Schlumberger

Performance Report: The FLOTHRU Reservoir Drill-In System Shows Excellent Results When Drilling Sidetracks in West Siberia, Russia

Challenge: For a few years M-I SWACO successfully provided drilling fluids technologies and engineering support services for sidetrack drilling and reservoir drill-in fluids for a leading Russian operator. During sidetracking operations which included about 60 wells a month on average a third-party company’s classical biopolymer systems were used, as well as M-I SWACO FLOPRO NT reservoir drill-in fluids. In developing and supporting the FLOPRO NT system, M-I SWACO used a complete package of know-how and technological solutions aimed at providing maximum quality and non-damaging reservoir drill-in, including geotechnical data analyses, actual core sample tests, the use of the OPTIBRIDGE program to determine the precise bridging particle-size distribution based on reservoir characteristics. Bridging agent content and its particle-size distribution was optimized while drilling using high-pressure ceramic disk filter presses and a calcimeter. Fluid rheological properties were controlled and optimized using the VIRTUAL HYDRAULICS program. A comprehensive engineering approach to drilling mud program development and support helped achieve excellent technical and economic results of sidetrack drilling at the customer’s fields. Following the internal program of performance improvement and optimization of well construction cost-performance ratio, the customer put special emphasis on new technologies in the field of exploratory and production drilling, and particularly for sidetracking. The customer turned to M-I SWACO for its new solutions in reservoir drill-in fluids.

Solution: M-I SWACO had implemented the new-generation polymer /carbonate drilling fluids, the FLOTHRU system, so it was suggested that the customer run a pilot test of the FLOTHRU system at its fields for the purpose of comparing its performance to previously applied drill-in fluid technologies. M-I SWACO, together with the customer, carried out the analysis of well-completion technology. The optimal formulation of FLOTHRU system for group A and B formation drilling was developed and suggested, in accordance with the results of the preparatory work performed.

Result: The tests proved to have some additional advantages of using FLOTHRU fluid over using FLOPRO NT fluid: An 80% reduction in water cut over the offset well production data; A 30% reduction of time necessary for the well to reach stable production over the offset production data; Planned or higher than planned oil production rates.

The technical solution was unique in the way that the water-based fluid was used to make an oleophilic filter cake, permeable for formation hydrocarbons, but at the same time built an effective barrier against filtrate invasion to the formation. Due to this ability, the new drilling fluid was less damaging to the formation and it ensured lower flow initiation pressure and shorter time for the well to attain stable production.

The tests were carried out while drilling six sidetracks in the customer’s three fields. In order to make a quality comparison of the drill-in fluid performance, similar well construction/casing programs were selected (124-mm openhole, 300- to 350-m long, completed with the 102-mm perforated liner).

The FLOTHRU parameters were maintained in accordance with the developed fluid programs and current project solutions. In all the cases the density of drilling fluid was 1.16-1.18 g/cm3 (9.7 -9.8 lb/gal) and the average abnormal formation pressure gradient was about 1.0 gm/cm3 (8.33 lb/gal).


Download: The FLOTHRU Reservoir Drill-In System Shows Excellent Results When Drilling Sidetracks in West Siberia, Russia (0.48 MB PDF)

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"The next generation reservoir drill-in fluids demonstrate their benefits to the market by reducing time necessary to put the well on stable production, reducing water cut, and generating excellent actual oil production rates after drilling sidetracks.”
Eugeny Chumakov and A.V.Medentsev
Senior Technical Services Engineer and WP TS Manager
M-I SWACO