GEOCHEMICAL AND GEOMECHANICAL STUDY OF LOWER BAONG FORMATION FOR PRELIMINARY UNCONVENTIONAL GAS SHALE PROSPECTIVITY

• Main Author: BAHESTI, FATRIAL
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/15649
• Institution: Institut Teknologi Bandung

The most common fallacy in evaluating shale gas potential in a basin is treated similar to those produced in the United States. In fact, each basin has unique characteristics that influence shale facies type and depositional. Lower Baong Formation is responsible for source rock filled up sandstones reservoir in the oil and gas field in the southeastern part of North Sumatra Basin. This study reveals the data and facts from the laboratory, drilling, wireline well logs and seismic through the integrated study of geochemistry, geomechanics and geological synthesis of Lower Baong Formation. An understanding of shale geochemistry, mineralogy and geomechanics is very important to understand how the shale reservoir has the potential to reserve and produce when carried out stimulation. Geochemical laboratory analysis is used to determine the richness, maturity and kerogen type. This information is limited to a certain depth point, so that it is necessary to conduct calibrations in order to estimate the shale productive reservoir interval on a wireline log scale. Limited core data and rock mechanics laboratory analysis represented by mineralogy and petrography then also calibrate wireline logs. Thus, geochemical and geomechanical log model tied to the seismic data, is a very useful tool for formation evaluation and broaden the understanding of reservoir facies distribution laterally and vertically in the borehole. Understanding shale facies needed to design fracturing horizontal hole in more detail. This study also classify shale based on organic richness, maturity, type, shale strengthness, shale brittleness and clay content. Shale facies in Lower Baong shale can be divided into 3 facies based on sweet spot area. Siliceous calcareous mudstone has high potential for shale gas with TOC values of 2-3.5%, kerogen type of II-III, maturity depth from 2300 m, sweet spot thickness of 350-425 m, UCS values of 10000-18000 psia, Young modulus of 3000-4000 psia, Poisson ratio of 0.18-0.22 and associated with foreland basin fill deep. Silty-shaly dolomitic mudstone has medium potential for shale gas with TOC values of 1.5-2.5%, kerogen type of II-III, maturity depth from 2200 m, sweet spot thickness of 200-325 m, UCS values of 8000-10000 psia, Young modulus of 2300-2600 psia, Poisson ratio of 0.21-0.23 and associated with foreland basin fill slope. Silty-shaly calcareous mudstone has medium potential for shale gas with TOC values of 0.8-2%, kerogen type of II-III, maturity depth from 2100 m, sweet spot thickness of 80-125 m, UCS values of 6000-8000 psia, Young modulus of 2200 psia, Poisson ratio of 0.22-0.24 and associated with foreland basin fill edge. <br /> <br /> <br /> <br /> <br /> The systematic and integrated approach for geochemical, geomechanical and geological synthesis for shale gas evaluation can help to realize the shale gas concept into shale gas potential in order to reduce exploration risk and its uncertainties.