Large physical simulation test of cavitation reservoir stimulation

Abstract

The cavitation reservoir stimulation technology is a kind of reservoir stimulation technology proposed in recent years for refined stimulation of reservoirs near the wellbore wall. It has the characteristics of less equipment required, simple process, clean and environmentally friendly, and low operating cost, and can effectively improve the heterogeneity of reservoir. However, the understanding of this technology is insufficient to provide technical support for its engineering application due to the lack of experimental research foundation. Therefore, this study developed a large-scale test device, conducted a physical model test of cavitation reservoir stimulation, and revealed the mechanism and treatment effect of cavitation reservoir stimulation technology. In accordance with the analysis of vibration monitoring parameters, the cavitation effect can produce pulse vibration in the wellbore when the pump pressure≥6 MPa. In accordance with the analysis of pressure monitoring data, the pressure in the middle part of wellbore (10–30 D) is the highest, which is about 1300 kPa, whereas the pressure in the outlet area of cavitation device is the lowest, which can produce a “negative pressure effect” in the simulated wellbore. In accordance with the physical parameters of the rock samples before and after the experiment, the average compressive strength and elastic modulus of rock samples are reduced by 75% and 80% respectively, by the cavitation reservoir stimulation, the impurities in rock voids are effectively removed, and the porosity and permeability are increased by about 20% and 200% respectively, to achieve a good reservoir stimulation effect. The research results of this study will provide key technical support for the theoretical research and engineering application of cavitation reservoir stimulation.