Specialised Designs for Complex and Record Drilling Project

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Belanak A platform is situated in the Natuna Sea region of Indonesia. The reservoir sections are high temperature (315°F BHST), and the openhole sections were planned to be between 3500 and 4500 ft horizontal, some with tortuous well paths required to meet the target. In order to ensure excellent drilling performance and optimum protection of the producing formation, a formate-based, low-solids reservoir drilling fluid was selected -the first time such a system had been used in Indonesia.In this paper, the authors detail the design and successful application of the unique reservoir drill-in fluid in the demanding and remote well.

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“…The field is being developed by ConocoPhillips Indonesia (COPI), Impex Natuna Ltd. and ChevronTexaco, with COPI as the operator 1 (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Reservoir Drilling Fluids-Designing for Challenging Wells in a Remote Location

Knox¹,

Bradshaw²,

Svoboda³

et al. 2005

Proceedings of SPE Annual Technical Conference and Exhibition

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Reservoir Drilling Fluids—Designing for Challenging Wells in a Remote Location

et al. 2005

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The Belanak A platform is situated in the Natuna Sea region of Indonesia. The reservoir sections are high temperature (315°F BHST), and the openhole sections were planned to be between 3500 and 4500 ft horizontal, some with tortuous well paths required to meet the target. In order to ensure excellent drilling performance and optimum protection of the producing formation, a formate-based, low-solids reservoir drilling fluid was selected - the first time such a system had been used in Indonesia. In this paper, the authors detail the design and successful application of the unique reservoir drill-in fluid in the demanding and remote well. Introduction The Belanak field is situated in the Natuna Sea in 300 ft of water, approximately 250 miles northeast of Singapore. The field is being developed by ConocoPhillips Indonesia (COPI), Impex Natuna Ltd. and ChevronTexaco, with COPI as the operator[1] (Fig. 1). The Belanak field comprises two platforms, A and B. The total project calls for drilling and completing over 30 wells from these two platforms.Both platforms are designed to produce oil and re-inject natural gas from two zones.An FPSO was constructed to process and inject the gas (Fig. 2). Six horizontal completions were planned to be drilled off of the ‘A’ platform during late 2003 to early 2004. These wells were designed to be completed using premium sand-exclusion liners. The 8½-in. reservoir sections of these wells were planned to be horizontal or near-horizontal between 3500 and 4500 ft through the reservoir - in most cases, the well path was fairly tortuous. This presented some challenges to the selection of the drilling fluid for the reservoir, as did the anticipated bottomhole static temperature of 315°F. In addition, the platform is located in an area far removed from other drilling locations in the region, and some 200 miles from the nearest major supply base. Engineering drilling fluids to meet the challenges of these complicated wells can be problematic, but manageable, with a nearby supply of fluid additive and contingency materials. However, in this case, the logistical constraints of working in this location necessitated a closer review of fluid design and maintenance to ensure that a high quality fluid was maintained while drilling the reservoir sections of this development. Laboratory Evaluation The challenge was to formulate a ‘non-damaging’ reservoir drill-in (RDF) fluid that would withstand 315°F.The final formulations would be judged on return permeability test through core samples taken from the Belanak Exploration wells.With logistics always an underlying consideration, all water-based formulations were mixed in seawater, in case drill-water supply became an issue at the location. Base Fluid Selection Initial testing involved formulating a fluid that would be thermally stable for lengthy periods at the anticipated bottomhole static temperature of 315°F. Low-solids water-based reservoir drilling fluids formulated with sodium chloride, sodium formate and potassium chloride were included in the testing.Formate salts are recognized for their ability to reduce polymer degradation at temperatures above conventional operating pressures.[2,3,4]This property has been used to design high-temperature drilling fluids for operations in other parts of the world, specifically the United Arab Emirates, Central Europe and the North Sea.[5,6] Despite the higher cost of the brine, these fluids in many cases have proven to be more economical overall, as chemical consumption is greatly reduced due to the improvement in thermal stability.

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Specialised Designs for Complex and Record Drilling Project

Cited by 2 publications

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Reservoir Drilling Fluids-Designing for Challenging Wells in a Remote Location

Reservoir Drilling Fluids-Designing for Challenging Wells in a Remote Location

Reservoir Drilling Fluids—Designing for Challenging Wells in a Remote Location

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