Effect of Multiple Flow Pulses on Hydraulic Fracture Network Propagation in Naturally Fractured Volcanic Rock

Energies

Xinfang Ma¹  Guangzhi Yang¹  Ning Li¹  Shicheng Zhang¹  Jia Wang²  Yushi Zou³ 

[1] College of Petroleum Engineering, China University of Petroleum–Beijing, Beijing 100083, China;Engineering Technology Research Institute of PetroChina Xinjiang Oilfield Company, Karamay 843000, Xinjiang, China;The Unconventional Oil and Gas Institute, China University of Petroleum–Beijing, Beijing 100083, China;

关键词: volcanic rock;    multiple flow pulses;    hydraulic fracture;    natural fracture;    fracture network;   

DOI  :  10.3390/en13030633

来源: DOAJ

【 摘 要 】

Exploring engineering methods for increasing fracture network complexity is important for the development of unconventional oil and gas reservoirs. In this study, we conducted a series of fracturing experiments on naturally fractured volcanic samples. An injection method, multiple flow pulses, is proposed to increase fracture complexity. The results show that fluid leaked into the natural fracture network (NFN) when the injection rate was low (0.2 mL/min); hydraulic-fracture-dominant fracture geometry was created with an injection rate of 2 and 5 mL/min. Under the 2 mL/min-injection scheme with 3 pulses, the injection pressure during the intermittent stage was low (<5 MPa), resulting in a limited increase in fracture complexity. When the number of the flow pulses increased to 5, the pressure drop rate in the fourth and fifth intermittent stage significantly increased, indicating an increase in the aperture of natural fractures (NFs) and in the fluid leak-off effect. Under the 5 mL/min injection scheme containing 5 pulses, besides the enhanced fluid leak-off, a sharp injection pressure drop was observed, indicating the activation of NFs. The complexity and the aperture of the ultimate fracture network further increased. The injection method, multiple flow pulses, can be used to create complex fracture networks effectively.

【 授权许可】

Unknown