FACIES ANALYSIS AND RESERVOIR DISTRIBUTION OF SANDSTONE IN LOWER GITA MEMBER , TALANG AKAR FORMATION, YVONNE B FIELD, SUNDA BASIN

• Main Author: HARDIANTO GAJAH - NIM 22014025, NOVERDI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29716
• Institution: Institut Teknologi Bandung

<p align="justify">Yvonne B field located in the western part of Sunda Basin has been produced oil from sandstone of Lower Gita in Talang Akar Formation. Considering the OOIP of this field approximately around 55.3 MMBO, the overall produced hydrocarbon has produced only around 32%. Oil production was maintained by drilling infill well and water injection. <br /> <br /> <br /> This study conducted to understand the reservoir distribution of Lower Gita Sandstone, through facies analysis based on core, sidewall core, wireline log, and seismic datas. Using lithofacies approach, eight facies defined in this interval, such as cross bedding sandstone (Spt), sandstone with mud-drape lamination (Sl), flaser sandstone (Sf), coarse sandstone (Sm), sandy /bioturbated claystone (Fsb), carbonaceous claystone (Fc), lenticular claystone (Fl), and coal (C). Considering the presence of mud-drape structure, flaser-lenticular sandstone,generally fine sand-clay grain size, and fining upward electrofacies pattern, the depositional environment in this interval interpreted as tide-dominated estuary. Biostratigraphy analysis also interpreted the Lower Gita Member as estuary affinity. <br /> <br /> <br /> Depositional environment model generated by integrating sand thickness map of Lower Gita interval with isochron map and seismic amplitude attribute map. Seismic data indicating there are local highs to the west of the study area. There are saddle between highs, interpreted as the river valley in the upstream of estuary system. Hence the estuaries have West-East trend. <br /> <br /> <br /> Porosity and permeability data used to define reservoir quality of Lower Gita Sandstone are obtained from petrophysical well log calculation (ELAN) and calibrated with core data. The conclusion is Sandstone A consist of cross bedding sandstone (Spt) and flaser sandstone (Sf). Sandstone B that consist of sandstone with mud drape (Sl), flaser-lenticular sandstone and coarse sandstone (Sm). Comparing four reservoir facies, coarse sandstone have the best reservoir quality. <br /> <br /> <br /> After considering isopach map, seismic attributes map, and porosity & permeability distribution map, the potential infill well located ± 800m to the southwest of Krisna-12. The other alternative is located ± 1300m to the west of Yvonne B-6.<p align="justify"> <br />