RheGuard X™ narrow-window flat rheology drilling fluid system helps overcome ECD issues in HP exploratory well. The RheGuard X system enabled a Gulf of Mexico (GOM) operator to drill the complex 14½-in × 16½-in section with 316-ft/h on-bottom ROP—13% faster than the world record.
A Gulf of Mexico operator was planning to drill its deepest well to date. Challenges for this ambitious exploratory well included high pressure; salt and rubble zones; narrow drilling windows; long, unplanned static periods; and barite sag tendency. In this field, density requirements for drilling fluids regularly exceed 15 lbm/galUS and can surpass 16 lbm/galUS, presenting challenges for fluid rheology optimization. To drill this complex well, the operator sought a high-performance drilling fluid that would balance a low rheological profile with weighting agent suspension.
Previous generations of drilling fluids were prone to barite sag from mud density fluctuations during circulation, which led to stuck pipe, wellbore stability issues, and even the complete loss of a section. With up to 25,000-psi bottomhole pressure, maintaining proper ECD was crucial.
To design and select the optimal low-ECD fluid for this well, SLB performed viscosity assessments, sag testing, and hydraulic simulations. On the basis of the testing data, SLB recommended RheGuard X narrow-window flat rheology drilling fluid system with MicroBar™ micronized weighting additive. Compared with API barite, the ultrafine MicroBar additive mitigates barite sag and settlement, reducing risk and NPT while drilling challenging hydraulic windows.
RheoProfiler™ automated rheometer and PRESSPRO RT™ real-time downhole performance measurement software provided frequent fluid measurements and live data analytics of drilling performance.
Despite an unplanned 21-day shut-in due tobecause of a hurricane in the Gulf of Mexico, the 15.9-lbm/galUS RheGuard X system remained stable with no observed sag. When drilling commenced, the RheGuard X system delivered high hole-cleaning performance and enabled drilling of the intricate 14½-in × 16 ½-in section through salt to TD at 7,818-m [25,650-ft] MD. The operator drilled 2,373 m [7,785 ft] of the salt section in 40 h—with 1,549 m [5,083 ft] drilled in just 24 h, beating the previous Gulf of Mexico record of 1,532 m [5,029 ft] drilled in 24 h. The RheGuard X system enhanced ROP, which reached 96-m/h [316-ft/h] on-bottom ROP with a 14½-in fixed cutter bit—exceeding the previous world record by 13%.
MicroBar, PRESSPRO RT, RheGuard X, and RheoProfiler are marks of M-I L.L.C., an SLB company.
