Recently the U.S. Department of Energy (DOE) has funded joint programs involving the Los Alamos National Laboratory, the Lawrence Berkeley National Laboratory, several universities, and several industrial companies. Tests in both the laboratory and field have shown that low frequency elastic waves (below 100 Hertz) can enhance the oil recovery rates by as much as 50%. These tests also show that pore pressure elastic waves as small as 70 Pa (0.01 psi) can improve the oil mobility and recovery rate.





Current research and analytical modeling are attempting to define the underlying mechanisms to explain how elastic wave stimulation can improve the fluid flow rates in abandoned oil fields. Several mechanisms have been suggested to explain why elastic wave stimulation increases the oil recovery rate. Oscillations caused by the elastic waves may induce the small, individual oil droplets to coalesce thereby increasing the oil flow. Elastic waves may increase the wettability of the formation material allowing the water flooding to be more effective. Exposure of laboratory samples to elastic waves has reduced the oil viscosity, perhaps caused by the heat generated by higher frequency stimulation. Elastic waves may increase the permeability of the oil bearing formation by “unplugging” the pores and pore throats in the formation. Elastic waves may also reduce the permeability by reducing the surface tension between the formation and oil-water mix.



When the current research is complete, the results will guide the selection of the elastic wave parameters (minimum amplitude and maximum frequency) that produce the optimum results for various geological and formation conditions and for different fluid properties. Until these studies are complete, the inherent flexibility of the HAI source can be used to generate elastic waves of different frequencies and amplitudes in order to experimentally arrive at the best elastic wave parameters for a particular oil field.



Hydroacoustics Inc. has identified domestic oil production as an industry ripe for successful translation of our acoustic source technology – specifically within the rapidly growing area of enhanced oil recovery (EOR).  We are currently in development of the Oil Recovery Tool (ORT), an acoustic source-based down-hole tool designed to increase oil production and extend the productive lifetime of existing wells.  The Oil Recovery Tool also has the potential for indirect reduction of the environmental footprint of Enhanced Oil Recovery operations through increased performance and yield per well.
HAI has teamed with oil producers to identify specifications desired for EOR, and is adapting them into a proprietary acoustic-engineering package suited for the down-hole environment.
Features include:
Reliable and rugged design (for low maintenance, increased uptime, and improved economics)
Adjustable frequency and power (able to be ‘tuned’  to the individual characteristics of the well)
Omni-directional wave propagation (for increased effective power and range)
Small diameter fits into existing injection wells (4.5 inch)
Adaptable to deep or shallow wells
Effective design, yet with fewer and less complex moving parts (for increased reliability)
Cost-achievable for even small producers
Applications in secondary (waterflood) and tertiary (EOR) oil recovery
HAI is committed to the nation’s energy security through increased domestic production and decreased dependency on foreign oil.  The Oil Recovery Tool helps operators in waterflood and EOR accomplish this through increased oil production and prolonged lifetime of existing wells.

 One of the standard ways that oil is taken out of the ground is through lowering the pressure in a well (via pumping), thereby inducing a pressure gradient that drives flow into the well. However, the presence of other fluids, especially water, tends to interfere with the flow of oil, and the entire system can exhibit quite complex, nonlinear, hysteretic and coupled behavior due to the presence of multiple fluid phases as well as any exchange phenomena across fluid-fluid or fluid-solid interfaces. Complex behavior and nonlinear feedbacks, from the pore scale to larger length scales, lead to oil recovery efficiencies on the order of 40%. That is, about 60% of the oil in a typical reservoir is left behind because it cannot be induced to flow into the well. 


a new EOR technique using Acoustic and Seismic energy to reduce interfacial tension and promote coalescence of oil ganglia using the resonant frequency principle. The technique uses pressure and sound waves at pre-determined frequencies to set the oil molecules in motion to promote coalescence and thus reducing the fingering effects. The flood pattern can be optimized by recovering oil from previously unswept areas. It thus enhances the life of the primary flood providing valuable economic savings. The process can also be applied to various reservoirs in their tertiary recovery phase to extend the life of the project. Experiments conducted in the lab show that the frequency of oil and water may differ from reservoir to reservoir and compositional analysis of samples is required to determine the resonating frequency. The design of the downhole tools for injector wells to implement this technique are also discussed briefly.



Seismic stimulation

Reports of low-frequency, high-energy elastic waves mobilizing oil date from the early 1950s when earthquakes were shown to increase oil production by as much as 45%. The first man-made low-frequency, high-energy source used to mobilize oil was a Russian surface vibroseis in the early 1980s.

Detailed Russian field studies using surface vibroseis proved oil could be successfully mobilized and more importantly the mobilized oil came from the virgin reservoir area; thus, the application of low-frequency, high-energy elastic waves is an enhanced oil recovery method.

In 1998, Los Alamos National Laboratories (LANL) showed only a small pore pressure disturbance, less than 70 Pa (0.01 psi), could increase the permeability of a saturated porous medium and mobilize trapped fluids; hence, the process does not need elastic waves with large magnitudes to improve oil production.

In real terms, seismic stimulation has improved oil production and oil cut in wells as far away as 1.4 mile from the well in which the tool was installed.

The mechanisms describing the process of mobilizing oil under low-frequency, high-energy elastic wave fields center on two main phenomena:

1. Dislodging oil droplets from pore walls.

2. Coalescence of two or more droplets or thin oil films into one of higher mobility.

World Oil Online June 2009 Vol. 230 No. 6  Simulations reveal mechanisms of seismic waves for EOR


Simulations reveal mechanisms of seismic waves for EOR

The pore-scale effects of seismic stimulation on two-phase flow are numerically modeled in random two-dimensional grain-pack geometries.

Steven R. Pride, Lawrence Berkeley National Laboratory; Eirik G. Flekkøy and Olav Aursjø, University of Osl



Production Enhancement Through Acoustic Stimulation
Mayank Rastogi, A K Mishra, ONGC, Mumbai
19th Annual India Oil & Gas Review Summit & International Exhibition 2012 
Discussion and Conclusion:
Laboratory studies have shown that application of acoustic or elastic waves to saturated porous media affect permeability and can increase the extraction of hydrocarbons dispersed in the pore spaces. The technique is more suited in depleted reservoirs and helps in improving recovery by producing the bypassed or residual oil trapped in the pore spaces, improving its mobility, coalescing the scattered oil droplets and enabling the flow towards the well bore. Of the techniques available commercially, acoustic stimulation treatment using downhole tool as well as surface mounted unit with antenna are found to be better and most cost effective as it does not require any downtime and does not hamper production.
1. Igor A. Breznev & Paul A. Johnson, “Elastic-wave stimulation of oil production: A review of methods and results”, Geophysics Vol 59, No. 6, (June 1994); page 1000-1017
2. Adinathan Venkitaraman, Peter M. Roberts, Mukul M. Sharma, “Ultrasonic removal of near well bore damage caused by fines and mud solids”, SPE 27388
3. Peter M. Roberts, Adinathan Venkitaraman, Mukul M. Sharma, “Ultrasonic removal of organic deposits and polymer-induced formation damage”, SPE 62046
4. Le Hui Zhang, Peter Ho, Yun Li, Shengning He, “Low frequency vibration recovery enhancement process simulation”, SPE 51914
5. Enhanced Oil Recovery with Downhole Vibration Stimulation, R. V. Westermark et. al. SPE 67303
6. Paul A. Johnson, “Seismic stimulation of oil production in depleted reservoirs: Proposal Summary”
7. Susan Jackson, “Advances in Seismic Stimulation Technologies” 8. Peter M. Roberts, “An integrated approach to Seismic Stimulation of Oil Reservoirs:
Laboratory, Field and Theoretical Results from DOE / Industry Collaborations”, LANL, 16th International Symposium on Nonlinear Acoustic




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