Measurements of cased hole have drastically improved over decades. While essential physical measurement process remains unchanged, there has been a significant advancement in the production of tools.
In spite of this advancement, there has been a great difficulty measuring porosity. Therefore there has been a significant risk in primary formation in cased well bores.
The very first measurement for this was introduced in 2015. It is known as the FNXS measurement; this is related to atom as opposed to bulk density. Inelastic cross sections with elemental changes are used in assessing gas volume. But the FNXS measurement reacts to liquids and rocks in the same manner
This measurement reacts differently to total porosity, gas volume and gas. This makes it the best alternative for use with another cased-hole measurement. the information extracted from cased wellbore can be used in computing total porosity. This can be achieved by combining FNXS gas volume with liquid-filled porosity.
When performing the primary evaluation in cased holes, a major challenge of not being able to measure gas formation is being encountered. Identification of gas bearing formation is made using gamma-gamma density measurement as far back as 1960.
This measurement (FNXS) will be useful, offering a wider solution than its counterpart cased-hole density measurement and replacing density measurement.