MILLING OUT RESTRICTIONS TO REDUCE GOR IN ALGERIA

Well Miller NPR for Milling Solutions

Background

A major operator in Algeria was experiencing a very high GOR in one of his wells and wanted to perform a gas shutoff operation using a casing patch. The selected patch had a running OD of 3.718” but it couldn’t be set in the 4 ½ liner due to the presence of two nipples in the production tubing, reducing the ID to 3.45”.

Previous attempts to remove these nipples, made of 9 Cr, with both snubbing and coiled tubing units have not had much success. And unfortunately, no workover rigs were available for several months.

With Welltec’s entry into Algeria in late 2015, the customer now had a cost effective alternative to turn to, milling out restrictions using only an e-line unit.

OPERATION

Welltec’s D&E team reviewed the problem and quickly designed a new, 3.8” MMC style bit. After the successful qualification testing using 13 Cr nipples in the workshop, the bit was shipped to Algeria. Once in country, it was combined with a Well Miller® and a Well Tractor® to provide an effective NPR (nipple profile removal) solution.

At the wellsite, the tools were rigged up using a crane and the e-line unit and deployed into the well on a 5 /16” monocable. With the use of an e-line solution and pressure control equipment, the well was not required to be killed.

After an initial pass using GR-CCL to correlate and generate an accurate depth and hardware reference log, the R nipple was tagged at ~ 10,900 ft. At this point, the milling operation began and within an hour, the 3.68” restriction was enlarged to 3.8”.

Then the tools were run deeper into the well, encountering the RN Nipple ~10,950 ft. Using the same BHA, milling operations began again. This nipple was a bit thicker, with an ID of 3.45”, but it only took 4h 15 min to enlarge the entire assembly out to 3.8” ID. To confirm the successful milling, four drift passes were performed with the toolstring, ensuring clearance and logging multiple correlations to confirm depth and record the new CCL signatures across the depths where the nipples had been.

The tools were back on surface safely before sunset. From rig-up to laying the tools down, the nipple removal operation took only 13 hrs.

Next morning the well was drifted to TD using the patch manufacturer recommended drift of 3.795” without any issues. Later on it was confirmed that the casing patch was set successfully.

ACHIEVEMENTS

In addition to completing the first e-line nipple profile removal operations in Algeria, Welltec® successfully demonstrated the capabilities of what is possible to achieve on e-line; rigless, lightweight, e-line intervention can perform or even outperform in many cases, work that is traditionally done using conventional snubbing and coiled tubing units. And in addition to being more efficient, the well can be kept alive and sometime even on production during the operation. No fluids were introduced into the well which may cause damage or require to be flowed back.

WELL DATA

DEVIATION: 0
TEMPERATURE: 108 C