tutorial for well log

8/10/2019 Tutorial For well log

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Object-2:Find the value of Rw with the help of the following available data:

Porosity ( ) equals 10%; cementation constant (m) is equal to 2; formationfactor (F) is equal to 0.81/ m.

Procedure:1) Find the porosity value (10%) on the left-hand scale.

2) Follow the value horizontally until it intersects the sloping Ro line.

3) Follow the value vertically down from the intersection to the RILd scale at thebottom, and read the value of Ro. In this case, Ro equals 5.6ohms.

In computing Rw from Ro, remember that:

Rw=Ro/F and F = 0.81/ m

Rw=5.6/81 , Rw=0.069 at formation temp.


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Pickett Crossplot

R ILd


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Now find out (Rw) at the given values:Given values for Porosity ( );

1. 08 % (at So = 0.29)

. .

3. 25 % (at Sw = 0.1)


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Object-3: Determining Rw from Hingle cross-plottechnique for the following given depths.

Hingle Crossplot Method

Theory:

Depth R deep t

4622 5 78

Example

Advantages

Even if matrix properties

ma and tma are unknown a value for water saturation can still be found


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1 10 100

Hingle Crossplot


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HINGLE CROSS-PLOT

Charted data from pg 106 JamesBrock

Given:100% water saturation line

t ma = 61 s (for matrix)

t f = 189 (for fluid)

SOLUTION:

Now, determining Rw. We have,

= t - t ma

t f - t ma

= 75-61 = 0.109

189-61

Now we calculate F = 1/(0.109) 2 = 84


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HINGLE

Ro given is 5 ohmm and as we knowthat,

Ro=F.Rw

Transposing Rw = Ro = 5 = 0.06 ohmm

FIND OUT THE VALUE OF (Rw) WHEN

Sw =0.5 and

R deep = 11


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Object:4 To determine Rt by drawing 50% water saturation line, asreservoir often not productive above 50% water saturation whileusing Hingle cross-plot method.Calculating resistivity at 50% water sat and 75 s.

HINGLE

We know

Rt = (1/(Sw) 2 ).Ro

If Sw=50% then

Rt=1/0.5 2 x Ro = (1/0.25) x Ro = 4Ro

Using the same circled points:

Ro = 5

Rt=4 x 5 = 20

Plot 20 ohmm at 75 s and draw the line from 61 s through the point to the resistivityscale.

It now becomes apparent this zone is not going to be producible. The entire zone is above50% Sw.


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tutorial for well log

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