Title: Study of Perforation Friction Pressure
Employing a Large-Scale Fracturing Flow Simulator
Author(s): D.L. Lord, Halliburton Energy Services,
S.N. Shah, R.G. Rein, J.T. Lawson, III, The University of
Oklahoma
Presentation: SPE Annual Technical Conference and
Exhibition
Location: New Orleans, Louisiana USA
Date: September 25-28, 1994
Abstract: Accurately estimating perforation friction
pressure is important to the design and analysis of
fracturing treatments. Currently, in the absence of a better
approach, the industry is using sharp-edged orifice
correlations developed with Newtonian fluids such as water.
These correlations, however, are probably inaccurate when
applied to the rheologically complex fracturing fluids being
used today.
A detailed investigation of the effects of fluid type,
fluid viscosity, perforation size, and perforation flow rate
is conducted with a unique large-scale, high-pressure
simulator (HPS). Construction of this simulator was a joint
effort involving the Gas Research Institute (GRI), the
Department of Energy (DOE), and the University of Oklahoma
(OU). Test fluids include water, linear polymer solutions,
and crosslinked polymer gels. After fluids are prepared
under simulated field mixing conditions, they are pumped
into a simulated wellbore through a set of four perforations
on the 1-ft spacing into a simulated fracture having
variable crack width. Differential pressure transducers are
used to monitor pressure drop across the perforations and
pressure recovery downstream in various crack widths.
Correlations are developed to describe the perforation
pressure-loss behavior. Predictions of these correlations
are shown to differ significantly from those made by
conventional orifice-type equations. In the new
correlations, pressure drop is shown to be dependent on
fluid type, viscosity, and perforation size in addition to
the conventional dependence on fluid density. These new
correlations should significantly improve real-time and
post-treatment pressure data analysis.