Inter-cluster interference in hybrid fracturing of tight oil reservoirs in Ordos Basin

Relevant research has been conducted to the effect of fracturing displacement in tight oil reservoirs in Ordos Basin and the inter-cluster stress interference on creation of complex fracture network. The discrete fracture network model and finite element software were used, and two wells were selected for comparison on fracturing design parameters, production and the results of micro-seismic monitoring. The research findings show that, large displacement and large liquid volume are the basis to guarantee creation of complex fracture network. There exists a critical pumping rate to create complex fracture network under certain formation conditions and fracturing parameters. In case of multi-cluster fracturing, the non-synchronous cracking of major fractures will lead to non-synchronous extension of major fractures. The firstly extended major fractures may suppress the extension or even initiation of the surrounding major fractures, but around the lately extended major fractures may occur shear-induced secondary fractures, which is favorable for creation of complex fracture network. Therefore, in hybrid fracturing design, a fracturing displacement which is larger than the critical pumping rate helps increase the area of stimulated reservoir and increase the oil well production, while the number of major fractures initiated and extended during multi-cluster fracturing may be less than the designed cluster quantity.