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Eliminating a rathole trip: case study from Baker Hughes

Hydrocarbon Engineering,

The Baker Hughes GaugePro™ Echo on-command digital reamer with StaySharp™ cutter technology enabled an operator in the Gulf of Mexico to drill and ream a section, then ream the rathole in one run, eliminating a second trip typically needed to ream the rathole. The operator saved 36 hours of rig time – the operating equivalent of US$2.1 million.

Deepwater well in the Gulf of Mexico

The challenging deepwater well required a durable, long-lasting reamer to enlarge the wellbore through several types of hard, abrasive formations. Additionally, a solution was needed to overcome the limitations of ball-drop reamers that required placement above the directional drilling bottomhole assemblies (BHAs), forcing a second trip to complete reaming of the rathole section.

“The GaugePro Echo digital reamer is a highly reliable tool that can be placed near the bit to combine drilling and reaming sections, and then ream ratholes in one run,” says Ahmed Al-Essa, Global Marketing Manager for Baker Hughes Directional Drilling. “It offers unlimited activation and deactivation cycles, along with real-time information, including blade status and position, hydraulic oil pressure, temperature, and vibration. It also includes a triple failsafe system to ensure it can trip out of hole. The reamer operates independently of pump flow rates, and we are able to individually control up to three GaugePro Echo reamers in a single BHA.”

At 21 290 ft (6489 m), the cement plug was drilled through to 22 073 ft (6728 m), and a main reamer placed above the BHA continued drilling and reaming to a total depth (TD) of 25 760 ft (7852 m). The BHA was then pulled back to 25 584 ft (7798 m), where the GaugePro Echo reamer, located near the bit in the BHA, was engaged within five minutes. Blade status was confirmed on surface via digital communication from the reamer, and the reamer began enlarging the rathole from 12¼ in. to 14½ in.

Using the gamma ray log, the drilling engineer was able to identify limestone stringers and shale sections, and to recommend optimum rotations per minute and weight-on-bit for best reaming performance. Rate of penetration ranged from 50 ft/hr (15.2 m/hr) to 70 ft/hr (21.3 m/hr).

The reamer finished opening the rathole at 25 739 ft (7845 m), reducing it from 176 ft (53.7 m) to 21 ft (6.4 m), and was pulled out of hole in excellent condition. “The subsequent casing run and cement operation was a success with higher than expected formation integrity test results,” Al-Essa says.

Written by Baker Hughes, edited for web by Cecilia Rehn

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