269

INDEX

Accessibility, 34, 66, 72. See also Pore-to-pore throat (size) ratio

Accommodation, 79Agha Jari fi eld, Iran, 191Amal fi eld, Libya, 190Analogs (“look-alikes”), 7, 156Analysis, complete core, 58Anatomy, depositional units, 89–90Andros Island, Bahamas

fracture-related caves on, 226–227tidal fl ats on, 117

Angle, contact (wettability), 62Anhydrite, pore fi lling and replacement, 166,

248Anhydrite-gypsum, stability relationships of,

166Anoxia, 98Anoxic, 130Antecedent topography (bathymetry), types of,

82Aquifers, groundwater, 4API units (gamma ray log), 161Arab D Formation, 61, 211Archie

cementation exponent (m), 10, 59equation, 59formation factor (F), 59resistivity index (I), 61resistivity ratio (Rt/Ro), 61

saturation exponent (n), 62tortuosity exponent (a), 59

Architecturebasin, 76reservoir, 77, 86, 203sequence, 102

Asmari fi eld, 184Asmari Limestone, Kirkuk fi eld, 191, 240Attached

beach-dune succession, 96, 111shoreline, 82

Australia, 124. See also “Roaring 40s”Lacepede shelf, 125, 211Shark Bay, 203

Baffl es, to reservoir fl ow, 1, 41, 107, 145Balearic Islands, 115Barriers, to reservoir fl ow, 1, 41, 107, 145, 250Berm, storm, 112Bioturbation, 15Black Sea, 129Bossier Shale Formation, isopach of, Overton

fi eld, Texas, 228Boundaries

facies, 77time, 77

Breccias, karst related, crackle and mosaic, 162Brittle domain, 177. See also Material, behavior

under stress

Geology of Carbonate Reservoirs: The Identifi cation, Description, and Characterization of Hydrocarbon Reservoirs in Carbonate RocksBy Wayne M. Ahr Copyright © 2008 John Wiley & Sons, Inc.

270 INDEX

Buildups, carbonatechemogenic, 82mounds, microbialite (Cambrian) Texas, 181“mud mounds”, 148, 181mudstone-cementstone, Early Carboniferous,

212, 247Bunter Sandstone, Triassic (Germany), 87Buttress and chute structures, 29, 125

Calcisiltite, 16Caliche, 115Cambro-Ordovician, North America, 117.

See also Transcontinental ArchCapillarity, 56Capillary

attraction, 63–64drainage curve, 71imbibition curve, 71injection curve, 71

Capillary pressure, 6–8, 17, 65, 67curves, 7, 64defi ned, 64–66mercury, measurements of (MICP), 7, 107,

145, 205, 209Carbonate(s)

defi ned, 2eolianites, 111factory, 81, 102, 129lacustrine, nonmarine, 109marine. See also Carbonate, factoryminerals, natural occurrences of, 4particles, see Constituents, carbonateprecipitation, inorganic, 81production

biogenic and chemogenic, 81principal zone of, 97, 102. See also

Carbonate, factoryrocks, classifi cation of, 20–21, 25–30

Carbonate compensation depth (CCD), 98, 129–130

aragonite and calcite, 129factors determining depth of, 129

Carlsbad Caverns, New Mexico, 153Capping facies, cycle, 28Caves

coastal zone, 162continental, 162

Cathode luminescence (CL), see Luminescence, cathode

CCD, see Carbonate compensation depthCements

botryoidal, 167ferroan calcite, 169isopachous, 167–168meniscus, 168poikilotopic, 169pore-lining, 168

Central Basin Platform, Texas, 152, 211Chalk

Austin (Cretaceous) Texas, 132–133fracture patterns in, 185

constituents of, 16, 131Ekofi sk fi eld, North Sea, reservoirs in, 185Europe, Middle East, and North America,

examples in, 124, 131North Sea

classifi cation of, 132–133fractured reservoirs in, 240

porosity and burial depth, 132typical age and depositional setting, 124turbidites, 213

Chalkifi cation (degradational diagenesis), 150Chert and chalcedony, 131, 238, 243. See also

Facies, basinal“Chicken wire” fabric, see Environments, tidal

fl at and lagoonChina, mainland, 109Clay minerals, K, Th, and U in, 202Coccolithophorids (coccoliths), 16, 131. See also

ChalkCondensed interval, 100Conformities

correlative, 85stratigraphic, 101

Conglomerates, fl at pebble, see Environments, tidal fl at and lagoon

Conley fi eld (Mississippian) Texas, 124Chappel Formation in, 219–221, 223depositional reservoir, as example of, 214,

219–224Ellenburger Formation in, 219Palo Pinto Formation in, 219

Constituents, carbonate. See also Minerals, metastable

biological, 9, 16chemical, 9depositional sedimentary, 108grain types, 15mineralogical, 15nonskeletal, 2skeletal, 20

Contact inhibition, 152Converting MICP data to oil-water equivalents,

69–70Coordination number, 66, 72–73Coriolis force, 127Correlations

geochronological, 84layer-cake, 99–100stratigraphic methods for, 86–87

Cotton Valley Formation (Jurassic) Texas“chalky” porosity in, 151neomorphic microporosity in, 159–160, 228salt domes and sedimentation of, 136

INDEX 271

Cow Creek Formation (Lower Cretaceous) Texas, 111

Crossplotsdensity–neutron, 202porosity–permeability, 194Schlumberger M–N, 202

Cross-cutting relationshipsin rock properties, 2, 156in thin sections, 156

Cross sections, structural and stratigraphic, 87Crystal boundaries, compromise, 151Crystal forms

aragonite cements, 148, 167calcite cements, 147–148, 167dolomite, saddle, 148Mg-calcite, 167

Crystal systems of common carbonates, 3Currents

contour, 98, 127density, 98, 122, 127, 130geostrophic, 122, 127, 130longshore, 111rip, 111thermohaline (density), 128turbidity, 98, 122, 127

Cycle skipping, acoustic log, 161, 244Cycles, stratigraphic

“greenhouse and icehouse climates”, infl uence on, 101

Milankovich, 101origins of, 101order of,101shallowing-upward, 28, 102

Darcy (laminar) fl ow, 44, 187Density, bulk, 31Depth shifting, core-to-log, 208Depositional

bodies, typical shapes of, 88dip, 88strike, 88successions, ideal (standard), 92–93, 96–98,

106, 203. See also Ideal depositional successions and environments

Detachedbeach–dune succession, 96, 111shoreline (barrier island), 82, 111

Diachroneity, 80Diagenesis, 9

bioerosion, 146cementation, 146, 164, 170compaction, mechanical, 146, 164, 170–171deep burial, 146defi nition of, 145dissolution, 146, 150

and cave formation, 225mesogenetic, 157, 160

fresh water, 116inversion, mineralogical, 159. See also

Neomorphismmarine phreatic, 116mechanisms of, 146mixing-zone, 116neomorphism, 148, 159, 165recrystallization, 146, 158–159, 170replacement, 146, 170stabilization, neomorphic, 150, 159vadose, 116

Diagenetic environments, 9, 224–225classifi cation, basis for, 3, 154fresh-water (meteoric) phreatic, 153, 156marine phreatic, 153mixing zone, 153subsurface (burial), 153, 167vadose, 153, 156, 167

Diagenetic facies, mapping of, 155Dickinson fi eld (Mississippian) North Dakota,

244–249. See also Williston BasinLodgepole Formation (Carboniferous) in,

244Lodgepole mounds in, 245

Discoasters, 131. See also ChalkDisconformities, stratigraphic, 101Diversity, taxonomic, 98, 115Dolomite, “hydrothermal”, 148Dolomicrites, 26Dolomitization

and reservoir porosity, 151–153“excess”, porosity reduction by, 152

Drill cuttings, microscopic examination of, 9Drilling breaks, 161, 193. See also Fractures,

presence in borehole, indirect evidence ofDukhan fi eld, Qatar, 191Dunes, coastal, 109Dysoxia, 98

El Abra Formation (Mexico), 46Enterolithic structures, see Environments, tidal

fl at and lagoonEnvironments. See also Ideal depositional

successions and environmentsabyssal, 98“always wet”, 112aphotic, 98basinal, 129–133bathyal, 98beach–dune–barrier island, 110–117diagenetic, see Diagenetic environmentsshallow subtidal (neritic), 121–124slope and slope-toe, 126–129slope-break, 124–126temperate, 81, 112–113, 115tidal fl at and lagoon, 117–121tropical, 113

272 INDEX

Epicontinental seas, 129Events, climatic, storms, tropical and

“northers”, 111

Fabric, 15biogenic, 18depositional, 18diagenetic, 18

Faciesbasinal, 129biological, 91defi ned, 91–92depositional, 8, 81diachronous, 83electro, 10, 49, 52eolian, 114high energy, 78micro, 91pore, 69, 156standard micro, 92–93time-transgressive (diachronous), 84, 94

Factor analysis, 91Faults

listric normal, 185graben-in-graben, 185

Fields, giant and supergiant, 226Fizz test, to distinguish calcite from dolomite, 2Flooding surface

marine, 101maximum, 101

FloridaKey Largo, 93keys, 80shelf, 93White Bank, 93, 125–126

Flow units, 1, 26, 41, 107, 145, 250mapping of, 173

Fluidfl ow, parallel plate theory of in fractures, 187nonwetting, 46recovery factor, in fracture systems, 182saturations, in fractures, 182wetting, 46, 57

Foldsanticlinal, fractures on, 185monoclinal fl exures, fractures on, 185

Fracturesclassifi cation of, genetic, 178–181conjugate shear, 178in Cretaceous carbonates, Lake Maricaibo

area, 240differential compaction and, 181, 245extension and tension, 178four types, Nelson’s, 190–191, 251induced and natural, 188intensity, 192morphological types of, 182

presence in boreholedirect confi rmation of, 192indirect evidence of, 192–194

slickensided, 182spacing, 186, 188spacing and intensity, factors that infl uence,

195surface-related, 181on tectonic structures, orientation of, 180trends in natural, 9types I- IV, reviewed, 239–240width, 186

Fragum hamelini, 203

Gahwar fi eld (Jurassic) Saudi Arabia, 103Gas, as nonwetting fl uid, 63Golden Lane trend (Mexico), 46Great Bahama Banks, 80, 134

Eleuthra Island, 222Exuma Sound, 222, 231Schooner Cays, 231

Great Salt Lake, Utah, 109Grain-to-mud ratio, 27Grain size (texture)

beach-dune deposits, 112categories in Grabau’s rock classifi cation, 15categories on Wentworth scale, 15measurement techniques, 15

Gravity, measurements of in exploration, 8Green River Formation (Eocene), 109Guadalupe Mountains, New Mexico, 226Guymon-Hugoton fi eld (Permian), 102Gypsum

presence of and log calculations, 51dewatering (transformation) of, 166

Haft Kel fi eld, Iran, 191Halokinetic (salt tectonic) structures, 214Happy fi eld (Permian, Clearfork Formation),

Texas, 231Hardgrounds, 155Hassi Messaoud fi eld, Algeria, 191Heterozoan biota, 123, 247HFS, see High-frequency depositional

sequencesHigh-frequency depositional sequences (HFS),

99High-stand systems tract (HST), 212Horner plot, 194, 251 see also Fractures,

borehole, indirect evidence of“Hot” lime and dolomite, 202HST, see High-stand systems tract

Ideal depositional successions and environmentsbasinal, 129–133beach-dune, 110–117illustrations of all, 133–139

INDEX 273

shallow subtidal (neritic), 121–124slope and slope toe, 126–129slope-break, 124–126tidal fl at and lagoon, 117–121

Image analysis, petrographic (PIA), 209Impedance contrast, 8, 53, 206Isooctane, in wettability experiments, 63

James Limestone Formation (Cretaceous) Texas, 124

Karst, 147caves, 162caverns, 147, 162paleocaves, 226

as reservoirs, 162–163pinnacles, 162Puckett fi eld (Lower Ordovician) Texas, 162sinkholes, 155, 162towers, 162Yates fi eld (Permian) Texas, 162

Kerogen, 145Keuper, evaporites, Triassic (Germany), 87Kirkuk fi eld, Iran, 191Kohout circulation, 155

Lattice, crystal, deformation, types of, 201Limestones, bituminous, 109Lisbon fi eld, Utah, 161“Lith logs”, 8

computer processed interpretation (cpi) log, 52

creating synthetic (Schlumberger M–N plot), 51

from well cuttings, precautions in using, 207–208

software applications to compute synthetic, 51Lithofacies, synthetic, 52

“STATMIN”, computer program for generating, 202

Lithogenetic units, 83. See also FaciesLogs, wireline

acoustic, 8, 107, 192caliper, 193cased hole, 47characteristics, as proxies for fundamental

rock properties, 204density, 8, 107dipmeter, 18, 107FMI®, FMS®, UBI® and fractures, 182, 193FMI® output illustrated, 183gamma ray, 8,10imaging, 9,18,49, 107, 249neutron, 8, 107NMR, 49, 107, 205, 209open hole, 47photoelectric effect, 8

resistivity, 8,10shapes, as indicators of depositional

environments in siliciclastics, 49, 202“signatures” as indicators of rock and pore

types, 202sonic amplitude, 192spontaneous potential (SP), 59velocity deviation, 50

Luminescence, cathode (CL), 168, 225

Magetism, earth, in exploration, 8Maps

depositional facies, 8electrofacies, 10, 49, 107

statistical (computer processed), 52interval isopach (paleostructure), 8, 219pore facies, 69subsurface, 84

Mariana Trench, 129Material, behavior of under stress, 44, 177Megafossils, benthic, 13Metamorphism

contrasted with diagenesis, 145organic, 145

Micrite, 15Micritization, 29Microbes, calcifi ed, 28Microcalcite, microrhombic, 150–151. See also

Porosity, “chalky”Microporosity, diagenetic, 91Microscopy, scanning electron (SEM), 209Microstructures, internal, 28Midland Basin, Texas, 231, 233

Eastern Shelf of, 233, 237Minerals

accessory, 201metastable

aragonite, 26, 126, 131, 148, 153, 166, 213calcite, magnesian (Mg), 26, 148, 153, 166,

213Mineralization

exotic in reservoirs, 161, 169metamorphic, 146Mississippi Valley Type (MVT), 146

Muschelkalk, limestone, Triassic (Germany), 87

Naphthenic acid, in wettability experiments, 63Neomorphism. See also Diagenesis

aggradational, 148defi ned, 159degradational, 148of limestones, 151

Neritic (shallow subtidal) environment, 97Nesson Anticline, 248North Haynesville (Smackover) fi eld, Louisiana,

223depositional reservoir, example of, 214–219

274 INDEX

Nuclear magnetic resonance (NMR), 8, 107, 145. See also Logs, wireline

T2 relaxation time, 53

Oaks fi eld (Smackover Formation), Jurassic, North Louisiana, 117, 216

barrier island sequence in, 117Oil

column, calculating height above free water level, 70

shales, 109“window”, 145

Olenellus, trilobite, 84OOIP, see Original oil in placeOozes, siliciclastic, 98Organic compounds, polar, 63. See also

WettabilityOrganic matter, sapropelic, 18Organisms

porosity in, 108–109reef-building, 81, 108rim-forming, 125

Original oil in place (OOIP), calculation of, 61Orogeny, Ancestral Rocky Mountain

(Carboniferous), 247Overcompaction and stylolites, 154, 165, 243Overton fi eld, Jurassic, Texas, 90, 159. 165, 227–

231. See also Porosity, “chalky”

Paleosols, 155Pathway, diagenetic, 164. See also Cross-cutting

relationshipsPeriplatform talus, 128Permeability

absolute, 45capacity to transmit fl uids, 34Darcy–Ritter equation for (Darcy’s law), 31,

186–187fl ow test, 194fracture, 182, 186intrinsic, 186matrix, 187relative, 46specifi c, 45statistical relationship with porosity, 7

Permian Basin, Texas, 128Persian Gulf, 211

water depth, 129tidal fl ats (sebkhas), 117

Petrographic image analysis (PIA), see Image analysis, petrographic

Petroleum system, elements in, 76Petrophysical calculations from wireline logs

density, 49lithology, 49porosity, 49resistivity, formation water (Rw), 49

saturation, water (Sw), 49Photozoan biota, 123Platform(s)

antecedent, 103carbonate, defi ned, 77carbonate and siliciclastic, slopes on, 127environmental “cells” or subdivisions on, 81isolated, 79margins, bypass and depositional, 127modern carbonate, examples of, 110paleotopography of, 135slope failure, types of, 127West Florida, 88

Polymorphs, CaCO3, 3Pore(s), see Porosity

cavernous, 151, 156, 176channel, 160, 176facies, 69fracture, 44, 176–177geometry, 107, 205interbreccia (karst), 162intercrystalline, 51, 144, 151interparticle, 10

enlarged, 160intraskeletal, 223moldic, 10, 147, 151, 156, 160, 162, 226roughness factor (a), in withdrawal effi ciency,

73vuggy, 10, 147, 151, 156, 160, 162, 176, 226vuggy and fracture, petrophysical behavior of,

190vugs, stromatactis, 210, 245, 248. See also

Buildups, carbonate, “mud mounds”Pore categories (types)

depositional, 14diagenetic, 14in detrital rocks, 108fracture-related, 14

Pore throats, 7dimensions of, 17effective radius of, 66median diameters of, 107sheet-like, 66size-sorting of, 66

Pore-to-pore throat (size) ratio, 34Pore volume, minimum unsaturated, 66Porosity

Ahr genetic classifi cation of, 26, 42–44Archie classifi cation of, 35–36bimodal, 30, 50, 160“bird’s eye”, 108calculated from neutron logs, 194capacity to store fl uids, 34core (measured), 194“chalky”, 151. See also Cotton Valley

FormationChoquette and Pray classifi cation of, 36–39

INDEX 275

dependence on rock properties, 31–33diagenetic, 30, 144, 150effective, 7equation defi ning, 31estimates of reservoir quality based on,

33–34fracture, 182, 186

calculating saturation (Sw) in, 189scale-dependency of, 188

Lonoy classifi cation of, 40–41Lucia classifi cation of, 39–40, 108proxies for, 26reduced during burial, 33sandstone, 9secondary index (Schlumberger SPI), 50separate vug, infl uence on Archie m

exponent, 60total, 107

Poza Rica trend (Mexico), 46Pressure

buildup tests, 193, 251. See also Fractures, presence in borehole, indirect evidence of

communication, 246confi ning, subsurface, 177, 187displacement, capillary, 66–67entry, capillary, 66threshold, capillary, 66transient test, 8, 246

Properties, rockcapillary, 57. See also Capillary pressuredependent (derived), 14, 30, 204fundamental (intrinsic), 14, 116, 202primary, 13, 106secondary, 13–14tertiary (latent), 14, 47

Quanah City fi eld, Texas, 241–244Chappel Formation (Mississippian) in, 241Ellenburger Formation (Ordovician) in, 241Spiculiferous zones in, 241

Ramp(s)distally-steepened, 78, 82environmental subdivisions on, 121homoclinal, 78, 82inner, 121middle, 121outer, 121slope angles on, 78, 82

Reef(s)conditions favorable for growth of, 82framestone, 125framework/detritus ratio, 30patch, 82, 124Stuart City trend (Cretaceous) Texas, 126trends, continuous, 82

Refl ux, brine and dolomitization, 152, 225

Reservoir(s)characterization, 5compartmentalized, 170depositional, checklist for identifying and

exploiting, 136–140description, 5diagenetic, checklist for identifying and

exploiting, 172–173engineering, 5facies-selective, 2fabric-selective, 2, 36–37fracture, checklist for identifying and

exploiting, 195fractured, defi ned, 177geology, 5hybrid

depositional-diagenetic (type I), 106diagenetic-fracture (type II) 176

net pay calculations in, 87net sand calculations in, 87oil-wet, 63

values of saturation exponent in, 62quality (rankings), 17

slice-map method, 234–236, 250recovery effi ciency, 71–72, 73

in karst reservoirs, 162rocks, multicomponent, 201stratabound, 2visualization of, 3D, 234water-wet, 63

Resistivityfl ushed zone (Rxo), 58formation at 100% water saturation (Ro),

58formation water (Rw), 59invaded zone (Ri), 58true formation (Rt), 58

Rhizocretions, 115“Roaring 40s” latitude (environment in), 124Rock typing, 34–35, 107, 205

Winland “R 35”, 205Rock units

hierarchical classifi cation of, 83time-transgressive, 88

Rudstone, 15

Sabine Uplift, ancestral, 228, 231Sacramento Mountains, New Mexico, 225Saddle dolomite

late, in fractures, 148, 166, 248late diagenetic, 238, 243thermochemical sulfate reduction (TSR) and,

148, 166Saint Louis Limestone Formation, 224. See also

Conley fi eldSalinity, hyper and hypo, 123Salt Basin, East Texas, 231

276 INDEX

San Andres Formation (Permian), Texas and New Mexico, peritidal deposits in, 117

Sand waves, Great Bahama Banks, 126Sands, tight gas, 46Saturation, 56

equilibrium and diagenesis, 147oil, 57water, 57

effective, 62, 160total, 62, 160

Scaling-up, pore-to-reservoir, 206–207Scanning electron microscopy (SEM), see

Microscopy, scanning electronSealing capacity (hmax), calculating, 70–71,

250Seals, 5, 69

anhydrite plugging, 166Sediment production vs retention, 81Seepage refl ux, see Refl ux, brine and

dolomitizationSeismic

amplitude versus offset (AVO) analysis, 191

attributes, 8, 191, 244data, 3D, 8refl ections, 53, 206traces, as correlation aids, 88velocities, 54wave characteristics, 53

Seismologyrefl ection, 83D, 53

Separability, limit of, 54, 206Shelves

environmental subdivisions on, 81Guadalupian (Permian),West Texas–New

Mexico, 126open, defi ned, 81rimmed, 79–80, 93rims, absence of, 81South Florida, 125

Shoals, grainstone, 124Siliciclastic sandstones

diagenesis in, 9ideal depositional successions (models) in, 95,

203Slickensides, 182Slope breaks, deep water, 82Smackover Formation (Jurassic)

Alabamacyclicity in, 170pore facies in, 69

Arkansas, capillary pressure curves from, 67Gulf Coast, 61, 211Louisiana, 161salt tectonics and depositional patterns in,

136

Snap-off, 72Source rocks, 5Spits, barrier, 116. See also detached shorelineSpraberry Sandstone trend, Texas, 191, 233.

See also Happy fi eldSpur and groove structures, 29, 125Stratigraphic

Code of Stratigraphic Nomenclature, 83correlation, 85International Guide To Stratigraphic

Classifi cation, 83mechanical, infl uence on fracturing, 185stacking patterns, sequence, 102

Stratigraphyallo, 100cement, 168, 171, 225chrono, time and time-rock units in, 83defi ned, 77genetic, 100litho, rock units in, 83parasequences, 101–102seismic, 53, 99sequence, 53, 80, 84

defi ned, 99Strain, defi ned, 177Stress

compression, 178defi ned, 177extension, 178principal, intermediate (σ2), maximum (σ1),

minimum (σ3), 178shear, 178

Structures, sedimentary, 15, 20in beach-dune deposits, 113–114in tidal fl at and lagoon deposits, 119–121

Tensionadhesion, 62, 65interfacial, 62, 66surface, 63

Texture. See also Grain sizedepositional, 9, 15grain packing, 17grain shape, 17sorting, 17

Thamama Group (Cretaceous) Middle East, reefs and grainstones in, 126

Tidal prism, 119Time, geological

absolute, 84–85relative, 84–85ways to measure, 84–85

Time-rock units, classifi cation of, 86Trace fossils, in basinal environments, 130Transcontinental Arch of North America,

Cambro-Ordovician tidal fl at deposits on, 120

INDEX 277

Transgressive systems tract (TST), 212, 247Traps, 5TST, see Transgressive systems tractTurbidites

channelized, proximal, 128distal, 131

“Turtle” structure, 124

Unconformities, 84, 90, 101, 155

Vents and seeps, seafl oor, 82

Walther’s rule, 93Washouts, wellbore, 161, 244Water

bearing zone in reservoir, 57conate, 57formation, resistivity of, 59interstitial, chemical composition of, and

cement mineralogy, 167subsurface (burial diagenetic), composition

of, 154Waulsortian (Mississippian) mounds, 243, 247.

See also Buildups, carbonateWave(s)

Airy, 111base, fair-weather, 78breaking, 111

climate, factors determining, 111period, 111shoaling transformation, 111solitary, 111

Wells, horizontal in fractured reservoirs, 244

Wettability, 56, 62Williston Basin

fractured Mississippian “mud mounds” in the, 181, 185, 240, 244

Paleozoic tidal fl at deposits in the, 119Winnowing, 18Withdrawal. See also Reservoir, recovery

effi ciencycurve, capillary pressure, 71effi ciency, mercury, 71

YucatánCampeche Bank, 89fractured reservoirs in, 240Isla Cancun, 89Isla Mujeres, 89oolite grainstones on NE coast of, 89, 115

Zone, reservoirproductive, 57transition, 57water-bearing, 57