Carbonate Porosity Families and Their Reservoir Potential* Robert F. Lindsay1 Search and Discovery Article #40643 (2010) Posted November 22, 2010
* Adapted from an oral presentation at AAPG Annual Convention and Exhibition, New Orleans, Louisiana, USA, April 11-14, 2010 1
Saudi Aramco, Dhahran, Saudi Arabia. (
[email protected])
Abstract Variations in carbonate porosity abundance and types are important contributors toward the creation of heterogeneous carbonate reservoirs. To assess reservoir potential and quantify the role of porosity variations, and to refine existing classification schemes of carbonate porosity, a pragmatic scheme is proposed wherein four porosity families are defined: 1) micro-porosity; 2) meso-porosity; 3) macro-porosity; and 4) megaporosity defined by a combination of pore type, pore size, pore throat radii size, and crystal-particle size. They are determined by detailed core/outcrop description, reflected light petrography, thin section transmitted light petrography, scanning-electron microscopy (SEM), and high-pressure mercury (Hg) porosimetry (MICP). Porosity families tend to overlap, with one or two porosity families typically most common and others subordinate to non-existent. Rarely are pure end members represented by only one porosity family. Micro-porosity is defined as intercrystal pores that are 10μ and much larger. Particle size is >30μ to much larger. Mega-porosity is highly productive and often characterized by "drill bit drops" through caves.
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References Abell-Hanger Foundation Collection, no date, The Permian Basin, Petroleum Empire of the Southwest, Era of Discovery, Era of Advancement (dating from the Depression to the 1970s): Permian Basin Petroleum Museum, El Paso, Texas, v. I, 200 photos, and II, 200 photos. Beard, D.C. and P.K. Weyl, 1973, Influence of Texture on Porosity and Permeability of Unconsolidated Sand: AAPG Bulletin, v. 57/2, p. 349-369. Choquette, P.W. and L.C. Pray, 1970, Geologic nomenclature and classification of porosity in sedimentary carbonates: AAPG Bulletin, v. 54/2, p. 207-244. Clerke, E.A. and J.J. Buiting, 2008, Multiple discrete pore systems in Arab D Limestone: AAPG Annual Meeting Abstracts, Search and Discovery article #90078, Web accessed 9 November 2010, http://www.searchanddiscovery.net/abstracts/html/2008/annual/abstracts/408760.htm?q=%2Btext%3Aclerke Craig, D.H., 1988, Caves and other features of Permian karst in San Andres Dolomite, Yates Field reservoir, west Texas, in N.P. James and P.W. Choquette, (eds.), Paleokarst: Springer- Verlag, p. 342-363. Folk, R.L., 1974, The petrology of sedimentary rocks: Austin, Texas, Hemphill Publishing Co., 182 p. Folk, R.L., 1965, Some aspects of recrystallization in ancient limestones, in L.C. Pray and R.S. Murray (eds.) Dolomitization and Limestone Diagenesis: SEPM Special Publication, v. 13, p. 14-48. Lindsay, R. F., D. L. Cantrell, G. W. Hughes, T. H. Keith, H.W. Mueller III, and S. D. Russell, 2006c, Ghawar Arab-D reservoir: Widespread porosity in shoaling-upward carbonate cycles, Saudi Arabia, in P. M. Harris and L. J. Weber, (eds.), Giant hydrocarbon reservoirs of the world: From rocks to reservoir characterization and modeling: AAPG Memoir 88, p. 1-44. Luo, P. and H.G. Machel, 1995, Pore size and pore-throat types in a heterogeneous Dolostone reservoir, Devonian Grosmont formation, Western Canada Sedimentary Basin: AAPG Bulletin, v. 79, p. 1698-1720.
Carbonate Porosity Families & Their Reservoir Potential
Robert F. Lindsay Saudi Aramco Dhahran, Saudi Arabia & University of Aberdeen, Scotland
AAPG 2010, New Orleans
Microporosity Crystal Size = 30 μ + Pore Throat Radii = 2.5 μ
Pore Size = >30 μ + Pore Type = Standard Choquette & Pray (1970) Pore Types, with Interparticle Pores Common
Pore Throat Radii = 10 μ
Pore Size = >30 μ + Pore Type = Standard Choquette & Pray (1970) Pore Types, with Moldic, Vugular, and Cavernous Pores Common
Microporosity, Mesoporosity, Macroporosity, and Megaporosity first described by Luo and Machel, 1995
Porosity Families Determined By: • • • •
Detailed Core/Outcrop Description Reflected Light Petrography Transmitted Light Petrography (Thin Section) Scanning-Electron Microscopy (SEM) Regular View & Relief Pore Casts
• High Pressure Hg Porosimetry (MICP)
Porosity Families Tend To: • Overlap • One or Two More Common & Others Subordinate to Non-Existent • Rarely are Pure End Members Represented By One Porosity Family
Macroporosity Choquette & Pray Pore Types with Interparticle Pores Common Depositional Porosity Porosity 47%
Diagenetic Porosity Tectonic Porosity
Porosity 26% Lucia, 1999
Macroporosity Choquette & Pray Pore Types with Interparticle Pores Common
Beard and Weyl, 1973
Lindsay et al., 2006
Macroporosity Choquette & Pray Pore Types with Interparticle Pores Common Grainstone
1.1 mm Gas
Oil
Grainstone Micro
Meso
Macro
Mega
Clerke et al. (2008)
0.55 mm Lindsay Lindsayetetal., al. 2006 (2006)
Macroporosity Choquette & Pray Pore Types with Interparticle Pores Common Grainstone 177-500 µ
Gas Oil
Micro
Meso Macro Mega
2.25 mm
Macroporosity Choquette & Pray Pore Types with Interparticle Pores Common Gas
Micro
Oil
Meso Macro Mega
Grainstone 177-500 µ
Micro-Meso-Macroporosity Moldic & Micro-Meso Pores w/Interparticle Pores Cemented Grainstone Pkstn Grain-rich 177-710 µ
Gas Oil
Micro
Meso Macro Mega
5.6 mm
Micro-Meso-Macroporosity Moldic & Micro-Meso Pores Types w/Interparticle Pores Cemented Grainstone Pkstn Grain-rich 177-710 µ
Mesoporosity to Macroporosity Intercrytal-Disssolution Pore Types No Interparticle Pores
Gas
Micro
Oil
Meso Macro Mega
Pkstn Mud-rich 125-177 µ Dissolution Macroporosity, Mesoporosity, & Microporosity
1.1 mm
Mesoporosity to Macroporosity Intercrystal-Dissolution Pore Types No Interparticle Pores Pkstn Mud-rich 125-177 µ
Macroporosity Intercrystal-Moldic Pore Types No Interparticle Pores
30 μ 0.2 mm Lindsay and Kendall,1985 Group 1
PTR 0.21 μ Ф 2.5-9.9% K 0.1-0.3 mD
Pkstn Mud-rich
Group 2
Lindsay and Kendall,1985
PTR 0.6 μ Ф 8.3-13.0% K 0.7-1.0 mD
Group 3
PTR 0.8 μ Ф 10-17.2% K 1-7 mD
Group 4
PTR 0.8 μ & 1.8-2.5 μ Ф 17.3-22.4% K 7-48 mD
Group 5
20 μ
PTR 2.5 μ Ф 21.8-27.6% K 48-146 mD
Oil Mega Macro
Meso
Gas Micro
10 μ 2 cm
2 cm
Lindsay and Kendall,1985
Desch et al., 1983
Megaporosity Choquette & Pray Pore Types with Moldic, Vugular & Cavernous Pores Common Depositional Porosity
Diagenetic Porosity Tectonic Porosity
Megaporosity Choquette & Pray Pore Types with Moldic, Vugular & Cavernous Pores Common
Phreatic Tube Horizon DQ Section Riyadh, Saudi Arabia
Photo Courtesy Dave Cantrell
Phreatic Tube Longhorn Cavern State Park, Texas
Megaporosity Choquette & Pray Pore Types with Moldic, Vugular & Cavernous Pores Common
Stages of Karstification Youth: Porosity Generation via Dissolution Maturity: Porosity Reduction via Breccia (Angular & Rounded), Cave Cement (Ornamentation) & Geopetal Old Age: Porosity Completely Cemented and/or Karst Profile Partially to Completely Eroded Craig, 1988
Megaporosity Choquette & Pray Pore Types with Moldic, Vugular & Cavernous Pores Common
Porosity Associated w/Paleowater Tables?
Megaporosity Choquette & Pray Pore Types with Moldic, Vugular & Cavernous Pores Common
Megaporosity Choquette & Pray Pore Types with Moldic, Vugular & Cavernous Pores Common Yates No. 30A 204,682 BOPD Choke: 15 Inch Casing
Craig, 1988
Craig, 1988 Abell-Hanger Foundation Collection Permian Basin Petroleum Museum
Microporosity & Mesoporosity Microspar with Intercrystal & Micromoldic Pores Pkstn Mud-rich
1.1 mm
Microporosity & Mesoporosity Micrite & Microspar with Intercrystal & Micromoldic Pores
Microporosity & Mesoporosity Microspar with Intercrystal & Micromoldic Pores 3.50
Incremental Pore Volume
3.00
Good Porosity Low Perm
213 224 236
2.50
Good Porosity Low Perm
2.00
Good Porosity Low Perm
1.50
Oil 1.00
Gas
0.50
Micro 0.00 0.0010
0.0100
Meso 0.1000
Macro 1.0000
Pore Throat Radii (Microns)
10.0000
Mega 100.0000
Microporosity to Mesoporosity Micrite Conversion to Microspar with Intercrystal & Micromoldic Pores
Folk, 1965
Folk, 1974
Microporosity Micrite with Intercrystal Pores Gas
Micro
Oil
Meso Macro Mega
Mdstn-Wkstn 62-125 µ
1.1 mm
Conclusions Microporosity Crystal Size = 30 μ + Pore Throat Radii = 2.5 μ
Pore Size = >30 μ + Pore Type = Standard Choquette & Pray (1970) Pore Types, with Interparticle Pores Common
Pore Throat Radii = 10 μ
Pore Size = >30 μ + Pore Type = Standard Choquette & Pray (1970) Pore Types, with Moldic, Vugular, and Cavernous Pores Common
Reservoir Potential Megaporosity: Highly Productive Vertical Wells Interbedded Lower Quality Reservoir May Require Horizontally Completions Macroporosity: Vertical Wells (Historically) Horizontal-Slant For Higher Productivity
Mesoporosity: Horizontal Completions Microporosity: Non-Productive
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