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In order to use Mineral Solver in Interactive Petrophysics, would you mind telling me whether I must have XRD data for input into Dry weight to Volume Conversion Tab or not?

Kindly regards,

Milky Way

You don't need XRD data to use Mineral Solver. You can run it solely based on well log data. However, it is good to have XRD data to validate your results, as the Mineral Solver can give you multiple solutions of the log response equations. It is more or less a simultaneous equation solver and may not give you a unique solution. That is why it is good have another source of information on mineral composition to validate your output results from the Mineral Solver.

Regards,

Ko Ko Kyi

Dear Ko Ko Kyi,

Thank you so much. Probably I should not use this module.

By the way, I do have doubt about bad hole conditions. Can you tell me what parameters are important in identifying bad holes? After knowing that, what should we do with the logs that we use for interpretation?

Please give me any references/book tittle in order to improve my understanding.

Kindly regards,

Milky Way

Milky Way,

The logs that I normally use tp identify bad hole sections are DCAL (Calipier - Bit Size) and DRHO. Bad hole or washed out sections primarily affect the density log and micro-resistivity log to a large degree and the neutron porosity log to a lesser degree. They also affect the GR log, since the extra amount of mud (due to enlarged hole) around the tool decreases the GR counts detected by the tool. In extreme cases washouts can adversely affect all logs, including resistivity logs.Usually, if the bad hole sections are not many and they are not critical, like in shale section, you can flag them and NULL the logs values effected so that they will not be used in the computation. However, if it is critical to use the affected logs, you may need to generate PSEUDO logs, using multiple regression using other logs and calibrate the affected logs in good hole sections.

There are many good books on petorphysics out there. One of the better ones is "Crain's Petrophysical Handbook", which is very comprehensive and practical. You can Google and access it on line.
If you like it, you can order the CD, with all the useful spreadsheets included, on line and it is relatively cheap (USD50.00 plus shipping).

Regards,

Ko Ko Kyi

Dear Ko Ko Kyi,

Thank you for prompt reply.

It is quite a challenge job for me as a non-petrophysicist and non-geologist student.

Based on Crain's Petrophysical Handbook, density data is useless if DRHO is greater than 0.20 gram/cc. Regarding this, I have seen that some depths in the well there are caves (Bit size: 12.25 in., CALI reading: up to 20 in.) and DRHO exceeds 0.20 gram/cc. Does it mean that I have to edit the logs before further analysis? Or are they already corrected by Service Company? (RHOB, NPHI are necessary for Clustering Analysis)

Many thanks for your supports.

Kindly regards,


PS, the provided data sets are composite logs.

Milky Way,

Yes, if the DRHO value is more than 0.20 gm/cc, the RHOB log cannot be used. I would even reduce the DRHO cutoff to 0.15 gm//c. If you still want to use a RHOB curve, you will have to generate a pseudo density log, using multiple regression or Neural Network (Fuzzy Logic). You can create a synthethic log if you have good well control (data from many well) or use the sections with good data to do a regression with other valid logs in the same well, if you do not have many wells.

All service companies provide you with a DRHO curve to tell you how much correction has been applied to the RHOB log. You do not need to correct the RHOB log again using the DRHO. However, the DRHO is sn indicator of how reliable your RHOB log is. If the DRHO (density log correction) is too high, the level of confidence in the RHOB log being correct is very low. That is why it cannot be used any more. In the intervals with DRHO more than 0.20 gm/cc, you will have to generate pseudo logs if you still want to use it.

Regards,

Ko Ko Kyi

Dear Ko Ko Kyi,

Many thanks for your kindness and help.

Best regards,

Milky Way

Thanks for sharing.........!