INTRODUCTION

In Neutron Log interpretation, it has been convenient and customary to say that, when properly calibrated for formation lithology, the Neutron Log responds only to the hydrogen of the formation. This hydrogen is that present in the formation water and in the hydrocarbons. Compare two formations of the compositions shown in Fig. 1. Formation "a" has a porosity of 15%, which is 100% water saturated, and formation "b" has a porosity of 30%, which is 50% water saturated and 50% saturated with low-pressure gas. Both formations contain the same bulk-volume fraction of water. Thus, taking the hydrogen index of the gas to be zero, they have the same hydrogen content. It would therefore be assumed that they would have the same Neutron log porosity response.

Keywords:
Upstream Oil & Gas, shale, slowing-down length, Symposium, neutron reading, neutron, Spwla Twelfth, excavation-effect correction, well logging, sketch
Subjects:
Formation Evaluation & Management, Open hole/cased hole log analysis
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1971. Society of Petrophysicists & Well Log Analysts
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