Acoustic measurements in rock formations for determining fracture orientation
AssigneeAtlantic Richfield Company
InventorGary L. White
Life of this patent
Estimating the term…
Abstract
A method and system for determining the probable direction of extension of a hydraulically induced fracture in a hydrocarbon bearing formation wherein prior to inducing the fracture, the formation region to be fractured is heated and thermally induced acoustic emissions from the formation are sensed to determine the orientation of the maximum and minimum horizontally directed in situ compressive stresses based on the acoustic emission rate and/or intensity. A device including a microwave energy generator and an array of acoustic transducers is lowered into a wellbore to generate and measure the thermally induced acoustic emissions.
Claims18
A method for determining the probable orientation of a hydraulically induced fracture in a predetermined region of a subterranean earth formation comprising the steps of:
- penetrating into said region with borehole means;
- heating said region to an elevated temperature;
- measuring thermally induced acoustic emissions of said formation at said region and over an angular range with respect to a generally vertical reference axis of said borehole means;
- and
- comparing the acoustic emissions over said range to determine the directional orientation of at least one of the maximum and minimum horizontal in situ compressive stresses in said region.
A method for determining the probable orientation of a hydraulically induced fracture in a predetermined region of a subterranean earth formation comprising the steps of:
- penetrating said region with borehole means;
- artificially heating said region to an elevated temperature;
- then measuring thermally induced acoustic emissions of said region and over a range with respect to a generally vertical reference axis of said borehole means;
- comparing the acoustic emissions over said range to determine the orientation of the horizontal in situ compressive stresses in said region;
- measuring the temperature of said formation at said region;
- and
- comparing the acoustic emissions from said region at said measured temperature with known values of acoustic emissions at said measured temperature and at selected values of in situ stresses in samples of said formation to determine the in situ stresses in formation at said region.
A method for determining the probable orientation of a hydraulically induced fracture in a predetermined region of a subterranean earth formation comprising the steps of:
- penetrating into said region with borehole means;
- measuring thermally induced acoustic emissions of said formation at said region and over an angular range with respect to a vertical reference axis of said borehole means;
- and
- comparing the acoustic emissions over said range to determine the orientation of the horizontal in situ compressive stresses in said region.
A method for determining the orientation of the horizontal in situ compressive stresses in a subterranean earth formation with respect to a wellbore penetrating within said formation comprising the steps of:
- heating said formation to increase the temperature of said formation in a predetermined zone in said formation;
- measuring thermally induced acoustic emissions of said formation in said zone and over a predetermined angular range with respect to a longitudinal reference axis of said wellbore;
- comparing the acoustic emissions over said angular range to determine the orientation of the horizontal in situ compressive stresses in said formation in said zone;
- measuring the temperature of said formation in said zone;
- and
- comparing the acoustic emissions from said formation at said measured temperature with known values of acoustic emissions at said measured temperature and at selected values of in situ stresses in samples of said formation to determine the in situ stresses in said formation in said zone.
A method for determining the orientation of the horizontal in situ compressive stresses in a subterranean earth formation with respect to a wellbore penetrating within said formation comprising the steps of:
- forming a wellbore penetrating within said formation;
- inserting a device into said wellbore for transmitting radiation into said formation from said wellbore, and generating radiation to be dispersed into said formation over a predetermined angular range with respect to a longitudinal reference axis of said wellbore for heating said formation to increase the temperature of said formation in a predetermined zone in said formation;
- measuring thermally induced acoustic emissions of said formation in said zone and over a predetermined angular range with respect to said longitudinal reference axis of said wellbore;
- and
- comparing the acoustic emissions over said range to determine the orientation of the horizontal in situ compressive stresses in said formation in said zone.
A system for determining the orientation of at least the generally horizontal in situ stresses in a subterranean formation comprising:
- a device adapted to be inserted into a wellbore extending within said formation, said device including means for transmitting radio frequency range radiation into said formation from said wellbore over a predetermined angular range with respect to the longitudinal central axis of said wellbore and acoustic transducer means for sensing acoustic emissions from said formation over a predetermined angular range with respect to said axis and generating signals related to said acoustic emissions;
- and
- means for receiving said signals so that said signals can be recorded for determining the orientation of at least the generally horizontal in situ stresses in said formation with respect to said axis.
Dependencies are inferred from the claim text.