Identification of Potential Unconventional Oil and Gas Zones Based on Permeability, Mobility, and Transmissibility in The North-East Java Basin

Bagus Sapto Mulyatno; Ordas Dewanto; Isti Nur Kumalasari; Andri Kurniawan; Asep Irawan; Andy Setyo Wibowo

doi:10.29017/scog.v49i2.2081

Authors

Bagus Sapto Mulyatno Universitas Lampung
Ordas Dewanto Universitas Lampung
Isti Nur Kumalasari Universitas Lampung
Andri Kurniawan Universitas Lampung
Asep Irawan Universitas Lampung
Andy Setyo Wibowo Pusat Survei Geologi

DOI:

https://doi.org/10.29017/scog.v49i2.2081

Keywords:

unconventional oil and gas, identification, permeability, mobility, transmissibility, North East Java Basin

Abstract

The North East Java Basin is one of the prospective unconventional hydrocarbon regions characterized by low-permeability carbonate reservoirs. However, quantitative evaluation of fluid flow behavior and the relationships among petrophysical parameters within tight carbonate systems in this basin remains limited. This study aims to identify unconventional hydrocarbon prospect zones and determine the dominant fluid type based on permeability, mobility, and transmissibility parameters in the BGS-2, BGS-4, and BGS-7 wells. The study integrates well-log data, Total Organic Carbon (TOC) estimation, and interparameter relationship analysis using permeability–mobility and permeability–transmissibility crossplots. The results show that TOC values range from 0.51 to 2.78 wt%, indicating moderate to very good organic richness. The main prospective zones occur at depths of 3235–6469.5 ft (BGS-2), 3617–10632 ft (BGS-4), and 1897–1988 ft (BGS-7). These intervals are characterized by very low permeability (<0.1 mD), low mobility (<10 mD/cP), and limited transmissibility (<100 mD·ft/cP), indicating tight carbonate reservoir characteristics. Crossplot analysis reveals a stronger positive relationship between permeability and mobility than between permeability and transmissibility. The integration of petrophysical parameters indicates that gas is the dominant fluid within the prospective intervals, suggesting that carbonate reservoirs in the North East Java Basin represent promising tight-gas unconventional hydrocarbon resources.

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