US 5,963,508 A · System and method for determining earth fracture propagation

Abstract

Hydraulic fracture extension in earth formation zones of interest may be monitored by placing one or more monitor wells in predetermined positions on opposite sides of an azimuth aligned with the expected fracture plane extending from a fluid waste injection well. The monitor wells are provided with arrays of vertically spaced triaxial geophone units and the signals from the geophones are transmitted to a central processing unit for treatment and analysis to determine the location of micro-earthquake events which occur as the fracture propagates radially and, usually, vertically away from the injection well. Geophone signals are converted to digital format and selectively stored on magnetic tapes or in a shared memory of a central processing unit which is operable to display selected channels for geophone signals in a way so that minimum arrival time of a signal at a particular geophone will indicate the growth of the fracture in real time to control fluid waste disposal, for example. The converted data may be selectively screened by a program which eliminates weak or spurious signals and the screened signals may then be analyzed by a location routine and displayed in a manner which indicates the location of the detected and screened events with respect to the injection well.

Claims12

Dependent claims

A method for determining the location of a hydraulic fracture extension within an earth formation zone of interest in real time wherein said hydraulic fracture is extendable from a fluid injection well in said earth formation, comprising the steps of:

determining an azimuth defining an expected direction of extension of said hydraulic fracture from said injection well;
injecting fluid comprising fluid wastes or a slurry of particulate solids into said injection well to extend a fracture from said injection well while simultaneously sensing micro-earthquake events resulting from extension of said fracture;
placing a plurality of seismic event sensors at predetermined positions with respect to said injection well;
said sensors providing signals to a real-time signal monitoring system including means for displaying signals from selected ones of said sensors at a predetermined minimum time after the occurrence of said events;
converting a selected number of signals from said sensors to digital format, momentarily storing said digital signals and transferring said digital signals, at will, to one of a signal storage device and an electronic memory device;
identifying each of a predetermined number of said signals as a function of time prior to transferring said signals to said one of said storage device and said memory device;
retrieving from said memory device a selected number of signals which have a predetermined amplitude for a predetermined time;
transmitting said selected signals to another storage device and displaying said signals;
and
determining a boundary point of said fracture with respect to the position of at least one of said sensors which receives a seismic signal caused by extension of said fracture earlier than said seismic signal is received by others of said sensors and displaying the location and extension of said fracture.

7 more elements

A process for real time management and verification of geologic containment of hazardous wastes injected into at least one subterranean hydraulic fracture, comprising the steps of:

a. Arranging and installing an array of high sensitivity, high resolution seismic sensors about a selected subterranean injection zone and a disposal well for injection disposal of hazardous wastes;
wherein said sensors are installed in boreholes, drilled to a selected depth;
wherein said sensors provide known sensor observation points for maximum practical coverage of said selected injection zone;
wherein said sensors comprise means for detecting and receiving passive seismic signals from micro-earthquake events in said selected injection zone as described in step (g) below;
and making precise measurement of location coordinates of said sensor observation points;
b. Connecting said sensors to a computer-based, real time, automatic seismic data processing system:
(1) Wherein said computer-based system comprises means for automatic processing of passive seismic signal data, on a real time basis, during fracturing in the selected injection zone at a given site;
and
(2) Wherein said computer-based system further comprises means for real time compression of passive seismic signal data, simultaneously receiving, recognizing, recording and processing continuously, signal data from as many as 50 channels or more of data at rates of 2,000 signals per second, per sensor, or greater, and for detecting, flagging, and recording precise measurements of arrival times of both primary and secondary wave phases of passive seismic signals on a real time basis as received, with only signal segments retained for further processing;
c. Determining precise velocities of seismic signals traveling through underground strata in and above said injection zone, wherein said determination comprises measuring origin times and arrival times of signals generated by perforation of said disposal well, as said signals travel from a known location of said perforation to said known sensor observation points;
d. Calibrating a best seismic velocity distribution model of said selected injection zone, wherein said calibration comprises the steps of:
(1) Making static corrections to observed seismic event arrival times to account for model bias;
(2) Calculating theoretical hypocenter locations using the hypocenter location routine from step 1 below, and a range of hypothetical velocities;
(3) Comparing said theoretical hypocenter locations with known locations of said perforation shots;
and
(4) Selecting a best velocity distribution model which gives calculated locations which are closest to known shot locations;
e. Pumping and injecting a slurry suitable for hydraulic fracturing and injection and comprising said hazardous wastes mixed with a selected liquid transport agent, wherein said slurry is injected through said perforation at pressures exceeding minimum principle stress of formations of said injection zone to cause controlled fracturization wherein hydraulic fractures are created in said formation which grow and propagate as additional slurry is injected;
and continuing to inject said slurry into fractures as generated in the selected injection zone at controlled rates while monitoring and controlling down-hole pressure and flow rates to ensure efficient and complete disposal of a required volume of said hazardous wastes;
f. Wherein said injecting and fracturization causes changes in local geologic effective stresses which trigger micro-earthquakes;
wherein said micro-earthquakes at the instant of fracture trigger weak passive seismic signals from the source of each said micro-earthquake event;
wherein said passive seismic signals travel through said formations to said sensors;
and wherein the sources of said passive seismic signals are known to be located within and acceptably close to said hydraulic fractures clustering in a narrow ellipsoidal volume of rock which encloses said induced fracture or network of fractures;
g. Receiving said passive seismic signals, at each said sensor;
converting them to analog electrical signals;
and transmitting them as received to said processing system;
h. Amplifying and digitizing said analog signals, wherein a separate channel of data is produced from each sensor;
i. Automatically detecting, measuring, and recording said digital data using a real time signal detection algorithm;
(1) Wherein, whenever the signal energy level of a channel exceeds the background noise level by a preset ratio, a signal is recognized and declared;
and
(2) Wherein arrival time and amplitude of said signal are measured and recorded;
j. Determining and recording, on a real time basis, which signals and arrival times are associated from the same micro-earthquake event, based on said known sensor locations and velocities in the selected injection zone;
k. Sorting and identifying said associated signals for real time, positive identification and recording of their phase types, which may be either primary waves or secondary waves;
and recording precise arrival times of said primary and secondary waves at each of said sensors;
l. Determining a hypocenter location and an origin time for signals from each said micro-earthquake event in real time as said events occur, based on hypocenter location data with an earthquake hypocenter location program;
m. Recording a hypocenter location and an origin time for each said micro-earthquake event in an event list in real time, wherein said list is continually updated with a new location and origin time of each said micro-earthquake event as said events occur;
n. Automatically calculating moment tensor source mechanisms for each event, by means comprising said signal amplitudes for each said event;
determining if said event has a tensional source, which indicates it is part of the hydraulic fracture, or a shear source, which indicates it is adjacent to but not in the hydraulic fracture and thus contains no waste slurry;
and recording each said tension source by type and location;
o. Determining orientation azimuth of the micro-fracture plane associated with each said event based on said moment sensors;
p. Creating and displaying an animated visualization image, using means comprising computer codes and real time event locations, source mechanisms and orientations, wherein said visualization image comprises:
(1) Displaying a rotatable, animated, three dimensional, real time visualization of said hypocenter location distributions, wherein a distinction is made between hypocenter locations based on said source mechanisms;
wherein said animated visualization is provided with high resolution;
(2) Animating said visualization in real time;
(3) Accurately imaging and visually displaying development, growth, propagation, direction and velocity of induced fractures in real time as said injection continues;
(4) Displaying said animated visualization on a large screen television for viewing;
(5) Rotating said three dimensional display on said screen as desired to show any desired cross section and map view;
(6) Displaying predicted fracture geometry and comparing it with current actual geometry as displayed in real time during said injection;
wherein said predicted fracture geometry is constantly updated on a real time basis to provide a continuing updated prediction and model of future growth;
and
(7) Displaying said fracture growth in real time displayed within a real time animated image of the local geology, in spatial relationship to other geologic formations, zones, reservoirs, wells, fractures and sources of potable water, and simultaneously providing the observer with a continuously updated visual image and display of data concerning the properties of the disposal operation including pressure, slurry volume, flow rate, and viscosity, as said injection continues;
q. Depicting and displaying said visual image and display of data with different colors or symbols in said animated visualization:
(1) Wherein the areal extent of said displayed sources provides a real time demonstration of the location and extent of waste filled fractures;
(2) Wherein said animated visualization provides a real time verification that said fracture is contained in said selected injection zone;
and
(3) Wherein a direction and a velocity of any migration of seismic activity toward a sensitive zone is immediately evident, permitting management decisions and actions including shut down or modification of injection flow rates and pressures to be accomplished long before said sensitive zone is threatened.

52 more elements

A work station device for real time passive seismic imaging and management of disposal of hazardous wastes by injection into at least one subterranean hydraulic fracture with verification of geologic containment, comprising:

a. Means for arranging and installing an array of high sensitivity, high resolution seismic sensors about a selected subterranean injection zone and disposal well for injection disposal of hazardous wastes;
wherein said sensors are installed in boreholes, drilled to a selected depth, wherein said sensors provide known sensor observation points for maximum practical coverage of said selected injection zone;
wherein said sensors comprise means for detecting and receiving passive seismic signals from micro-earthquake events in said selected injection zone as described in step (g) below;
and making precise measurement of location coordinates of said sensor observation points;
(1) Wherein said computer-based system comprises means for automatic processing of passive seismic signal data, on a real time basis during fracturing in the selected injection zone at a given site;
and
(2) Wherein said computer-based system further comprises means for real time compression of passive seismic signal data, simultaneously receiving, recognizing, recording and processing continuously, signal data from as many as 50 channels or more of data at rates of 2,000 signals per second, per sensor, or greater, and for detecting, flagging, and recording precise measurements of arrival times of both primary and secondary wave phases of passive seismic signals on a real time basis as received, with only signal segments retained for further processing;
c. Means for determining precise velocities of seismic signals traveling through underground strata in and above said injection zone, wherein said determination comprises measuring origin times and arrival times of signals generated by perforation of said disposal well, as said signals travel from a known location to said perforation to said known sensor observation points;
d. Means for calibrating a best seismic velocity distribution model of said selected injection zone, wherein said calibration comprises the steps of:
(1) Making static corrections to observed seismic event arrival times to account for model bias;
(2) Calculating theoretical hypocenter locations using the hypocenter location routine from step 1 below, and a range of hypothetical velocities;
(3) Comparing said theoretical hypocenter locations with known locations of said perforation shots;
and
(4) Selecting a best velocity distribution model which gives calculated locations which are closest to known shot locations;
e. Means for pumping and injecting a slurry suitable for hydraulic fracturing and injection and comprising said hazardous wastes mixed with a selected liquid transport agent, wherein said slurry is injected through said perforation at pressures exceeding minimum principle stress of formations of said injection zone to cause controlled fracturization wherein hydraulic fractures are created in said formation which grow and propagate as additional slurry is injected;
and continuing to inject and slurry into fractures as generated in the selected injection zone at controlled rates while monitoring and controlling down-hole pressure and flow rates to ensure efficient and complete disposal of a required volume of said hazardous wastes;
f. Wherein said injecting and fracturization causes changes in local geologic effective stresses which trigger micro-earthquakes;
wherein said micro-earthquakes at the instant of fracture trigger weak passive seismic signals from the source of each said micro-earthquake event;
wherein said passive seismic signals travel through said formations to said sensors;
and wherein the sources of said signals are known to be located within and acceptably close to said hydraulic fractures clustering in a narrow ellipsoidal volume of rock which encloses said hydraulic fracture or network of fractures;
g. Means for receiving said passive seismic signals, at each said sensor;
converting them to analog electrical signals;
and transmitting them as received to said processing system;
h. Means for amplifying and digitizing said analog signals, wherein a separate channel of data is produced from each sensor;
i. Means for automatically detecting, measuring, and recording said digital data using a real time signal detection algorithm:
(1) Wherein, whenever the signal energy level of a channel exceeds the background noise level by a preset ratio, a signal is recognized and declared;
and
(2) Wherein arrival time and amplitude of said signal are measured and recorded;
j. Means for determining and recording, on a real time basis, which signals and arrival times are associated from the same micro-earthquake event, based on said known sensor locations and velocities in the selected injection zone;
k. Means for sorting and identifying said associated signals for real time, positive identification and recording of their phase types, which may be either primary waves or secondary waves;
and recording precise arrival times of said primary and secondary waves at each of said sensors;
l. Means for determining a hypocenter location and an origin time for signals from each said micro-earthquake event in real time as said events occur, based on hypocenter location data and an earthquake hypocenter location program;
m. Means for recording a hypocenter location and an origin time for each said micro-earthquake event in an event list in real time, wherein said list is continually updated with a new location and origin time of each said micro-earthquake event as said events occur;
n. Means for automatically calculating moment tensor source mechanisms for each event, based on said signal amplitudes for each said event;
determining if said event has a tensional source, which indicates it is part of the hydraulic fracture, or a shear source, which indicates it is adjacent to but not in the hydraulic fracture and thus contains no waste slurry;
and recording each said tension source by type and location;
o. means for determining orientation azimuth of the micro-fracture plane associated with each said event based on said moment sensors;
p. Means for creating and displaying an animated visualization image, using computer codes and said real time event locations, source mechanisms and orientations, wherein said visualization image comprises:
(1) Displaying a rotatable, animated, three dimensional, real time, visualization of said hypocenter location distributions, wherein a distinction is made between hypocenter locations based on said source mechanisms;
wherein said animated visualization is provided with high resolution;
(2) Animating said visualization in real time;
(3) Accurately imaging and visually displaying development, growth, propagation, direction and velocity of induced fractures in real time as said injection process continues;
(4) Displaying said animated visualization on large screen television for viewing;
(5) Rotating said three dimensional display on said screen as desired to show any desired cross section and map view;
(6) Displaying predicted fracture geometry and comparing it with current actual geometry as displayed in real time during said injection;
wherein said predicted fracture geometry is constantly updated on a real time basis to provide a continuing updated prediction and model of future growth;
and
(7) Displaying said fracture growth in real time displayed within a real time animated image of the local geology, in spatial relationship to other geologic formations, zones, reservoirs, wells, fractures and sources of potable water, and simultaneously providing the observer with a continuously updated visual image and display of data concerning the properties of the disposal operation including pressure, slurry volume, flow rate, and viscosity, as said injection continues;
q. Means for depicting and displaying said visual image and display with different colors or symbols in said animated visualization:
(1) Wherein the areal extent of said displayed sources provides a real time demonstration of the location and extent of waste filled fractures;
(2) Wherein said animated visualization provides a real time verification that said fracture is contained in said selected injection zone;
and
(3) Wherein a direction and a velocity of any migration of seismic activity toward a sensitive zone is immediately evident, permitting management decisions and actions including shut down or modification of injection flow rates and pressures to be accomplished long before said sensitive zones are threatened;
and
r. Means for integrating a data installing, receiving, acquisition, compression, processing, calculating, determining and visualization means into a modularized work station system for in-process management and control of hydraulic fracture treatments and for verification of geologic containment of hydraulic fractures.

52 more elements

A process for real time management and verification of geologic containment of hazardous wastes injected into at least one subterranean hydraulic fracture, comprising the steps of:

a. Arranging and installing an array of high sensitivity, high resolution seismic sensors about a selected subterranean injection zone and disposal well for injection disposal of hazardous wastes;
wherein said sensors are installed in boreholes, drilled to a selected depth;
wherein said sensors provide known sensor observation points for maximum practical coverage of said selected injection zone;
wherein said sensors comprise means for detecting and receiving passive seismic signals from micro-earthquake events in said selected injection zone as described in step (g) below;
and making precise measurement of location coordinates of said sensor observation points;
b. Connecting said sensors to a computer-based, real time, automatic seismic data processing system:
(1) Wherein said computer-based system comprises means for automatic processing of passive seismic signal data, on a real time basis, continuously during fracturing in the selected injection zone at a given site;
and
(2) Wherein said computer-based system further comprises means for real time compression of passive seismic signal data, simultaneously receiving, recognizing, recording and processing continuously, signal data from as many as 50 channels or more of data at rates of 2,000 signals per second, per sensor, or greater, and for detecting, flagging, and recording precise measurements of arrival times of both primary and secondary wave phases of passive seismic signals on a real time basis as received, with signal segments retained for further processing;
c. Determining precise velocities of seismic signals traveling through underground strata in and above said selected injection zone;
d. Calibrating a best seismic velocity distribution model of said strata;
e. Pumping and injecting a slurry suitable for hydraulic fracturing and injection, wherein said slurry is injected into said selected injection zone at pressures exceeding minimum principle stress of formations of said injection zone to cause controlled fracturization wherein hydraulic fractures are created in said formation which grow and propagate as additional slurry is injected;
and continuing to inject said slurry into fractures as generated in said selected injection zone at controlled rates while monitoring and controlling down-hole pressure and flow rates to ensure efficient and complete disposal of a required volume of said slurry;
f. Wherein said injecting and fracturization causes changes in local geologic effective stresses which trigger micro-earthquake events;
wherein said micro-earthquake events at the instant of fracture trigger weak passive seismic signals from the source of each said micro-earthquake event;
g. Receiving said passive seismic signals, at each said sensor;
converting them to analog electrical signals;
and transmitting them as received to said processing system;
h. Amplifying and digitizing said analog signals, wherein a separate channel of data is produced from each said sensor;
i. Detecting, measuring, and recording said digital data using a real time signal detection algorithm;
j. Determining and recording, on a real time basis, which signals and arrival times are associated from the same micro-earthquake event, based on said known sensor locations and velocities in the selected injection zone;
k. Sorting and identifying said associated signals for real time, positive identification and recording of their phase types, which may be either primary waves or secondary waves;
and recording precise arrival times of said primary and secondary waves at each of said sensors;
l. Determining a hypocenter location and an origin time for signals from each said micro-earthquake event in real time as said events occur, based on hypocenter location data with an earthquake hypocenter location program;
m. Recording a hypocenter location and an origin time for each said micro-earthquake event in an event list in real time, wherein said list is continually updated with a new location and origin time of each said micro-earthquake event as said events occur;
n. Creating and displaying a visualization image, using means comprising computer codes and said real time event locations, wherein said visualization image comprises:
(1) Displaying a rotatable, three dimensional, real time visualization of said hypocenter location distributions, wherein said visualization is provided with high resolution;
(2) Accurately imaging and visually displaying development, growth, propagation, direction and velocity of induced fractures in real time as said injection continues;
(3) Displaying said visualization;
(4) Rotating said three dimensional visualization on said screen as desired to show any desired cross section and map view;
(5) Displaying predicted fracture geometry and comparing it with current actual geometry as displayed in real time during said injection;
wherein said predicted fracture geometry is updated on a real time basis to provide continuing updated predictions and models of future growth;
and
(6) Visualizing said fracture growth in real time displayed within an image of the local geology, in spatial relationship to other geologic formations, zones, reservoirs, wells, fractures and sources of potable water, and simultaneously providing the observer with a continuously updated visual image and display of data concerning the properties of the disposal operation including pressure, slurry volume, flow rate, viscosity, as injection continues;
o. Depicting and displaying a map visualization:
(1) Wherein the areal extent of said fractures provides a real time demonstration of the location and extent of fractures;
(2) Wherein said map provides real time verification that said fractures are contained in said selected injection zone;
and
(3) Wherein the direction and velocity of any migration of seismic activity toward a sensitive zone is immediately evident, permitting management decisions and actions including shut down or modification of injection flow rates and pressures to be accomplished.

36 more elements

A word station device for real time passive seismic imaging and management of disposal of hazardous wastes by injection into subterranean hydraulic fractures with verification of geologic containment, comprising:

a. Means for arranging and installing an array of high sensitivity, high resolution seismic sensors about a selected subterranean injection zone and disposal well for injection disposal of hazardous wastes;
wherein said sensors are installed in boreholes, drilled to a selected depth, wherein said sensors provide known sensor observation points for maximum practical coverage of said selected injection zone;
wherein said sensors comprise means for detecting and receiving passive seismic signals from micro-earthquake events in said selected injection zone as described in step (g) below;
and making precise measurement of location coordinates of said sensor observation points;
b. Means for connecting said sensors to a computer-based, real time, automatic seismic data processing system:
(1) Wherein said computer-based system comprises means for automatic processing of passive seismic signal data, on a real time basis, during fracturing in the selected injection zone at a given site;
and
(2) wherein said computer-based system further comprises means for real time compression of passive seismic signal data, simultaneously receiving, recognizing, recording and processing continuously, signal data from as many as 50 channels or more of data at rates of 2,000 signals per second, per sensor, or greater, and for detecting, flagging, and recording precise measurements of arrival times of both primary and secondary wave phases of passive seismic signals on a real time basis as received, with signal segments retained for further processing;
c. Means for determining precise velocities of seismic signals traveling through underground strata in and above said selected injection zone;
d. Means for calibrating a best seismic velocity distribution model of said strata;
e. Means for pumping and injecting a slurry suitable for hydraulic fracturing and injection, wherein said slurry is injected into said selected injection zone at pressures exceeding minimum principle stress of formations of said injection zone to cause controlled fracturization wherein hydraulic fractures are created in said formation which grow and propagate as additional slurry is injected;
and continuing to inject said slurry into fractures as generated in said selected injection zone at controlled rates while monitoring and controlling down-hole pressures and flow rates;
f. Wherein said injecting and fracturization causes changes in local geologic effective stresses which trigger micro-earthquake events;
wherein said micro-earthquake events at the instant of fracture trigger weak passive seismic signals from the source of each said micro-earthquake event;
g. Means for receiving said passive seismic signals, at each said sensor;
converting them to analog electrical signals;
and transmitting them as received to said processing system;
h. Means for amplifying and digitizing said analog signals, wherein a separate channel of data is produced from each sensor;
i. Means for automatically detecting, measuring, and recording said digital data using a real time signal detection algorithm;
j. Means for determining and recording, on a real time basis, which signals and arrival times are associated from the same micro-earthquake event, based on said known sensor locations and velocities in the selected injection zone;
k. Means for sorting and identifying said associated signals for real time, positive identification and recording of their phase types, which may be either primary waves or secondary waves;
and recording precise arrival times of said primary and secondary waves at each of said sensors;
l. Means for determining a hypocenter location and an origin time for signals from each said micro-earthquake event in real time as said events occur, based on hypocenter location data with an earthquake hypocenter location program;
m. Means for recording a hypocenter location and an origin time for each said micro-earthquake event in an event list in real time, wherein said list is continually updated with a new location and origin time of each said micro-earthquake event as said events occur;
n. Means for creating and displaying a visualization image, using computer codes and real time event locations, source mechanisms and orientations, wherein said visualization image comprises:
(1) Displaying a rotatable, three dimensional, real time, visualization of said hypocenter locations, wherein said visualization is provided with high resolution;
(2) Accurately imaging and visually displaying development, growth, propagation, direction and velocity of fractures in real time as said injection continues;
(3) Displaying said visualization;
(4) Rotating a three dimensional display on a screen as desired to show any desired cross section and map view;
(5) Displaying predicted fracture geometry and comparing it with current actual geometry as displayed in real time during said injection process;
wherein said predicted fracture geometry is updated on a real time basis to provide continuing updated predictions and models of future growth;
and
(6) Visualizing said fracture growth in real time displayed within an image of the local geology, in spatial relationship to other geologic formations, zones, reservoirs, wells, fractures and sources of potable water, and simultaneously providing the observer with an updated visual image and display of data concerning the properties of the disposal operation including pressure, slurry volume, flow rate and viscosity, as injection continues;
o. Means for depicting and displaying map visualizations:
(1) Wherein the areal extent of said map provides a real time demonstration of the location and extent of waste filled fractures;
(2) Wherein said map provides real time verification that said fractures are contained in said selected injection zone;
and
(3) Wherein the direction and velocity of any migration of seismic activity toward a sensitive zone is immediately evident, permitting management decisions and actions including shut down or modification of injection flow rates and pressures to be accomplished;
and
p. Means for integrating a data installing, receiving, acquisition, compression, processing, calculating, determining and visualization means into a modularized work station system for in-process management and control of hydraulic fracture treatments and for verification of geologic containment of hydraulic fractures.

37 more elements

Dependencies are inferred from the claim text.

System and method for determining earth fracture propagation

Life of this patent

System and method for determining earth fracture propagation

Life of this patent

Abstract

Claims12