Source rock analysis, thermal maturation and hydrocarbon generation using rock-eval pyrolysis in parts of Krishna–Godavari basin, India: a case study

K Ramachandran,Vinay Babu,T Harinarayana,Bijaya K Behera

doi:10.1007/s13202-012-0041-y

Abstract

Among the various techniques available, the geochemical technique involving total organic carbon content (TOC) and rock-eval pyrolysis are regularly being used in hydrocarbon exploration. They provide information on the kerogen type, sedimentary environment, effective source rock identification and its thermal maturity. In the present study, core samples from three deep boreholes in Krishna–Godavari basin are analyzed to understand the hydrocarbon scenario in parts of the basin. Based on TOC and rock-eval pyrolysis significantly thick, indigenous immature to early mature gas-prone shales from borehole GERMI #1; while non-indigenous, early mature to mature oil and gas-prone shales from borehole GERMI #2 and GERMI #3. Interpreted hydrocarbon typing is supported by well-testing analysis. Break in vitrinite reflectance (Ro) profile is also observed; indicative of significant erosion during Late Cretaceous sedimentation due to tectonic uplift during this time and associated high heat flow causes for thermal maturation of overlying units.

Highlights

There are three major sedimentary basins along the east cost of India, namely, the Cauvery, the Krishna–Godavari and Mahanadi
Among the various techniques available, the geochemical technique involving total organic carbon content (TOC) and rock-eval pyrolysis are regularly being used in hydrocarbon exploration
Rock samples are pyrolyzed using Rock-Eval 6 apparatus at ACS core laboratory. This technique evaluates oil and gas potential, the generation, thermal maturity and identifies organic matter type (Peters 1986; Tissot and Welte 1978). This instrument uses a ramped temperature pyrolysis technique, whereby a small amount of sample (70–100 mg) is heated in an inert atmosphere and combusted with air to obtain several key geochemical parameters relating to the hydrocarbon potential of the rock such as the total organic carbon (TOC), type or quality of organic matter and maturity level (Peters 1986; Lafargue et al 1998; Behar et al 2001)

Summary

Introduction

There are three major sedimentary basins along the east cost of India, namely, the Cauvery, the Krishna–Godavari and Mahanadi. Abstract Among the various techniques available, the geochemical technique involving total organic carbon content (TOC) and rock-eval pyrolysis are regularly being used in hydrocarbon exploration. Keywords Source Á Rock potential Á Rock-eval pyrolysis Á Total organic carbon Á Krishna–Godavari Basin

Results

Conclusion