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| | part = Critical elements of the petroleum system | | | part = Critical elements of the petroleum system |
| | chapter = Formation fluid pressure and its application | | | chapter = Formation fluid pressure and its application |
− | | frompg = 5-1 | + | | frompg = 5-16 |
− | | topg = 5-64 | + | | topg = 5-18 |
| | author = Edward A. Beaumont, Forrest Fiedler | | | author = Edward A. Beaumont, Forrest Fiedler |
| | link = http://archives.datapages.com/data/specpubs/beaumont/ch05/ch05.htm | | | link = http://archives.datapages.com/data/specpubs/beaumont/ch05/ch05.htm |
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| * Total dissolved solids (TDS) | | * Total dissolved solids (TDS) |
| | | |
− | It is the mass of the formation water per unit volume of the formation water and is given in metric units (g/cm<sup>3</sup>). For reservoir engineering calculations, it is considered equivalent to specific gravity. | + | It is the mass of the formation water per unit volume of the formation water and is given in metric units (g/cm<sup>3</sup>). For reservoir engineering calculations, it is considered equivalent to specific [[gravity]]. |
| | | |
| ==Estimating density from TDS== | | ==Estimating density from TDS== |
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| | | |
| ==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 />). |
| | | |
− | {| class = "wikitable"
| + | # 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 [[:file:formation-fluid-pressure-and-its-application_fig5-5.png|Figure 1]]. |
− | ! Step
| + | # Estimate density from wt % NaCl and temperature using [[:file:formation-fluid-pressure-and-its-application_fig5-6.png|Figure 2]]. |
− | ! Action
| |
− | |-
| |
− | | 1
| |
− | | 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.
| |
− | |-
| |
− | | 2
| |
− | | Estimate sodium chloride (NaCl) concentration from R using Figure 5-5.
| |
− | |- | |
− | | 3
| |
− | | Estimate density from wt % NaCl and temperature using Figure 5-6.
| |
− | |} | |
| | | |
| ==Gather data== | | ==Gather data== |
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| * Formation water resistivity | | * Formation water resistivity |
| | | |
− | {| class = "wikitable"
| + | # 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> |
− | ! Step
| + | #*::where: |
− | ! Action
| + | #*::: T<sub>s</sub> = average surface temperature (°F) |
− | |-
| + | #*::: D<sub>f</sub> = depth to the formation (ft) |
− | | 1
| + | #*::: BHT = bottom-hole temperature (found on log header) (°F) |
− | | Estimate formation temperature T<sub>f</sub> using the following formula:
| + | #*::: 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) | |
− | |-
| |
− | | 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:
| |
− | * 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>== |
− |
| |
− | [[file:formation-fluid-pressure-and-its-application_fig5-5.png|300px|thumb|{{figure number|1}}Determining NaCl concentration. Copyright: Schlumberger.]]
| |
| | | |
| 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. |
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| | | |
| ==Estimate density== | | ==Estimate density== |
− |
| |
− | [[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 (1972).]]
| |
| | | |
| 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. |
| | | |
− | {| class = "wikitable"
| + | # Enter the chart along the X-axis using formation temperature. |
− | |-
| + | # Proceed vertically to the appropriate salt concentration expected in the zone. |
− | ! Step
| + | # Proceed horizontally to read the liquid density at atmospheric pressure. |
− | ! Action
| + | # Using the “Effects of Pressure” segment of the chart, add a density increment to the above-computed density to correct for pressure effects. |
− | |-
| |
− | | 1
| |
− | | Enter the chart along the X-axis using formation temperature.
| |
− | |-
| |
− | | 2
| |
− | | Proceed vertically to the appropriate salt concentration expected in the zone.
| |
− | |-
| |
− | | 3
| |
− | | Proceed horizontally to read the liquid density at atmospheric pressure.
| |
− | |-
| |
− | | 4
| |
− | | Using the “Effects of Pressure” segment of the chart, add a density increment to the above-computed density to correct for pressure effects.
| |
− | |}
| |
| | | |
| ==See also== | | ==See also== |
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| [[Category:Critical elements of the petroleum system]] | | [[Category:Critical elements of the petroleum system]] |
| [[Category:Formation fluid pressure and its application]] | | [[Category:Formation fluid pressure and its application]] |
| + | [[Category:Treatise Handbook 3]] |