Study of Continuous Rheological Measurements in Drilling Fluids

Abstract

-Drilling an oil well involves using drilling fluids that perform cleaning and cooling functions, but that most importantly maintain the fluids of the geological formation contained by hydraulic pressure. A fundamental role in predicting the hydraulic pressure of the well consists of monitoring the fluid's rheological behavior. This paper summarizes an ongoing effort to measure, by evaluating the performance of two online viscometers, drilling fluids' rheological behavior in real time. One online method proposes a modified Couette system. The other consists of a standard pipe viscometer with default modeling. The performances of the online devices were compared with an offline method -a Couette device commonly used in oilfields as a benchmark. For Newtonian fluids, agreement between the rheological behaviors was found for all instruments, validating the methodology proposed. For non-Newtonian fluids, there were divergences, which were investigated and their probable causes determined to be the following: homogeneity, slippage effects, and interaction in the fluid/gap interfaces. A case study demonstrated that these divergences were not significant during the prediction of hydraulic pressure, meaning that the methodology proposed has the potential to improve overall drilling performance.

Real-Time Measurement of Drilling Fluid Rheological Properties: A Review

“…Magalhães et al [ 26 , 27 ] used a rheology measurement instrument obtained by a modifying a Brookfield process viscometer, TT-100. The operational condition limits of the device were 1 to 15 bar (14.7 to 220.5 psi) of total pressure, temperature up to 160 °C (256 °F), and volumetric flow rate between 1 and 3 m 3 /h.…”

“…Because the online rotational Couette viscometer is easily blocked, Vajargah [ 31 ], Magalhães [ 27 ], Sercan Gul [ 32 ], Knut Taugbøl [ 33 , 34 ], Hansen [ 2 ], Krogsæter [ 35 ], and Frøyland [ 36 ] used pipe viscometers to test drilling fluid rheological properties. According to Ahmed and Miska [ 37 ], the reliability and accuracy of pipe viscometers often outweigh rotational viscometers.…”

“…Magalhães Filho et al [ 27 ] compared three drilling fluid rheological property real-time testing methods: a standard Couette viscometer FANN35A, online Couette viscometer TT-100, and pipe viscometer. For the Newtonian fluids, the viscosities measured by the three instruments were consistent.…”