Uncovering The Potential of Low Resistivity Reservoirs Through Integrated Analysis: A Case Study from The Talang Akar Formation in The South Sumatra Basin

Abstract

The study area is an oil and gas field that has a low resistivity reservoir zone in the Talang AkarFormation, South Sumatera Basin. The reservoir zone is composed of siltstone and sandstone that was depositedin a shallow to transitional marine environment. The aim of this study is to identify and determine the potential oflow resistivity reservoirs in the study formation. The data used in the study include well log, mud log, core data(porosity, permeability, petrography), formation water analysis, and biostratigraphy. The methodology includesqualitative analysis to determine reservoir potential zones (quick look interpretation) and the reason for low resistivityreservoirs, as well as quantitative analysis to calculate petrophysical parameters. The results of the quicklook analysis showed 77 low resistivity reservoir zones, but the petrophysical analysis identified 25 low resistivityreservoir zones as potential candidates for drill steam test (DST). Factors causing low resistivity reservoirs inthe study area include clay mineral content (kaolinite and illite), conductive minerals (pyrite and siderite), highsalinity formation water (10,000 ppm), very fine to medium sand grain size (0.063 - 0.5 mm) distribution ofclay minerals (laminated and dispersed clay), and thin laminates. The results of the petrophysical analysis showthat shale volume is less than 30%, porosity is greater than 14%, permeability is greater than 10 mD, and watersaturation is less than 70%.

Assessing Fracture Intensity and Petrophysical Properties in the Jatibarang Formation's Volcanic Reservoirs, North West Java Basin

“…𝑓𝑟𝑎𝑐𝑡𝑢𝑟𝑒 𝑖𝑛𝑑𝑒𝑥 = (((𝐷𝑇𝑐 > 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 + 𝑆𝑡𝑑𝑒𝑣) + (𝑀𝑆𝐹𝐿 < 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 − 𝑆𝑡𝑑𝑒𝑣) + (𝑅𝐻𝑂𝐵 < 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 − 𝑆𝑡𝑑𝑒𝑣) + (𝐶𝐴𝐿𝐼 > 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 + 𝑆𝑡𝑑𝑒𝑣) + (𝑃𝐸𝐹 > 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 + 𝑆𝑡𝑑𝑒𝑣))/𝑛 (1) where: Stdev = standar deviation Average = average N = number of thresholds tested Well logging plays a crucial role in identifying effective formations and providing reliable formation parameters by studying the response of logging tools and presenting data in a triple combo log curve [2]. Various log-derived fracture indicators can be combined, allowing for a wide range of inputs.…”

“…However, this does not align with the current state of hydrocarbon reserves from sedimentary rocks, which are increasingly depleting. Exploration is essential in the oil and gas industry, and well logging is a crucial technique used to analyze subsurface rock properties and locate hydrocarbon reserves [2]. These challenges have prompted the development of studies and concepts regarding alternative reservoirs, such as volcanic reservoirs.…”

Evaluating Hydrocarbon Prospects and Petrophysical Properties in Sepinggan Formation, East Kalimantan's Lower Kutai Basin

“…Oil and gas exploration is one such activity, requiring a diverse range of experts, including geologists, petrophysicists, reservoir engineers, and drilling engineers. Exploration is a critical aspect of the oil and gas industry, with formation evaluation being one of its essential components [1].…”