Prediction of sealing capacity by the equivalent grain size method

Nakayama, Keisuke; Sato, Daichi

doi:10.1016/s0928-8937(02)80006-6

Cited by 11 publications

(4 citation statements)

References 9 publications

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“…Correspondingly, the breakthrough median pressures in the WF-LM1 (58–81 MPa) and LM2-LM3 (80–90 MPa) members show a similar rule compared with that for the breakthrough pressure (Figure c). The capacities of caprocks to seal hydrocarbons depended on the sizes of the pore throats within the interconnected pore system that the leaking hydrocarbons would penetrate. ,, Lash (2006) concluded that the median pore throat diameter negatively correlated with sealing capacity in shale samples. Therefore, the breakthrough radius and medium radius can reflect the maximum pore throat of hydrocarbon breakthrough a seal rock, the smaller the pore throat was, the stronger the sealing ability was .…”

Section: Discussionmentioning

confidence: 99%

Sealing Mechanism of the Roof and Floor for the Wufeng-Longmaxi Shale Gas in the Southern Sichuan Basin

et al. 2020

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Exploration activities revealed that high-efficient sealings of the roof and floor for the Wufeng-Longmaxi (WF-LM) gas-bearing shales were the indispensable conditions for shale gas preservation and enrichment in the Sichuan Basin. However, little attention has been paid to their sealing mechanism and sealing model. In this paper, systematic core samplings (Ning-A and YY-B) and a series of supporting experiments (geochemical and rock components analysis, physical properties measurements, pore structure characterization, and sealing capacity tests) were carried out for further analyses and discussion. Results show that the roof and floor have four-level vertical sealing capacities for the WF-LM shale gas, where the direct roof is the argillaceous shale and silty shale of the LM1–2 and LM1–3 members (the middle and upper members of the first part of the Longmaxi Formation) and the floor is the nodular limestone of the Linxiang Formation (LX Fm.). Heterogeneous lithofacies and steady thickness of the roof and floor lead to strong lithologic sealing capacities. The roof and floor are characterized by higher density and water saturation, lower porosity and permeability, lower pore volumes, and poor pore connectivity, resulting in developing larger capillary pressure at the interface and thereby forming strong petrophysical sealing capacities. Based on the sealing model, the great sealing capacities are attributed to the well-developed laminar fabrics, lower TOC content, less (organic matter) OM-related pores, and the compacted clay mineral fragments reoriented into lamellar ones, as well as the unconnected clay-related interparticle pores in the roof shales and high breakthrough pressure in the floor. This study will provide guidance for evaluating the preservation condition and sweet spot prospecting of shale gas exploration in the Sichuan Basin.

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Section: Discussionmentioning

confidence: 99%

Sealing Mechanism of the Roof and Floor for the Wufeng-Longmaxi Shale Gas in the Southern Sichuan Basin

et al. 2020

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“…The grainsize-based approach to estimate permeability and capillary seal capacity of intra-delta mudstones involves a number of assumptions and approximations that introduce uncertainty in the calculation results. Probably the main uncertainty is in the use of the equivalent grain size method of Nakayama and Sato (2002) to calculate pore throats (Ten Veen et al, 2013). Knowing that capillary seal capacity is a multi-scale property, and that mudstones also act as permeability seals and faulting and fracture zones crossing the mudstones influence the seal capacity, the grainsize-based method should be seen as a first phase of a more comprehensive approach to estimate preserved gas columns in bright spots in the SNS delta (Ten Veen et al, 2013;.…”

Section: Discussionmentioning

confidence: 99%

“…These equations were developed by Aplin (2004, 2010) for calculating mudstone porosity and permeability, respectively. The pore throats are calculated from approaches that use the calculated porosities and median grain size, based on equations published by Nakayama and Sato (2002). Knowing the pore throats, the sealing capacity could be determined by estimating the water densities from WFT pressure measurements, and gas densities and gas-water interfacial tensions from established relations using known temperature and pressure changes with depth (NIST Chemistry WebBook: http:// webbook.nist.gov/chemistry/fluid/; Nordgård Bolås et al, 2005, respectively).…”

Section: Entrapment and Sealsmentioning

confidence: 99%

Generation, migration, entrapment and leakage of microbial gas in the Dutch part of the Southern North Sea Delta

Verweij

Nelskamp

Veen

et al. 2018

Marine and Petroleum Geology

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“…Trap) (Nakayama and Sato, 2002;Sawamura and Nakayama, 2005)においては，集積され得 A1 STEP 1: Estimation of pseudo-regional trend under abnormally high pressure condition. Pseudo-regional gas/oil/water trends are drawn from observed pressure data for each phase.…”

mentioning

confidence: 99%

Unexpected Form of Oil Accumulation under Abnormally High Pressure Condition

Nakayama¹,

Takahashi²,

Katoh³

2013

J. Geogr.

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Oil and gas column heights and accumulation status within the reservoir can be understood from the relationship between top seal capacity and height of trap (level of spill point) . In previous studies, such evaluations were limited to hydrostatic conditions. This paper presents a study on abnormally high pressure conditions where pressure increases stepwise in sandstone layers toward the core of a folded structure, as in the case study offshore Sabah, Malaysia. First, the stepwise convex-upward shaped oil water contact (OWC) is investigated in the field, from which it is concluded that abnormally high pressures caused the conditions. A gradually progressive pressure increase toward the core axis within the folded structure contributed to the reduction in the column height of oil accumulated at the central part, showing a stepwise upwardly convex OWC. Second, an attempt is made to quantitatively predict conditions by applying data from only the exploration well. Estimated oil reserves based on this form of accumulation were found to be more than double that assumed by the conventional flat OWC. This concept will widen the scope of applications for future oil exploration.

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Prediction of sealing capacity by the equivalent grain size method

Cited by 11 publications

References 9 publications

Sealing Mechanism of the Roof and Floor for the Wufeng-Longmaxi Shale Gas in the Southern Sichuan Basin

Sealing Mechanism of the Roof and Floor for the Wufeng-Longmaxi Shale Gas in the Southern Sichuan Basin

Generation, migration, entrapment and leakage of microbial gas in the Dutch part of the Southern North Sea Delta

Unexpected Form of Oil Accumulation under Abnormally High Pressure Condition

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