Open Access

ARTICLE

Hydraulic Fracture Conductivity Loss Mechanisms for Unconsolidated Sands Considering Fine Migrations and Proppant Embedments

Xian Shi^1,2,*, Botao Zhang^1,2, Weidong Zhang^1,2, Zenghua Ma³, Bo Zhang³, Ahmad Ramezanzadeh⁴, Bin Li⁵, Jian Mao⁵
1 State Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao, 266580, China
2 College of Petroleum Engineering, China University of Petroleum (East China), Qingdao, 266580, China
3 Oilfield Production Research Institute of COSL, Tianjin, 300452, China
4 Faculty of Mining, Petroleum & Geophysics Engineering, Shahrood University of Technology, Shahrood, 3619995161, lran
5 Directional Well Technical Service Company of XDEC (Drilling Measurement and Control Research Center), Urumqi, 830063, China
* Corresponding Author: Xian Shi. Email:

Energy Engineering https://doi.org/10.32604/ee.2025.073586

Received 21 September 2025; Accepted 12 November 2025; Published online 05 December 2025

Abstract

To investigate the mechanism governing the continuous decline in fracture conductivity of unconsolidated sandstone reservoirs post-hydraulic fracturing, this study centers on the synergistic effects of two key mechanisms—particle migration and proppant embedment. Through the integration of laboratory experiments and computational fluid dynamics-discrete element method (CFD-DEM) coupled numerical simulations, this study systematically examines the influence patterns of varying closure pressures, particle concentrations, fluid properties, and proppant parameters on fracture conductivity. The experimental results demonstrate that particle migration induces pore blockage within the proppant packing layer. When the fines mass concentration reaches 10%, fracture conductivity is almost entirely lost. Furthermore, the embedment depth of proppants increases with increasing closure pressure, and the embedment depth of proppants with a high elastic modulus is twice that of those with a low elastic modulus under a closure pressure of 35 MPa. Numerical simulations further reveal that fluid viscosity and displacement rate significantly govern the migration range and blockage pattern of particles. When the fluid viscosity is 10 mPa·s and the displacement rate is 200 mL/min, a balance between fracturing construction efficiency and fracture damage can be attained. The coupled model developed in this study accurately predicts the attenuation law of fracture conductivity under the synergistic effect of these two mechanisms. This model addresses the gap in understanding the coupled effects of mechanisms in unconsolidated sandstone reservoirs in existing literature and provides a theoretical foundation and engineering guidance for parameter optimization in the fracturing design of such reservoirs.

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Keywords

Fine migration; proppant embedment; fracture conductivity loss; unconsolidated sandstone reservoir

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