Description

During the drilling of wellbores into the earth, certain types of low permeability formations (such as shale) are encountered, become weakened, and often collapse into the wellbore. It was estimated in 1996 that such problems costs the oil and gas industry over $500 million per year. Today that number is expected to have doubled due to the complexity of wells being drilled.

Studies have shown that the cause of these failures can be traced to the invasion of the low permeability clay-containing rocks by water and other components in the drilling fluids. The invasion increases the pore pressure of the rock, develops swelling pressures, and reduces its strength. It is then easy for external stresses to crush the shale and thereby produce a borehole collapse.

Inventors at The University of Texas at Austin have developed a novel solution for reducing the permeability of shale formations using specific nanoparticles in the drilling fluids. By identifying the pore throat radii of shale samples, the investigators were able to select fine particles that would fit into the pore throats during the drilling process and create a non-permeable shale surface. Tests have shown reduction from 80% to 95% reduction in permeability of the shale, which results in drastic reduction of absorbed water and potential for collapse.

Benefits

• Fluid blockage or permeability reduction
  
• Eliminates need for using saline muds and chemicals during the drilling process
  
• Improved wellbore stability
  

Market Potential/Applications

Shale formations are becoming increasing popular in the search for natural gas and oil within the United States. As the United States expands its energy infrastructure to rid itself of foreign dependence, the need for increasing stability in these types of formations is expected to increase substantially.

Contact:

University of Texas,
Austin, USA
Website : www.otc.utexas.edu