Measuring the oil content in oil-based drilling fluids

A drilling method, comprising:

• circulating an oil-based drilling fluid through a wellbore while drilling the wellbore
• feeding a sample of the oil-based drilling fluid through a line to a container in a fluid analysis system fluidically coupled to a drilling system while the circulating is continuously performed;
• performing electro impedance spectroscopy on the sample by a process that comprises applying an alternating electric current to the sample and measuring a response of sample to obtain electro impedance spectroscopy measurements;
• determining an estimate of the oil content of the sample based, at least partially on the electro impedance spectroscopy measurements, by determining phase angle for a range of angular frequencies, wherein the phase angle is a function of an oil-to-water ratio and low-gravity solids;
• and
• adding base oil and/or aqueous fluid to the oil-based drilling fluid in response to the estimate.

A drilling system comprising:

• a drill string;
• a drill bit attached to a distal end of the drill string;
• and
• a fluid monitoring and handling system comprising
• a mud pit operable to receive an oil-based drilling fluid from a wellbore;
• a mud pump operable to circulate the oil-based drilling fluid;
• and
• a fluid analysis system comprising a sample container for a sample of oil-based drilling fluid, an electronics device for measuring impedance of the sample;
• and
• a computer system in signal communication with the fluid analysis system, wherein the computer system comprises a processor and a non-transitory computer readable storage medium that when executed by the processor causes the computer system to send a signal to initiate an electro impedance spectroscopy measurement and estimate an oil content of the sample based, at least partially, on the electro impedance spectroscopy measurement, by determining phase angle for a range of angular frequencies, wherein the phase angle is a function of an oil-to-water ratio and low-gravity solids.