Numerical simulation of acidizing in fractured carbonate rocks considering temperature effects

doi:10.3969/j.issn.1006-6535.2025.04.018

Abstract

Abstract: To address the unclear mechanism of wormhole propagation during acidizing in deep fractured carbonate rocks,an MFCAC mathematical model coupling seepage field,chemical field,and temperature field for multi-mineral component acidizing was established based on a dual-scale continuum model and discrete fracture treatment method.The mechanism of wormhole propagation and acid-etching characteristics in fractured reservoirs considering temperature effects were analyzed,and the influences of the initial content ratio of CaMg(CO₃)₂ to CaCO₃,acid temperature,and reaction exotherm on wormhole propagation were studied.The study shows that the propagation direction of the main wormhole is mainly dominated by the control domain of nearby fractures;temperature effects increase the acid-rock reaction rate but decrease the H⁺ mass transfer rate,resulting in fewer natural fractures connected by the main wormhole;the increased H⁺ diffusion rate caused by temperature effects makes acid easier to diffuse into pores in all directions,leading to more complex wormhole morphology;the pore volume to breakthrough (PVBT) first decreases and then increases with increasing initial CaMg(CO₃)₂ content;when the initial content ratio of CaMg(CO₃)₂ to CaCO₃ is 1.5,the corresponding PVBT is the smallest;PVBT increases with increasing acid temperature;compared to ignoring reaction exotherm,considering reaction exotherm results in a smaller PVBT.This research provides a theoretical basis for the precise control of dynamic wormhole propagation and optimization of operational parameters during acidizing operations in deep fractured carbonate reservoirs.

Key words: wormhole propagation, content ratio, pore volume to breakthrough (PVBT), acid temperature, reaction exotherm

CLC Number:

TE348

YANG Junchao, CHENG Yuanfang, HAN Zhongying, HAN Songcai, YAN Chuanliang, ZHAO Zhuyu, SUN Bo. Numerical simulation of acidizing in fractured carbonate rocks considering temperature effects[J]. Special Oil & Gas Reservoirs, 2025, 32(4): 149-157.

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