Logging tool with electric dipole source and magnetic sensor for positive lateral imaging
阅读说明:本技术 具有电偶极子源和用于正侧位成像的磁传感器的测井工具 (Logging tool with electric dipole source and magnetic sensor for positive lateral imaging ) 是由 T·荻原 于 2018-04-10 设计创作,主要内容包括:一种用于对地下地层(14)的正侧位部分成像的测井方法和系统。电偶极子源(28、34)产生地层(14)中的电磁场(172,180),利用与电偶极子源(28、34)间隔开的磁通量传感器(40、46)对其进行感测。所得电偶极子(I<Sub>X</Sub>、I<Sub>Z</Sub>)可为轴向或横向,并且磁通量传感器(40、48)可感测轴向或正交取向的磁场(172、180)。轴向和横向电偶极子源(28、34)可并置,并且感测轴向或正交磁场的磁通量传感器(40、46)可并置。分析磁通量传感器(40、46)感测的信号的幅值变化可指示在电偶极子源(28、34)前方和侧部是否存在地层界面(52)及其距离。(A logging method and system for imaging a positive laterality portion of a subterranean formation (14). An electric dipole source (28, 34) generates an electromagnetic field (172, 180) in the formation (14) that is sensed with a magnetic flux sensor (40, 46) spaced apart from the electric dipole source (28, 34). The resulting electric dipole (I) X 、I Z ) May be axial or transverse, and the magnetic flux sensor (40, 48) may sense an axially or orthogonally oriented magnetic field (172, 180). Axial and transverse electric dipole sources (28, 34) may be juxtaposed, and magnetic flux sensors (40, 46) sensing axial or orthogonal magnetic fields may be juxtaposed. Analyzing the change in amplitude of the signal sensed by the magnetic flux sensors (40, 46) may indicate the presence and distance of a formation interface (52) in front of and to the side of the electric dipole source (28, 34).)
1. A method of operation in a borehole 12, comprising:
generating an electric dipole I in said borehole 12 with an electric dipole source 28, 34 comprising oppositely charged electrodes (30, 31), (36, 37)X、IZSaid electric dipole IX、IZForming electromagnetic fields 172, 180 in the formation 14 surrounding the borehole 12;
sensing a magnetic flux B generated by the electromagnetic field 172, 180 with coils (42, 44, 48) in the borehole 12 at a location axially spaced from the electrodes (30, 31), (36, 37)Y、BZ(ii) a And is
It is characterized in that the preparation method is characterized in that,
based on sensing magnetic flux BY、BZIdentifying a distance and direction from the electric dipole sources 28, 34 to a formation boundary 52 in the formation 14.
2. The method of claim 1, wherein the formation interface 52 is axially aligned with the electric dipole I in the borehole 12XSpaced apart.
3. Method according to claim 1 or 2, characterized in that said electric dipole IXAlong an axis A substantially perpendicular to said bore 12ZIn which the measured magnetic flux BYDirection of (1)Extending along a path oriented substantially parallel to the axis of the bore 12.
4. The method of claim 1, wherein the formation interface 52 is radially oriented with the electric dipole I from the borehole 12ZSpaced apart.
5. The method of claim 4, wherein said electric dipole IZAlong an axis A substantially parallel to said bore 12ZAnd wherein the measured magnetic flux BZIs oriented along a with the bore hole 12ZThe axes extend in substantially orthogonal paths.
6. The method of claim 1, wherein said electric dipole I isXAlong an axis A substantially perpendicular to said bore 12ZAnd wherein the measured magnetic flux BYAlong an axis a oriented with said bore hole 12ZAnd a path extension substantially orthogonal to the orientation of the electric dipole source 28.
7. The method of claim 6, further characterized by being along an axis A oriented with the borehole 12ZMeasuring the magnetic flux B in a direction in which the substantially orthogonal paths extendY。
8. The method of claim 1, wherein electric dipole IX、IZIncluding along an axis a substantially parallel to said bore 12ZIs oriented by the path ofXSaid method being further characterized by producing a beam along an axis A substantially parallel to said bore 12ZIs oriented by the path ofZ。
9. Method according to claim 1, characterized in that the measured magnetic flux BYAlong an axis substantially parallel to said bore 12AZIs indicative of a formation interface 52 spaced from the electric dipole.
10. The method of claim 1, wherein the stratigraphic interface 52 is along an axis a substantially perpendicular to the borehole 12ZAnd the electric dipole IX、IZSpaced apart.
11. The method of claim 1, wherein the stratigraphic interface 52 is along an axis a substantially perpendicular to the borehole 12ZIs spaced from the electric dipole.
12. A method of operation in a borehole 12, comprising:
by generating an electric dipole I in said bore 12X、IZGenerating magnetic fields 172, 180 in the formation 14 surrounding the borehole 12;
measuring the magnetic flux B in the borehole 12 at a location axially spaced from the electric dipoleY、BZ(ii) a And is
It is characterized in that the preparation method is characterized in that,
based on measuring magnetic flux BY、BZIdentify stratigraphic interfaces 52 in the formation 14.
13. The method of claim 12, wherein said electric dipole I isX、IZExtending along a path substantially perpendicular to the axis of said bore 12 to define a transverse electric dipole IXAnd wherein the measured magnetic flux lines 170, 174 extend along a path selected from the group consisting of: substantially parallel to the axis A of the bore 12ZAnd an axis A substantially orthogonal to said bore 12ZAnd the transverse electric dipole IX。
14. The method of claim 12, wherein said electric dipole I isX、IZAlong a line substantially parallel to said bore 12The path of the shaft extends to define a parallel electric dipole IZAnd wherein the lines of magnetic flux being measured are along an axis A with the borehole 12XOrthogonal path extension, and wherein said parallel electric dipoles IZFormed in a drill string 18 having a drill bit 16, the method further includes steering the drill bit 16 away from the formation interface 52.
15. A tool for use in a borehole 12, comprising:
means 28, 34 for forming an electric dipole I for generating a magnetic field 172, 180 in the formation 14 surrounding the borehole 12X、IZ;
Means 40, 46 for sensing by said electric dipole IX、IZGenerated magnetic flux BY、BX;
A housing 26 positionable in said bore 12 and coupled for forming said electric dipole IX、IZAnd is coupled to the means 28, 34 for sensing the magnetic flux BY、BZThe means 40, 46; and
means 53 for identifying the presence of a bed boundary 52 in the formation 14 in a direction axially and radially spaced from the housing 26.
16. The tool of claim 15, for forming an electric dipole IX、IZComprises transversely arranged electrodes 30, 31 which generate an axis A perpendicular to the housing 26XExhibiting transverse dipole IXAnd wherein for sensing said electric dipole IX、IZGenerated magnetic flux BY、BZComprises a shaft A identical to that of the housing 26XThe orthogonally extending paths are substantially coaxial windings 42, 44.
17. The tool of claim 15, for forming an electric dipole IX、IZComprises generating an axis perpendicular to said housing 26AXDipole I of the presentationXFor sensing the electric dipole I, wherein for sensing the electric dipole IXGenerated magnetic flux BY、BZComprises a shaft A connected to the housing 26XA substantially coaxial winding 48.
18. The tool of claim 15, for forming an electric dipole IX、IZComprises generating an axis A substantially parallel to said housing 26XDipole I of the presentationZAnd wherein for sensing said electric dipole I, axially spaced ring electrodes 36, 37, andX、IZgenerated magnetic flux BY、BZComprises a shaft A identical to that of the housing 26XThe orthogonally extending paths are substantially coaxial windings 42, 44.
19. The tool of claim 15, wherein for forming an electric dipole IX、IZComprises generating an axis A perpendicular to said housing 26XDipole I of the presentationXAnd wherein for sensing through said electric dipole IX、IZGenerated magnetic flux BY、BZComprises a shaft A identical to that of the housing 26XWindings 42, 44 extending orthogonally and substantially coaxially with the path of the housing 26 and axis aXA substantially coaxial winding 48.
20. The tool of claim 15, wherein for forming an electric dipole IX、IZComprises transversely arranged electrodes 30, 31 and axially spaced ring electrodes 36, 37, the transversely arranged electrodes 30, 31 being perpendicular to the axis A of the housing 26XIt is assumed that the axially spaced ring electrodes 36, 37 produce an axis A that is substantially parallel to the housing 26XDipole I of the presentationZAnd wherein for sensing through said electric dipole IX、IZGenerated magnetic flux BY、BZComprises a shaft A identical to that of the housing 26XThe orthogonally extending paths are substantially coaxial windings 42, 44.
Technical Field
The present disclosure relates to imaging a rock formation located directly to an imaging device. More particularly, the present disclosure relates to a logging tool having an electric dipole source and a magnetic sensor that images the formation directly lateral to the tool.
Background
Resistivity measurements are a typical subsurface formation evaluation procedure in which a log of the resistivity near the wellbore is measured. The formation resistivity is a function of any fluid trapped in the subsurface formation. Accordingly, resistivity is typically measured to determine the location of water and/or hydrocarbons in the formation. Changes in the resistivity of the subsurface formations may be abrupt and define formation boundaries. Resistivity may be measured with wireline tools or Logging While Drilling (LWD) tools. Measuring resistivity using a current (DC) resistivity device typically involves forming a potential in the formation and measuring a voltage between electrodes of the device. In an induction measuring device, a magnetic flux/field is induced in the formation by a current in a transmitter; it induces a measured voltage in a receiver of the tool axially spaced from the transmitter. During LWD operations, "look ahead" is required to avoid drilling through stratigraphic interfaces or faults, as well as to avoid any subsurface geological hazards.
Because the in-phase response of the induction log is approximately proportional to the formation conductivity, induction logging tools have been used to measure formation resistivity. In general, the in-phase response is much weaker than the out-of-phase inductive response, so the out-of-phase signal is suppressed using the opposing coils. Propagation tools for LWD and geosteering operations measure formation resistivity through phase differences and response attenuation between a pair of receivers. In geosteering operations, resistivity measurements are sometimes used to detect bed boundaries and to help estimate the distance to the bed boundaries. Generally, in geosteering operations, the primary consideration is to identify bed boundaries rather than obtain resistivity measurements. Formation boundaries can be more easily detected and estimated using a stronger out of phase response in an induction tool or the response of a single receiver in an LWD propagation tool. For example, a cross-component response between a pair of orthogonal axial transmitters and transverse receivers may detect the formation interface around the tool. However, once the distance exceeds approximately the length of the transmitter-receiver offset, the sensitivity to the bed distance in the primary response is reduced.
Disclosure of Invention
Described herein are examples of methods of operating in a borehole, comprising: generating an electric dipole by creating a magnetic field in the formation surrounding the borehole; sensing a magnetic flux generated by the electric dipole with a coil in the borehole at a location axially spaced from the electric dipole; and identifying a distance and direction of a formation interface in the formation from the electric dipole based on the step of sensing the magnetic flux. In one example, the formation interface is spaced from the electric dipole in an axial direction of the borehole, or alternatively, the formation interface is spaced from the electric dipole in a radial direction of the borehole. In an embodiment, the electric dipole is oriented along a path substantially perpendicular to the axis of the borehole, and wherein the measured direction of magnetic flux extends along a path oriented substantially parallel to the axis of the borehole. In one example, the electric dipole is oriented along a path that is substantially parallel to the axis of the borehole, and wherein the measured direction of magnetic flux extends along a path that is oriented substantially orthogonal to the axis of the borehole and the electric dipole. In an alternative form, the electric dipole is oriented along a path substantially perpendicular to the axis of the borehole, and wherein the measured direction of magnetic flux extends along a path oriented substantially orthogonal to the axis of the borehole and the electric dipole. Optionally, the method further comprises: measuring the magnetic flux in a direction extending along a path oriented substantially orthogonal to the axis of the borehole, or alternatively, the method further comprises: an electric dipole oriented along a path substantially parallel to the axis of the borehole is generated. There are embodiments in which the measured magnetic flux provides an indication of a formation interface spaced from the electric dipole along a path substantially parallel to the axis of the borehole. The measured magnetic flux optionally provides an indication of a formation interface spaced from the electric dipole along a path substantially perpendicular to the axis of the borehole. In another example, the measured magnetic flux provides an indication of a formation interface spaced from the electric dipole along a path substantially perpendicular to the axis of the borehole.
Also shown herein are examples of methods of operation in a borehole, comprising: generating a magnetic field in the formation surrounding the borehole by generating an electric dipole in the borehole; measuring the magnetic flux at a location in the borehole axially spaced from the electric dipole; and identifying formation boundaries in the formation based on the step of measuring the magnetic flux. In an alternative form, the electric dipole extends along a path substantially perpendicular to the axis of the borehole, wherein the measured lines of magnetic flux extend along a path selected from the group consisting of substantially parallel to the axis of the borehole and substantially orthogonal to the axis of the borehole. In one example, the electric dipole extends along a path substantially parallel to an axis of the borehole, and wherein the measured lines of magnetic flux extend along a path orthogonal to the axis of the borehole, wherein the electric dipole is formed in a drill string having a drill bit, the method further comprising steering the drill bit away from the formation interface.
Also described herein are examples of a tool for use in a borehole, comprising: means for forming an electric dipole that generates a magnetic field in a formation surrounding a borehole, the means coupled to the housing; means for sensing the magnetic flux generated by the electric dipole; a housing positionable in a borehole coupled to a means for forming an electric dipole and to a means for sensing magnetic flux; and means for identifying the presence of a formation boundary in the formation in a direction axially and radially spaced from the housing. Optionally, the means for forming an electric dipole comprises: generating transversely arranged electrodes of a dipole that is presented perpendicular to the axis of the housing, and wherein the means for sensing the magnetic flux generated by the electric dipole has windings substantially coaxial with a path extending orthogonally to the axis of the housing. In an alternative form, the means for forming an electric dipole is a transversely arranged electrode producing a dipole that appears perpendicular to the axis of the housing, and wherein the means for sensing the magnetic flux produced by the electric dipole comprises a winding substantially coaxial with the axis of the housing. In an alternative form, the means for forming an electric dipole is constituted by axially spaced annular electrodes producing a dipole that appears substantially parallel to the axis of the housing, and wherein the means for sensing the magnetic flux produced by the electric dipole comprises windings substantially coaxial with a path extending orthogonally to the axis of the housing. In one embodiment, the means for forming an electric dipole comprises laterally arranged electrodes producing a dipole that appears perpendicular to the axis of the housing, and wherein the means for sensing the magnetic flux produced by the electric dipole comprises a winding substantially coaxial with a path extending orthogonally to the axis of the housing and a winding substantially coaxial with the axis of the housing. In an alternative form, the means for forming an electric dipole has transversely arranged electrodes producing dipoles that lie perpendicular to the axis of the housing and spaced apart annular electrodes producing axes of dipoles that lie substantially parallel to the axis of the housing, and wherein the means for sensing magnetic flux produced by the electric dipole is constituted by windings substantially coaxial with a path extending orthogonally to the axis of the housing.
Drawings
Having stated some features and advantages of the present invention, others will become apparent when the description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a cross-sectional view of an example of a drilling system forming a borehole in an earth formation and a logging tool for imaging the earth formation;
FIG. 2A is a side, partially cut-away perspective view of an example of a transverse electric dipole source;
FIG. 2B is a side, partially cut-away perspective view of an example of an axial electric dipole source;
FIG. 2C is a side, partially cut-away perspective view of an example of an orthogonal magnetic sensor;
FIG. 2D is a side, partially cut-away perspective view of an example of an axial magnetic sensor;
FIG. 3A is a side partial cross-sectional view of another embodiment of a portion of the logging tool of FIG. 1 and having a transverse electric dipole source and an orthogonal magnetic sensor;
FIG. 3B is a side partial cross-sectional view of another embodiment of a portion of the logging tool of FIG. 1 and having a transverse electric dipole source and an axial magnetic sensor;
FIG. 3C is a side partial cross-sectional view of another embodiment of a portion of the logging tool of FIG. 1 and having an axial electric dipole source and orthogonal magnetic sensors;
FIG. 3D is a side, partial cross-sectional view of another embodiment of a portion of the logging tool of FIG. 1 and having an axial electric dipole source and an orthogonal magnetic sensor with an axial magnetic sensor;
FIG. 3E is a side partial cross-sectional view of another embodiment of a portion of the logging tool of FIG. 1 and having an axial electric dipole source with a transverse electric dipole source and an orthogonal magnetic sensor;
FIG. 4 is a cross-sectional view of an example of the drilling system and logging tool of FIG. 1 encountering a formation boundary;
FIGS. 5A-5C are graphs of signal offset values versus distance for known and presently disclosed transducer configurations;
FIGS. 6A and 6B are graphs of signal deviation values versus distance for sensors and transmitters of different pitches;
FIGS. 7A and 7B are graphs of signal deviation values versus distance for sensors and transmitters of different pitches;
FIG. 8A, FIG. 9A, and FIG. 10A are partial cross-sectional views of an example of a downhole tool imaging a homogeneous formation;
FIG. 8B, FIG. 9B, and FIG. 10B are cross-sectional views of the example of the tool of FIGS. 8A, 9A, and 10A, respectively, approaching a formation change;
while the invention will be described in conjunction with the preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.
Detailed Description
The methods and systems of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. The methods and systems of the present disclosure may take many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope to those skilled in the art. Like numbers refer to like elements throughout. In one embodiment, the use of the terms "about", "substantially" and "generally" includes +/-5% of the magnitude involved.
It is further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to those skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.
Shown in partial cross-sectional side view in FIG. 1 is an example of a
Fig. 2A-2D show alternative examples of the
An alternative example of a device that generates an electromagnetic field is shown in fig. 2B and is referred to as an axial
Fig. 2C shows an example of a transverse
Shown in the side cross-sectional view of FIG. 2D is an example of an axial
FIG. 3A shows another example of an
FIG. 3B shows another embodiment of an
FIG. 3C illustrates another example of an
Shown in side-view partial cross-sectional view in FIG. 3D is another alternative example of an imaging tool 20D, where the source is a transverse electric transducer 28D with electrodes 30D, 31D, and is perpendicular to the axis A of the housing 26DZ. The sensing unit shown in fig. 3D is a pair of juxtaposed sensors, including a transverse magnetic sensor 40D and an axial magnetic sensor 46D. In a non-limiting example, the term juxtaposition describes sensor or signal sources at substantially the same location on the imaging tool. In the example of fig. 3D, embodiments of the sensors of fig. 3A and 3B are shown in combination. As shown, the transverse magnetic sensor 40D and the axial magnetic sensor 46D are spaced apart from the transverse electric transducer 28D by a distance LD。
In the example of FIG. 3E, another embodiment of an imaging tool 20E is shown in side partial cross-sectional view, with the dipole sources juxtaposed. More specifically, the dipole source is shown as an example of a transverse electric transducer 28E, with electrodes 30E, 31E arranged at substantially the same axial location on housing 26E, but circumferentially distant from each other on an outer surface of housing 26E. Here, the electrodes 30E, 31E are energized to form an electric dipole I along the X-axisX. Juxtaposed with the electrodes 30E, 31E is another dipole source, which is an axial electric transducer 34E having electrode rings 36E, 37E, which by energizing the rings 36E, 37E produces a dipole I along the Z-axisZ. The sensors of imaging tool 20E of FIG. 3E include one example of a transverse magnetic sensor 40E with coils or windings 42E, 44E along the Y-axis and sensing magnetic field BY. The juxtaposed electric dipole source and magnetic sensor are shown spaced apart from each other by a distance LE。
FIG. 4 shows another example of an
Also shown in fig. 4 is an example of a
Referring to FIG. 5A, an example of a
Shown in fig. 5B is a
Shown in fig. 5C is a
As shown in fig. 5C, the tool with the magnetic sensor detected a 10% change in the sensing response at a distance/L ratio of 5, while the electric dipole/electric field sensor tool detected a 10% change in the sensing response at a distance/L ratio of 2. Thus, the results of using a tool with a magnetic sensor (line 82) provide sensitivity for detecting formation interfaces at greater distances than using a tool with an electric dipole source and an electric field sensor (line 84). Further, in fig. 5C, the distance is in a look-around application. It should be noted that the cross component electric field measurements of
Referring now to FIG. 6A, a
Referring now to FIG. 7A, shown is an example of a
An alignment chart similar to that of fig. 7A is shown in the
Referring now to FIG. 8A, an example of the
As shown in FIG. 8B, the
Shown in FIG. 9A is a plan partial cross-sectional view of an example of the
Referring now to FIG. 10A, an example of an
As shown in fig. 10B,
Thus, the invention described herein is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the invention disclosed herein and the scope of the claims.
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