Automatic non-artificially extended fault surface based horizon modeling system

• US 6,138,076 A
• Filed: 08/10/1999
• Issued: 10/24/2000
• Est. Priority Date: 10/31/1996
• Status: Expired due to Term

• Current Assignee: A Division Of Schlumberger Geoquest
• Original Assignee: A Division Of Schlumberger Geoquest
• Inventors: Vassilev, Apostol T., Graf, Kermit E.
• Primary Examiner(s): McElheny, Jr., Donald E.
• Application Number:
  US09/371,225
• Time in Patent Office: 441 Days
• Field of Search: 702/16, 702/17, 702/11, 702/12, 702/13, 702/14, 702/2, 367/72, 367/73
• US Class Current: 702/14
• CPC Class Codes: G01V 1/28 Processing seismic data, e.g. for interpretation or for event detection G01V1/48 takes precedence
• CPC Class Codes: G01V 1/301 for determining seismic cross-sections or geostructures
• CPC Class Codes: G01V 1/34 Displaying seismic recordings or visualisation of seismic data or attributes
• CPC Class Codes: G01V 11/00 Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00
• CPC Class Codes: G01V 2210/66 Subsurface modeling
• CPC Class Codes: G06T 17/05 Geographic models

Abstract

An automatic, non-artificially extended, fault surface based horizon modeling method and apparatus produces a final faulted horizon model which is a three dimensional representation of a faulted earth formation including all the horizons and all the faults in response to seismic data, well log data, and fault surfaces and relationships data. The horizon modeling apparatus produces the final faulted horizon model by filtering input horizon data and removing bad (wrong-sided) data points. This is accomplished by: (a) computing intersections between each horizon and each fault that intersects the horizon, (b) assessing the quality of each intersection, (c) filtering in the vicinity of the intersection by decreasing the slope between the intersecting fault and its respective horizon, (d) generating a horizon surface and reassessing their quality, (e) reintroducing the eliminated data points between the fault and the horizon, (f) re-filtering the reintroduced data points, (g) generating an initial faulted horizon model, (h) generating a set of final fault locations, and (i) generating a final faulted horizon model.

Claims

1. A device adapted for storing instructions, said instructions adapted to be executed by a processor of a workstation, said workstation adapted to receive data including horizon data representing one or more horizons in an earth formation and fault data representing one or more faults intersecting at least some of said horizons, said instructions, when executed by said processor of said workstation, conducting a process comprising the steps of:

(a) computing a preliminary unfaulted horizon model using only said horizon data,

(b) computing intersections between said preliminary unfaulted horizon model and each of the faults intersecting said horizon model, at least some of said intersections between said horizon model and said each of said faults being inconsistent intersections, and

(c) filtering in the vicinity of said inconsistent intersections.

2. The device of claim 1, wherein said inconsistent intersections exhibit geometric characteristics that are inconsistent with the geometric characteristics of said each of the faults, and wherein the filtering step (c) comprises the step of:

(c1) eliminating some of said horizon data in the vicinity of said inconsistent intersection thereby decreasing a slope of said horizon model in the vicinity of said inconsistent intersection and generating a new said horizon model having a surface which includes one or more clean and consistent intersections between said new horizon model and each of the faults intersecting said new horizon model, each of said clean and consistent intersections representing an initial fault location.

3. The device of claim 2, wherein said instructions, when executed by said processor, conduct said process further comprising the step of:

(d) when said surface of said horizon model including said clean and consistent intersections is generated, reintroducing said some of said horizon data which was eliminated during the eliminating step (c1).

4. The device of claim 3, wherein said instructions, when executed by said processor, conduct said process further comprising the step of:

(e) re-filtering said some of said horizon data which was reintroduced during the reintroducing step (d).

5. The device of claim 4, wherein the re-filtering step (e) comprises the step of:

(e1) eliminating certain ones of said horizon data which are located within a narrow filtering zone around said initial fault locations thereby generating clean horizon data.

6. The device of claim 5, wherein said instructions, when executed by said processor, conduct said process further comprising the step of:

(f) generating an initial faulted horizon model in response to said clean horizon data generated during the eliminating step (e1) and said initial fault locations, said initial faulted horizon model including a horizon having a substantially vertically sloped fault or discontinuity passing therethrough at each of said initial fault locations.

7. The device of claim 6, wherein said instructions, when executed by said processor, conduct said process further comprising the step of:

(g) generating a set of final fault locations on said horizon model in response to said initial faulted horizon model generated during the generating step (f), the final fault locations representing a horizon model having a non-vertically sloped fault or discontinuity passing therethrough, the horizon model having a fault zone including an opening through which the non-vertically sloped fault passes when said final fault locations represent said horizon model having said non-vertically sloped fault passing therethrough.

8. The device of claim 7, wherein said instructions, when executed by said processor, conduct said process further comprising the step of:

(h) generating a final faulted horizon model in response to said final fault locations generated during the generating step (g) but not in response to said initial fault locations generated during the eliminating step (c1),

said final faulted horizon model including one or more accurately represented intersections between a horizon and one or more faults passing through the horizon, whereby underground deposits of hydrocarbon are potentially located adjacent to said intersections.

9. The device of claim 8, wherein said fault data includes fault surfaces data and relationships data, said fault surfaces data including a plurality of pairs of fault surfaces, said relationships data identifying intersecting ones of said plurality of pairs of fault surfaces, each fault surface of said intersecting ones of said plurality of pairs of fault surfaces having a major status and a minor status, said relationships data further including the major status and the minor status of each fault surface of said intersecting ones of said plurality of pairs of fault surfaces.

10. A method of determining an accurate estimate of underground deposits of hydrocarbon in an earth formation, comprising the steps of:

(a) introducing data representing one horizon;

(b) generating a preliminary horizon model, said horizon model including horizon data;

(c) computing intersections between said preliminary horizon model and each fault intersecting said horizon model;

(d) improving said preliminary horizon model, the improving step (d) including the step of filtering said horizon data in the vicinity of at least some of said intersections which exhibit geometric characteristics not in good agreement with the geometric characteristics of the corresponding faults passing through said intersections; and

(e) repeating steps (a) through (d) for each horizon model until said horizon model exhibits clean intersections between said horizon model and faults intersecting said horizon model, said clean intersections representing initial fault locations which have geometric characteristics matching well the geometric characteristics of the corresponding fault.

11. The method of claim 10, further comprising the steps of:

(f) refiltering the horizon data thereby removing bad, wrong sided data points, the refiltering step including the steps of;

(f1) reintroducing eliminated horizon data which was filtered during the filtering step (d), and refiltering the reintroduced horizon data by eliminating certain ones of the horizon data which are located within a narrow filtering zone in the vicinity of said initial fault locations thereby generating clean horizon data.

12. The method of claim 11, further comprising the steps of:

(g) determining an initial faulted horizon model in response to said clean horizon data generating during step (f1) and the initial fault locations, the initial faulted horizon model including a horizon having a substantially vertically sloped fault passing through the initial fault location on the horizon.

13. The method of claim 12, further comprising the steps of:

(h) determining a final faulted horizon model, the determining step (h) including the steps of,

(h1) generating a set of final fault locations in response to said initial fault locations and said initial faulted horizon model determined during the determining step (g), said final fault locations representing a horizon having a non-vertically sloped fault passing through a fault zone, said fault zone including an opening through which the non-vertically sloped fault passes.

14. The method of claim 13, further comprising the steps of:

(i) determining an accurate estimate of underground deposits of hydrocarbon in the earth formation, the determining step (i) including the steps of,

(i1) generating a final faulted horizon model in response to the final fault locations generating during the generating step (h1) but not in response to the initial fault locations generating during the repeating step (e),

said final faulted horizon model including one or more accurately represented intersections between one or more horizons and one or more faults passing through the horizons, the underground deposits of hydrocarbon being located adjacent said intersections.