US 2017/0248719 A1Published application

Methods of generation of fracture density maps from seismic data

AssigneeThe Board of Regents for Oklahoma State University

InventorsROBERT HOLMAN, PRIYANK JAISWAL

Life of this patent

Estimating the term…

Loading patent…

Abstract

A method is herein presented to statistically combine multiple seismic attributes for generating a map of the spatial density of fractures. According to an embodiment a first step involves interpreting the formation of interest in 3D seismic volume first to create its time structure map. The second step is creating depth structure of the formation of interest from its time structure map. In this application geostatistical methods have been used for depth conversional, although other methods could be used instead. The third step is extraction of a number of attributes, such as phase, frequency and amplitudes, from the time structure map. The next step is to project the fracture density onto the top of the target formation. The final step is to combine these attributes using a statistical method known as Multi-variant non-linear regression to predict fracture density.

Claims11

Dependent claims

A method of seismic exploration of a region of the subsurface of the earth containing structural or stratigraphic features conducive to the presence, migration, or accumulation of hydrocarbons, wherein is provided a plurality of seismic traces collected in a seismic survey conducted proximate to the region of the subsurface of the earth and at least one FMI well log obtained from a horizontally drilled well proximate to said seismic survey, at least a portion of said FMI well log being within a target formation, said target formation having a top defined by a plurality of depths within the subsurface, the method comprising the steps of:

(b) within a computer,
(i) obtaining a plurality of fracture density measurements from said FMI log, thereby producing a fracture density log;
(ii) accessing said plurality of seismic traces from said seismic survey;
(iii) identifying said target formation top within each of said accessed plurality of seismic traces, thereby producing a picked time within each of said accessed plurality of seismic traces;
(iv) using said picked time associated with each of said accessed plurality of seismic traces and said plurality of depths defining said target formation to adjust said picked time of said each of said seismic traces to match a corresponding depth of said formation top;
(v) projecting said at least a portion of said fracture density log onto said formation top along a fracture dip direction, thereby obtaining formation density estimates along said formation top;
(vi) calculating a plurality of different seismic attributes for each of said accessed plurality of seismic traces from seismic data proximate in depth to said target formation top;
(vii) using said calculated plurality of different seismic attributes for each of said accessed plurality of seismic traces and said formation density estimates along said formation top to obtain a prediction equation that relates said plurality of seismic attributes to said fracture density estimates along said formation top;
and,
(viii) using said prediction equation and at least a portion of said seismic survey to predict fracture density away from said horizontally drilled well;
(b) making an exploration or production decision based on said predicted fracture density away from said horizontally drilled well.

8 more elements

A method of exploration of a region of the subsurface of the earth, wherein is provided a plurality of seismic traces collected in a seismic survey conducted proximate to the region of the subsurface of the earth and a fracture density log obtained from a horizontally drilled well proximate to said seismic survey, at least a portion of said fracture density log being within a target formation, said target formation having a top defined by a plurality of depths within the subsurface, the method comprising the steps of:

(a) within a computer,
(i) accessing said fracture density log;
(ii) accessing said plurality of seismic traces from said seismic survey;
(iii) identifying said target formation top within each of said accessed plurality of seismic traces, thereby producing a picked time associated with each of said accessed plurality of seismic traces;
(iv) using said picked time associated with each of said accessed plurality of seismic traces and said plurality of depths defining said target formation to adjust said picked time of said each of said seismic traces to match a corresponding depth of said formation top;
(v) projecting said at least a portion of said fracture density log onto said formation top along a fracture dip direction, thereby obtaining formation density estimates along said formation top;
(vi) calculating a plurality of different seismic attributes from said depth adjusted seismic data;
(vii) using said calculated plurality of different seismic attributes for each of said accessed plurality of seismic traces and said formation density estimates along said formation top to obtain a prediction equation that relates said plurality of seismic attributes to said fracture density estimates along said formation top;
and,
(viii) using said prediction equation and at least a portion of said seismic survey to predict fracture density away from said horizontally drilled well;
(b) making an exploration or production decision based on said predicted fracture density away from said horizontally drilled well;
and,
(c) drilling a well based on said exploration or production decision.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/506,733Filed 3 Sep 2015
Priority: 3 Sep 2014
Published: 31 Aug 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

G01V 1/306
Analysis: for determining physical properties of the subsurface, e.g. impedance, porosity or attenuation profiles
E21B 7/046
Directional drilling: horizontal drilling
E21B 49/003
Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to…:…
G01V 1/28
Seismology; Seismic or acoustic prospecting or detecting: processing seismic data, e.g. for interpretation or for event detection