New Warrior PNN Logging Screen

There is two new sections, positioned on the bootom

Figure 1:

1. Tool Ratio Porosity Calculation

2. Fractional Ratio Porosity Calculation

Tool Ratio Porosity Calculation allows porosity calculation

taking account ratio between SS and LS. Outputs SS and LS

represents total counts rates (sum of counts from channel

1 to 60) from short space and long space detector. Output

RATIO is input for porosity calculation. Because each PNN

tool has same polynomial, input in calculation is Tool

Constant (on picture is 0.323). Tool Constant is user

parameter which multiply RATIO before applying

polynomial multiplication. Depending on the tool, and

environment for logging this parameter MUST BE FOUND,

and used for this tool. Using same parameter for other tool

can cause wrong results. Output RATPOR is derived

porosity in (limestone porosity units) p.u.

Figure 1 – Warrior Logging Screen

Fractional Ratio Porosity Calculation allows porosity calculation taking account ratio between SSadd and LSadd.

Outputs SSadd and LSadd represents sum of counts rates from predefined channels (sum of counts from channel

SS Begin to SS End, LS Begin and SS End) from short space and long space detector. On Figure 2, SSadd is sum of

counts from channel 5 to 10, and LSadd is sum of counts from channel 1 to 10. Output RATadd is input for porosity

calculation. Because each PNN tool has same polynomial, input in calculation is Tool Constant (on picture is 0.83).

Tool Constant is user parameter which multiply RATadd before applying polynomial multiplication. Depending on

the tool, and environment for logging this parameter MUST BE FOUND, and used for this tool. Using same

parameter for other tool can cause wrong results. Output CNPOR is derived porosity in p.u.

All mentioned parameters connected with Porosity calculation can be initially set thru Warrior Tool Editor as it is

shown on figure 2.

How to adjust parameters for POROSITY logging?

There is several posibilities:

1. Using Tank calibrator with know porosity. Adjust porosity reading on logging screen manipulationg with

Tool Constant to show same porosity as Tank.

2. During going down with the the tool beffore logging using marker zone in well, where porosity is known

from e.g. OPEN HOLE readings.

3. In recalculation mode, if there is any comparative porosities logs, adjust parameters to show as much as

possible close to adopted porosity log.

Figure 2 – Warrior Tool Editor Setup

Limitation of Porosity logging:

1. Changed environment comparing with previous logging. Most influence on porosity logging is thru casing

thickness, cement thickness, and salinity. While casing and cement thickness generally decrease apparent

porosity, borehole salinity can increase or decrease apparent porosity depending on salinity and borehole

size. This can be very visible if Tool Constants were found comparing with OH log, and applied during PNN

logging. In this case corrections must be applied later.

2. Decreasing neutron flux from generator itself can cause that ratio between short space and long space

will not be the same at the beginning of life time and at the end of the life time of generator. Suggestion is

that adjusting parameters (Tool Constants or channel assignment for Fractional Porosity Calculation)

should be checked/readjusted periodically.

3. Multiple strings and equipment in the well can also cause different POROSITY readings from expected, but

usually this might be corrected after logging in recalculation.

4. Logging software does not support zones in parameters sections, so eventually changing parameters (Tool

Constant) on exit from tubing to casing, or from two casing zone to one casing zone must be applied

manually.

Example – 128

Figure 3- 128

On figure 4 above, on the left side is NPHI from log and RATPOR from Hotwell derived after logging.

On the right side is is PNN_FPOR (porosity from fractional ratio SSadd/LSass) and PNN_TPOR (porosity

from total ratio SS/LS) curves in the same scale as NPHI and RATPOR.

For calculation is used Interactive Petrophysics Software which has same calculation procedure as Warrior

Logging Software, so expected results from Warrior Logging Software should be the same.

Two zones are used during calculation: 1. 4064 to 4340 with Total Tool Constant 0.35, Fractioanl Tool

Constant 0.99, and zone from 4340 to 4795 with Total Tool Constant 0.32, Fractioanl Tool Constant 0.85.

In both zones, channel assigment for SS were 5-10 and for LS 1-10.

On figure 6 is presented Repeat section recalculated thru Warrior Logging Software. On the left side is

detail from IP calculation and on the right side is Warrior Logging software calculation.

Figure 6 – Repeat Section thru Warrior Logging software