A Narayan

SIP Vs TWT, BUILD UP TEST, DRAWDOWN TEST

Source data- PLT Survey Vs Bin size Couples - [Pressure, Flow Rate] closely

assosiated IPR curve - Pressure Vs Rate correlation Condition - Multilayered reservoir tests Output - Avg. Pressure, PI(b/d/psi) Composite - composite IPR curve

Selective inflow performance (SIP) provides a mean of establishing the IPR for each rate producing layer.

Performed under stabilized condition and suitable for medium to high permeability layers

The well is flowed at several different stabilized surface rates and for each rate, a production log is run across the entire producing interval to record simultaneous profiles of downhole flow rates and flowing pressures.

At least two surveys required at two different bin sizes.

SIP is applicable for multilayered reservoirs.

It is to create a drop in the bottom hole pressure, which causes reservoir fluids to flow at certain rate from rock to wellbore, followed by a shut in period .The production period is generally referred to as the “pressure drawdown” whereas the shut in period is called as pressure build up.

Output of well testing - Reservoir pressure, K, Porosity, skin depth, PI and other related data like wellbore condition and reservoir boundaries, degree of connectivity to other wells.

PLT measures flow rate accurately for any small rate change.

TWT partially distinguishes pressure changes caused by reservoir characteristics and those caused by varying flow rates.

TWT measures reservoir parameters at one moment of time in the life of reservoir.

TWT tests rely on pressure measurements assuming constant flow rate.

Pressure build up tests are also sometimes undesirable because of production loss and difficult to return on production of poor flow zone.

Pressure drawdown test have constant flow rates which is also not possible and not been preferred over TWT to achieve the same.

So SIP tests have been preferred over TWT, Build up Test, Drawdown Test.

Flow rate is measured at well head and interpretation models are based on reservoir conditions.

To each reservoir zone corresponds for each survey/interpretation a couple [rate, pressure] used in the SIP

For the pressure, the interpretation reference channel is interpolated at the top of the zone.

For the rate, the value used in the SIP is the contribution from the particular layer.

A SIP module is run to determine the IPR curve for each producing layers.

Static/ Avg/Formation pressure of each layer can be estimated from the point at which the individual IPR curve intersects the vertical axis.

Straight line, q = PI (Pavg - P) LIT, Pavg**2 – P**2 = A q + Bq**2,

A=turbulence term,B=Darcy’s flow term Fetkovitch, q =C x (Pavg**2 –P**2)**N

C=Cofficient dependent on flow properties.N=Exponent(0.5-1.0)

Pseudo pressure m(p) is used for gas wells.

Composite IPR (total rate and single pressure at the top of uppermost layer.

Use couples for each reservoir zones in SIP calculation.

Pressure : at the top of each layer (with temp.)

Rates : It is calculated as the difference

between at the top of that zone and at bottom of that zone.

Top: T_top, P_top, q_top Bottom: T_bot, P_bot, q_bot Then contribution of each phase is calculated with mass balance as dQ=q_top-q_bot*(den_bot/den_top) The default is to generate the SIP without pressure correction to a common datum

however there is option for pressure correction in emeraude.

We can do SIP surface or reservoir condition for individual layer or all combined.

Pavg Pavg,cor

Flow rate(b/d)

PI(b/d per psi)

Composite IPR

612 611 122043 199

Zone 1 611 631 106300 178

Zone 2 772 611 7785 10

Zone 3 773 610 9068 11

SIP is used to determine optimum production rate for each producing layers.

IPR curve and avg. formation pressure for each layer.

PI(Productivity Index,b/d per psi) Composite rate and pressure at the top of

topmost reservoir zone.

Transient test rely on pressure measurements assuming a constant flow rate during the test.

Flow rate and pressure is measured near the top of the reservoir.

Well doesn’t have to be shut for long period.

It is vertually impossible to measure individual layer properties for multilayered reservoirs by conventional well testing methods.

SIP theory is only applicable for single phase flow(ideal condition).

But two phase flow can be limited to one phase flow if one can withdraw minor contribution from marginal phases.

Otherwise mixed phase can be considered as single phase provided phase ratio should be around 80:20.

If bottom zone is producing water in a oil or gas well.

*****