Title: Some Improvements of the "Ideal" Theory for Real Reservoirs
1Some Improvements of the "Ideal" Theory for Real
Reservoirs
2The general diffusivity equation Shape Factor
- Inner boundary(well)
- No flow (shut-in)
- Constant rate
- Constant flowing pressure
- Outer boundary
- Infinite acting
- No flow
- Constant pressure (or given influx)
Wellbore storage or not
- Time behavior
- Transient
- Stabilized (time invariant in some respect)
- Steady-state
- Pseudo-steady state
- Boundary dominated flow regime
3Dietz Shape Factor CA
- Well centered in a circular reservoir
- General
A area in ft2 rw wellbore radius in ft expg
1.781 CA shape factor (31.62 for a centered
circular reservoir) 1/cr 141.2 for field units
4Dietz Shape FactorsShape of drainage area AND
location of well
CA 30.88
CA 31.62
CA 21.86
1
Sometimes the effect of shape is also expressed
in the form of a skin factor.
2
CA 2.07
1
2
5Some Forms of PSS Gas Deliverability for "Real"
Gases
- Original "slightly compressible" AND Gas
pressure form - Gas pressure-square form
- Gas Pseudo-pressure form
where Bg is in RB/MSCF
6Some modifications for multiphase flow
- Perrine and Martin What to consider "total"
compressibility for a multiphase system?
oil expands
water expands
gas expands
Pore space gets smaller
7Some modifications for non-Darcy flow
- Can be incorporated into any form, here we show
how to incorporate it into the Pseudo-pressure
form
Non-Darcy "skin effect" (rate dependent)
Origin Forcheimer Correlations for D are
available
8- Basic concepts of PVT
- Well testing basics
- Material balance
- Steady-state solution, skin, equivalent wellbore
radius - Pseudo-steady state and Boundary dominated flow
regime - Productivity Index
- Transient solution log approximation
- Gas diffusivity eq forms, "deviations from
ideality" - CALCULATE