Changes

  | part    = Predicting the occurrence of oil and gas traps

  | part    = Predicting the occurrence of oil and gas traps

  | chapter = Predicting reservoir system quality and performance

  | chapter = Predicting reservoir system quality and performance

  | frompg  = 9-1

  | frompg  = 9-40

  | topg    = 9-156

  | topg    = 9-43

  | author  = Dan J. Hartmann, Edward A. Beaumont

  | author  = Dan J. Hartmann, Edward A. Beaumont

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch09/ch09.htm

==Interpreting a relative permeability curve==

==Interpreting a relative permeability curve==

[[file:predicting-reservoir-system-quality-and-performance_fig9-27.png|thumb|{{figure number|2}} Modified from Arps.<ref name=Arps_1964>Arps, J. J. 1964, [http://archives.datapages.com/data/bulletns/1961-64/data/pg/0048/0002/0150/0157.htm Engineering concepts useful in oil finding]: AAPG Bulletin, v. 48, no. 2, p. 943-961.</ref>]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-27.png|300px|thumb|{{figure number|2}}Three relative permeability curves. Modified from Arps.<ref name=Arps_1964>Arps, J. J. 1964, [http://archives.datapages.com/data/bulletns/1961-64/data/pg/0048/0002/0150/0157.htm Engineering concepts useful in oil finding]: AAPG Bulletin, v. 48, no. 2, p. 943-961.</ref>]]

The diagram in [[:file:predicting-reservoir-system-quality-and-performance_fig9-27.png|Figure 2]] shows relationships between relative permeability curves (drainage and imbibition), [[capillary pressure]], and fluid distribution in a homogeneous section of a reservoir system. The reservoir system rock has a [[porosity]] of 30% and a permeability of 10 md (r₃₅ = 1.1μ). Laboratory single-phase air permeability is typically used to represent absolute permeability (K_a when determining relative permeability to oil or water at a specific S_w.

The diagram in [[:file:predicting-reservoir-system-quality-and-performance_fig9-27.png|Figure 2]] shows relationships between relative permeability curves (drainage and imbibition), [[capillary pressure]], and fluid distribution in a homogeneous section of a reservoir system. The reservoir system rock has a [[porosity]] of 30% and a permeability of 10 md ([[Characterizing_rock_quality#What_is_r35.3F|r₃₅]] = 1.1μ). Laboratory single-phase air permeability is typically used to represent absolute permeability (K_a when determining relative permeability to oil or water at a specific S_w.

[[: [[:file:predicting-reservoir-system-quality-and-performance_fig9-27.png|Figure 2]] depicts three relative permeability curves:

[[:file:predicting-reservoir-system-quality-and-performance_fig9-27.png|Figure 2]] depicts three relative permeability curves:

* Water (K_rw)—similar for both drainage and imbibition tests

* Water (K_rw)—similar for both drainage and imbibition tests

==Pore throat size and k_r==

==Pore throat size and k_r==

Every pore type has a unique relative permeability signature. Consider the hypothetical drainage relative permeability type curves shown below. Curves A, B, and C represent the relative permeability relationships for rocks with different port types: macro, meso, and micro, respectively. Curve A represents a rock with greater performance capability than B or C. Note how critical water saturation decreases as pore throat size increases. Also note the changing position of K_ro–K_rw crossover with changes in pore throat size.

 

 

Every pore type has a unique relative permeability signature. Consider the hypothetical drainage relative permeability type curves shown in [[:file:predicting-reservoir-system-quality-and-performance_fig9-28.png|Figure 3]]. Curves A, B, and C represent the relative permeability relationships for rocks with different pore types: macro, [[Wikipedia:Mesoporous material|meso]], and micro, respectively. Curve A represents a rock with greater performance capability than B or C. Note how critical water saturation decreases as pore throat size increases. Also note the changing position of K_ro–K_rw crossover with changes in pore throat size.

==Critical water saturation==

==Critical water saturation==

==Critical water saturation==

==Critical water saturation==

The critical S_w value is different for each port type. Curve A in Figure 9-28 represents rocks with macroporosity. It has a critical S_w less than 20%. Curve B represents a rock (continued) with [[Wikipedia:Mesoporous material|mesoporosity]]. Mesoporous rocks have a critical S_w of 20–60%. Curve C represents rocks with microporosity. They have a critical S_w of 60–80%.

 

The critical S_w value is different for each port type. Curve A in Figure 9-28 represents rocks with macroporosity. It has a critical S_w less than 20%. Curve B represents a rock (continued) with mesoporosity. Mesoporous rocks have a critical S_w of 20–60%. Curve C represents rocks with microporosity. They have a critical S_w of 60–80%.

The table below summarizes representative critical S_w values for macro-, meso-, and micropore types that correspond to A, B, and C, respectively, in [[:file:predicting-reservoir-system-quality-and-performance_fig9-28.png|Figure 3]].

The table below summarizes representative critical S_w values for macro-, meso-, and micropore types that correspond to A, B, and C, respectively, in [[:file:predicting-reservoir-system-quality-and-performance_fig9-28.png|Figure 3]].

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Predicting reservoir system quality and performance]]

[[Category:Predicting reservoir system quality and performance]]