Application of Pulse Hydraulic Fracturing for Tight Oil Reservoir with low frequency

Abstract

Abstract A promising stimulation technique to increase effective permeability is pulse hydraulic fracturing. A particular frequency of fracturing fluid injection causes rock failure and may lead to the formation of a complex fracture network due to cyclic loading. When compared to hydraulic fracturing, pulse hydraulic fracturing has produced better fluid extraction results. Although it would be extremely difficult given the various downhole operating conditions, adopting pulse hydraulic fracturing technology to enhance the fracturing effect of tight reservoirs is an issue that merits consideration. This study developed an experimental setup for triaxial rock that was subjected to cyclic damage at various frequencies and amplitudes. Moreover, this study developed an experimental setup for triaxial rock that was subjected to cyclic damage with low amplitudes. The pulse frequency can be adjusted from 0 to 50Hz, and the pulse pressure amplitude varies from 1MPa to 5MPa. The comparison of rock failure studies under various cyclic loads as well as the impact of various hydraulic pulse parameters and rock characteristics on rock damage were done. According to experimental findings, load amplitude affects rock compressive strength and breakdown pressure differently depending on the rock's qualities. The impact on rock's compressive and tensile strength grows as pulse pressure amplitude increases. The influence on rock fracture pressure increases initially with an increase in hydraulic pulse processing time before tending to stabilize. The compressive and tensile strength of rock samples were reduced by 15% and 12%, respectively, while the drop rate of the breakdown pressure was roughly 18%. Hydraulic pulse has the largest impact on tight reservoirs collected from various levels of the Ordos Basin in China. High fluid pressure is advantageous for quick fracture initiation and propagation, but low fluid pressure might cause the fracture to originate and propagate with a protracted pulse fracturing time. A downhole hydraulic pulse generator is conceived and created based on the experimental findings that the preferred hydraulic pulse frequency is between 18 and 20 Hz. The results of the experiment demonstrate that the generator's performance satisfies the design specifications. Field trials of pulse hydraulic fracturing with low amplitude were carried out in 2 oil wells in a tight reservoir. The actual application demonstrates that the average breakdown pressure was reduced obviously and the average daily production per well increased significantly compared to adjacent wells with similar geological and reservoir conditions.