Water Soluble Chemical Encapsulation for Well Stimulation, Transportation, and Particle Formation
Physical Sciences : Petroleum
Available for licensing
- Kishore Mohanty, Ph.D. , Petroleum and Geosystems Engineering
- Krishna Panthi, Ph.D. , University of Texas at Austin
- Robin Singh , Petroleum and Geosystems Engineering
Shale formations, even when fractured, have very low porosity permeability and yield minimal well productivity. Acid can be used to enhance the permeability of these shale formations, which ultimately increases hydrocarbon production for well collection. The issue with using acid as a chemical stimulant for shale reservoirs lies with the delivery of the acid to the well bore. If injected directly, a majority of the acid is consumed by the well bore and only a small fraction enters the shale’s deep target fractures. Previous studies have attempted to utilize polymers as a delivery system for acids through small shale pores. However, such polymers have failed because they tend to plug the shale’s pores. Some sort of mechanism must be used to deliver and release the acid to the shale’s fractures while minimizing chemical risks and maximizing reservoir stimulation.
A method for the encapsulation of acids or other water-soluble chemicals in microparticles was developed for ease of transport to the delivery site. Any acid or water-soluble chemical is synthesized into a solid powder through a simple process, which can then be dispersed by any gas, oil, or hydrophobic liquid. The microparticles are small enough to easily pass through the shale’s natural micro-fractures by a carrier fluid. After the well is shut down for a few days to soak the reservoir in the carrier fluid, the pressure is lowered and the shale’s fractures collapse on the particles in order to destroy the encapsulation and release the trapped acid to the delivery site. Thus, only the mechanical squeezing by the fractures themselves are needed to release the chemical stimulant rather than another chemical reaction. This process can be repeated numerous times during any stage of shale oil production to increase shale permeability.
- Can encapsulate any acid or water-soluble chemical
- No chemical reaction needed to release the chemical stimulant
- Encapsulated chemical can be transported by a variety of carrier fluids (gas, oil, hydrophobic liquid)
- Simple synthesis of the encapsulated microparticles
- Ease of deep fracture penetration in shale reservoirs
- Novel encapsulation method that does not clog reservoir pores
- Simple procedure that can be repeated any number of times
- Increases permeability of shale reservoirs in any target area
- Encapsulation technique can apply to manufacturing of any small particle
- Increases efficiency of a shale reservoir in its entirety
The proposed encapsulation technique applies mainly to the delivery of acid stimulants to shale reservoirs to increase permeability and productivity. Oil and gas companies that seek to maximize shale production can greatly benefit from this method for increasing reservoir permeability. Other applications of this encapsulation technique include transportation of hazardous chemicals, formation of macroemulsions, and manufacturing of small particles. Chemical companies and research facilities may find that encapsulation by microparticles can significantly increase the efficiency of any chemical process.
- 1 PCT patent application filed