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Line 44: − {| class = "wikitable"+ − |-+ − ! Step+ − ! Action+ − |-+ − | 1+ − | Estimate formation temperature T<sub>f</sub> using the following formula:+ − + − + − + − + − + − − − − |- − | 2 − | Estimate formation pressure (psi) by multiplying 0.433 (freshwater gradient) by formation depth. − |- − | 3 − | Obtain formation water resistivity R<sub>w</sub> [ohm.m] in one of three ways: − − − − |} − − [[file:formation-fluid-pressure-and-its-application_fig5-5.png|300px|thumb|{{figure number|1}}Determining NaCl concentration. Copyright: Schlumberger.]] Line 75:
Line 64: − − [[file:formation-fluid-pressure-and-its-application_fig5-6.png|300px|thumb|{{figure number|2}}Use to estimate formation water density from ppm NaCl and temperature. Copyright: Gearhart-Owens.<ref name=G-O1972> − Gearhart-Owens Industries, 1972, GO Log Interpretation Reference Data Handbook: − Fort Worth, Gearhart-Owens Industries Inc., 226 p</ref>]]
Formation water density (view source)
Revision as of 20:01, 25 November 2014
, 20:01, 25 November 2014no edit summary
==Procedure: estimating density from r<sub>w</sub>==
==Procedure: estimating density from r<sub>w</sub>==
[[file:formation-fluid-pressure-and-its-application_fig5-5.png|300px|thumb|{{figure number|1}}Determining NaCl concentration. Copyright: Schlumberger.]]
[[file:formation-fluid-pressure-and-its-application_fig5-6.png|300px|thumb|{{figure number|2}}Use to estimate formation water density from ppm NaCl and temperature. Copyright: Gearhart-Owens.<ref name=G-O1972>Gearhart-Owens Industries, 1972, GO Log Interpretation Reference Data Handbook: Fort Worth, Gearhart-Owens Industries Inc., 226 p</ref>]]
Use the procedure outlined in the table below to estimate formation water density at reservoir conditions using R<sub>w</sub>. The approximate error is ±10% (after <ref name=ch05r4 />).
Use the procedure outlined in the table below to estimate formation water density at reservoir conditions using R<sub>w</sub>. The approximate error is ±10% (after <ref name=ch05r4 />).
# Gather data: formation temperature (T<sub>f</sub> ), water resistivity (R<sub>w</sub> ), and formation pressure. Estimate pressure by multiplying depth by 0.433 psi/ft or other appropriate gradient. Check for T<sub>f</sub> errors.
# Gather data: formation temperature (T<sub>f</sub> ), water resistivity (R<sub>w</sub> ), and formation pressure. Estimate pressure by multiplying depth by 0.433 psi/ft or other appropriate gradient. Check for T<sub>f</sub> errors.
# Estimate sodium chloride (NaCl) concentration from R using Figure 5-5.
# Estimate sodium chloride (NaCl) concentration from R using [[:file:formation-fluid-pressure-and-its-application_fig5-5.png|Figure 1]].
# Estimate density from wt % NaCl and temperature using Figure 5-6.
# Estimate density from wt % NaCl and temperature using [[:file:formation-fluid-pressure-and-its-application_fig5-6.png|Figure 2]].
==Gather data==
==Gather data==
* Formation water resistivity
* Formation water resistivity
# Estimate formation temperature T<sub>f</sub> using the following formula:
#*:<math>\mbox{T}_{\rm f} = \mbox{T}_{\rm s} + \mbox{D}_{\rm f} \left(\mbox{BHT} - \frac{\mbox{T}_{\rm s}}{\mbox{TD}}\right)</math>
#*::where:
#*::: T<sub>s</sub> = average surface temperature (°F)
#*::: D<sub>f</sub> = depth to the formation (ft)
#*::: BHT = bottom-hole temperature (found on log header) (°F)
#*::: TD = total depth (BHT and TD must be from the same log run) (ft)
# Estimate formation pressure (psi) by multiplying 0.433 (freshwater gradient) by formation depth.
:<math>\mbox{T}_{\rm f} = \mbox{T}_{\rm s} + \mbox{D}_{\rm f} \left(\mbox{BHT} - \frac{\mbox{T}_{\rm s}}{\mbox{TD}}\right)</math>
# Obtain formation water resistivity R<sub>w</sub> [ohm.m] in one of three ways:
#* From a sample of water from the formation of interest measured for R<sub>w</sub>
where:
#* Using a water catalog
* T<sub>s</sub> = average surface temperature (°F)
#* Calculating it from an [[SP log]]
* D<sub>f</sub> = depth to the formation (ft)
* BHT = bottom-hole temperature (found on log header) (°F)
* TD = total depth (BHT and TD must be from the same log run) (ft)
* From a sample of water from the formation of interest measured for R<sub>w</sub>
* Using a water catalog
* Calculating it from an [[SP log]]
==Determine NaCl concentration from r<sub>w</sub>==
==Determine NaCl concentration from r<sub>w</sub>==
The predominant solute in most formation water is sodium chloride (NaCl). Its concentration determines formation water density and R<sub>w</sub>. When only R<sub>w</sub> is available, we can use NaCl concentration to determine density.
The predominant solute in most formation water is sodium chloride (NaCl). Its concentration determines formation water density and R<sub>w</sub>. When only R<sub>w</sub> is available, we can use NaCl concentration to determine density.
==Estimate density==
==Estimate density==
Estimate formation water density from ppm NaCl and temperature using the chart in [[:file:formation-fluid-pressure-and-its-application_fig5-6.png|Figure 2]]. The following table describes the procedure to use with the chart.
Estimate formation water density from ppm NaCl and temperature using the chart in [[:file:formation-fluid-pressure-and-its-application_fig5-6.png|Figure 2]]. The following table describes the procedure to use with the chart.