Performance Report: Better Caliper Logs with BLACK FURY


Challenge: An operator in South America using a polymer-base drilling fluid was experiencing significant washouts in front of shale sections and undergauge hole in front of sandstone sections. Consequent issues included liner and logging tools not reaching bottom and poor cement bonds. M-I SWACO was asked to assist with the fluid design to improve the hole caliper

Solution: The drilling team proposed using the BLACK FURY product to improve wellbore conditions along the section with the aim of creating a thinner and better cake quality in the sand formations. The drilling plan required additions of the BLACK FURY product from 7,700 ft (2,349 m) in the middle of the Tena formation in order to drill the more sensitive and sloughing shale encountered in the 8½-in. section.

Result: BLACK FURY product was added to the active system, reaching a concentration of 2% volume at 7,700 ft (2,349 m). No negative property variations were observed. The logs ran to bottom trouble-free, and the condition of the hole while tripping was stable, with no cavings or high amount of materials on shakers. The caliper log showed improvements compared to the previous well. Also, there was a reduction on filter-cake thickness in front of the sand formations, which helped improve cement bond quality.

The Details

The polymer-base fluid used on this well was similar to the one used to drill the 8½-in. section in the previous well. The change in composition was made at 7,700 ft (2,349 m) MD with a treatment of 2% of BLACK FURY (~7.0 lb/bbl) product to drill the Lower Tena and Napo shales. The product was added to the active system with no adverse effects to the mud properties.

BLACK FURY additive was used in conjunction with calcium carbonate resulting in notable reduction on spurt losses and total fluid losses measured with the PPT (permeability plugging tester) at 190°F, 800 psi and 35 micron disc as porous media. The cleaning of the hole was ensured and monitored with M-I SWACO Virtual Hydraulics software. There were no problems tripping in or out of hole. Circulation prior to cementing showed steady pressures.

The caliper log showed considerable improvement from a previous well where the BLACK FURY product was not used. The peak diameter reduced from 16 in. to 12 in. The average enlarged hole went from 11.06 in. to 10.08 in. In the sand section, the average cake thickness was estimated as 0.35 in. in the first well, while in the well with the BLACK FURY product, it was only 0.22 in. With a reduction of 10% in hole diameter, the cementing volume was reduced by 36%. The operator is now implementing the use of BLACK FURY product on the upcoming wells for four other fields as a cost-effective solution to enlarged hole issues.

Download: Better Caliper Logs with BLACK FURY (0.84 MB PDF)

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