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  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

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The displacement pressure (P_d) is routinely inferred by forcing mercury into the pore space of a sample (cores or cuttings) and measuring the percent of mercury saturation vs. increasing pressure.

The displacement pressure (P_d) is routinely inferred by forcing mercury into the pore space of a sample ([[Core description|cores]] or [[Mudlogging: drill cuttings analysis|cuttings]]) and measuring the percent of mercury saturation vs. increasing pressure.

==Procedure==

==Procedure==

[[file:evaluating-top-and-fault-seal_fig10-48.png|300px|thumb|{{figure number|1}}Typical mercury capillary curve for a sandstone.<ref name=ch10r67>Schowalter, T., T., 1979, [http://archives.datapages.com/data/bulletns/1977-79/data/pg/0063/0005/0700/0723.htm Mechanics of secondary hydrocarbon migration and entrapment]: AAPG Bulletin, vol. 63, no. 5, p. 723–760.</ref>]]

[[file:evaluating-top-and-fault-seal_fig10-48.png|300px|thumb|{{figure number|1}}Typical mercury capillary curve for a sandstone.<ref name=ch10r67>Schowalter, T., T., 1979, [http://archives.datapages.com/data/bulletns/1977-79/data/pg/0063/0005/0700/0723.htm Mechanics of secondary hydrocarbon migration and entrapment]: AAPG Bulletin, vol. 63, no. 5, p. 723–760.</ref>]]

[[:file:evaluating-top-and-fault-seal_fig10-48.png|Figure 1]] shows a typical mercury capillary curve for a sandstone. Mercury is first forced into the largest connected pore throats. Saturation increases with increasing pressure as mercury continues to be forced into progressively smaller pore throats.

[[:file:evaluating-top-and-fault-seal_fig10-48.png|Figure 1]] shows a typical mercury capillary curve for a sandstone. Mercury is first forced into the largest connected [[Pore throat size and connectivity|pore throats]]. Saturation increases with increasing pressure as mercury continues to be forced into progressively smaller pore throats.

==Values of displacement pressure>==

==Values of displacement pressure>==

Samples for mercury injection laboratory analysis can include cores as well as cuttings. Measurements made from cuttings do not yield the same value as those from cores, so they require an empirical correction factor that ranges from 15–250 psi.<ref name=ch10r78>Sneider, R., M., Bolger, G., 1993, Estimating seals from wireline logs of clastic seals and reservoir intervals, in Ebanks, J., Kaldi, J., Vavra, C., eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg Research conference, unpublished abstract.</ref>

Samples for mercury injection laboratory analysis can include cores as well as cuttings. Measurements made from cuttings do not yield the same value as those from cores, so they require an empirical correction factor that ranges from 15–250 psi.<ref name=ch10r78>Sneider, R., M., Bolger, G., 1993, Estimating seals from wireline logs of clastic seals and reservoir intervals, in Ebanks, J., Kaldi, J., Vavra, C., eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg Research conference, unpublished abstract.</ref>

Seals with low permeability and small pore throats may require longer equilibration times during mercury injection.<ref name=ch10r87>Vavra, C., L., Kaldi, J., G., Sneider, R., M., 1992, [http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0006/0000/0840.htm Geological applications of capillary pressure: a review]: AAPG Bulletin, vol. 76, no. 6, p. 840–850.</ref>

Seals with low [[permeability]] and small pore throats may require longer equilibration times during mercury injection.<ref name=ch10r87>Vavra, C., L., Kaldi, J., G., Sneider, R., M., 1992, [http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0006/0000/0840.htm Geological applications of capillary pressure: a review]: AAPG Bulletin, vol. 76, no. 6, p. 840–850.</ref>

==Converting laboratory measurements==

==Converting laboratory measurements==

:<math>\mbox{P}_{\rm dh} = \frac{\gamma_{\rm h}\cos \theta_{\rm h}\mbox{P}_{\rm dm}}{\gamma_{\rm m} \cos \theta_{\rm m}}</math>

:<math>\mbox{P}_{\rm dh} = \frac{\gamma_{\rm h}\cos \theta_{\rm h}\mbox{P}_{\rm dm}}{\gamma_{\rm m} \cos \theta_{\rm m}}</math>

Displacement pressures measured in the air-mercury system are then converted to the hydrocarbon–water system at subsurface conditions. To convert, we must know the temperature, pressure, [[wettability]], and coefficient of interfacial tension for the hydrocarbon phase. These parameters are commonly inferred from the composition, gas–oil ratio, and API gravity.<ref name=ch10r67 /><ref name=ch10r87 /> For the air–mercury system, the wettability of mercury is 140° (cos 140 = 0.766). The coefficient of interfacial tension for mercury is 485 dynes/cm.<ref name=ch10r87 />

Displacement pressures measured in the air-mercury system are then converted to the hydrocarbon–water system at subsurface conditions. To convert, we must know the temperature, pressure, [[wettability]], and coefficient of interfacial tension for the hydrocarbon phase. These parameters are commonly inferred from the composition, http://www.enggcyclopedia.com/2012/03/gas-oil-ratio-gor/ [gas–oil ratio], and [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=API%20gravity API gravity].<ref name=ch10r67 /><ref name=ch10r87 /> For the air–mercury system, the wettability of mercury is 140° (cos 140 = 0.766). The coefficient of interfacial tension for mercury is 485 dynes/cm.<ref name=ch10r87 />

==See also==

==See also==