Open Access

ARTICLE

Numerical Simulation of Complex Hydraulic Fracture Propagation in Naturally Fractured Tight Sandstone Reservoirs

Zhengrong Chen^1,2,*, Yu Qi², Maojun Fang², Bo Wang², Xin Xie², Le Sun², Wei Liu¹
1 China University of Petrleum (Beijing), College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, 102249, China
2 CNOOC Research Institute Co, Ltd., Beijing, 100028, China
* Corresponding Author: Zhengrong Chen. Email:
(This article belongs to the Special Issue: Integrated Geology-Engineering Simulation and Optimizationfor Unconventional Oil and Gas Reservoirs)

Energy Engineering https://doi.org/10.32604/ee.2025.064770

Received 23 February 2025; Accepted 20 June 2025; Published online 19 January 2026

Abstract

The migration, accumulation, and high yield of hydrocarbons in tight sandstone reservoirs are closely tied to the natural fracture systems within the reservoirs. Large-scale fracture networks not only enhance reservoir seepage capacity but also influence effective productivity and subsequent fracturing reconstruction. Given the diverse mechanical behaviors, such as migration, penetration, or fracture arrest, traditional assumptions about fracture interaction criteria fail to address this complexity. To resolve these issues, a global cohesive element method is proposed to model random natural fractures. This approach verifies intersection models based on real-time stress conditions rather than pre-set criteria, enabling better characterization of interactions between hydraulic and natural fractures. Research has shown that the elastic modulus, horizontal stress difference, and fracturing fluid pumping rate significantly promote the expansion of hydraulic fractures. The use of low viscosity fracturing fluid can observe a decrease in the width of fractures near the wellbore, which may cause fractures to deflect when interacting with natural fractures. However, simulations under these conditions did not form a “complex network of fractures”. It is worth noting that when the local stress difference is zero, the result is close to the formation of this network. Excessive spacing will reduce the interaction between fractures, resulting in a decrease in the total length of fractures. By comprehensively analyzing these factors, an optimal combination can be identified, increasing the likelihood of achieving a “complex fracture network”. This paper thoroughly investigates hydraulic fracture propagation in naturally fractured reservoirs under various conditions, offering insights for developing efficient fracturing methods.

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Keywords

Natural fracture; hydraulic fracture; complex fracture network; global cohesive element method

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