中国石油大学Jun Yao研究小组经过不懈努力，对超临界CO₂压裂中支撑剂与流体相非均匀温度场进行了数值研究。该项研究成果发表在2023年12月13日出版的《颗粒学报》上。

该研究提出了一种耦合计算流体动力学离散元方法(CFD-DEM)和传热的模型，以研究支撑剂床层形状以及支撑剂-壁、支撑剂-流体和流体-壁的传热对流体和支撑剂温度场的影响。通过计算Sc-CO₂的体积平均密度来评估不同温度条件下Sc-CO₂的体积膨胀。研究人员仔细分析了支撑剂尺寸、形状、导热系数、浓度、温差和注入速度等因素，以阐明它们的影响。研究结果阐明了其在流体温度场中存在四个不同的带。

在不同的条件下，每个区域都表现出不同程度的温度变化，并随着支撑剂层的发展发生动态变化。C区和D区流体壁传热和流体温度受注入流体速度(控制加热持续时间)、流体与地层温差(影响热流通量大小)、支撑剂床层形状(控制有效加热面积)的影响显著。

此外，支撑剂壁和支撑剂流体的传热决定了B区支撑剂层和流体的温度，与支撑剂导热系数、支撑剂尺寸、注入速度和温差有很强的相关性。所提出的耦合模型为压裂液和支撑剂的温度分布和流动行为提供了有价值的见解。

据了解，超临界CO₂ (Sc-CO₂)压裂中温度分布的不均匀影响了Sc-CO₂的密度、粘度和体积膨胀或收缩速率，影响了支撑剂的运移。

附：英文原文

Title: Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical CO2 fracturing

Author: anonymous

Issue&Volume: 2023/12/13

Abstract: The non-uniform temperature distribution in supercritical CO2 (Sc-CO2) fracturing influences the density, viscosity, and volume expansion or shrinkage rate of Sc-CO2, impacting proppant migration. This study presents a coupled computational fluid dynamics-discrete element method (CFD-DEM) and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall, proppant-fluid, and fluid-wall on the fluid and proppant temperature fields. The Sc-CO2 volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-CO2 density. Several factors, including proppant size, shape, thermal conductivity, concentration, temperature difference, and injection velocity, are carefully analyzed to elucidate their impacts. The findings elucidate the existence of four distinct zones in the fluid temperature field. Each zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant bed. The fluid-wall heat transfer and the fluid temperatures in Zones C and D are significantly subject to the fluid injection velocity (governing the heating duration), the temperature difference between fluid and formation (impacting the magnitude of heat flux), and the proppant bed shape (controlling the effective heating area). Additionally, the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B, showing a strong correlation with proppant thermal conductivity, proppant size, injection velocity, and temperature difference. The proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

DOI: 10.1016/j.partic.2023.12.002

Source: https://www.sciencedirect.com/science/article/abs/pii/S167420012300319X