Application of a complex polyol drilling fluid in Albania

Identifiant ISSN : 0179-3187 CODEN : EEKOEY
Editeur Urban; Urban
Source Erdöl, Erdgas, Kohle A. 2005, vol. 121, n° 9, pp. OG124-OG127 [bibl. : 8 ref.]


A 5360 m well, the Kanina I, has been drilled near the Adriatic coast of Albania in the Vlora district near the town of Kanina. In this tectonically active region, drilling fluids that provide superior inhibition characteristics are required. For this well, a complex polyol-potassium carbonate based system has been successfully utilized in the critical intermediate sections from 1610 to 4653 m. Mineralogical analysis of cuttings from the well indicates the formations drilled are reactive and dispersive. In the 16 (406 mm), 12 1/4 (311 mm), and 8 3/8 (213 mm) hole sections, a 1.20 to 2.05 specific gravity (SG) mud has been utilized with 12 vol% of the complex polyol additive, 40 kg/m3 of potassium carbonate and 2 vol% of a lubricating, rate-of-penetration enhancing additive. Rates-of-penetration have been much higher than expected and PDC bit performance has been good in this inhibitive water-based fluid. Additionally, a non-viscosifying additive, humalite, was used to control filtration properties in the complex polyol system. The dilution rates to maintain mud properties were the same or lower than those programmed while maintaining reactive solids as measured by methylene blue test in the 40 kg/m3 range. Analysis of caliper logs is complicated by the variable performance of the under-reamers used to drill the 16 section. 13 3/8 (340mm) casing was set at 2764 m without incident. At this time, drilling continued in the 12 1/4 section to 4622 m with a mud SG of 2.05. Tool failure necessitated a sidetrack. A cement plug was set and a 9 5/8 (244 mm) liner was successfully run to 4072 m. An 8 3/8 sidetrack was drilled to casing depth of 4653 m in 15 days with no major problems experienced. A 7 (178 mm) liner was set at 4653 m. The complex polyol fluid was displaced from the well. Drilling continued in the 57/8 (149 mm) production section with a low-solids polymer drill-in fluid system to a depth of 5362 m. At this depth, the reservoir was evaluated and completion operations were commenced.