Two-step Wireline Log Analysis of Overpressure in the Bekapai Field, Lower Kutai Basin, Indonesia

Ramdhan, A.; Goulty, N.

doi:10.3997/2214-4609.201800763

Cited by 3 publications

(7 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This causes dissolution and precipitation of rock, and mainly causes cementation (leading to very low porosity rock). In diagenetically-influenced mudstones, pore pressure may be underestimated, if mechanical-compaction models is assumed, because the effective stress may be overestimated (Ramdhan and Goulty, 2017).…”

Section: Theorymentioning

confidence: 99%

“…As a rule of thumb, it has been argued that empirical methods for pore pressure prediction do not work for mudstone temperatures greater than around 70 °C, due to pronounced effect of chemical compaction (diagenesis), because that will tend to remove mudstones from their position on the NCT (Ramdhan and Goulty, 2017; Swarbrick, 2002). However, that point varies from basin to basin.…”

Section: Theorymentioning

confidence: 99%

“…Cementation generally reduces the porosity relative to normal compaction, and if effective-stress methods for pressure prediction are used in this compaction domain, the pore pressure may be underestimated. Ramdhan and Goulty (2017) proposed a method to predict pore pressure where chemical compaction plays an important role, at temperatures of around 100 °C. This effect was not considered in our study where the temperatures are generally lower than 100 °C, but the possible effect of chemical processes is important to bear in mind, especially for the deeper and hotter intervals.…”

Section: Theorymentioning

confidence: 99%

“…In many offshore basins around the world, pore pressure has been successfully predicted based on the principles of mechanical compaction (Eaton, 1975; Bowers, 1995; Kumar et al., 2006) and chemical compaction (Bowers, 1995; Ramdhan and Goulty, 2017). However, it was initially unclear to what extent these models can be applied to this basin.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Assessment of mudstone compaction in exploration wells in the Rovuma Basin, offshore Mozambique

Nhabanga

Ringrose

2019

Heliyon

View full text Add to dashboard Cite

In order to develop an improved pore pressure prediction model for the overburden mudstones in the Rovuma Basin, offshore Mozambique, we apply Eaton's method to example well data from three exploration wells, which intersect Quaternary, Tertiary and Cretaceous sediments over depth intervals down to ∼3 km below seafloor. The predictive method only included the effects of mechanical compaction, which is a reasonable assumption for the low-temperature shallow sections. We found that Eaton's method applied to resistivity and acoustic log attributes works well and can be used to identify the mudstones that display over-pressured or normally pressured sections. The predicted pore pressures showed a good match to pore pressures in permeable formations. Using this calibration, we derived an improved pore-pressure prediction method for these wells and for the Rovuma Basin in general. The resulting model should give a good basis for future analysis of compaction processes and pore pressure in this basin.

show abstract

Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Assessment of mudstone compaction in exploration wells in the Rovuma Basin, offshore Mozambique

Nhabanga

Ringrose

2019

Heliyon

View full text Add to dashboard Cite

show abstract

“…Numerical models that involve a complete inclusion and description of chemical and physical phenomena, such as coupled thermal and fluid flow processes have been developed and calibrated with exploration well and seismic data (Marín-Moreno et al, 2013b;Colombo et al 2017). These models use empirical methods applied to wireline-logs such as Eaton's Method (Eaton 1975;van Ruth et al 2004;Ramdhan & Goulty 2018) to test model predictions, using advanced geophysical inversion techniques.…”

Section: The Role Of Chemical Processesmentioning

confidence: 99%

Predicting fluid pressure in sedimentary basins from seismic tomography

O’Reilly

Prada

Lavoué

et al. 2019

Geophysical Journal International

View full text Add to dashboard Cite

SUMMARY Gravitational compaction of thick (2–10 km) sediment accumulations in sedimentary basins is controlled by the interplay of mechanical and chemical processes that operate over many orders of magnitude in spatial scale. The compaction of sediments into rock typically involves a density increase of ≈500 to 1000 kg m−3, occurring over a depth-scale of several kilometres. The volume decrease in the compacting sediments releases vast volumes of water, which plays an important part in the global hydrological cycle and also in tectonic and geochemical processes; including the formation of hydrocarbon and mineral deposits. This study utilizes recently developed tomographic seismic images from the Porcupine Basin, which lies in the deep-water North Atlantic Ocean. A generic method for predicting fluid pressure variations that are driven by gravitational compaction is developed over the scale of the entire sedimentary basin. The methodology is grounded upon both observational evidence and empirically based theories, relying on geophysical measurements and relationships between sediment porosities and densities. The method is based upon physical concepts that are widely used in the petroleum industry and applied extensively in models of overpressure development in sedimentary basins. Geological and geophysical data from exploration wells are used to test the predictions of the method at two locations within the basin and are found to be in good agreement with the theory.

show abstract

Use of rock‐physics analysis of well logs to determine compaction history of Cretaceous shales in the Rovuma basin, Offshore Mozambique

Nhabanga

Ringrose

Holt

2021

Geophysical Prospecting

View full text Add to dashboard Cite

Cretaceous shales from the emerging gas province of the Rovuma basin are examined using well‐log data from two exploration wells. The P‐wave acoustic impedance (AIp) data were estimated, and then brittleness and ductility were assessed within the framework of the Reuss–Voigt limits for acoustic impedance. We then predicted the shale consolidation using a weighting function (Wc) which varies between 0 for the case of grains in suspension (the Reuss limit) and 1 for the case of consolidated rock or cemented shale (the Voigt limit). At the Reuss limit, the formation AIp is highly sensitive to pressure while at the Voigt limit the formation AIp is insensitive to pressure. For the wells in this study, most data plot close to the lower bound with Wc < 0.5, hence showing a significant sensitivity to pressure. Although the Cretaceous shales in the Rovuma basin are dominated by a mechanical compaction regime, some onset of chemical compaction is observed. The rock‐physics analysis showed that the same shale in these two exploration wells had very distinctive and contrasting elastic properties. The deeper well interval clearly shows a ductile shale while the shallower well shows a range of ductile to brittle behaviour matching with the onset of chemical diagenesis at temperatures >58°C. These differences in the development and rate of chemical diagenesis in the same formation are likely due to contrasts in the rate of burial and have important implications for future seismic exploration studies.

show abstract

Two-step Wireline Log Analysis of Overpressure in the Bekapai Field, Lower Kutai Basin, Indonesia

Cited by 3 publications

References 21 publications

Assessment of mudstone compaction in exploration wells in the Rovuma Basin, offshore Mozambique

Assessment of mudstone compaction in exploration wells in the Rovuma Basin, offshore Mozambique

Predicting fluid pressure in sedimentary basins from seismic tomography

Use of rock‐physics analysis of well logs to determine compaction history of Cretaceous shales in the Rovuma basin, Offshore Mozambique

Contact Info

Product

Resources

About