Oriented coring avoids wellbore damage in the Gulf of Mexico

Oriented coring for MSCT and XL-Rock produces positive results

In an offshore well in the Gulf of Mexico an operator requested to cut cores from the side of the 8.5” wellbore. Rock mechanics analysis indicated that it would be preferable to cut cores from the side of the wellbore in order to protect the stress cage and thereby reduce losses during cementing.

In deviated wells, cores cut horizontally will generally be parallel to the bedding planes. Consequently, lab measurements of core permeability are relevant for modelling the reservoir flow characteristics. Horizontal cores from the side of the wellbore are cut parallel to the bedding planes and have more value for core analysis. There is also less risk of cuttings jamming the kinematics section.

Core recovery on this particular job was 100% with 12/12 cores recovered. Since this first job, Petromac has performed several oriented coring jobs with an average core recovery of 97%.

Cutting at 90deg to the low side of the wellbore avoids cuttings and near wellbore damage (above).

Imaging logs confirmed that all cores were cut between 75-90deg from the low side (below).

CHALLENGE

Due to rock mechanics, the operator wanted to avoid coring from the low side of the wellbore. Coring at 90 deg to the low side was preferred to protect the stress cage.

SOLUTION

Petromac Tool Taxis were run on the XL-Rock to orient the coring bit at 90 deg to the low side of the wellbore.

RESULTS

The operator obtained high quality cores, cut parallel to the bedding planes and achieved 100% recovery.

Back

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.

CHALLENGE

In ‘vertical’ wellbores large ledges will persistently holdup toolstrings, even on TLC operations.

SOLUTION

Petromac Tool Taxis ensure that the angled holefinder is always oriented upwards, allowing the toolstring to slide seamlessly over ledges.

RESULTS

A well which could not be logged on TLC was subsequently logged using the Petromac holefinder system (6 successful runs in hole).

Back