A New Extreme HP/HT Viscometer for New Drilling Fluid Challenges

Abstract

Abstract Growing demand for natural gas in North America is driving the E&P industry to look for new resources in previously unexplored areas and the deep Gulf of Mexico (GOM) Continental Shelf is currently attracting a lot of attention. Several of the current deep shelf HP/HT wells have anticipated bottom-hole temperatures that significantly exceed the limits of existing MWD/LWD tools; therefore, down-hole annular pressure measurements will not be available for pressure management. This leaves temperature/hydraulic models as our best, if not our only source of down-hole pressure information. These models depend on accurate surface inputs and laboratory measured fluid properties under down-hole conditions. Unfortunately, these anticipated temperatures and pressures also exceed the operating limits of conventional HP/HT viscometers. This lack of measured fluid properties under these extreme conditions will severely limit the ability of hydraulic models to predict down-hole pressures. A new extreme HP/HT (XHP/HT) concentric cylinder viscometer was designed and built to fill this important technology gap for the GOM deep shelf HP/HT wells. The instrument is capable of measuring typical drilling fluid viscosities up to 600°F (316°C) and 40,000 psig (276.0 MPa) and is capable of accurate measurements of drilling fluid properties containing ferromagnetic materials. Subsequent verification and validation testing proved the new viscometer compares favorably to commercially available field viscometers and more sophisticated laboratory rheometers and therefore lends itself towards widespread industry use. This paper reviews the development of the instrument, automated control system and HS&E issues related to testing drilling fluids at these extreme conditions. The paper will also present results of the verification and validation testing on invert-emulsion drilling fluids.