Ann: Mukuyu 1 & Sidetrack Well Results Amendment, page-300

orion
there are more strands to this:

- high porosity (=phi) is good but the important thing is that the pores have to be connected (-> permeability (=k)). There is a phi-k relation and good phi delivers a good k. But not always. Sometimes you have a rock with very, very good pores. But nothing can flow through this rock because the pores are not connected.

- phi, k from a core. it is like a measurement from single point. The picture can be completly different 2 meters deeper for example. Moreover the measurements from a core have to be corrected (= difficult) because when you reemove the core from a depth of 3,000 m it will be deformed

- phi. k from a log. It is a like a 2 dimensional line. The picture can be completly different 10 m away from the well bore, where the log was measured. One big questionmark is the calibration as kiwigeo elaborated already. If the calibration is wrong you get bull$it data. For calibration of the reservoir water resistivity: there are sedimentary basins with fresh water and there are basins with, layers with saturated salt water. When you have no measured data because of the missing sample you have to take an average number for oil and gas fields from literature and take plus/minus for the error. +.- 10%, +.- 25% ...?

- k from a production well test. this is the number we need because it is the measurement from a 3 dimensional rock block. And this is the number which is used for the calculation of the producable reserves = $$$$ (the only bbl=$$ banks accept for example from oil companies for a loan)

But you need all data, interdisciplianry to get the whole picture right. Some years ago I coached a student for his master thesis, comparing the numbers from all 4 mentioned methods for one field.400% discrepancy for the same parameter. You see compared to kiwigeo, I have less problems to use a big thumb to guesstimate the reservoir resistivity of the reservoir water to decide which formation should be perforated for a production test at Mukuyu 1 with the first or a second sidetrack (as long as the collected data are not hopeless - but we read that Scott Macmillan used the word fantastic ..LOL)