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reservoir system and depositional env

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    • 1. WEEK 1RESERVOIR SYSTEMAND DEPOSITIONAL ENVIRONMENT
    • 2. RESERVOIR SYSTEM• Reservoir: porous medium• Trap: seal medium• Kitchen: sources of petroleum, should not be too far.
    • 3. Fig. 1 – Mosaic of different geologic trap mechanisms
    • 4. DEPOSITIONAL ENVIRONMENTCHARACTER OF MAJOR DEPOSITIONAL SYSTEMS - Terrigenous Fan System - Fluvial Depositional Systems - Deltaic Depositional Systems - Barrier/ Strandplain Systems - Terrigenous Shelf Systems - Slope and Abyssal Depositional Systems - Eolian Systems
    • 5. Terminology and Definition in Reservoir Characterization
    • 6. Terminology and Definition in Reservoir Characterization• Genetic approach to facies analysis This approach benefits from detailed, three-dimensonal studies of modern facies that are related to sedimentary environments and the associated depositional processes.
    • 7. Terminology and Definition in Reservoir Characterization
    • 8. Terminology and Definition in Reservoir Characterization• Sedimentary Environment Defined as a part of the earth’s surface that is physically, chemically, and biologically distinct from adjacent areas (Selley, 1978). Physical parameters: current velocity and direction, water depth, temperature, wind speed and direction. Chemical parameters: water salinity, pH, oxidation potential. Biological parameters: effects of organisms, energy- damping effects of vegetation, and contributions of organic matter.
    • 9. Terminology and Definition in Reservoir Characterization
    • 10. Terminology and Definition in Reservoir Characterization• Focus of Geological Models External Geometry: most, these models have been primarily used in exploration. Internal Geometry: fewer, finer-scale of depositional components, shows strong relation between original depositional controls, reservoir quality, and hydrocarbon distribution.
    • 11. Terminology and Definition in Reservoir Characterization• Internal Geometry
    • 12. Terminology and Definition in Reservoir Characterization• Facies - Derived from the latin “facia”, relating to the external appearance or look of something (Walker, 1984). - A three-dimensional body of sediment (Modern) or rock (Ancient) whose genesis (environment, processes) can be inferred reliably from its composition, petrography, external geometry, sedimentary structures, organic content, stratigraphic relations, and spatially associated facies (Fisher an Brown, 1984).- Middleton (1978) noted that facies may simply be given alphabetic or numeric designations or brief descriptive names defined by lithology, sedimentary structures, or prominent trace fossils, but it is understood that each facies will ultimately be given an environmental interpretation.
    • 13. Terminology and Definition in Reservoir Characterization• Depositional system - A three-dimensional assemblage of lithogenetic facies linked by observed (Modern) or inferred (Ancient) depositional environments and associated processes (Fisher and McGowen, 1967; Fisher an Brown, 1984).• Genetic stratigraphy - The process of interpreting sedimentary rocks using lithogenetic facies as the fundamental stratigraphic unit, and the organization of those facies into depositional systems.
    • 14. Terminology and Definition in Reservoir Characterization• Major Depositional Systems
    • 15. Character of Major Depositional Systems Terrigenous Fan Systems Fluvial Depositional Systems Deltaic Depositional Systems Barrier/ Strandplain Systems Terrigenous Shelf Systems Slope and Abyssal Depositional Systems Eolian Systems
    • 16. Terrigenous Fan Systems• Allufial Fans Consist of conical piles of sediment, predominantly coarse-grained clastics Form the most poorly sorted and source-proximal depositional systems in the subaerial environment (Galloway an Hobday, 1983; Fisher and Brown, 1984). Produce hydrocarbons only in a limited number of settings because they do not contain and are not associated laterally with source rocks, do not have wide areal extent (especially in semiarid environments), are often not deeply buried, and may have low porosities and permeabilities and following diagenesis, primarily where carbonate cementation has occurred (Nilsen, 1982).
    • 17. Terrigenous Fan Systems
    • 18. Terrigenous Fan Systems• Allufial Fans Concave in longitudinal profile, convex-upwards in transverse profile, and may slope from a few hundreds feet to a view hundred feet per mile to a fiew feet per mile. Slopes are steepest on the proximal, upper part of the fan where sediments are coarsest and texturally immature. Coalescing often forms an alluvial plain that extends parallel to the uplifted source area.
    • 19. Terrigenous Fan Systems
    • 20. Terrigenous Fan Systems
    • 21. Terrigenous Fan Systems
    • 22. Terrigenous Fan Systems• Operating processes Combination of stream flow and debris flow, depending on the avaliable sediment size distribution and the climate (water). Stream Flow: Dominant where fines are not available Debris Flow: Occur in arid to semi arid regions contrast with wet alluvial fans.
    • 23. Terrigenous Fan Systems• Dominant Stream Flow
    • 24. Terrigenous Fan Systems• Fan-Delta System
    • 25. Terrigenous Fan Systems• Mobeetie Field Study A study in the Texas Panhandle, fan-delta progadation onto a shallow, carbonate-shelf environment in the Andarko Basin.
    • 26. Terrigenous Fan Systems• Isopach Map S1 Fan-delta Sandstone
    • 27. Terrigenous Fan Systems• Isopach Map S2 Sandstone
    • 28. Terrigenous Fan Systems• Isopach Map S3 Sandstone
    • 29. Terrigenous Fan Systems• Reservoir Characteristic at Mobeetie Field Porosities: - thin section = 0 to 14% - core plugs = 21% Permeabilities: - 0.1md to 1450md - 10’s md to 100’s md (mostly) Updip fluvial and undisturbed distal fan-delta deposits have good porosity and permeability, whereas reworked fan-delta deposits are not productive owing to calcite cement.
    • 30. Character of Major Depositional Systems Terrigenous Fan Systems Fluvial Depositional Systems Deltaic Depositional Systems Barrier/ Strandplain Systems Terrigenous Shelf Systems Slope and Abyssal Depositional Systems Eolian Systems
    • 31. Fluvial Depositional Systems• Fluvial Systems Transport terrigenous clastic depositional sediments from a source area into lacustrine or marine basins. Sediment accumulations may occur in fluvial systems such as tectonically stable coastal plains, intermontane basin, and broad tectonic forelands. Internal structure of the channel fill and distribution of the component facies is determined primarily by the geometry of the channel segment.
    • 32. Fluvial Depositional Systems
    • 33. Fluvial Depositional Systems
    • 34. Fluvial Depositional Systems
    • 35. Fluvial Depositional Systems• Braided Fluvial Systems Typically the most source-proximal of fluvial systems. Their develpoment is favored by rapid fluctuatuions on discharge, and compared with meandering systems, braided systems tend to have higher slope, a heavier load of coarse sediment, and more easily erodible baks of non-cohesive sediment. Contain multilateral sand bodies with high thickness ratio that are deposited in low sinuosity streams.
    • 36. Fluvial Depositional Systems
    • 37. Fluvial Depositional Systems• Braided Fluvial Systems Two bar types predominate: 1. Longitudinal Bars 2. Transverse or oblique bars Sediments are relatively coarse, consisting mostly of medium- grained sand to gravel, with little preservation of mud and silt. The sedimetary structures is limited relative to meandering systems and is dominated by planar bedding and byy low- angle-avalanche and tabular cross-stratification.
    • 38. Fluvial Depositional Systems
    • 39. Fluvial Depositional Systems• Meandering Fluvial Systems: Fine Grained Represent the opposite end of an idealized continuum of fluvial types compared with the braided system. Develop under low gradients, moderately high and uniform discharge, and high suspended load. The primary depositional environment for sand is the point bar, which develops by lateral accretion and migrates downstream. Sedimentary structures are more varied than in the braided systems.
    • 40. Fluvial Depositional Systems
    • 41. Fluvial Depositional Systems
    • 42. Fluvial Depositional Systems• Meandering Fluvial Systems: Fine Grained Sand bodies display moderate thickness ratio and commonly develop multistory sand bodies enclosed within overbank muds.
    • 43. Fluvial Depositional Systems• Meandering Fluvial Systems: Coarse Grained This system is midway between braided and fine-grained meandering fluvial types. Develops in the lower reaches of moderate to high bed- load fluvial systems. Sand bodies are multilateral with high thickness ratio, and deposits consist of partly developed point bars and channel fill. the coarsest sediment typically occurs as main channel lag and in chute channels.
    • 44. Fluvial Depositional Systems
    • 45. Core Data & Sequence Stratigraphic Widuri 01 FS ESTUARINE CHANNEL SB FS LOW SINOUS MEANDERING CHANNEL Analysis SB FS CREVASSE SPLAY SB FS MEANDERING CHANNEL SB BRAIDED- LOW SINOUS MEANDERING CHANNEL
    • 46. Core Data & Sequence Stratigraphic Analysis FS FS FS SB SB Widuri A-01
    • 47. Character of Major Depositional Systems Terrigenous Fan Systems Fluvial Depositional Systems Deltaic Depositional Systems Barrier/ Strandplain Systems Terrigenous Shelf Systems Slope and Abyssal Depositional Systems Eolian Systems
    • 48. Deltaic Depositional Systems• Deltaic Deposition Involves the discharges of water and sediment by a river system into a standing body of water. Formed by the interaction of fluvial and marine or lacustrine processes. Waves, tidal proccesses or both are active in determining delta type according to a three-part classification.
    • 49. Deltaic Depositional Systems
    • 50. Deltaic Depositional Systems• Effect of Flufial Processes and Sediment Influx Where sediment input is dominant, the delta developes an elongate shape Increasing tidal-energy flux leads to dip-oriented subtidal and intertidal sand ridges.
    • 51. Deltaic Depositional Systems
    • 52. Deltaic Depositional Systems• Basic Delta Geometries High-constructive deltas (river dominated) are referred to as high- constructive elongate or high-constructive lobate, depending on their geometry. High-destructive deltas (marine dominated) may be either high- destructive, wave dominated or high-destructive, tide dominated.
    • 53. Deltaic Depositional Systems
    • 54. Deltaic Depositional Systems• River-Dominated Deltas Progadation due to sediment inpput exceeds the capability of waves, tidal currents, and longshore currents to redistribute and disperse sediment. Example: Modern Mississippi delta
    • 55. Deltaic Depositional Systems River-Dominated Deltas• • Elongate Geometries Distributary channels with subaerial and subaqeous levees and distributary mouth bars are major framework components of prograding river-dominated systems. These systems commonly have a low bed-load to suspend-load ratio and they develop relatively straight distributary channels.
    • 56. Deltaic Depositional Systems
    • 57. Deltaic Depositional Systems River-Dominated Deltas• • Lobate Geometries Delta geometry changes from elongate to lobate with increasing wwave influence in the receiving basin.
    • 58. Deltaic Depositional Systems River-Dominated Deltas• • Lobate Geometries Upward-coarsening textural trends are well defined
    • 59. Deltaic Depositional Systems• Wave-Dominated Deltas In these systems, mouth-bar deposits are continually reworked alongshore into a series of curved beach ridges that may laterally fill interdistributary bays or accrete to the mainland shoreline. The resulting overall sand geometry is strike elongate and may be skewed in one direction. Progadation is less rapid and extensive than for river-dominated deltas The sequence is upward coarsening. The proportion of sand and silt beds increases upward.
    • 60. Deltaic Depositional Systems
    • 61. Deltaic Depositional Systems• Tide-Dominated Deltas The difference between wave- and tide-dominated deltas depends primarily on which marine process reworks deltaic sediment. The estuarine distributary-channel-fill consists of multiple, stacked, slightly upward-fining sequence. Tide-dominated estuarine distributaries tend to fill with sand and form seaward-thickening and seaward-widening lenses. A generalized vertical profile consists of an upward-coarsening sequence from prodelta and shelf muds.
    • 62. Deltaic Depositional Systems Tide-Dominated Deltas• • The Mahakam Delta Deposited in a moderately tide-dominated environment.
    • 63. Deltaic Depositional Systems Tide-Dominated Deltas• • The Mahakam Delta Sedimentary sequences defined in the Handil and Badak fields show strong lateral variability in delta-plain marine environments at scale of 1500 to 5000 feet. Channel mouth-bars are less crescentric and wave elongate parallel to tidal current direction than in fluvially-dominated deltas.
    • 64. Deltaic Depositional Environment F344 sand
    • 65. M-50 M-76S M-12 M-100ST M-9010 F340 Channel sand F340 TZF344Crevasse Splay sand F344 Crevasse Splay sand F342 TZ F344 TZ F344 Mouth Bar sand F348 Channel sand F348 Mouth Bar sand F346 TZ F348 TZ F350 TZ F352 TZ DELTA PLAIN F354 TZ G302 TZ
    • 66. M-50 M-76S M-12 M-100ST M-9010 F340 Channel sand F340 TZF344Crevasse Splay sand F344 Crevasse Splay sand F342 TZ F344 TZ F344 Mouth Bar sand F348 Channel sand F348 Mouth Bar sand F346 TZ MARINE/ PRODELTA F348 TZ F350 TZ F352 TZ DELTA PLAIN F354 TZ G302 TZ
    • 67. M-50 M-76S M-12 M-100ST M-9010 F340 Channel sand F340 TZF344Crevasse Splay sand F344 Crevasse Splay sand F342 TZ F344 TZ F344 DELTA PLAIN F348 Channel sand Mouth Bar sand F348 Mouth Bar sand F346 TZ MARINE/ PRODELTA F348 TZ DELTA FRONT F350 TZ F352 TZ DELTA PLAIN F354 TZ G302 TZ
    • 68. M-50 M-76S M-12 M-100ST M-9010 F340 Channel sand F340 TZF344Crevasse Splay sand F344 Crevasse Splay sand DELTA PLAINF346 F342 TZCrevasse Splay sand F344 TZ F344 DELTA PLAIN F348 Channel sand Mouth Bar sand F348 Mouth Bar sand MARINE/ PRODELTA F346 TZ F348 TZ DELTA FRONT F350 TZ F352 TZ DELTA PLAIN F354 TZ G302 TZ
    • 69. M-50 M-76S M-12 M-100ST M-9010 F340 Channel sand F340 TZF344Crevasse Splay sand F344 Crevasse Splay sand DELTA PLAINF346 F342 TZCrevasse Splay sand F344 F344 TZ DELTA PLAIN F348 Channel sand Mouth Bar sand F348 DELTA FRONT Mouth Bar sand MARINE/ PRODELTA F346 TZ F348 TZ DELTA FRONT F350 TZ F352 TZ DELTA PLAIN F354 TZ G302 TZ
    • 70. M-50 M-76S M-12 M-100ST M-9010 F340 Channel sandF344 DELTA PLAIN F340 TZCrevasse Splay sand F344 Crevasse Splay sand DELTA PLAINF346 F342 TZCrevasse Splay sand F344 F344 TZ DELTA PLAIN F348 Channel sand Mouth Bar sand F348 DELTA FRONT Mouth Bar sand MARINE/ PRODELTA F346 TZ F348 TZ DELTA FRONT F350 TZ F352 TZ DELTA PLAIN F354 TZ G302 TZ
    • 71. Character of Major Depositional Systems Terrigenous Fan Systems Fluvial Depositional Systems Deltaic Depositional Systems Barrier/ Strandplain Systems Terrigenous Shelf Systems Slope and Abyssal Depositional Systems Eolian Systems
    • 72. Barrier/ Strandplain Systems• Barrier-island and Strandplain Systems These systems are marginal marine depositional systems distinguished by the presence or absence of lagoonal facies Develop under wave-dominated conditions characterized by strike-parallel longshore reworking and transport of sediment.
    • 73. Barrier/ Strandplain Systems• Barrier-islands Barrier islands or barrier spits are flanked lanward by lagoonal deposits. Vertical barrier sequences vary, depending on wheter regression or marine transgression predominate.• Strandplains Strandplains, wheter sand rich or mud rich, are prograding coastal margins fed laterally by a sediment source but not separated by a lagoon from delta-plain and other mainland facies. Strandplains systems are often cut by distributary channels, the sediment sources from which they develop, and as such are a component of wave-dominated, cuspate delta system.
    • 74. Barrier/ Strandplain Systems
    • 75. Barrier/ Strandplain Systems• Internal Barrier Geometry The precenses of tidal inlets and the extent of their lateral migration are significants determinants of internal barrier geometry.
    • 76. Barrier/ Strandplain Systems• Barrier Systems In macrotidal environment (such as the Gulf Coast), barriers tend to be long and relatively narrow with widely spaced tidal inlets. On mesotidal coasts, barriers are short and stubby and are more frquently interrupted by tidal inlets. Climate also acts as an important control on component facies of the barrier system, and also eolian activity (example: the Texas Gulf Coast, where a semiarid climate limits vegetation growth on the barrier).
    • 77. Barrier/ Strandplain Systems
    • 78. Barrier/ Strandplain Systems• Facies Distributions of Barrier Systems Divide into three major assemblages: 1) shoreface facies on the seaward side of the barrier. 2) tidal-inlet facies. 3)Barrier-lagoon facies transition.
    • 79. Barrier/ Strandplain Systems
    • 80. Barrier/ Strandplain Systems Shoreface facies• Shoreface facies are upward coarsening from subtidal shelf muds into overlying intertidal barrier foreshore facies. The lower shoreface is defined as seaward of the break in slope of the nearshore sediment prism, predominantly very fine sand and silt. The middle to upper shoreface contains cleaner sands and shows more variability in sedimentary structures.
    • 81. Barrier/ Strandplain Systems
    • 82. Barrier/ Strandplain Systems• Inlet facies Tidal-inlet facies may be subdevided into tidal-delta and tidal- cahnnel deposits. Tidal deltas are arcuate, roughly shore-normally oriented deposits consisting of a series of a channels and shoals occuring on the lanward (flood-tidal delta) and seaward (ebb- tidal delta) side of the barrier system. The latter would form a seal for any hydrocarbons within the tidal-delta deposits. Tidal-channel deposits are laid down while tidal inlets migrate laterally. Texturally, tidal-inlet deposits tend to have a coarse base and fine upwards, but a slight coarsening may occur at the top of the sequence.
    • 83. Barrier/ Strandplain Systems
    • 84. Barrier/ Strandplain Systems Landward Barrier Margins• Shoreface facies are upward coarsening from subtidal shelf muds into overlying intertidal barrier foreshore facies. Landward interfingering of barrier sandstones with organic-rich facies can provide a ready path of primary migration into barrier reservoirs. The middle to upper shoreface contains cleaner sands and shows more variability in sedimentary structures.
    • 85. Barrier/ Strandplain Systems• Strandplain Systems Strandplains tend to form relatively thin, tabular unit that parallel to shoreline and contain an upward-coarsening shoreface-beach sequence. Often associated with the flanks of delta systems and may be cut by distributary channels. Sand-rich strandplains develop by the seaward accretion of beach ridges.
    • 86. Barrier/ Strandplain Systems
    • 87. Character of Major Depositional Systems Terrigenous Fan Systems Fluvial Depositional Systems Deltaic Depositional Systems Barrier/ Strandplain Systems Terrigenous Shelf Systems Slope and Abyssal Depositional Systems Eolian Systems
    • 88. Terrigenous Shelf Systems• Terrigenous Shelf Systems Consist of land-derived clastic material, in contrast to biogenic systems, which consist of organic sediments, and authigenic sediments, which consist of mainly glauconite and phosporite.
    • 89. Terrigenous Shelf Systems
    • 90. Terrigenous Shelf Systems• Depositional Models of Transgressive and Prograding Shelf Systems
    • 91. Terrigenous Shelf Systems• Transgressive Shelf Systems Transgressive storm-dominated shelf sequences are typically upward finning with a reworked shoreline deposit at the base grading upward through a decreasing scale of sedimentary structures. The structures might include trough cross-stratification, hummocky cross-stratification, and graded, parallel- laminated, storm deposits. The sequence is capped by shelf muds. Transgressive tide-dominated shelf squence is also upward fining, with deposits of sand ridges and sand waves toward the base and large-scale, low-angle accretion surfaces toward the middle of the sequence.
    • 92. Terrigenous Shelf Systems
    • 93. Terrigenous Shelf Systems• Regressive Shelf Systems Regressive, or prograding, storm-dominated shelf sequences will pass from burrowed shelf muds to crossbedded or storm-reworked and hummocky shelf sandstones and may, with full regression, be capped by marginal-marine deposits such as barrier and lagoonal sediments. the sequence will be upward coarsening.
    • 94. Character of Major Depositional Systems Terrigenous Fan Systems Fluvial Depositional Systems Deltaic Depositional Systems Barrier/ Strandplain Systems Terrigenous Shelf Systems Slope and Abyssal Depositional Systems Eolian Systems
    • 95. Slope and Abyssal Depositional Systems• Slope and Abyssal Depositional Systems Found along continental margins, deep lakes, and cratonic basins and they develop in reltively deep water beyond the shelf break. Modern slopes (depth 150 to 1000 feet) are predominantly erosional because of the rapid postglacial rice in sea level. Present upper slopes are typically areas of sedimentary bypassing with local progadation and canyon cutting and filling.
    • 96. Slope and Abyssal Depositional Systems
    • 97. Slope and Abyssal Depositional Systems• Depositional Sequences in Slope Systems • Classical Turbidite Sequences defined as five elements that range upward from a massive, presumably rapidly deposited bed, trough upper flow regime flat bed, rippled bed, and parallel- laminated bed, to turbidite and hemipelagic mud. Consist of monotonous alternations of parallel-bedded sandstones and shales.
    • 98. Slope and Abyssal Depositional Systems
    • 99. Character of Major Depositional Systems Terrigenous Fan Systems Fluvial Depositional Systems Deltaic Depositional Systems Barrier/ Strandplain Systems Terrigenous Shelf Systems Slope and Abyssal Depositional Systems Eolian Systems
    • 100. Eolian Systems• Eolian Systems Characterized by the transport of loose, uncohessive sediment by wind. Eolian sediments tend to be well sorted becouse of continous active reworking and are typically fine- to medium-grained quartzose sand. Interdunal area: poorly sorted, impermeable Extradune: are not those of dune building, other depositional system
    • 101. FINISH

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