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Line 25:
Line 25: − + − ! RFTs − ! DSTs − + − − − + − − − + − − − + − − − + − − − + − − − + − − − − + − − − + − − − + − −
Formation fluid pressure from repeat formation testers (view source)
Revision as of 01:01, 20 October 2014
, 01:01, 20 October 2014→Differences between RFTs and DSTs
{| 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
|}
|}