Mobil Oil Corporation

W L Medlin

James H Sexton

Lucien Masse

An acoustic logging tool traverses a fluid-filled cased well with an asymmetric acoustic energy transducer. Pressure waves created in the well fluid by the transducer generate asymmetric tube waves in the well casing. At least one spaced-apart transducer receives these asymmetric tube waves after they have traveled directly to the receiver through the well casing. Changes in tube wave ampltiude as detected by the receiver are used to identify the azimuth and height of any fracture interval in the formation behind the well casing.

Method for determining induced fracture azimuth in formations

The porosity of a formation surrounding a cased well is determined from a shear wave log of the formation. Shear wave velocity is derived from the log and formation porosity is identified from a predetermined correlation between core-derived porosity for the type of formation traversed by the cased well and shear wave velocity.

Method of shear wave porosity logging of a subsurface formation

A method of logging a wellbore to identify oil, gas and water zones in a hydrocarbon-bearing formation that is characterized by acoustic velocities which are maximum when saturated with oil, minimum when saturated with water and intermediate when saturated with gas. The formation is logged with a sonic logging system utilizing a frequency within the range of 0.1 to 10 KHz and logged with a lithologic logging system to account for variations in lithology on the sonic log. Thereafter the sonic log is compared with the known acoustic velocity characteristic of the hydrocarbon-bearing formation to identify the oil, gas and water zones therein.

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Dallas, TX, United States of America

W L Medlin