Bulletin of Earth Sciences of Thailand

Channel Evolution in Southern Pattani Basin, Gulf of Thailand from Pliocene to Present Day

KAUNGKHANT ZAW — Thu, 30 Jul 2026 00:00:00 +0700

Channel evolution in southern Pattani Basin, Gulf of Thailand was systematically characterized across three stratigraphic intervals corresponding to the Pliocene (~5Ma), Pleistocene (~2Ma), and present-day seabed. These intervals were examined using Root-Mean-Square (RMS) amplitude, variance attribute, and morphometric analysis within Petrel 2017. A total of nine sub-units were identified and key parameters including sinuosity index (SI), channel width, channel belt width, orientation, and incision depth were measured from more than 35 channel segments. The results indicate that sea-level fluctuation was the primary control on channel development; Highstand conditions favored highly sinuous meandering channels with SI values reaching 2.24 with an average of 1.74 , whereas lowstand periods were characterized by straighter and more deeply incised channels with SI values approaching 1.00 with an average of 1.08. A progressive reduction in sinuosity through the Pleistocene succession records sustained base level fall associated with glacial interglacial cycles. Structural inheritance exerted a secondary influence with WSW directed drainage locally aligned with NW-SE fault systems inherited from Paleogene rifting. Reoccupation of older valleys by younger channels resulted in vertically stacked channels bodies, reflecting repeated channel reuse through time. These observations provide new insights into large Neogene-Quaternary channel evolution and sediment distribution within the Pattani Basin.

3D Fault Architecture and Coal-Seam Continuity in the Central Sub-basin, Mae Moh Basin, Northern Thailand

Suchat Sooksrisawat — Thu, 30 Jul 2026 00:00:00 +0700

The Mae Moh Basin hosts Thailand’s largest lignite mine, where planned underground development requires an accurate understanding of fault geometry and coal-seam continuity. This study integrates a newly acquired high-resolution, depth-domain 3D seismic dataset covering approximately 9.6 km² with borehole data to construct a mine-focused 3D structural model of the Central Sub-basin. The Red Bed, K, Q, and R horizons were interpreted together with fault surfaces to characterize fault orientation, linkage, vertical extent, dip variation, and their effects on the coal-bearing succession. The interpreted network is dominated by N–S- to NW–SE-striking normal faults. Short, discontinuous fault segments at shallow levels commonly link downward into larger composite surfaces. Major faults exhibit listric geometries, with steep upper segments progressively flattening below the principal coal seams. Fault density and displacement generally increase with depth, resulting in greater structural compartmentalization of the R seam than of the shallower K and Q seams. The K and Q seams remain laterally continuous across much of the survey but are locally offset, deformed, or omitted near major fault zones. In the eastern part of the study area, the no-coal area is associated with linked east-dipping listric faults that structurally omit and juxtapose parts of the coal-bearing succession. The resulting 3D fault model improves the delineation of fault-bounded coal blocks and provides a geological framework for coal-reserve estimation, underground mine planning, targeted drilling, and assessment of fault-related geological uncertainty.

A Geothermal Heat Assessment of the Suphan Buri Basin, Thailand, Using Horner-Corrected Bottom-Hole Temperatures

BA HEIN KYAW — Thu, 30 Jul 2026 00:00:00 +0700

The Suphan Buri Basin is a Cenozoic half-graben in central Thailand with a mature petroleum history and extensive legacy subsurface dataset that can be re-purposed for geothermal screening. This study presents an integrated geothermal play-fairway assessment that estimates true formation temperature from bottom-hole temperature (BHT) records using the Horner method, rather than a depth-only empirical correction. The complete 67-well study area inventory was screened, and 25 wells were found to record two or more wireline logging-rum maximum temperatures at approximately the same depth, together with the elapsed time after the end of mud circulation (EOC). These wells meet the data requirements of a Horner correction. For each well, the static formation temperature (T_f) was obtained by extrapolating the successive logging-run temperatures to infinite shut-in time, from which an apparent geothermal gradient and the depths to target temperatures were derived. Horner-corrected formation temperatures range from about 88 to 154 °C, and apparent gradients from about 39 to 51 °C/km (basin median ≈ 44 °C/km), in close agreement with the ~42 °C/km previously reported from BP1-well thermal-history modelling. The temperature-depth data define a coherent, near-linear basin trend (R² ≈ 0.83), consistent with a predominantly conduction-dominated regime modified locally by fault-controlled fluid flow. Well BS1 (Ban Don Sa-Nuan) is the strongest thermal anomaly, with T_f ≈ 154 °C, a gradient of ~50 °C/km, and 150 °C at about 2.45 km. Play-fairway mapping that integrates corrected temperature, gradient and depth-to-150 °C with the seismically interpreted structural framework identifies the Ban Don Sa-Nuan–Sang Krajai–U-Thong trend as the most favourable fairway. The workflow provides a transparent, reproducible framework for preliminary geothermal screening of data-rich sedimentary basins in Thailand, and a basis for evaluating reservoir quality, fluid productivity, and development concepts including direct use, binary-cycle power and enhanced geothermal systems (EGS).

Machine-Learning-Assisted Seismic Facies Screening of Reservoir-Seal Architecture for CO₂ Storage in the Nong Phak Chi Field, Thailand

Rattanaporn Thongson, Sukonmeth Jitmahantakul — Thu, 30 Jul 2026 00:00:00 +0700

Geological carbon capture and storage (CCS) requires secure reservoir-seal systems and robust assessment of additional containment. This study screens potential secondary CO₂-containment pairs and additional reservoir candidates in the depleted Nong Phak Chi field, Suphan Buri Basin, Thailand. The workflow integrates Relative Geological Time (RGT) modelling, horizon-stack interpretation, multi-attribute seismic facies classification using an Unsupervised Vector Quantizer (UVQ) neural network, and seismic-to-well calibration across four wells. A seven-attribute dataset derived from the conditioned 3D seismic volume was partitioned into three seismic facies classes. After calibration with well-log data, the classes were interpreted as sandstone-prone, silty sandstone-prone, and shale-prone facies. The UVQ model produced a 94% average vector-matching score, which indicates internal classification consistency rather than independent lithological prediction accuracy. Horizon 24/S5 is the preferred primary reservoir candidate for CO₂ injection, and the overlying shale-rich Horizon 53 is the interpreted primary seal. Horizon 58 is a potential CO₂-accumulation interval above the primary reservoir-seal system, and Horizon 62 is a potential upper seal. Together, H58-H62 form the most plausible candidate secondary-containment pair. In contrast, Horizon 9/D6 lies below S5 and is therefore treated as a separate deeper reservoir candidate for dedicated CO₂ injection, not as a secondary trap or secondary-containment interval. The results indicate a multilayer reservoir-seal architecture in the Nong Phak Chi field. Confirmation of long-term storage performance will require petrophysical analysis, fault-seal assessment, static reservoir modelling, dynamic CO₂ flow simulation, and geochemical and geomechanical evaluation.