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Displacement pressure estimation from pore size (view source)
Revision as of 15:34, 31 January 2014
, 15:34, 31 January 2014Initial import
{{publication
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Predicting the occurrence of oil and gas traps
| chapter = Evaluating top and fault seal
| frompg = 10-1
| topg = 10-94
| author = Grant M. Skerlec
| link = http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
==Method==
Displacement pressure can be estimated from pore size using Washburn's<ref name=ch10r90>Washburn, E., W., 1921, Note on a method of determining the distribution of pore sizes in a porous material: Proceedings of the National Academy of Science, vol. 7, p. 115–116.</ref> equation,
:<math>\mbox{P}_{\rm d} = \frac{-2\gamma \cos \theta}{\mbox{r}}</math>
==Techniques for estimating ''r''==
Pore throat radius, ''r'', can be estimated in three ways:
* Thin-section analysis of pore throats;<ref name=ch10r20>Dullien, F., A., L., Dhawan, G., K., 1974, Characterization of pore structure by a combination of quantitative photomicrography and mercury porosimetry: Journal of Colloid and Interface Science, vol. 47, no. 2, p. 337–349., 10., 1016/0021-9797(74)90265-3</ref> Etris et al., 1988; ;<ref name=ch10r53>Macdonald, I., F., Kaufmann, P., Dullien, F., A., L., 1986, Quantitative image analysis of finite porous media 2: Specific genus of cubic lattice models and Berea sandstone: J. Microscopy, vol. 144, p. 297–316., 10., 1111/jmi., 1986., 144., issue-3</ref> see also <ref name=ch10r88>Wardlaw, N., C., 1990, Quantitative determination of pore structure and application to fluid displacement in reservoir rocks, in Kleppe, J., Berg, E., W., Buller, A., T., Hjemeland, O., Torsaeter, O., eds., North Sea Oil and Gas Reservoirs: London, Graham & Trotman, p. 229–243.</ref>
* Thin-section analysis of grain size and assumptions of spherical grains and rhombohedral packing<ref name=ch10r5>Berg, R., R., 1975, [[Capillary pressure]] in [[stratigraphic trap]]s: AAPG Bulletin, vol. 59, no. 6, p. 939–956.</ref>
* Empirical correlation of [[permeability]], [[porosity]], and pore throat radius (Wardlaw and <ref name=ch10r89>Wardlaw, N., C., Taylor, R., P., 1976, Mercury [[capillary pressure]] curves and the interpretation of pore structure and capillary behavior in reservoir rocks: Canadian Petroleum Geology Bulletin, vol. 24, no. 2, p. 225–262.</ref><ref name=ch10r94>Wells, J., D., Amafuele, J., O., 1985, Capillary pressure and permeability relationships in tight gas sands: SPE/DOE paper 13879.</ref><ref name=ch10r88 /><ref name=ch10r63>Pittman, E., D., 1992, Relationship of porosity and permeability to various parameters derived from mercury injection-capillary pressure curves for sandstone: AAPG Bulletin, vol. 76, no. 2, p. 191–198.</ref>
Although these methods can estimate the P<sub>d</sub> of sands, they do not apply easily to shales and finer grained rocks that comprise top seals. The assumptions of spherical grains and rhombohedral packing used to infer pore throat radius to not apply to shales that contain plate-like clay minerals.<ref name=ch10r5 />). Nor is the pore-size distribution easily determined from thin sections of fine-grained shales<ref name=ch10r44>Krushin, J., 1993, Entry pore throat size of nonsmectite shales, in Ebanks, J., Kaldi, J., Vavra, C., eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg Research conference, unpublished abstract.</ref> Use of permeability and porosity is thwarted by the lack of a distinct apex in the mercury injection data of low-permeability rocks (<ref name=ch10r63 /> as well as the difficulty of measuring the permeability of shales.
==Theory and experiment==
Predicting top seal capacity is difficult—even in idealized experiments in which all variables are known to a degree unobtainable in practical prospect assessment. The predicted height of hydrocarbon columns calculated from pore throat diameters in uniform glass bead packs is 160–500T larger than heights actually observed in experiments.<ref name=ch10r12>CatalanXiaown, L., F., Chatzis, I., Dullien, F., A., L., 1992, An experimental study of secondary oil [[migration]]: AAPG Bulletin, vol. 76, no. 5, p. 638–650.</ref> If we cannot predict the height of hydrocarbon columns trapped in a controlled experiment with uniform glass beads and known variables, then we must be cautious in prospect analysis.
==See also==
* [[Estimating displacement pressure]]
* [[Measuring Pd using mercury injection]]
* [[Estimating Pd from sedimentary facies and well logs]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Predicting the occurrence of oil and gas traps]]
[[Category:Evaluating top and fault seal]]
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Predicting the occurrence of oil and gas traps
| chapter = Evaluating top and fault seal
| frompg = 10-1
| topg = 10-94
| author = Grant M. Skerlec
| link = http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
==Method==
Displacement pressure can be estimated from pore size using Washburn's<ref name=ch10r90>Washburn, E., W., 1921, Note on a method of determining the distribution of pore sizes in a porous material: Proceedings of the National Academy of Science, vol. 7, p. 115–116.</ref> equation,
:<math>\mbox{P}_{\rm d} = \frac{-2\gamma \cos \theta}{\mbox{r}}</math>
==Techniques for estimating ''r''==
Pore throat radius, ''r'', can be estimated in three ways:
* Thin-section analysis of pore throats;<ref name=ch10r20>Dullien, F., A., L., Dhawan, G., K., 1974, Characterization of pore structure by a combination of quantitative photomicrography and mercury porosimetry: Journal of Colloid and Interface Science, vol. 47, no. 2, p. 337–349., 10., 1016/0021-9797(74)90265-3</ref> Etris et al., 1988; ;<ref name=ch10r53>Macdonald, I., F., Kaufmann, P., Dullien, F., A., L., 1986, Quantitative image analysis of finite porous media 2: Specific genus of cubic lattice models and Berea sandstone: J. Microscopy, vol. 144, p. 297–316., 10., 1111/jmi., 1986., 144., issue-3</ref> see also <ref name=ch10r88>Wardlaw, N., C., 1990, Quantitative determination of pore structure and application to fluid displacement in reservoir rocks, in Kleppe, J., Berg, E., W., Buller, A., T., Hjemeland, O., Torsaeter, O., eds., North Sea Oil and Gas Reservoirs: London, Graham & Trotman, p. 229–243.</ref>
* Thin-section analysis of grain size and assumptions of spherical grains and rhombohedral packing<ref name=ch10r5>Berg, R., R., 1975, [[Capillary pressure]] in [[stratigraphic trap]]s: AAPG Bulletin, vol. 59, no. 6, p. 939–956.</ref>
* Empirical correlation of [[permeability]], [[porosity]], and pore throat radius (Wardlaw and <ref name=ch10r89>Wardlaw, N., C., Taylor, R., P., 1976, Mercury [[capillary pressure]] curves and the interpretation of pore structure and capillary behavior in reservoir rocks: Canadian Petroleum Geology Bulletin, vol. 24, no. 2, p. 225–262.</ref><ref name=ch10r94>Wells, J., D., Amafuele, J., O., 1985, Capillary pressure and permeability relationships in tight gas sands: SPE/DOE paper 13879.</ref><ref name=ch10r88 /><ref name=ch10r63>Pittman, E., D., 1992, Relationship of porosity and permeability to various parameters derived from mercury injection-capillary pressure curves for sandstone: AAPG Bulletin, vol. 76, no. 2, p. 191–198.</ref>
Although these methods can estimate the P<sub>d</sub> of sands, they do not apply easily to shales and finer grained rocks that comprise top seals. The assumptions of spherical grains and rhombohedral packing used to infer pore throat radius to not apply to shales that contain plate-like clay minerals.<ref name=ch10r5 />). Nor is the pore-size distribution easily determined from thin sections of fine-grained shales<ref name=ch10r44>Krushin, J., 1993, Entry pore throat size of nonsmectite shales, in Ebanks, J., Kaldi, J., Vavra, C., eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg Research conference, unpublished abstract.</ref> Use of permeability and porosity is thwarted by the lack of a distinct apex in the mercury injection data of low-permeability rocks (<ref name=ch10r63 /> as well as the difficulty of measuring the permeability of shales.
==Theory and experiment==
Predicting top seal capacity is difficult—even in idealized experiments in which all variables are known to a degree unobtainable in practical prospect assessment. The predicted height of hydrocarbon columns calculated from pore throat diameters in uniform glass bead packs is 160–500T larger than heights actually observed in experiments.<ref name=ch10r12>CatalanXiaown, L., F., Chatzis, I., Dullien, F., A., L., 1992, An experimental study of secondary oil [[migration]]: AAPG Bulletin, vol. 76, no. 5, p. 638–650.</ref> If we cannot predict the height of hydrocarbon columns trapped in a controlled experiment with uniform glass beads and known variables, then we must be cautious in prospect analysis.
==See also==
* [[Estimating displacement pressure]]
* [[Measuring Pd using mercury injection]]
* [[Estimating Pd from sedimentary facies and well logs]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Predicting the occurrence of oil and gas traps]]
[[Category:Evaluating top and fault seal]]