Field Result of Equivalent-Circulating-Density Reduction With a Low-Rheology Fluid

Abstract

TX 75083-3836 U.S.A., fax 1.972.952.9435. AbstractTo qualify for use on a world record extended reach drilling (ERD) well, a trial well was selected to demonstrate the technical benefits of using a uniquely designed, low-rheology, synthetic-based drilling fluid. The 8½-in., production hole section was 1,755 ft (535 m) long and drilled to 20,472 ft (6,240 m) at an angle of 25°. Prior to drilling this section, a low-rheology drilling fluid was selected. Selection analysis was based on assessment of key drilling parameters as compared with wells drilled previously using a conventional API barite-weighted synthetic fluid. A unique characteristic of the low-rheology drilling fluid is its use of specially treated, micron-sized, barite-weight material (TMSB). It can be formulated with a much-reduced rheological profile without the risk of barite sag. This paper presents the background work performed leading up to the field trial. Field data is presented comparing the drilling performance and fluid characteristics between the low-rheology fluid and the previously used conventional API barite-weighted synthetic fluid system. Significant reductions in equivalent circulating density and standpipe pressures were accomplished, as well as torque reductions of up to 30%. Results demonstrated the low-rheology, synthetic-based drilling fluid's ability to reduce drilling risk. This paper reports the economic and technical benefits realized from using this fluid, including the first use of 400-mesh prototype shaker screens (API 200 mesh), the much reduced dilution factors, and cuttings re-injection volumes.

ECD optimization with specially designed low rheology drilling fluids

“…The tests results are very satisfying [2] and Table 2 shows the pump pressures and ECD recorded by the PWD tool at the point of displacing the conventional fluid system to the TMSB system. Additionally, Table 3 presents the fluid properties of the conventional synthetic fluid compared with the TMSB fluid at the time of displacement.…”

“…Bolivar, Young et al [2] conducted a research in order to prepare a project of a world record ERD well, where major drilling complications related to high ECD and lost circulation or extensive circulating and conditioning due to barite sag were expected. According to collected field data, significant reductions in ECD, stand pipe pressures (SPP) and torque were accomplished as special, low rheology fluid was used.…”

Hydraulic Behavior in Cased and Open Hole Sections in Highly Deviated Wellbores

“…The fluid applied in all tests reported here is an oil-based drilling fluid commonly used on the NCS. Similar fluids have frequently been used for drilling extended reach wells, including for example wells at the Hibernia field offshore Newfoundland [14]. The fluid is constructed from standard OBM components except from the weight material that is a micronized barite slurry of 2.3 SG.…”

Meeting the Ultrahigh-Temperature/Ultrahigh-Pressure Fluid Challenge

“…This treated ultrafine barite allows invert-emulsion drilling fluids to be formulated at higher densities and with lower rheology profiles than can be achieved with API-grade barite, providing low ECD, low pressure drops, and low break circulation pressures with a weighting-agent sag profile that meets the requirements of the conditions being studied (Fimreite et al 2004;Oakley 2006;Bolivar et al 2007;Roedbro 2007). One solution to this problem came from the use of a new weighting material composed of a high-grade barite that is milled to an average particle size of less than 2 lm and chemically treated with a thermally stable oil-wetting agent.…”