Detailed Lithological Study Leads to New Insights about the Pre-Tertiary and Tertiary Reservoirs in the Suban Gas Field, South Sumatra Basin, Indonesia

Mapping Intimacies ◽

10.29118/ipa21-g-91 ◽

2021 ◽

Author(s):

B. R. Permana

Keyword(s):

Seismic Data ◽

Common Knowledge ◽

Crystalline Rock ◽

Carbonate Reservoir ◽

Age Dating ◽

Integrated Analysis ◽

The South ◽

Gas Field ◽

Absolute Age ◽

Reservoir Facies

The basement igneous intrusive rock lithology in the South Sumatra Basin was previously suggested to be a solely granitic rock. It is also a common knowledge that the Miocene Baturaja Formation carbonates are one of the prolific reservoirs. However, after a comprehensive reservoir recharacterization had been conducted in the Suban Field, new insights regarding these two rock types were revealed. The basement lithology consists of a more complex metasediment containing Andesite, Granodiorite, and Gabbro and an Oligocene-age carbonate reservoir was also identified. The reservoir recharacterization was carried out by conducting an integrated analysis to reconstruct the complex reservoir configuration utilizing seismic data, core, cuttings, absolute age dating, and biostratigraphy. Seismic data was utilized as a general framework for reservoir architecture due to the resolution that allowed to describe the reservoir configuration in detail. Core and cuttings were used to identify the reservoir facies, and absolute age dating along with biostratigraphy were used to construct geochronology for each reservoir facies. Finally, well to well correlation was performed to reconstruct complex reservoir configurations. The result of the study indicated that the reservoir age in the field can be divided into two parts, pre-Tertiary (PRT) basement and Tertiary sediments. The PRT of Suban Field comprises several types of crystalline rock that will have different respond to the stresses and the Tertiary section that consists of clastic and several carbonate facies of different ages that vary across the study area. This study offers new insights regarding the basement configuration and the emerging carbonate play. Different igneous rock compositions reflect a complex magmatism process in South Sumatra. Oligocene carbonates that were identified in Suban could open the opportunity to discover a hydrocarbon-bearing Oligocene carbonate play in the South Sumatra Basin.

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3-D seismic imaging and seismic attribute analysis of genetic sequences deposited in low‐accommodation conditions

Geophysics ◽

10.1190/1.1444058 ◽

1996 ◽

Vol 61 (5) ◽

pp. 1351-1362 ◽

Cited By ~ 19

Author(s):

B. A. Hardage ◽

D. L. Carr ◽

D. E. Lancaster ◽

J. L. Simmons ◽

D. S. Hamilton ◽

...

Keyword(s):

Seismic Data ◽

Sediment Accumulation ◽

Gas Reservoirs ◽

Seismic Attribute ◽

Gas Field ◽

Reservoir System ◽

Depositional Processes ◽

Genetic Sequences ◽

Data Windows ◽

Reservoir Facies

A multidisciplinary team, composed of stratigraphers, petrophysicists, reservoir engineers, and geophysicists, studied a portion of Boonsville gas field in the Fort Worth Basin of North‐Central Texas to determine how modern geophysical, geological, and engineering techniques could be combined to understand the mechanisms by which fluvio‐deltaic depositional processes create reservoir compartmentalization in a low‐ to moderate‐accommodation basin. An extensive database involving well logs, cores, production, and pressure data from 200‐plus wells, [Formula: see text] [Formula: see text] of 3-D seismic data, vertical seismic profiles (VSPs), and checkshots was assembled to support this investigation. The reservoir system we studied was the Bend Conglomerate, a productive series of gas reservoirs composed of Middle Pennsylvanian fluvio‐deltaic clastics 900 to 1300 ft (275 to 400 m) thick in our project area. We were particularly interested in this reservoir system because evidence suggested that many of the sequences in this stratigraphic interval were deposited in low‐accommodation conditions (that is, in an environment where there was limited vertical space available for sediment accumulation), and our objective was to investigate how fluvio‐deltaic reservoirs were compartmentalized by low‐accommodation depositional processes. Using an extensive well log database (200 plus wells) and a core‐calibrated calculation of rock facies derived from these logs, we divided the Bend Conglomerate interval into ten genetic sequences, with each sequence being approximately 100 ft (30 m) thick. We then used local VSP and checkshot control to transform log‐measured depths of each sequence boundary to seismic two‐way time coordinates and identified narrow seismic data windows encompassing each sequence across the [Formula: see text] [Formula: see text] 3-D seismic grid. A series of seismic attributes was calculated in these carefully defined data windows to determine which attributes were reliable indicators of the presence of productive reservoir facies and which attributes could, therefore, reveal distinct reservoir compartments and potentially show where infield wells should be drilled to reach previously uncontacted gas reservoirs. Our best success was the seismic attribute correlations we found in the Upper and Lower Caddo sequences, at the top of the Bend Conglomerate. These sequences were deposited in a low‐accommodation setting, relative to other Boonsville sequences, and we found that reflection amplitude and instantaneous frequency, respectively, were reliable indicators of the areal distribution of reservoir facies in these low‐accommodation sequences.

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Geophysical pore type inversion in carbonate reservoir: integration of cores, well-logs, and seismic data (Yadana field, offshore Myanmar)

Geophysics ◽

10.1190/geo2020-0486.1 ◽

2021 ◽

pp. 1-69

Author(s):

Thomas Teillet ◽

François Fournier ◽

Luanxiao Zhao ◽

Jean Borgomano ◽

Fei Hong

Keyword(s):

Seismic Data ◽

Effective Medium Theory ◽

Rock Physics ◽

Carbonate Reservoir ◽

Well Logs ◽

Inversion Method ◽

Gas Field ◽

Medium Theory ◽

Scale Thickness ◽

Pore Types

Detection of pore types and diagenetic features from seismic data is a major challenge for the evaluation of carbonate reservoirs in the subsurface. Based on a detailed petrographical and petrophysical analysis of carbonate rock using optical and scanning electron microscopy, mercury-injection measurements, digital image analysis, and well logs, we have determined the potential of the geophysical pore type (αP) inversion a rock physics inversion scheme based on the differential effective medium theory – to quantitatively and qualitatively characterize the pore type distribution from acoustic data in the Yadana carbonate gas field (Early Miocene, offshore Myanmar). The geophysical pore type (αP) is revealed to be an upscalable parameter, whose depositional/diagenetic interpretation may be performed at well log and at seismic scales. We apply the inversion method on a 3D seismic data to map the reservoir-scale distribution and highlight the occurrence of laterally extended (100–1000 m) subseismic- to seismic-scale (thickness >5 m) geologic bodies. From this approach, two main reservoir geobodies are discriminated and interpreted in terms of depositional and diagenetic fabrics: (1) highly microporous, decameter-scale reservoir units (approximately 80% of the reservoir), mainly consisting of foraminiferal, red algae floatstone to rudstone with vuggy, moldic porosity, and characterized by moderate to high αP (0.11–0.20) and (2) thin, stratiform, cemented scleractinian floatstone/brecciated units (5–10 m; approximately 20% of the reservoir) with low microporosity and macroporosity and exhibiting low αP values (<0.11).

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