Dynamic fracture propagation mechanism and applicationin tight oil reservoir

被引：0
|
作者：
Di S. [1 ]
Cheng S. [1 ]
Bai W. [1 ]
Wei C. [1 ]
Wang Y. [1 ]
Qin J. [2 ]
机构：
[1] MOE Key Laboratory of Petroleum Engineering, China University of Petroleum (Beijing), Beijing
[2] State Key Laboratory of Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu
来源：
Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics | 2021年 / 53卷 / 08期
关键词：
Fracture propagation; Fracture tip stress; Linear displacement; Reverse imbibition; Tight oil reservoir; Water-injection huff and puff;
D O I：
10.6052/0459-1879-21-154
中图分类号：
学科分类号：
摘要：
Tight oil reservoirs have achieved certain oil increase effect by supplementing formation energy with water-injection huff and puff. However, formation pressure and production decrease rapidly after multiple rounds of water injection. In order to improve the oil enhancement effect of tight oil reservoirs, changing the development method quickly became hotspot research. This paper analysis the stress field distribution near the tip of type I fracture considered the complex fracture morphology of tight oil reservoirs based on Irwin theory and elastic mechanics. A multi-fracture cross-fracture propagation model is established based on seepage mechanics, fractured tight reservoir characteristics and dynamic fracture seepage characteristics. The fracture propagation length is obtained based on the fracture propagation mechanism and the energy conservation principle. It is proposed to turn water-injection huff and puff into unstable pulse water injection according to the principle of reverse imbibition in tight oil reservoirs. Comparative analysis of two energy supplementary generation methods, water-injection huff and puff and pulse water injection, predicting cumulative oil production, pressure and remaining oil distribution in 10 years. The results show that the net internal pressure of the fracture increases with the increase of water injection, and the stress field intensity factor also increases. When the stress field intensity factor reaches the fracture toughness, it will expand at the fracture tip. The expanded and extended natural fractures communicate with each other, presenting irregular and complex fracture networks. Reverse imbibition mainly occurs in the complex fracture networks. Pulse water injection has a high cumulative oil production, a wide area of water injection and strong reverse imbibition. The findings of this study can help for better understanding of the transformation of water-injection huff and puff into pulsed water injection from horizontal wells in fractured tight oil reservoirs. It can give full play to the effects of reverse imbibition and linear displacement. This research provides guidance for it can achieve the purpose of effective oil displacement of the dynamic fracture network. © 2021, Chinese Journal of Theoretical and Applied Mechanics Press. All right reserved.
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页码：2141 / 2155
页数：14
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