Schlumberger

Case Study: Achieve Isolation in HPHT, Weak-Formation Well

BG Norge uses advanced cementing technology in Norwegian North Sea

Challenge: Maintain hydraulic isolation in a high-pressure, high-temperature (HPHT) well with potential for severe lost circulation.

Solution: Used a combination of advanced cementing products and services, including: CemSTRESS cement sheath analysis software to design the cement, LiteCRETE lightweight slurry system for strength, CemNET advanced fiber technology to control losses.

Result: Achieved hydraulic isolation and obtained designed top of cement.

HPHT conditions

In the Mandarin well on the Norwegian continental shelf, BG Norge encountered HPHT conditions and the potential for severe lost circulation. The high-profile Mandarin well is similar to the Jackdaw wells offshore the UK. The shallow formations are weak and require superior support.

BG Norge planned a later high-pressure drillstem test that would stress the 20-in cemented section of the well, so hydraulic isolation between the surface and deeper sections was essential. It was also critical that the designed top of cement be achieved on this high-volume job.

Schlumberger solutions

CemSTRESS cement sheath analysis software was used to determine the ideal properties of the set cements. Multiple simulations were conducted to select the best cement, including modeling the planned pressure test.

The field-proven LiteCRETE lightweight slurry system was chosen because of its ability to achieve high compressive strength despite low density. To minimize lost circulation, CemNET advanced fiber technology was added to the cement slurry.

Cementing success

BG Norge pumped a record volume (238 m3 [1,500 bbl]) of high-strength LiteCRETE slurry across the weak shallow formation, adding CemNET fibers. The job was executed and placed without incident. It achieved the designed top of cement and provided superior well support and hydraulic isolation.


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