Shale compaction and abnormal pressure evaluation application to the offshore Mahakam

Bois, Michel; Grosjean, Yves; Pazzis, Louis de

doi:10.29118/ipa.2429.245.259

Cited by 7 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3) shows that the sedimentation rate during the last 8 Ma has been fairly constant at around 300 m Ma -1 . This ongoing deposition of fine-grained sediment has been interpreted previously as being responsible for the generation of overpressure by disequilibrium compaction in this area (Bois et al 1994;Bates 1996;Burrus 1998).…”

Section: Introductionmentioning

confidence: 93%

See 1 more Smart Citation

Overpressure-generating mechanisms in the Peciko Field, Lower Kutai Basin, Indonesia

Ramdhan

Goulty

2010

View full text Add to dashboard Cite

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACT:The Peciko Field contains gas in multiple stacked reservoirs within a Miocene 8 deltaic sequence. In the deeper reservoirs, gas is trapped hydrodynamically by high lateral 9 overpressure gradients. We have analysed overpressure and compaction in this field by using 10 wireline log, pressure, temperature, and vitrinite reflectance data. The top of overpressure is 11 located below 3 km burial depth, below the depth range for transformation of discrete 12 smectite to mixed-layer illite/smectite. Density-sonic and density-resistivity crossplots for 13 mudrocks show reversals within the transition zone into hard overpressure below 3.5 km 14 depth. Vitrinite reflectance measurements indicate that the start of unloading coincides with 15 the onset of gas generation. Moreover, mudrock density continues to increase with depth in 16 the overpressured section to values above 2.6 g cm -3 . We conclude that gas generation and 17 chemical compaction are responsible for overpressure generation, contradicting previous 18 interpretations that disequilibrium compaction is the principal mechanism for generating 19 overpressure in the Lower Kutai Basin. The particular circumstances which make our radical 20 interpretation plausible are that it is a warm basin with lateral reservoir drainage, so the 21 overpressured mudrocks are probably overcompacted as a result of diagenesis. 22 23

show abstract

Section: Introductionmentioning

confidence: 93%

“…A transition zone into hard overpressure is encountered in the field at depths of 11 000-14 000 ft (3350-4250 m). The primary mechanism responsible for overpressure generation in this area has been interpreted previously to be disequilibrium compaction (Bois et al 1994;Bates 1996;Burrus 1998).…”

Section: Introductionmentioning

confidence: 96%

Overpressure-generating mechanisms in the Peciko Field, Lower Kutai Basin, Indonesia

Ramdhan

Goulty

2010

View full text Add to dashboard Cite

show abstract

“…The cause of the hard overpressure in the Lower Kutai Basin has been attributed by previous studies to disequilibrium compaction associated with rapid burial (e.g. Bois et al,1994;Bates, 1996;Burrus, 1998). However, more recent studies have reappraised these analyses, and noted resistivity and sonic logs display reversals in the transition zone into hard overpressure.…”

Section: Introductionmentioning

confidence: 99%

The Resistivity Log and Its Role in Understanding Sediment Unloading in the Lower Kutai Basin, Indonesia

O’Connor,

Ramdhan,

Arifin

et al. 2023

Indonesian J. Geosci.

View full text Add to dashboard Cite

High overpressure is a critical drilling issue in the Lower Kutai Basin. Typical pore pressure prediction approaches involve an empirical relationship, such as Eaton’s method using sonic log data. In areas with high geothermal gradients, such as the Lower Kutai Basin, there is evidence for additional overpressure from gas generation such that sediment unloading must be considered to interpret pore pressure correctly. In this paper a repeatable deterministic model is presented for pore pressure from sonic data and, using selected wells from the Lower Kutai Basin, also the use of the resistivity log in a similar model. In the Lower Kutai Basin, sonic logs are often absent from the logging suite or otherwise running over limited intervals, making an alternative log-based prediction method particularly valuable. As a caveat, shallow freshwater encroachment is reported in the Lower Kutai Basin, means the shallow resistivity data can be problematic to use to define both top of overpressure and a normal compaction trend. Care must therefore be taken if resistivity is to be used for the interpretation of unloaded pore pressure, and chiefly applied and this likely to be more successful where encroachment is less pronounced, such as pro-delta shales. Assuming the additional care needed in using resistivity data, this paper suggests that resistivity can be a useful tool for pore pressure prediction in unloaded shale at elevated temperatures within the Lower Kutai Basin. At present the technique has been applied to only a limited dataset due to data availability limitations, but it is hoped with further refinement it will form a helpful additional approach in the pore pressure prediction toolkit. Keywords: pore pressure, resistivity, unloading, Lower Kutai Basin

show abstract

“…Rapid burial during the Neogene was thought by earlier researchers to have generated the overpressure by disequilibrium compaction (Burrus et al 1992;Bois et al 1994;Bates 1996;Burrus 1998). Although doubts had been expressed about the quality of the density logs, the low mudstone porosities observed in the zone of hard overpressure are inconsistent with the disequilibrium compaction mechanism.…”

mentioning

confidence: 99%

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

Ramdhan¹,

Goulty²

2018

Proceedings

View full text Add to dashboard Cite

Shale compaction and abnormal pressure evaluation application to the offshore Mahakam

Cited by 7 publications

References 0 publications

Overpressure-generating mechanisms in the Peciko Field, Lower Kutai Basin, Indonesia

Overpressure-generating mechanisms in the Peciko Field, Lower Kutai Basin, Indonesia

The Resistivity Log and Its Role in Understanding Sediment Unloading in the Lower Kutai Basin, Indonesia

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

Contact Info

Product

Resources

About