Hydraulic fracture development in conglomerate reservoirs simulated using combined finite-discrete element method
Hydraulic fracture development in conglomerate reservoirs simulated using combined finite-discrete element method
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DOI：
10.1016/j.engfracmech.2023.109063
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发表时间：
2023-01
影响因子：
5.4
通讯作者：
M. Sharafisafa;A. Sato;Z. Aliabadian
中科院分区：
文献类型：
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作者：
M. Sharafisafa;A. Sato;Z. Aliabadian
众所周知，水力压裂是通过产生水力裂缝（HF）来提高裂缝性储层渗透性的最有效的增产措施。高频流体注入的效率很大程度上取决于预先存在的不连续性或不均匀性来源。在高频操作设计中需要考虑这些特征。在这些特征中，基质中含有块体的砾岩储层尽管存在于深层岩石中，但在很大程度上被忽视。本研究重点关注此类地基中的高频发展，并利用有限离散元组合方法（FDEM）模拟其流体力学行为，该方法完全能够模拟非均质岩石中的高频传播。首先，根据现有分析解决方案和实验流体注入验证 FDEM 的功能，然后用于模拟 HF 开发。在砾岩模型中，模拟了三个具有低到高强度特性的区块，以评估区块强度对 HF 开发模式的影响。研究了各种控制参数，包括原位应力、流量、流体运动粘度、定向高频 (DHF)、块体和基体之间的界面特性及其对高频路径的影响。结果表明矩阵中的块对 HF 模式有显着影响。高频与不同形状和尺寸的块体的相互作用被证明是复杂的，并且根据对结果的仔细观察，识别出六种块体的相互作用类型。研究还发现，要在此类土壤中成功注入氢氟酸，低流速和低粘度流体可能是一个很好的策略。此外，研究还表明，块体的强度会显着影响失效类型（拉伸或剪切）和破坏压力。
Hydraulic fracturing is known to be the most effective stimulation to enhance fractured reservoir permeability by creating hydraulic fractures (HFs). The efficiency of a HF fluid injection largely depends on the pre-existing discontinuities or sources of heterogeneities. These features need to be considered in a HF operation design. Amongst these features, conglomerate reservoirs containing blocks in a matrix are largely ignored despite their presence in deep rocks. This study focuses on the HF development in such grounds and simulates their hydro-mechanical behaviour by using the combined finite-discrete element method (FDEM), which is fully capable of modelling HF propagation in heterogeneous rocks. First, the capabilities of the FDEM are verified against existing analytical solutions and experimental fluid injection and then employed to model HF development. In the conglomerate models, three blocks with low to high strength properties are simulated to assess the effect of block strength on the HF development pattern. Various controlling parameters, including in-situ stresses, flow rate, fluid kinematic viscosity, directional HF (DHF), properties of the interface between the blocks and matrix, and their effects on the HF path are investigated. The results show a significant influence of blocks in a matrix on the HF pattern. The HF interaction with the blocks of different shapes and dimensions is shown to be complex, and six interaction types for the blocks are identified based on the close observation of the results. It is also found that to achieve a successful HF injection in such grounds, a low flow rate with a low viscous fluid can be a good strategy. Also, it is shown that the blocks' strength significantly affects the type of failure (tensile or shear) and the breakdown pressure.