GEOMECHANICAL STUDY AND BRITTLENESS INDEX FOR EVALUATION SHALE GAS POTENCY BATU KELAU FORMATION KUTAI BASIN

• Main Author: Radityo, Daniel
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/32338
• Institution: Institut Teknologi Bandung

Shale gas is gas formed in the source rock, that have shale form, and as a reservoir rock. Accumulation shale gas occured because have low value of porosity and permeability. Shale gas needs geomechanic, geochemistry, and petrophysic study formation as source rock and as reservoir rock. This research have a purpose to explain shale facies characterization process Batu Kelau Formation, based on differences in geological conditions, geomechanic, geochemistry; and provide information about appropriate artificial fracture criteria for gas distribution at each shale facies Batu Kelau Formation to increase production. The research done on Batu Kelau Formation at Kutai Basin, East Kalimantan Province. This research uses field report, wireline well log, seismic, and geochemistry. Wireline well log processed, then produce shale petrophysic, geomechanic, and geochemistry. Field report and XRD done for support wireline well log data as stratigraphy correlation. After that, interpret the horizon Batu Kelau Formation with its fault for seismic interpretation. Result of seismic interpretation produce Depth Structure Map, Thickness Map, and Paleogeografi Map Late Eocene age Batu Kelau Formation. Volume Shale Map, Shale Facies Map, Brittleness Index Map, and TOC Distribution Map obtained from the petrophysic results. TOC, BI and volume shale data then combined so it can created Batu Kelau Formation Shale Gas Potency Map. The petrophysical process is divided into three stage: shale property petrophysic that discusses shale volume, mineral volume, porosity, permeability, water saturation geomechanic petrophysic that discusses UCS, poisson ratio, young modulus, brittleness index; and geochemistry petrophysic that discusses TOC Passey method. Determination of brittleness index uses brittleness index average method by using poisson ratio, and young modulus parameters. Calculation of TOC Passey method uses resistivity log and sonic log. Results of shale property petrophysic, geomechanic petrophysic, and geochemistry petrophysic are combined and then analyzed. Batu Kelau Formation is gray shale, compact, there are silt nodules, not carbonaceous, contains carbon, freactured localy. This formation deposited at middle neritic – upper bathyal with Late Eocene age. Analysis shale geomechanic petrophysic log Batu Kelau Formation Kutai Basin have value of young modulus (E) 26,06 – 118,99 Mpa, value of poisson ratio (v) 0,27 – 0,40, value of UCS 9,15 – 262,82 MPa, dan value of Brittleness Index (BI) 0,22 – 0,93, average 0,57. Average of Brittleness Index Batu Kelau Formation Kutai Basin is brittle category. Analysis geochemistry Batu Kelau Formation Kutai Basin which is done from shale sample geochemistry laboratory have value of total organic carbon (TOC) from poor – good (0 – 1,06%) and log data (0 – 7,1%), with maturity temperature partly immature partly mature (208 – 454oC), value of Ro (0 – 1,16%), value of Hydrogen Index (0 – 291) which is gas with organic material type III and IV. Batu Kelau Formation Kutai Basin have property that meets the criteria artificial fracture so the gas can flow. Total gas in place potency shale gas resource Batu Kelau Formation in Kutai Basin is 3,479 TCF.