Using Chemicals to Optimize Conformance Control in Fractured Reservoirs – 2001

R.S. Seright – 2001

Abstract

Third and final year of the conformance optimization project. X-ray CT imaging in Berea sandstone shows DPR occurs by gel trapping oil, forcing water through narrow pores and films. In oil-wet polyethylene, DPR occurs by a different mechanism — oil films and specific small pore pathways provide conduits unavailable to water. Gel extrusion pressure gradients and dehydration factors are similar at 20 to 80 degrees C, confirming limited temperature effect. In wider fractures (0.08 to 0.16 inches), gel washout can occur at lower pressure gradients than during placement. Software Version 2.0 adds support for gas wells with water production and SI units.

Key Takeaways

  • In strongly water-wet Berea sandstone, DPR occurs by gel trapping residual oil (Sor jumps from 18 to 51 percent), forcing water through narrow pore throats, gel, and films.
  • In oil-wet polyethylene, DPR occurs by a different mechanism — oil films and small pore pathways provide conduits for oil that are largely unavailable to water, without significant oil trapping.
  • Gel extrusion pressure gradients and dehydration factors are similar at 20, 40, 60, and 80 degrees C — confirming limited temperature sensitivity over this practical range.
  • In fractures wider than 0.08 inches, gel can be mobilized during brine injection at pressure gradients lower than during gel placement — washout risk must be addressed in wide-fracture applications.
  • Gelant treatment sizing software Version 2.0 adds gas well support and SI unit inputs, significantly expanding field applicability.
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