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| | isbn = 0891816607 | | | isbn = 0891816607 |
| }} | | }} |
− | Stratigraphically complex fields are those that exhibit a high degree of vertical and lateral heterogeneity that is directly controlled by the environment of deposition (Table 1). This heterogeneity occurs at all scales (see [[Geological heterogeneities]]). It can result in a highly variable distribution of rock properties within one reservoir and the division of a single stratigraphic interval into multiple reservoirs that act as independent, self-contained compartments. | + | Stratigraphically complex fields are those that exhibit a high degree of vertical and [[lateral]] heterogeneity that is directly controlled by the environment of deposition (Table 1). This heterogeneity occurs at all scales (see [[Geological heterogeneities]]). It can result in a highly variable distribution of rock properties within one reservoir and the division of a single stratigraphic interval into multiple reservoirs that act as independent, self-contained compartments. |
| | | |
| ==Degree of hetrogeneity== | | ==Degree of hetrogeneity== |
| {| class = "wikitable" | | {| class = "wikitable" |
| |- | | |- |
− | |+ {{table number|1}}Tentative, relative depositional heterogeneity ranking of reservoir facies based primarily on Texas petroleum fields | + | |+ {{table number|1}}Tentative, relative depositional heterogeneity ranking of reservoir facies based primarily on Texas [[petroleum]] fields |
| |- | | |- |
| ! Depositional Environment | | ! Depositional Environment |
| ! Heterogeneity Rank | | ! Heterogeneity Rank |
| |- | | |- |
− | | ''' Siliciclastic Systems ''' | + | | colspan=2 | ''' Siliciclastic Systems ''' |
− | |
| |
− | | |
| |- | | |- |
| | Submarine slope/fan/canyon fill, silty to muddy | | | Submarine slope/fan/canyon fill, silty to muddy |
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| | 8.0 | | | 8.0 |
| |- | | |- |
− | | Fluvial or deltaic sandstone on carbonate shelf | + | | Fluvial or deltaic [[sandstone]] on carbonate shelf |
| | 8.0 | | | 8.0 |
| |- | | |- |
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| | 2.0 | | | 2.0 |
| |- | | |- |
− | | ''' Carbonate Systems ''' | + | | colspan=2 | ''' Carbonate Systems ''' |
− | |
| |
− | | |
| |- | | |- |
| | Evaporitic flats (sabkhas) | | | Evaporitic flats (sabkhas) |
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| | 8.5 | | | 8.5 |
| |- | | |- |
− | | Open shelves, extensive diagenesis | + | | Open shelves, extensive [[diagenesis]] |
| | 8.0 | | | 8.0 |
| |- | | |- |
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| | 8.0 | | | 8.0 |
| |- | | |- |
− | | Karstic unconformity zones | + | | Karstic [[unconformity]] zones |
| | 8.0 | | | 8.0 |
| |- | | |- |
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| * Questionable correlation of depositional packages between wells | | * Questionable correlation of depositional packages between wells |
| * Presence of numerous vertical [[permeability]] barriers at a variety of scales | | * Presence of numerous vertical [[permeability]] barriers at a variety of scales |
− | * Complex [[porosity]]-permeability and [[capillary pressure]] relationships (a broad scatter in the data indicates different lithofacies and pore types) | + | * Complex [[porosity]]-permeability and [[capillary pressure]] relationships (a broad scatter in the data indicates different [[lithofacies]] and pore types) |
| * Anomalous changes in pressure gradient | | * Anomalous changes in pressure gradient |
| * Variable oil and water chemical composition | | * Variable oil and water chemical composition |
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| | | |
| * Multiple [[fluid contacts]] at different structural elevations | | * Multiple [[fluid contacts]] at different structural elevations |
− | * Irregular reservoir distribution (such as a dry hole surrounded by producers) | + | * Irregular reservoir distribution (such as a [[dry hole]] surrounded by producers) |
| * Anomalous fluid relationships (such as a gas zone underlying an oil zone or an oil zone downdip of water) | | * Anomalous fluid relationships (such as a gas zone underlying an oil zone or an oil zone downdip of water) |
| * Irregular and/or highly directional waterflood response | | * Irregular and/or highly directional waterflood response |
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| | | |
| ==Evaluation== | | ==Evaluation== |
| + | |
| + | [[file:evaluating-stratigraphically-complex-fields_fig1.png|thumb|300px|{{figure number|1}}Example of electrofacies map showing distribution of SP log patterns. (From Galloway and Cheng.<ref name=pt06r35>Galloway, W. E., Cheng, E. S. S., 1985, Reservoir facies architecture in a microtidal barrier system—Frio Formation, Texas Gulf Coast: The University of Texas Bureau of Economic Geology, Report of Investigations, v. 144, 36 p.</ref>)]] |
| | | |
| Recognition and three-dimensional characterization of reservoir heterogeneity in a stratigraphically complex field requires a well-by-well analysis of the following: | | Recognition and three-dimensional characterization of reservoir heterogeneity in a stratigraphically complex field requires a well-by-well analysis of the following: |
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| | | |
| * Understand the basic regional and local geological setting. | | * Understand the basic regional and local geological setting. |
− | * Describe lithofacies and interpreted depositional environment(s) (see “Lithofacies and Environmental Analysis of Clastic Depositional Systems”). | + | * Describe lithofacies and interpreted depositional environment(s) (see [[Lithofacies and environmental analysis of clastic depositional systems]]). |
| * Determine the relationship between lithofacies/depositional environment and reservoir distribution and quality. | | * Determine the relationship between lithofacies/depositional environment and reservoir distribution and quality. |
| * Determine reservoir distribution. | | * Determine reservoir distribution. |
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| * Use reservoir simulation model to manage field. | | * Use reservoir simulation model to manage field. |
| * Refine reservoir description and calibrate reservoir simulation model. | | * Refine reservoir description and calibrate reservoir simulation model. |
− |
| |
− | [[file:evaluating-stratigraphically-complex-fields_fig1.png|thumb|{{figure number|1}}Example of electrofacies map showing distribution of SP log patterns. (From <ref name=pt06r35>Galloway, W. E., Cheng, E. S. S., 1985, Reservoir facies architecture in a microtidal barrier system—Frio Formation, Texas Gulf Coast: The University of Texas Bureau of Economic Geology, Report of Investigations, v. 144, 36 p.</ref>.)]]
| |
| | | |
| ==See also== | | ==See also== |
| * [[Introduction to geological methods]] | | * [[Introduction to geological methods]] |
| * [[Lithofacies and environmental analysis of clastic depositional systems]] | | * [[Lithofacies and environmental analysis of clastic depositional systems]] |
− | * [[Monte carlo and stochastic simulation methods]]
| |
| * [[Subsurface maps]] | | * [[Subsurface maps]] |
| * [[Flow units for reservoir characterization]] | | * [[Flow units for reservoir characterization]] |
| * [[Effective pay determination]] | | * [[Effective pay determination]] |
− | * [[Multivariate data analysis]] | + | * [[Cross section]] |
− | * [[Geological cross sections]]
| |
| * [[Evaluating structurally complex reservoirs]] | | * [[Evaluating structurally complex reservoirs]] |
| * [[Conversion of well log data to subsurface stratigraphic and structural information]] | | * [[Conversion of well log data to subsurface stratigraphic and structural information]] |
| * [[Evaluating tight gas reservoirs]] | | * [[Evaluating tight gas reservoirs]] |
− | * [[Correlation and regression analysis]]
| |
| * [[Reservoir quality]] | | * [[Reservoir quality]] |
− | * [[Carbonate reservoir models: Facies, diagenesis, and flow characterization]] | + | * [[Carbonate reservoir models: facies, diagenesis, and flow characterization]] |
| * [[Fluid contacts]] | | * [[Fluid contacts]] |
| * [[Geological heterogeneities]] | | * [[Geological heterogeneities]] |
| * [[Evaluating fractured reservoirs]] | | * [[Evaluating fractured reservoirs]] |
| * [[Evaluating diagenetically complex reservoirs]] | | * [[Evaluating diagenetically complex reservoirs]] |
− | * [[Statistics overview]]
| |
| | | |
| ==References== | | ==References== |
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| | | |
| [[Category:Geological methods]] | | [[Category:Geological methods]] |
| + | [[Category:Methods in Exploration 10]] |