Determination of Total Organic Carbon (TOC) of Chichali Formation through well logs. Case study: Chanda oil & gas fields in KP, Pakistan

Abstract

Total organic carbon (TOC) present in source rocks can significantly affect the response of various wireline logs. This paper discusses the well logs anomalies caused by TOC in Chichali Formation of Cretaceous age. The open hole well logs (LLD, DT, RHOB, GR, Caliper and CNL) of Chanda-1 well of Kohat Basin, Khyber Pakhtunkhwa (KP) were utilized to determine the organic contents of Chichali Shales. The source rock was distinguished from non-source rock based on low density, high sonic transit time, high porosity and high resistivity. The ΔlogR technique yielded TOC values ranging between 0 to 1.38 % for the formation which is in close agreement with the value obtained by geochemical analysis. This study reveals that TOC of a source rock, using well logs can provide a good estimate of its organic contents before going for detailed geochemical analysis.