Patent ID: 6098020
Filing Date: 2000-08-01
Classification: E21B

Abstract:
A method for monitoring physical characteristics of fluids in the pore spaces of an underground formation surrounding a wellbore, the method comprising the steps of:creating in the wellbore a measuring chamber which is in fluid communication with the pore spaces of the formation but which is hydraulically isolated from the rest of the wellbore, thereby creating a body of substantially stagnant fluid in the chamber; and,measuring physical characteristics of the fluid in the chamber by means of a plurality of sensors that are mounted within the chamber:wherein the sensors are capacitive sensors which are effective to detect the presence of water, crude oil and/or natural gas in the region of the sensor;wherein a string of sensors is arranged in the chamber which sensors are axially spaced with respect to a longitudinal axis of the wellbore and which sensors are connected to fluid level monitoring equipment which is adapted to identify the presence and location of an interface between different fluids, such as water, crude oil and/or natural gas in the region of the string of sensors; and,wherein the measuring chamber is an annular chamber which is isolated from the rest of the wellbore by means of a fluid tight sleeve and a pair of axially spaced packers that are arranged between the sleeve and an inner surface of the wellbore.