Method and system for dip picking and zonation of highly deviated well images

• US 10,641,922 B2
• Filed: 10/24/2017
• Issued: 05/05/2020
• Est. Priority Date: 11/02/2016
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: He, Alexis, Kherroubi, Josselin, Maeso, Carlos
• Primary Examiner(s): Bhat, Aditya S
• Application Number:
  US15/792,032
• Publication Number:
  US 20180120477A1
• Time in Patent Office: 924 Days
• Field of Search: None
• CPC Class Codes: G01V 1/50 Analysing data
• CPC Class Codes: G01V 11/002 Details, e.g. power supply systems for logging instruments, transmitting or recording data, specially adapted for well logging, also if the prospecting method is irrelevant means for transmitting well survey signals E21B47/12; signal transmission systems in general G08C; transmission in general H04B
• CPC Class Codes: G01V 3/18 specially adapted for well-logging

Abstract

In one embodiment, a computer-based method includes obtaining a borehole image deriving from a downhole tool in a borehole of a geological formation, performing dip picking on the borehole image to derive one or more structural dips, deriving a continuous structural dip based on the one or more structural dips, defining one or more locations of zone boundaries on the borehole image, deriving one or more zone boundaries based on the continuous structural dip and the one or more locations of zone boundaries, and defining one or more zones of the wellbore in a second image based on the one or more zone boundaries.

Claims

1. A computer-based method (40) comprising:

obtaining (42) a borehole image (44) deriving from a downhole tool (12) in a borehole of a geological formation (14);

performing (46) dip picking on the borehole image (44) to derive one or more structural dips (42) in a depth interval, wherein a structural dip is an orientation of a 3D plane crossing the borehole;

deriving (54) a continuous structural dip (56) based on the one or more structural dips (42), wherein the continuous structural dip is a function representing continuously the structural dip as a function of depth in the depth interval;

defining (58) one or more locations of zone boundaries (60) on the borehole image (44);

deriving (62) one or more zone boundaries (64) based on the continuous structural dip (56) and the one or more locations of zone boundaries (60); and

defining (66) one or more zones (68) of the wellbore in a second image based on the one or more zone boundaries (64).

2. The method (40) of claim 1, wherein the geological formation (14) includes a well that is highly deviated, horizontal, or both.

3. The method (40) of claim 1, wherein performing (46) dip picking comprises determining an orientation of one or more boundaries, faults, or both in the borehole image (44) by selecting multiple dips at substantially the same time for each of the one or more boundaries, faults or both, wherein the orientation is characterized by an inclination and an azimuth.

4. The method (40) of claim 1, comprising deriving (114) a vertical symmetry probability for each of the one or more structural dips (52) using image data from the borehole image (44) within an azimuth range around an intersection trace, and determining whether the vertical symmetry probability for each of the one or more structural dips (52) meets a sufficient value on a scale.

5. The method (40) of claim 1, wherein the dip picking is performed based on a borehole trajectory (50) comprising an azimuth and a deviation, a borehole geometry (50) comprising a caliper, user input (48) comprising a collection of points on the borehole image, or some combination thereof.

6. The method (40) of claim 1, wherein the continuous structural dip (56) is a function of the one or more structural dips (52), wherein, at depths in the borehole where no structural dips are derived, interpolation is used to derive the continuous structural dip (56), and, at depths where multiple structural dips (52) are derived, a subset of the structural dips (52) are processed to derive the continuous structural dip (56).

7. The method (40) of claim 1, wherein defining (58) the one or more locations of zone boundaries (60) on the borehole image (44) comprises defining points in three-dimensional (3D) space where the zone boundaries cross the borehole.

8. The method (40) of claim 7, wherein defining the points in the 3D space where the zone boundaries cross the borehole comprises:

programmatically defining the one or more locations of zone boundaries (60) on the borehole image (44) using image processing;

receiving user input (46) comprising points on the borehole image (44) indicative of the one or more locations of zone boundaries (60);

or

some combination thereof.

9. The method (40) of claim 1, wherein deriving (66) one or more zone boundaries (64) based on the continuous structural dip (56) and the one or more locations of zone boundaries (60) comprises deriving an intersection of a zone boundary of the one or more zone boundaries (64) and the borehole incrementally depth by depth using Cartesian coordinates of a center of the borehole, wherein at a given measured depth, a borehole geometry (50), a borehole trajectory (50), and the continuous structural dip (56) are used to characterize a borehole slice and determine whether the zone boundary (64) intersects the borehole slice.

10. The method (40) of claim 9, wherein determining whether the zone boundary (64) intersects the borehole slice is based on the following relationship:

at a depth d, for;

A, known intersection point of both the zone boundary and the borehole slice at d

p, known pole of the zone boundary at d, with inclination θ and

azimuth α

S, known point of the borehole slice at d at azimuth α

B, unknown intersection point of both the zone boundary and the borehole slice at d′

, located at azimuth β

R, radius of the borehole at d′

including DOI

given the following formula;

0={right arrow over (AB)}·

{right arrow over (p)}=({right arrow over (AS)}+{right arrow over (SB)})·

{right arrow over (p)}=({right arrow over (AS)}·

{right arrow over (p)})_true+({right arrow over (SB)}·

{right arrow over (p)})_apparent

apparent refers to apparent coordinate system, true refers to true coordinate system, and using the borehole geometry and the borehole trajectory, ({right arrow over (AS)}·

{right arrow over (p)})_true is completely defined,

with;

11. A system (10), comprising:

one or more sensors configured to obtain a borehole image (44) of a geological formation (14); and

one or more data processing systems (28) comprising one or more processors (30) that;

receive (42) the borehole image (44); and

perform (46) dip picking on the borehole image (44) to derive one or more structural dips (52), wherein dip picking comprises determining an orientation of one or more boundaries, faults, or both in the borehole image (44) by identifying multiple dips at substantially the same time for each of the one or more boundaries, faults, or both, and wherein the orientation is characterized by an inclination and an azimuth,

derive (114) a vertical symmetry probability for each of the one or more structural dips (52) using image data from the borehole image (44) within an azimuth range around an intersection trace, and determining whether the vertical symmetry probability for each of the one or more structural dips (52) meets a sufficient value on a scale.

12. The system (10) of claim 11, wherein the one or more processors (30):

derive (54) a continuous structural dip (56) based on the one or more structural dips (52), wherein the continuous structural dip is a function representing continuously the structural dip as a function of depth;

define (58) one or more locations of zone boundaries (60) on the borehole image (44);

derive (62) one or more zone boundaries (64) based on the continuous structural dip (56) and the one or more locations of zone boundaries (60); and

define (66) one or more zones (68) of the wellbore in a second image based on the one or more zone boundaries (64).

13. The system (10) of claim 11, wherein defining (66) one or more zones (68) of the wellbore in a second image based on the one or more zone boundaries (64) comprises aggregating each of the zone boundaries (64) to divide the borehole into the one or more zones (68) on the second image.