Summary
Core-flow efficiency (CFE) is defined to quantitatively evaluate the flow
performance of single-shot perforation. To calculate CFE, the flow rate of the
ideal perforation flow in the core target is needed. The ideal flow rate is
typically calculated with numerical simulators, but the computation may be time
consuming and costly.
This paper presents the 2D analytical solution of the steady-state flow
model (mass-conservation equation) for an ideal single-shot perforation in a
cylindrical core sample. The separation-of-variable method is used to solve the
partial-differential equation (PDE) of the flow model. Pressure and velocity
distributions in (r, z) space are obtained, along with the
flow-rate distribution along the perforation tunnel.
The accuracy and convergence of the analytical solution for ideal
single-shot perforation flow are investigated and compared with those of the
numerical solution of the commercial software ANSYS Fluent (ANSYS Fluent 12.0
User's Guide 2001). The analytical solution for the governing equation of ideal
perforation flow is composed of an infinite number of Bessel functions. To
compute CFE by making use of this analytical solution, the analytical solution
is approximated with a limited number of Bessel functions. The approximated
analytical solution is analyzed and compared with the numerical solutions from
ANSYS Fluent.
Further, the axial-, radial-, and radial/axial-flow geometries of an ideal
single-shot perforation are characterized with their approximated analytical
solutions. Interactions between the boundary condition, perforation parameters,
and core parameters are investigated for these flow geometries.
The analysis results show that: (1) The analytical solution has no grid
effects, (2) the boundary condition of the perforated core is the dominant
factor in the ideal flow rate of the perforated core, and (3) the penetration
depth and anisotropic permeability are the significant factors in the flow
performance of the perforated core.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
17 February 2010
- Meeting paper published:
11 February 2010
- Revised manuscript received:
7 July 2011
- Manuscript approved:
22 July 2011
- Published online:
16 April 2012
- Version of record:
11 June 2012