Method and apparatus for water-based mud filtrate contamination monitoring in real time downhole water sampling

• Main Authors: Pop, Julian, Gisolf, Adriaan, Zuo, Youxiang, Desai, Chetankumar, Mullins, Oliver
• Format: Patent
• Language: English
• Published: 04.06.2019
• Subjects: EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FIXED CONSTRUCTIONS; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; MINING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS; PHYSICS; TESTING

A method for contamination monitoring includes measuring water based mud filtrate density and resistivity at downhole conditions, logging properties of a downhole fluid to find at least a resistivity and a density of a fluid sample at the downhole conditions, establishing a linear relationship between a water based mud filtrate conductivity at downhole conditions and the water based mud filtrate density at the downhole conditions, determining a density and a resistivity for native formation water, estimating a density for water based mud filtrate using the linear relationship between conductivity and density, and estimating a water based mud filtrate contamination.