Real-Time Density/Viscosity Sensing for Automated Drilling: Fluid Mixing in a Drilling Fluid Processing Plant

Abstract During drilling, monitoring of drilling fluid density and viscosity provides critical information that affects both the safety and efficiency of the drilling operation. Here, an in-tank real-time density/viscosity sensing platform was tested at a drilling fluid processing facility during mixing and reconditioning operations of non-aqueous fluids. Data was gathered continuously during six weeks of operation, capturing both fluid properties live inside a 300-barrel mixing unit. The tested system is an in-tank instrument comprised of four sensors deployed at different locations within the mixing unit. The sensors are electromechanical tuning fork resonators, able to obtain density and viscosity simultaneously. Each sensor was housed in a submergible enclosure along with a temperature sensor. Two sensors were suspended into the tank at the top and bottom of fluid level at the suction side of the tank, while the remaining two were located, in a similar configuration, at the center of the tank. The four sensors transmitted live data to the control room for live visualization by the operator. As deployed, the system collected data continuously for six weeks, during which several drilling fluid reconditioning operations were ran. Various fluids were tested during mixing, their densities ranging from 7 to 17 pounds-per-gallon (ppg). Reference density measurements were taken 3-4 times per day during each drilling fluid mixing period using a standard drilling fluid balance measurement. Funnel viscosity measurements were also taken. Full drilling fluid reports, including Fann 35 rheology, were produced once per testing day. The density was found to be, typically, within about 0.13-0.26 ppg of the drilling fluid balance measurements or less, providing very good quantitative drilling fluid weight information. However, the automated system provided real-time data, allowing the operators to visualize every step of the drilling fluid weighing process. The measured viscosity was found to be sensitive to the flowing conditions within the tank and, although it cannot be numerically compared to the funnel viscosity, it followed the expected trends during operation. The system showed potential for autonomous monitoring of viscosity and density during fast-changing operational conditions such as during mud mixing and for mud monitoring during drilling operations.