Dual FMI passes at 0° and 45° provide 100% coverage in 12.25” hole
Preventing rotation of imaging tools is desirable to prevent image overlap. This is particularly important in large wellbores where borehole coverage is lower.
In 12.25” hole FMI wellbore coverage is only 52%. Whilst repeat passes can be made to try to cover the remaining area, the tool will typically follow the same path each time, leaving a large portion of the wellbore unlogged.
In Iraq, Tool Taxis were used to perform two sequential runs in a 12.25” wellbore. The first run with the tool oriented at 0°, and the second run with the tool rotated by 45°. The combined images increased the wellbore wall coverage from 52% to 100% – a vital piece of information in a geologically challenging field.
FMI borehole coverage is low in large holes. Multiple passes typically result in the tool tracking in the original path with no new data recorded in the extra passes.
Petromac Tool Taxis were used to record two passes, one at 0° and one at 45° to the original.
High quality logs were obtained with no rotation. The dual passes resulted in a borehole coverage increase from 52% to 100% .
The logs were also devoid of any stick slip artifacts due to the smooth tool motion caused by the Tool taxis.
Holefinder system facilitates wireline logging in an ‘impossible well’ in Iraq
Near Vertical ‘Impossible Well’ Logged in Iraq
An operator in Iraq was combating major issues with wellbore ledges in a well with only 6 deg deviation. After two wireline runs which were held up at shallow depth, the operator undertook a wiper trip, only to experience similar problems again on the 3rd attempt. The decision was made to run a TLC operation, however this was also unsuccessful.
In all a total of 5 days of rig time had been lost trying to pass a 20” washout with associated ledge.
Frustrated with the lack of results from conventional wireline and TLC, the operator sought the expertise of Petromac to log this critical well. A total of 6 descents were made with Petromac Wireline Express – all seamlessly conveyed to TD.
Without a holefinder, wireline toolstrings are easily held up by ledges and washouts.
Using the Wireline Express holefinder, the toolstring does not loose any momentum as it slides over wellbore obstructions.
In ‘vertical’ wellbores large ledges will persistently holdup toolstrings, even on TLC operations.
Petromac Tool Taxis ensure that the angled holefinder is always oriented upwards, allowing the toolstring to slide seamlessly over ledges.
A well which could not be logged on TLC was subsequently logged using the Petromac holefinder system (6 successful runs in hole).