PIT49IAGI-P-046-05 : Source Rock Characterization and Oil to Source Rock Correlation in Jambi ...

Summary

This presentation discusses a geochemical study of the Jambi depression, focusing on the Jambi Merang area in South Sumatra. It details an analysis of oil and rock samples from various formations, including the Talang Akar, Baturaja, and Gumai formations. The study uses standard geochemical methods like Rock Eval, GC-MS, and carbon isotopic analysis to classify oils and sediments, revealing a mix of marine and terrestrial influences. The findings suggest that the Jambi Merang area has distinct oil and gas source groups, with variations in maturity and geochemical composition across different regions, which can help refine future exploration and development strategies.

Takeaways

• 😀 The study focuses on the Jambi depression area, specifically the Jambi Merang block in South Sumatra, Indonesia, operated by PHHE Jambi Merang.
• 😀 Geochemical analysis methods include Total Organic Carbon (TOC), Rock Eval, visual kerogen typing, and more advanced techniques like GC-MS and carbon isotopes.
• 😀 Data used in the study include rock cuttings from wells in Ketaling and Merangis, as well as oil and condensate samples from nearby fields.
• 😀 The primary goal is to classify crude oils and sediments in the Jambi Merang area, using qualitative and quantitative analysis based on chromatograms and mass fragmentograms.
• 😀 Hydrogen Index (HI) vs. Oxygen Index (OI) analysis reveals that the rocks in the area are mainly Type II and Type Kogen, suggesting both oil and gas potential.
• 😀 The study identifies potential hydrocarbon sources, with the Lower Talang Akar and Upper Talang Akar formations showing significant potential for oil and gas generation.
• 😀 Thermal maturity assessments reveal that the Muara and Air Pakat formations are thermally immature, while the Gumai and Baturaja formations are at optimum maturity for gas generation.
• 😀 The GC profiles suggest that the Gumai and Baturaja formations may not be mature enough to be considered viable source rocks for oil and gas production.
• 😀 The study finds that oil and condensate samples from the area are predominantly saturate-rich, indicating they are paraffinic oils, with some oils showing slight biodegradation.
• 😀 Crossplots of carbon isotopes indicate that oils and source rocks from different areas (Northern, Southern, and Western) have different isotopic signatures, reflecting varying marine and terrestrial influences on their origin.

Q & A

What is the main focus of the study discussed in the transcript?

The study focuses on the Jambi depression, specifically in the vicinity of the Jambi Merang block in South Sumatra Basin. It analyzes oil and gas potential using various geochemical methods.

What types of geochemical analysis were used in this study?

The study used standard geochemical analyses such as Total Organic Carbon (TOC), Rock Eval pyrolysis, visual kerogen typing, and vitrinite reflectance. More detailed methods included liquid chromatography, GC, GC-MS, and carbon isotopic analysis.

Which formations were identified as having significant oil and gas potential?

The formations identified with significant oil and gas potential include the Lower Talang Akar and Upper Talang Akar formations, as well as parts of the Batu Raja formation.

How were the samples for this study collected?

The samples for this study were collected from rock cuttings obtained from various wells, mostly located in the Ketaling and Merangis areas. Oil and condensate samples from fields were also included.

What does the Hydrogen Index versus Oxygen Index graph indicate?

The Hydrogen Index versus Oxygen Index graph shows that most of the rocks in the study area are classified as type II kerogen, which suggests the presence of both oil and gas, matching the characteristics of nearby fields that produce gas and condensate.

What is the thermal maturity of the Muara and Air Pakat formations?

The Muara and Air Pakat formations in the study area are thermally immature, suggesting a low potential for oil and gas generation, with the best generation potential occurring at an optimal maturity level.

What did the GC profiles suggest about the Baturaja and Kumai formations?

The GC profiles of the Baturaja and Kumai formations suggested that these formations were immature, with a predominance of sterane compounds, and therefore might not contribute significantly to hydrocarbon generation.

How did the study evaluate the maturity of the rock samples?

The study evaluated the maturity of the rock samples using aromatic maturity specific biomarkers and found that the Upper and Lower Talang Akar formations are thermally mature, consistent with data from both saturated and aromatic fractions.

What were the characteristics of the oil samples in the Jambi Merang area?

The oil samples in the Jambi Merang area were characterized by a higher content of saturates than aromatics, indicating that the oils are paraffinic in nature. Some oil samples, however, showed slight biodegradation.

What is the significance of the carbon isotope data in the study?

The carbon isotope data was used to categorize the oils and extracts into four groups based on isotopic variation, with the results indicating that the oils in the northern and southern areas of the study are sourced from different formations, with a mixture of marine and terrestrial influences.