Oriented HRSCT: Optimum sidewall-core recovery in Mexico

Oriented Coring improves recovery rate from 35% to over 90%


The recovery of sidewall-cores has historically been very low in Mexico, specially in large holes, where a large hole kit (LHK) needs to be run. The protuberance created by this LHK causes the tool to lean on its side, which creates an oblique contact between the coring bit and the borehole wall (specially in deviated wells) and has a negative impact on the recovery rate.

In an attempt to improve the recovery rate, one of the operators decided to convey the HRSCT with Tool Taxis so that the coring bit would penetrate the formation perpendicular, while keeping the tool firmly set.

Core recovery on this job was 80.6% with 29/36 cores
recovered. In the following eight months, Petromac performed another six jobs, reaching an average core recovery of 91.2%, with a total of 197 recovered cores out of 216 attempts.


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CHALLENGE

When running HRSCT in 12.5” holes or more, a large hole kit needs to be installed. This causes the tool to lean on its side and creates an oblique contact between the coring bit and the borehole wall, which translates into a very poor core recovery.


SOLUTION

Petromac Tool Taxis were installed on the HRSCT, to orient the coring bit perpendicular to borehole wall.


RESULTS

The operator obtained high quality cores while improving the recovery rate from 35% to over 90%.


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.

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Without a holefinder, wireline toolstrings are easily held up by ledges and washouts.

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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).


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