Downhole Harmonic Vibration Oil-Displacement System: A New IOR Tool

Excessively large amplitude excitations resulting from earthquakes, explosions, or mechanically vibrated systems are found to generate macroscopic and microscopic mechanisms that have beneficial effects on the production of wellbores. A downhole harmonic vibration oil-displacement system (DHVOS) that generates a sudden large amplitude excitation to the liquid in the wellbore was developed by researchers at CNPC (China National Petroleum Company). Compared with other downhole artificial vibration systems, the DHVOS system is a heavy-duty unit that can provide long period operations and large amplitude excitations. This system has been implemented in CNPC's oil fields such as Liaohe, Huabei, Shengli and Zhongyuan. The DHVOS system provides a harmonic vibration frequency of 88 shocks per minute with each shock having 5-ton strength. More than 100 oil-producing wells have been stimulated with the downhole vibration system since 1997. The field results demonstrated that periodic application of large amplitude excitation to oil reservoirs led to increased oil production rates and decreased produced fluid water content. The observed oil production-rate increments ranged from 27.5% to over 400% with an average increment of 47.6% compared to the pre-vibration production rates. The reduction in water oil ratio (WOR) varied 10% to 75% with an average of 48.4% in WOR reduction.