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Predicting reservoir drive mechanism (view source)
Revision as of 16:59, 31 January 2014
, 16:59, 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 = Predicting reservoir system quality and performance
| frompg = 9-1
| topg = 9-156
| author = Dan J. Hartmann, Edward A. Beaumont
| link = http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
One can predict drive type by analyzing (1) the reservoir system of a prospect and (2) the production history characteristics of similar nearby reservoirs.
==Predicting drive type==
Reservoir analysis includes making cross sections, structural maps, and isopach maps. Analyzing nearby producing fields yields the best set of inferential data. This includes (1) making plots of historical oil, gas, condensate, and water production and pressure decline and (2) making cumulative production maps. When all available information has been assembled, find the drive type that best fits the prospective reservoir system. The table below summarizes typical characteristics of primary drive types.
{| class = "wikitable"
|-
! Drive
! Characteristics
|-
| Water
| * Quality of aquifer pore geometry comparable to reservoir pore geometry * Aquifer volume at least 10 times greater than reservoir volume * Flat to gradual production and pressure declines * Gradually to rapidly increasing water production late in life of reservoir * Early increasing water production from downdip wells * GOR (gas–oil ratio) relatively constant * High recovery factor (50% or more)
|-
| Gas expansion
| * Moderate drop in reservoir pressure * Moderate production decline * Water-free production (or relatively minor) * GOR flat for first 50% of production, then increases * GOR increases rapidly in structurally high wells * Moderate recovery factor (typically 30%)
|-
| Solution gas
| * Rapid drop in reservoir pressure early in production history * Exponential production decline * Water-free production (or relatively minor) * Increasing GOR early, decreasing later as gas is exhausted * Low recovery factor (20% or less)
|-
| Rock drive
| * Unconsolidated reservoir such as sandstone, chalk, or diatomite * Reservoir in overpressure section * No decline while reservoir compacts, then rapid production decline
|-
| Gravity
| * Steeply dipping beds or vertical [[permeability]] greater than horizontal * Fractured reservoir * Low-viscosity oil (in general) * Rapid production decline * High recovery rate (75% or more), but often with low recovery volume
|}
==Production history characteristics for drives==
The graphs below show oil reservoir production history characteristics for water, gas expansion, and gas solution drives. To predict reservoir drive type, if possible, plot the production history of nearby fields with analogous reservoir systems and compare with these graphs.
[[file:predicting-reservoir-system-quality-and-performance_fig9-8.png|thumb|{{figure number|9-8}}Modified. Copyright: Levorsen, 1954; courtesy W.H. Freeman and Co.]]
==Recoveries of oil vs. gas reservoirs==
The table below shows typical recovery rates for oil vs. gas reservoir systems for different reservoir drive mechanisms with mega and macro port type systems (John Farina, personal communication, 1998; .<ref name=ch09r21>Garb, F., A., Smith, G., L., 1987, Estimation of oil and gas reserves, in Bradley, H., B., ed., Petroleum Engineering Handbook: SPE, p. 40-1–40-32.</ref> Recoveries would be lower for meso to micro port systems. Use this table to project the recoveries for your prospects.
{| class = "wikitable"
|-
! Reservoir drive mechanism
! Percent ultimate recovery
! Gas
! Oil
|-
| Strong water
| 30–40
| 45–60
|-
| Partial water
| 40–50
| 30–45
|-
| Gas expansion
| 50–70
| 20–30
|-
| Solution gas
| N/A
| 15–25
|-
| Rock
| 60–80
| 10–60
|-
| Gravity drainage
| N/A
| 50–70
|}
==Recoveries for sandstone vs. carbonate reservoirs==
The American Petroleum Institute conducted a study to determine recovery amounts and efficiencies for water vs. solution gas drives for sandstone and carbonate reservoirs, summarized in the table below (Arps, 1967). Use the table to project recoveries for your prospects.
{| class = "wikitable"
|-
! Drive
! Units
! Sandstone
! Carbonate
! Min.
! Ave.
! Max.
! Min.
! Ave.
! Max.
|-
| Water
| bbl/acre-ft
| 155
| 571
| 1,641
| 6
| 172
| 1,422
|-
| m<sup>3</sup> /h-m
| 199
| 735
| 2,113
| 8
| 221
| 1,831
|-
| % <xref ref-type="table-fn" rid="ch09tblfn1"> * </xref>
| 28
| 51
| 87
| 6
| 44
| 80
|-
| Solution gas
| bbl/acre-ft
| 47
| 154
| 534
| 20
| 88
| 187
|-
| m<sup>3</sup> /h-m
| 60
| 198
| 688
| 26
| 113
| 241
|-
| % <xref ref-type="table-fn" rid="ch09tblfn1"> * </xref>
| 9
| 21
| 46
| 15
| 18
| 21
|}
==See also==
* [[Reservoir system basics]]
* [[What is a reservoir system?]]
* [[Analyzing a reservoir system]]
* [[Defining flow units and containers]]
* [[Reservoir drive mechanisms]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.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:Predicting reservoir system quality and performance]] [[Category:Pages with bad references]]
| 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 = Predicting reservoir system quality and performance
| frompg = 9-1
| topg = 9-156
| author = Dan J. Hartmann, Edward A. Beaumont
| link = http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
One can predict drive type by analyzing (1) the reservoir system of a prospect and (2) the production history characteristics of similar nearby reservoirs.
==Predicting drive type==
Reservoir analysis includes making cross sections, structural maps, and isopach maps. Analyzing nearby producing fields yields the best set of inferential data. This includes (1) making plots of historical oil, gas, condensate, and water production and pressure decline and (2) making cumulative production maps. When all available information has been assembled, find the drive type that best fits the prospective reservoir system. The table below summarizes typical characteristics of primary drive types.
{| class = "wikitable"
|-
! Drive
! Characteristics
|-
| Water
| * Quality of aquifer pore geometry comparable to reservoir pore geometry * Aquifer volume at least 10 times greater than reservoir volume * Flat to gradual production and pressure declines * Gradually to rapidly increasing water production late in life of reservoir * Early increasing water production from downdip wells * GOR (gas–oil ratio) relatively constant * High recovery factor (50% or more)
|-
| Gas expansion
| * Moderate drop in reservoir pressure * Moderate production decline * Water-free production (or relatively minor) * GOR flat for first 50% of production, then increases * GOR increases rapidly in structurally high wells * Moderate recovery factor (typically 30%)
|-
| Solution gas
| * Rapid drop in reservoir pressure early in production history * Exponential production decline * Water-free production (or relatively minor) * Increasing GOR early, decreasing later as gas is exhausted * Low recovery factor (20% or less)
|-
| Rock drive
| * Unconsolidated reservoir such as sandstone, chalk, or diatomite * Reservoir in overpressure section * No decline while reservoir compacts, then rapid production decline
|-
| Gravity
| * Steeply dipping beds or vertical [[permeability]] greater than horizontal * Fractured reservoir * Low-viscosity oil (in general) * Rapid production decline * High recovery rate (75% or more), but often with low recovery volume
|}
==Production history characteristics for drives==
The graphs below show oil reservoir production history characteristics for water, gas expansion, and gas solution drives. To predict reservoir drive type, if possible, plot the production history of nearby fields with analogous reservoir systems and compare with these graphs.
[[file:predicting-reservoir-system-quality-and-performance_fig9-8.png|thumb|{{figure number|9-8}}Modified. Copyright: Levorsen, 1954; courtesy W.H. Freeman and Co.]]
==Recoveries of oil vs. gas reservoirs==
The table below shows typical recovery rates for oil vs. gas reservoir systems for different reservoir drive mechanisms with mega and macro port type systems (John Farina, personal communication, 1998; .<ref name=ch09r21>Garb, F., A., Smith, G., L., 1987, Estimation of oil and gas reserves, in Bradley, H., B., ed., Petroleum Engineering Handbook: SPE, p. 40-1–40-32.</ref> Recoveries would be lower for meso to micro port systems. Use this table to project the recoveries for your prospects.
{| class = "wikitable"
|-
! Reservoir drive mechanism
! Percent ultimate recovery
! Gas
! Oil
|-
| Strong water
| 30–40
| 45–60
|-
| Partial water
| 40–50
| 30–45
|-
| Gas expansion
| 50–70
| 20–30
|-
| Solution gas
| N/A
| 15–25
|-
| Rock
| 60–80
| 10–60
|-
| Gravity drainage
| N/A
| 50–70
|}
==Recoveries for sandstone vs. carbonate reservoirs==
The American Petroleum Institute conducted a study to determine recovery amounts and efficiencies for water vs. solution gas drives for sandstone and carbonate reservoirs, summarized in the table below (Arps, 1967). Use the table to project recoveries for your prospects.
{| class = "wikitable"
|-
! Drive
! Units
! Sandstone
! Carbonate
! Min.
! Ave.
! Max.
! Min.
! Ave.
! Max.
|-
| Water
| bbl/acre-ft
| 155
| 571
| 1,641
| 6
| 172
| 1,422
|-
| m<sup>3</sup> /h-m
| 199
| 735
| 2,113
| 8
| 221
| 1,831
|-
| % <xref ref-type="table-fn" rid="ch09tblfn1"> * </xref>
| 28
| 51
| 87
| 6
| 44
| 80
|-
| Solution gas
| bbl/acre-ft
| 47
| 154
| 534
| 20
| 88
| 187
|-
| m<sup>3</sup> /h-m
| 60
| 198
| 688
| 26
| 113
| 241
|-
| % <xref ref-type="table-fn" rid="ch09tblfn1"> * </xref>
| 9
| 21
| 46
| 15
| 18
| 21
|}
==See also==
* [[Reservoir system basics]]
* [[What is a reservoir system?]]
* [[Analyzing a reservoir system]]
* [[Defining flow units and containers]]
* [[Reservoir drive mechanisms]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.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:Predicting reservoir system quality and performance]] [[Category:Pages with bad references]]