Model of Tight Oil Reservoirs Considering the Effects of Multiple Factors

1
College of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China
2
Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum (East China), Ministry of Education, Qingdao 266580, China
3
Exploration and Development Research Institute, Shengli Oilfield Company, SINOPEC, Dongying 257015, China
*
Author to whom correspondence should be addressed.
Academic Editor: Boming Yu
Fractal Fract. 2022, 6(3), 153; https://doi.org/10.3390/fractalfract6030153
Received: 16 January 2022 / Revised: 10 February 2022 / Accepted: 22 February 2022 / Published: 11 March 2022
(This article belongs to the Special Issue Applications of Fractal Geometry Theory in Porous Media)
The prediction of permeability and the evaluation of tight oil reservoirs are very important to extract tight oil resources. Tight oil reservoirs contain enormous micro/nanopores, in which the fluid flow exhibits micro/nanoscale flow and has a slip length. Furthermore, the porous size distribution (PSD), stress sensitivity, irreducible water, and pore wall effect must also be taken into consideration when conducting the prediction and evaluation of tight oil permeability. Currently, few studies on the permeability model of tight oil reservoirs have simultaneously taken the above factors into consideration, resulting in low reliability of the published models. To fill this gap, a fractal permeability model of tight oil reservoirs based on fractal geometry theory, the Hagen–Poiseuille equation (H–P equation), and Darcy’s formula is proposed. Many factors, including the slip length, PSD, stress sensitivity, irreducible water, and pore wall effect, were coupled into the proposed model, which was verified through comparison with published experiments and models, and a sensitivity analysis is presented. From the work, it can be concluded that a decrease in the porous fractal dimension indicates an increase in the number of small pores, thus decreasing the permeability. Similarly, a large tortuous fractal dimension represents a complex flow channel, which results in a decrease in permeability. A decrease in irreducible water or an increase in slip length results in an increase in flow space, which increases permeability. The permeability decreases with an increase in effective stress; moreover, when the mechanical properties of rock (elastic modulus and Poisson’s ratio) increase, the decreasing rate of permeability with effective stress is reduced. View Full-Text
Keywords: permeability model; fractal theory; slip length; irreducible water; stress sensitivity; tight reservoir permeability model; fractal theory; slip length; irreducible water; stress sensitivity; tight reservoir
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MDPI and ACS Style

Wu, Z.; Cui, C.; Yang, Y.; Zhang, C.; Wang, J.; Cai, X. A Fractal Permeability Model of Tight Oil Reservoirs Considering the Effects of Multiple Factors. Fractal Fract. 2022, 6, 153. https://doi.org/10.3390/fractalfract6030153

AMA Style

Wu Z, Cui C, Yang Y, Zhang C, Wang J, Cai X. A Fractal Permeability Model of Tight Oil Reservoirs Considering the Effects of Multiple Factors. Fractal and Fractional. 2022; 6(3):153. https://doi.org/10.3390/fractalfract6030153

Chicago/Turabian Style

Wu, Zhongwei, Chuanzhi Cui, Yong Yang, Chuanbao Zhang, Jian Wang, and Xin Cai. 2022. "A Fractal Permeability Model of Tight Oil Reservoirs Considering the Effects of Multiple Factors" Fractal and Fractional 6, no. 3: 153. https://doi.org/10.3390/fractalfract6030153

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