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Line 66: − + − {| class = "wikitable"+ − |-+ − ! Step+ − ! Action+ − |-+ − | 1+ − | Use well logs to pick permeable zones for formation pressure measurements. Look for an invasion profile. − |- − | 2 − | Plot mud hydrostatic and formation pressure at the well site to recognize anomalies or tool errors and to optimize station coverage. − |- − | 3 − | Occasionally repeat formation pressure measurements at the same depth to check for consistency. − |- − | 4 − | Repeat at some of the same depths for multiple surveys to help normalize the different surveys. − |- − | 5 − | Sample both water- and hydrocarbon-bearing intervals to establish both the water and hydrocarbon pressure gradients. − |- − | 6 − | Plot pressures at the same scale as well logs to aid in interpretation. − |} − + − {| class = "wikitable"+ − |-+ − ! Step+ − ! Action+ − |-+ − | 1 − | Inspect the tool and check calibration before going in the hole. − |- − | 2 − | Run quartz and strain gauges simultaneously. Record both readings independently. Normalize to one another after completing the survey. − |- − | 3 − | Maintain a slight overflow of mud to keep the level in the borehole constant during the survey and to prevent mud hydrostatic pressure errors. − |- − | 4 − | Take mud hydrostatic pressures while descending into the hole to give the instruments time to equilibrate to changing temperature and pressure and to provide a mud hydrostatic pressure profile. − |- − | 5 − | Check for tool errors by calculating mud hydrostatic pressures at different depths from mud weight; check them against measured mud hydrostatic pressures at the same depths. − |} Line 154:
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Formation fluid pressure from repeat formation testers (view source)
Revision as of 17:55, 17 February 2022
, 17:55, 17 February 2022added Category:Treatise Handbook 3 using HotCat
| 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 = 5-33
| topg = 5-64
| topg = 5-35
| 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
{| class = "wikitable"
{| class = "wikitable"
|-
|-
! Consideration
! Consideration || RFTs || DSTs
|-
|-
| Time to take one measurement
| Time to take one measurement || Less than 5 minutes for permeable formations || More than 90 minutes
| Less than 5 minutes for permeable formations
| More than 90 minutes
|-
|-
| Drilling delay to run test
| Drilling delay to run test || About one logging run (wireline conveyed) || About equal to two trips with drillstring
| About one logging run (wireline conveyed)
| About equal to two trips with drillstring
|-
|-
| Sampling interval
| Sampling interval || Small || Several feet or more; generally tests multiple flow units
| Small,
| Several feet or more; generally tests multiple flow units
|-
|-
| Samples per run
| Samples per run || Many || Few
| Many
| Few
|-
|-
| Expense per test
| Expense per test || Small || Large
| Small
| Large
|-
|-
| Purpose of tool
| Purpose of tool || Pressure measurement || Fluid recovery and pressure
| Pressure measurement
| Fluid recovery and pressure
|-
|-
| Survey problems
| Survey problems ||
|
* Getting good seat to measure pressure
* Getting good seat to measure pressure
* Screen plugging with material in drilling mud
* Screen plugging with material in drilling mud
|
|
* Packer failure
* Packer failure
* Depth determination
* Depth determination
|-
|-
| Fractured reservoir
| Fractured reservoir || May be unreliable || Good if fractures intersect wellbore
| May be unreliable
| Good if fractures intersect wellbore
|-
|-
| Layered reservoir
| Layered reservoir || Not representative || Good if many layers are included in tested interval
| Not representative
| Good if many layers are included in tested interval
|-
|-
| Skin damage
| Skin damage || Can be major error || Can be measured and corrected for
| Can be major error
| Can be measured and corrected for
|}
|}
==Operating an RFT survey==
==Operating an RFT survey==
The table below explains how to operate an RFT survey (see Gunter & Moore<ref name=ch05r9>Gunter, J., M., Moore, C., V., 1987, Improved use of wireline testers for reservoir evaluation: Journal of Petroleum Technology, p. 635–644.</ref>).
The list below explains how to operate an RFT survey (see Gunter & Moore<ref name=ch05r9>Gunter, J., M., Moore, C., V., 1987, Improved use of wireline testers for reservoir evaluation: Journal of Petroleum Technology, p. 635–644.</ref>).
# Use well logs to pick permeable zones for formation pressure measurements. Look for an invasion profile.
# Plot mud hydrostatic and formation pressure at the well site to recognize anomalies or tool errors and to optimize station coverage.
# Occasionally repeat formation pressure measurements at the same depth to check for consistency.
# Repeat at some of the same depths for multiple surveys to help normalize the different surveys.
# Sample both water- and hydrocarbon-bearing intervals to establish both the water and hydrocarbon pressure gradients.
# Plot pressures at the same scale as well logs to aid in interpretation.
==Controlling RFT quality==
==Controlling RFT quality==
The table below describes how to control RFT quality. For details, see Gunter & Moore.<ref name=ch05r9 />
The list below describes how to control RFT quality. For details, see Gunter & Moore.<ref name=ch05r9 />
# Inspect the tool and check calibration before going in the hole.
# Run quartz and strain gauges simultaneously. Record both readings independently. Normalize to one another after completing the survey.
# Maintain a slight overflow of mud to keep the level in the borehole constant during the survey and to prevent mud hydrostatic pressure errors.
# Take mud hydrostatic pressures while descending into the hole to give the instruments time to equilibrate to changing temperature and pressure and to provide a mud hydrostatic pressure profile.
# Check for tool errors by calculating mud hydrostatic pressures at different depths from mud weight; check them against measured mud hydrostatic pressures at the same depths.
==See also==
==See also==
[[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]]