Laboratory Experiments Contrasting Growth of Uniformly and Nonuniformly Spaced Hydraulic Fractures
Laboratory Experiments Contrasting Growth of Uniformly and Nonuniformly Spaced Hydraulic Fractures
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DOI：
10.1029/2020jb020107
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发表时间：
2021-01-01
影响因子：
3.9
通讯作者：
Bunger, Andrew P.
中科院分区：
文献类型：
--
作者：
Gunaydin, Delal;Peirce, Anthony P.;Bunger, Andrew P.
相邻生长的水力裂缝相互作用，竞争注入井筒的流体，导致一些裂缝占优势，另一些裂缝被抑制。这一现象在石油工业的水平井增产中普遍存在，也可能与多个横向传播的岩浆岩墙群的就位有关。出于验证力学模型的需要，本文主要针对多个同时发育的水力裂缝的行为进行了实验室实验及其与模拟结果的比较。通过将葡萄糖或甘油为基础的溶液注入透明的(聚甲基丙烯酸甲酯)块，实验需要均匀和非均匀间隔的水力裂缝的扩展。然后将观察到的裂缝增长与完全耦合的平行平面3D水力压裂模拟器的预测进行比较。实验和模拟结果证实了裂缝间距均匀时对内部裂缝的抑制作用。对于某些不均匀的间距，实验和模拟都显示了对中心裂缝的抑制。具体地说，从注射开始，5裂缝阵列中的中间裂缝与外部裂缝的生长几乎相等。此外，随着一些延迟，用均匀间隔构型抑制的另外两个骨折生长，并最终达到超过阵列中其他三个骨折的速度。因此，这些实验首次提供了模型预测行为的实验室证据，在这种行为中，某些不均匀的裂缝间距会导致阵列内所有裂缝的生长急剧增加。
Hydraulic fractures that grow in close proximity to one an other interact and compete for fluid that is injected to the wellbore, leading to dominance of some fractures and suppression of others. This phenomenon is ubiquitously encountered in stimulation of horizontal wells in the petroleum industry and it also bears possible relevance to emplacement of multiple laterally propagating swarms of magma-driven dykes. Motivated by a need to validate mechanical models, this paper focuses on laboratory experiments and their comparison to simulation results for the behavior of multiple, simultaneously growing hydraulic fractures. The experiments entail the propagation of both uniformly and nonuniformly spaced hydraulic fractures by injection of glucose or glycerin-based solutions into transparent (polymethyl methacrylate) blocks. Observed fracture growth is then compared to predictions of a fully coupled, parallel-planar 3D hydraulic fracturing simulator. Results from experiments and simulations confirm the suppression of inner fractures when the spacing between the fractures is uniform. For certain non-uniform spacing, both experiments and simulations show mitigated suppression of the central fractures. Specifically, the middle fracture in a 5-fracture array grows nearly equally to the outer fractures from the beginning of injection. Furthermore, with some delay, the other two fractures that are suppressed with uniformly spaced configurations grow, and eventually achieve a velocity exceeding the other three fractures in the array. Hence, these experiments give the first laboratory evidence of a model-predicted behavior wherein certain nonuniform fracture spacings result in drastic increases in the growth of all fractures within the array.