Screening and Evaluation of Modified Starches as Water Shutoff Agents in Fractures Conference Paper uri icon

abstract

  • Abstract In the past, starch hydrocolloids have not been effective alternates to partially hydrolyzed polyacrylamides, copolymers and xanthan gum polymers as water shutoff agents in fractures and in matrix flow configurations. Poor injectivity and questionable stability have prevented their use in profile control applications. However, chemically modified starches have properties suitable for improved recovery technology. They do not hydrolyze in harsh saline environments, are made more resistant to biodegradation, and because of their wide spectrum of molecular weight distributions can be tailored to specific lithologies. The development of new materials with superior functionality and reliability has been among the most important technological advances that can significantly increase oil and gas reserves and reduce production costs. Chemically and/or physically modified starch polymer samples were subjected to preliminary screenings involving rheological tests, sedimentation tests, and stability tests at varying pH and temperature. The samples passing these tests were selected for core flow testing. The functionality of a new generation of modified starches was evaluated for profile control applications in matrix and in fracture flow configurations. A new type of fractured core cell was designed and constructed for testing the polymer samples. The device allows the aperture of the fracture to be set independently during the experiment. Results to date in the evaluation of modified starches are very encouraging. Specific materials have been identified that have the necessary stability under reservoir conditions for extended time periods. Testing in porous media indicate that certain types of the polymers have sufficient injectivity to allow propagation out into the reservoir matrix. Crosslinked polymer gel systems indicate that the modified starches may offer an alternative to currently used polyacrylamide, particularly for lower temperature systems, because of lower reaction times and adequate retention properties in porous media and in fractured core systems. P. 363

author list (cited authors)

  • Barrufet, M. A., Burnett, D., & Macauley, J.

citation count

  • 5

publication date

  • January 1998

publisher

  • SPE  Publisher