CN115327650A - Porosity measurement method and device, computing equipment and computer storage medium - Google Patents
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Abstract
The invention discloses a porosity measurement method, a porosity measurement device, computing equipment and a computer storage medium, wherein the method comprises the following steps: emitting pulsed neutrons based on a pulsed neutron emitter; gamma rays generated after fast neutrons emitted by the pulse neutron emitter react with the formation are respectively detected based on the far-side gamma detector and the near-side gamma detector; respectively collecting an inelastic scattering total energy spectrum and a capturing energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measuring time window; performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the borehole diameter correction and the far-near non-elastic count ratio correction; and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC to perform porosity quantitative evaluation. The solution is not affected by the degree of mineralization and results are obtained with a higher degree of conformity to the response of conventional chemical source measurement methods.
Description
Technical Field
The invention relates to a porosity measurement method, in particular to a porosity measurement method, a porosity measurement device, computing equipment and a computer storage medium.
Background
In the field of petroleum and natural gas, formation porosity measurement is a necessary measurement project in a well logging process, and mature measurement methods are available in the prior art. But conventional measurement methods require the use of a chemical radiation source. With the deep humanity of the green environmental protection concept, the use of chemical sources is more and more limited. In some complex measurements of well conditions, the acquisition of open hole data has to be abandoned in view of the safety of radioactive sources.
In recent years, with the development of controllable source technology, some porosity measurement methods based on controllable source technology are developed, for example, a method referring to traditional compensation neutrons is used for measuring thermal neutron distribution by using a He3 tube, and porosity is obtained by combining a correction template; the porosity is also obtained, for example, by the count ratio of two gamma detectors.
Both of the above methods are significantly affected by factors such as the mineralization of the formation, which is unknown or even variable in many cases, and this makes the measurement of porosity difficult.
Disclosure of Invention
In view of the above, the present invention has been developed to provide a porosity measurement method, apparatus, computing device and computer storage medium that overcome or at least partially address the above-identified problems.
According to an aspect of the present invention, there is provided a porosity measurement method, including:
emitting pulsed neutrons based on a pulsed neutron emitter;
respectively detecting gamma rays after fast neutrons emitted by the pulse neutron emitter react with the formation on the basis of a far-side gamma detector and a near-side gamma detector;
respectively collecting an inelastic scattering total energy spectrum and a capturing energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measuring time window;
performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the borehole diameter correction and the far-near non-elastic count ratio correction; and
and acquiring a thermal neutron elastic scattering cross section of the formation based on the LOGNL _ BSC to perform porosity quantitative evaluation.
Optionally, the acquiring the total inelastic scattering spectrum and the capturing spectrum respectively according to the pre-designed pulse emission timing sequence and the spectrum measurement time window, further comprises:
a first inelastic scattering total energy spectrum and a first capture energy spectrum are acquired by the distal gamma detector and a second inelastic scattering total energy spectrum and a second capture energy spectrum are acquired by the proximal gamma detector.
Optionally, performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the well diameter correction and the far-near non-elastic count ratio correction, further comprising:
acquiring a far-near non-elastic counting ratio based on the first inelastic scattering total energy spectrum and the second inelastic scattering total energy spectrum, and taking a natural logarithm of the far-near non-elastic counting ratio;
acquiring a far-near capture count ratio based on the first capture energy spectrum and the second capture energy spectrum, and taking a natural logarithm of the far-near capture count ratio;
acquiring a far-near capture count ratio LOGNL after correction of the far-near non-missile count ratio based on the far-near non-missile count ratio after natural logarithm and the far-near capture count ratio after natural logarithm; and
and correcting the LOGNL based on the borehole structure information to obtain a far-near capture count ratio LOGNL _ BSC after the far-near non-shot count ratio correction of the borehole diameter correction.
Optionally, acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC to perform porosity quantitative evaluation, further comprising:
establishing a functional relation between LOGNL _ BSC and a formation thermal neutron elastic scattering cross section; and
and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC, and performing porosity quantitative evaluation by using a volume model based on formation lithology profile information.
Optionally, correcting the LOGNL based on the borehole structure information to obtain a near-far capture count ratio LOGNL _ BSC after the near-far non-shot count ratio correction after the borehole diameter correction, further comprising:
LOGNL_BSC＝[1-C·(8-BS)]·LOGNL+D·(8-BS)
the LOGNL is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the LOGNL _ BSC is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the borehole diameter is corrected, the size 8 is the size of a standard borehole, the BS is the actual borehole diameter, and the C, D is a fitting parameter.
Optionally, the method includes acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC, and performing quantitative porosity evaluation by using a volume model based on formation lithology profile information, and further includes:
T＝ΦT 1 +(1-Φ)T 2
wherein, T 1 Elastic scattering cross-section of thermal neutrons, T, for ponding water in a single volume 2 The thermal neutron elastic scattering cross section of the rock in unit volume, T is the measured thermal neutron elastic scattering cross section of the stratum in unit volume, and phi is the stratum porosity.
Optionally, the source distance of the far-side gamma detector is 75.9cm, the source distance of the near-side gamma detector is 36.5cm,
according to another aspect of the present invention, there is provided a porosity measuring device including:
a pulsed neutron emitter adapted to emit pulsed neutrons;
the far-side gamma detector and the near-side gamma detector are suitable for respectively detecting gamma rays after fast neutrons emitted by the pulse neutron emitter react with the stratum;
the acquisition module is suitable for respectively acquiring an inelastic scattering total energy spectrum and a capturing energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measurement time window;
the calculation module is suitable for performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the borehole diameter is corrected and the far-near non-elastic count ratio is corrected; and
and the evaluation module is suitable for acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC so as to perform porosity quantitative evaluation.
Optionally, the acquisition module is further adapted to:
a first inelastic scattering total energy spectrum and a first capture energy spectrum are acquired by the distal gamma detector and a second inelastic scattering total energy spectrum and a second capture energy spectrum are acquired by the proximal gamma detector.
Optionally, the calculation module is further adapted to:
acquiring a far-near non-elastic counting ratio based on the first inelastic scattering total energy spectrum and the second inelastic scattering total energy spectrum, and taking a natural logarithm of the far-near non-elastic counting ratio;
acquiring a far-near capture count ratio based on the first capture energy spectrum and the second capture energy spectrum, and taking a natural logarithm of the far-near capture count ratio;
acquiring a far-near capture count ratio LOGNL after correction of the far-near non-missile count ratio based on the far-near non-missile count ratio after natural logarithm and the far-near capture count ratio after natural logarithm; and
and correcting the LOGNL based on the borehole structure information to obtain a far-near capture count ratio LOGNL _ BSC after the far-near non-shot count ratio correction after the borehole diameter correction.
Optionally, the evaluation module is further adapted to:
establishing a functional relation between LOGNL _ BSC and a formation thermal neutron elastic scattering cross section; and
and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC, and performing porosity quantitative evaluation by using a volume model based on formation lithology profile information.
Optionally, the calculation module is further adapted to obtain the corrected hole diameter LOGNL _ BSC based on the following formula:
LOGNL_BSC＝[1-C·(8-BS)]·LOGNL+D·(8-BS)
the LOGNL is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the LOGNL _ BSC is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the borehole diameter is corrected, the size 8 is the size of a standard borehole, the BS is the actual borehole diameter, and the C, D is a fitting parameter.
Optionally, the evaluation module is further adapted to perform a quantitative evaluation of porosity based on the following formula:
T＝ΦT 1 +(1-Φ)T 2
wherein, T 1 Elastic scattering cross section of thermal neutrons as water in unit volume, T 2 The thermal neutron elastic scattering cross section of the rock in unit volume, T is the measured thermal neutron elastic scattering cross section of the stratum in unit volume, and phi is the stratum porosity.
Optionally, the source distance of the distal gamma detector is 75.9cm and the source distance of the proximal gamma detector is 36.5cm.
According to yet another aspect of the present invention, there is provided a computing device comprising: the processor, the memory and the communication interface complete mutual communication through the communication bus;
the memory is used for storing at least one executable instruction, and the executable instruction enables the processor to execute the operation corresponding to the porosity measurement method.
According to yet another aspect of the present invention, a computer storage medium is provided, wherein at least one executable instruction is stored in the storage medium, and the executable instruction causes a processor to perform operations corresponding to the porosity measurement method.
According to the porosity measurement method, the porosity measurement device, the porosity measurement computing equipment and the computer storage medium, the pulse neutron emitter emits pulse neutrons; gamma rays generated after fast neutrons emitted by the pulse neutron emitter react with the formation are respectively detected based on the far-side gamma detector and the near-side gamma detector; respectively collecting an inelastic scattering total energy spectrum and a capturing energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measuring time window; performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the well diameter correction and the far-near non-elastic count ratio correction; and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC to perform porosity quantitative evaluation. The porosity measurement method of the scheme is not influenced by the mineralization degree, and the obtained result has higher conformity with the response of the traditional chemical source measurement method.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 shows a schematic flow diagram of a porosity measurement method according to an embodiment of the invention;
FIG. 2 is a schematic structural diagram of a porosity measuring device according to a second embodiment of the present invention; and
fig. 3 shows a schematic structural diagram of a computing device according to a fourth embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Fig. 1 is a schematic flow chart of a porosity measurement method according to a first embodiment of the invention. As shown in fig. 1, the method includes:
step S110, emitting pulse neutrons based on the pulse neutron emitter.
Specifically, the pulsed neutron emitter may be, for example, a deuterium-tritium pulsed neutron emitter, and the specific pulsed neutron emitter may be selected according to specific needs, which is not limited herein.
And S120, respectively detecting gamma rays after fast neutrons emitted by the pulse neutron emitter react with the formation based on the far-side gamma detector and the near-side gamma detector.
Specifically, the far-side gamma detector and the near-side gamma detector both need to satisfy a certain source distance requirement, for example, the source distance of the far-side gamma detector is 75.9cm, the source distance of the near-side gamma detector is 36.5cm, and the specific source distance may be set according to specific needs, which is not limited herein.
And step S130, respectively collecting the total inelastic scattering energy spectrum and the capture energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measurement time window.
Specifically, the pulse emission timing and the energy spectrum measurement time window correspond to each other. When the pulse neutron emitter emits pulse neutrons, namely the working time of the pulse neutron emitter, the acquired energy spectrum is the total inelastic scattering energy spectrum; when the pulse neutron emitter does not emit neutrons, namely the non-working time of the pulse neutron emitter, the acquired energy spectrum is a capture energy spectrum.
In an alternative embodiment, a first total inelastic scattering energy spectrum and a first capture energy spectrum are acquired by the far-side gamma detector, and the number of the acquired first total inelastic scattering energy spectrum and the number of the acquired first capture energy spectrum are counted, respectively denoted as A1 and B1; and acquiring a second inelastic scattering total energy spectrum and a second capturing energy spectrum through a near-side gamma detector, and counting the number of the acquired second inelastic scattering total energy spectrum and the acquired second capturing energy spectrum, which are respectively marked as A2 and B2.
Step S140, the inelastic scattering total energy spectrum and the capture energy spectrum are subjected to function calculation to obtain a far-near capture count ratio LOGNL _ BSC after the well diameter correction and the far-near inelastic count ratio correction.
Specifically, the natural logarithm is taken as the count ratio of the first inelastic total scattering energy spectrum and the second inelastic total scattering energy spectrum, for example, as can be seen from step S130, the numbers of the first inelastic total scattering energy spectrum and the second inelastic total scattering energy spectrum obtained are A1 and A2, respectively, that is, the count ratio of the first inelastic total scattering energy spectrum and the second inelastic total scattering energy spectrum is A1/A2, and the natural logarithm is taken as the value M for the count ratio A1/A2. The count ratio of the first capture energy spectrum and the second capture energy spectrum is a natural logarithm, for example, as shown in step S130, the numbers of the acquired first capture energy spectrum and second capture energy spectrum are B1 and B2, respectively, that is, the count ratio of the first capture energy spectrum and the second capture energy spectrum is B1/B2, and the natural logarithm of the count ratio B1/B2 is recorded as a value N. The point values (M, N) obtained above are plotted in a coordinate system having the horizontal axis as the natural logarithm of the count ratio A1/A2 and the vertical axis as the natural logarithm of the count ratio B1/B2 to obtain the near-far capture count ratio LOGNL after correction of the near-far non-ballistic count ratio, wherein:
LOGNL＝log(CapRatioNL)+a 1 (log(BurstRatioNL))^2+a 2 log(BurstRatioNL)+
a 3
wherein CapRatioNL represents a distance/near capture count ratio, burstratioNL represents a distance/near non-ballistic count ratio, and a 1 、a 2 、a 3 As fitting parameters (a) 1 、a 2 、a 3 The acquisition mode is as follows: taking experimental or simulation data under the same porosity, respectively using far and near capture count ratio and far and near non-elastic count ratio as transverse and longitudinal axis to shoot points, and fitting the shooting results by using the formula, a 2 Typically a small amount).
In the coordinate system, points corresponding to the same porosity are distributed on a straight line, and different porosities correspond to different straight lines. The slopes of the straight lines drawn in the coordinate system are the same, the intercepts are different, and different porosities can be distinguished according to the intercepts of the corresponding straight lines.
After acquiring the LOGNL, the LOGNL is corrected based on the borehole structure information, and a distance capture count ratio LOGNL _ BSC after distance and near non-shot count ratio correction after borehole diameter correction is acquired, wherein the borehole structure information comprises a borehole diameter. Specifically, the LOGNL for different wellbore diameters with the same porosity is corrected by the following equation:
LOGNL_BSC＝[1-C·(8-BS)]·LOGNL+D·(8-BS)
the LOGNL is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the LOGNL _ BSC is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the borehole diameter is corrected, the size 8 is the size of a standard borehole, the BS is the actual borehole diameter, and the C, D is a fitting parameter.
And step S150, acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC to perform porosity quantitative evaluation.
Specifically, a relationship between the LOGNL _ BSC after the borehole diameter correction and the reciprocal of a formation thermal neutron scattering cross section is established based on experimental data to obtain the formation thermal neutron scattering cross section, and a volume model is used for quantitative evaluation of porosity according to formation lithology profile information, wherein the lithology profile information comprises the composition of formation rock components, such as 45% of grey rock and 55% of sandstone. By volume model is meant in particular that a certain physical quantity can be weighted averaged according to the volume fraction of the substance. For example, for the physical quantity X, there is a mixture of substances in a unit volume where the ratio of the volume of substance A is 0.4 and the value of the physical quantity X is X 1 The volume ratio of the substance B is 0.6, and the value of the physical quantity X is X 2 Then the value of the physical quantity X per unit volume of the mixed substance is X 3 ＝0.4X 1 +0.6X 2 Specifically, in this embodiment, assuming that the formation porosity is Φ (unknown), the pores are filled with water, and the formation porosity Φ can be calculated according to the following formula:
T＝ΦT 1 +(1-Φ)T 2
wherein, T 1 Is a thermal neutron elastic scattering cross section in unit volume of water, T 2 Thermal neutron bomb per unit volume of rockAnd (4) a sexual scattering cross section, wherein T is a thermal neutron elastic scattering cross section of the formation in unit volume obtained by measurement, and phi is the porosity of the formation.
According to the porosity measurement method of the embodiment, the influence of the mineralization on the porosity measurement can be eliminated by selecting a proper pulse emission time sequence and a proper energy spectrum measurement time window; the porosity is measured by the inelastic scattering total energy spectrum counting ratio and the capture energy spectrum counting ratio which are acquired by the far and near gamma detectors with different source distances, the influence of the borehole diameter on the porosity measurement can be eliminated, and the acquired result has higher conformity with the response of the traditional chemical source measurement method.
Fig. 2 is a functional structure diagram of a porosity measurement apparatus according to a second embodiment of the present invention. As shown in fig. 2, the apparatus includes: a pulsed neutron emitter 210, a distal gamma detector 221, a near-side gamma detector 222, an acquisition module 230, a calculation module 240, and an evaluation module 250.
A pulsed neutron emitter 210 adapted to emit pulsed neutrons;
a far-side gamma detector 221 and a near-side gamma detector 222, which are adapted to detect gamma rays after fast neutrons emitted by the pulsed neutron emitter 210 react with the formation, respectively;
an acquisition module 230 adapted to acquire an inelastic scattering total energy spectrum and a capture energy spectrum respectively according to a pre-designed pulse emission timing sequence and an energy spectrum measurement time window;
the calculation module 240 is suitable for performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the borehole diameter correction and the far-near non-elastic count ratio correction; and
and the evaluation module 250 is suitable for acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC so as to perform porosity quantitative evaluation.
In an alternative embodiment, the acquisition module 230 is further adapted to:
a first inelastic scattering total energy spectrum and a first capture energy spectrum are acquired by the distal gamma detector 221 and a second inelastic scattering total energy spectrum and a second capture energy spectrum are acquired by the proximal gamma detector 222.
In an alternative embodiment, the calculation module 240 is further adapted to:
acquiring a far-near non-elastic counting ratio based on the first inelastic scattering total energy spectrum and the second inelastic scattering total energy spectrum, and taking a natural logarithm of the far-near non-elastic counting ratio;
acquiring a far-near capture count ratio based on the first capture energy spectrum and the second capture energy spectrum, and taking a natural logarithm of the far-near capture count ratio;
acquiring a far-near capture count ratio LOGNL after correction of the far-near non-missile count ratio based on the far-near non-missile count ratio after natural logarithm and the far-near capture count ratio after natural logarithm; and
and correcting the LOGNL based on the borehole structure information to obtain a far-near capture count ratio LOGNL _ BSC after the far-near non-shot count ratio correction after the borehole diameter correction.
In an alternative embodiment, the evaluation module 250 is further adapted to:
establishing a functional relation between LOGNL _ BSC and a formation thermal neutron elastic scattering cross section; and
and acquiring a formation thermal neutron elastic scattering cross section based on LOGNL _ BSC, and performing porosity quantitative evaluation by using a volume model based on formation lithology profile information.
In an alternative embodiment, the calculation module 240 is further adapted to obtain a corrected far-near capture count ratio LOGNL _ BSC based on the following formula:
LOGNL_BSC＝[1-C·(8-BS)]·LOGNL+D·(8-BS)
the LOGNL is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the LOGNL _ BSC is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the borehole diameter is corrected, the size 8 is the size of a standard borehole, the BS is the actual borehole diameter, and the C, D is a fitting parameter.
In an alternative embodiment, the evaluation module 250 is further adapted to perform a quantitative evaluation of porosity based on the following formula:
T＝ΦT 1 +(1-Φ)T 2
wherein, T 1 Is elastic heat neutron scattering in unit volume of waterSection of penetration, T 2 The thermal neutron elastic scattering cross section of the unit volume rock, T is the measured thermal neutron elastic scattering cross section of the unit volume stratum, and phi is the stratum porosity.
In an alternative embodiment, the source distance of the distal gamma detector 221 is 75.9cm and the source distance of the proximal gamma detector 222 is 36.5cm.
Therefore, according to the porosity measurement device of the embodiment, the influence of the mineralization on the porosity measurement can be eliminated by selecting a proper pulse emission time sequence and a proper energy spectrum measurement time window; the porosity is measured by the inelastic scattering total energy spectrum technology ratio and the capture energy spectrum counting ratio of the far and near gamma-ray detectors with different source distances, the influence of the well diameter on the porosity measurement can be eliminated, and the obtained result has higher conformity with the response of the traditional chemical source measurement method.
According to a third embodiment of the present invention, a non-volatile computer storage medium is provided, where at least one executable instruction is stored in the computer storage medium, and the computer executable instruction may execute the method in any of the above-mentioned method embodiments.
The executable instructions may be specifically configured to cause the processor to:
emitting pulsed neutrons based on a pulsed neutron emitter;
gamma rays generated after fast neutrons emitted by the pulse neutron emitter react with the formation are respectively detected based on the far-side gamma detector and the near-side gamma detector;
respectively collecting an inelastic scattering total energy spectrum and a capturing energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measuring time window;
performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the borehole diameter correction and the far-near non-elastic count ratio correction; and
and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC to perform porosity quantitative evaluation.
In an alternative embodiment, the executable instructions may be specifically configured to cause the processor to:
a first inelastic scattering total energy spectrum and a first capture energy spectrum are acquired by the distal gamma detector and a second inelastic scattering total energy spectrum and a second capture energy spectrum are acquired by the proximal gamma detector.
In an alternative embodiment, the executable instructions may be specifically configured to cause the processor to:
acquiring a far-near non-elastic counting ratio based on the first inelastic scattering total energy spectrum and the second inelastic scattering total energy spectrum, and taking a natural logarithm of the far-near non-elastic counting ratio;
acquiring a far-near capture count ratio based on the first capture energy spectrum and the second capture energy spectrum, and taking a natural logarithm of the far-near capture count ratio;
acquiring a far-near capture count ratio LOGNL after correction of the far-near non-missile count ratio based on the far-near non-missile count ratio after natural logarithm and the far-near capture count ratio after natural logarithm; and
and correcting the LOGNL based on the borehole structure information to obtain a far-near capture count ratio LOGNL _ BSC after far-near non-shot count ratio correction after borehole diameter correction.
In an alternative embodiment, the executable instructions may be specifically configured to cause the processor to:
establishing a functional relation between LOGNL _ BSC and a formation thermal neutron elastic scattering cross section; and
and acquiring a formation thermal neutron elastic scattering cross section based on LOGNL _ BSC, and performing porosity quantitative evaluation by using a volume model based on formation lithology profile information.
In an alternative embodiment, the executable instructions may be specifically configured to cause the processor to:
the corrected hole diameter LOGNL _ BSC is obtained based on the following formula:
LOGNL_BSC＝[1-C·(8-BS)]·LOGNL+D·(8-BS)
the LOGNL is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the LOGNL _ BSC is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the borehole diameter is corrected, the size 8 is the size of a standard borehole, the BS is the actual borehole diameter, and the C, D is a fitting parameter.
In an alternative embodiment, the executable instructions may be specifically configured to cause the processor to:
the porosity was quantitatively evaluated based on the following formula:
T＝ΦT 1 +(1-Φ)T 2
wherein, T 1 Is a thermal neutron elastic scattering cross section in unit volume of water, T 2 The thermal neutron elastic scattering cross section of the unit volume rock, T is the measured thermal neutron elastic scattering cross section of the unit volume stratum, and phi is the stratum porosity.
In an alternative embodiment, the source distance of the distal gamma detector is 75.9cm and the source distance of the proximal gamma detector is 36.5cm.
Therefore, according to the porosity measurement method of the embodiment, the influence of the mineralization on the porosity measurement can be eliminated by selecting a proper pulse emission time sequence and a proper energy spectrum measurement time window; the porosity is measured by the total inelastic scattering energy spectrum count ratio and the capture energy spectrum count ratio of the far and near gamma-ray detectors with different source distances, the influence of the well diameter on the porosity measurement can be eliminated, and the obtained result has higher conformity with the response of the traditional chemical source measurement method.
Fig. 3 is a schematic structural diagram of a computing device according to a fourth embodiment of the present invention, and the specific embodiment of the present invention does not limit the specific implementation of the computing device.
As shown in fig. 3, the computing device may include: a processor (processor) 302, a communication Interface 304, a memory 306, and a communication bus 308.
Wherein: the processor 302, communication interface 304, and memory 306 communicate with each other via a communication bus 308. A communication interface 304 for communicating with network elements of other devices, such as clients or other servers. The processor 302 is configured to execute the program 310, and may specifically perform the relevant steps in the above method embodiments.
In particular, program 310 may include program code comprising computer operating instructions.
The processor 302 may be a central processing unit CPU, or an Application Specific Integrated Circuit (ASIC), or one or more Integrated circuits configured to implement an embodiment of the invention. The computing device includes one or more processors, which may be the same type of processor, such as one or more CPUs; or may be different types of processors such as one or more CPUs and one or more ASICs.
And a memory 306 for storing a program 310. Memory 306 may comprise high-speed RAM memory and may also include non-volatile memory (non-volatile memory), such as at least one disk memory.
The program 310 may specifically be configured to cause the processor 302 to perform the following operations:
emitting pulsed neutrons based on a pulsed neutron emitter;
gamma rays generated after fast neutrons emitted by the pulse neutron emitter react with the formation are respectively detected based on the far-side gamma detector and the near-side gamma detector;
respectively collecting an inelastic scattering total energy spectrum and a capturing energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measuring time window;
performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the borehole diameter correction and the far-near non-elastic count ratio correction; and
and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC to perform porosity quantitative evaluation.
In an alternative embodiment, the program 310 may be specifically configured to cause the processor 302 to perform the following operations:
a first inelastic scattering total energy spectrum and a first capture energy spectrum are acquired by the distal gamma detector and a second inelastic scattering total energy spectrum and a second capture energy spectrum are acquired by the proximal gamma detector.
In an alternative embodiment, the program 310 may be specifically configured to cause the processor 302 to perform the following operations:
acquiring a far-near non-elastic counting ratio based on the first inelastic scattering total energy spectrum and the second inelastic scattering total energy spectrum, and taking a natural logarithm of the far-near non-elastic counting ratio;
acquiring a far-near capture count ratio based on the first capture energy spectrum and the second capture energy spectrum, and taking a natural logarithm of the far-near capture count ratio;
obtaining a distance and near capture count ratio LOGNL after correcting the distance and near non-ballistic count ratio based on the distance and near non-ballistic count ratio after the natural logarithm and the distance and near capture count ratio after the natural logarithm; and
and correcting the LOGNL based on the borehole structure information to obtain a far-near capture count ratio LOGNL _ BSC after the far-near non-shot count ratio correction of the borehole diameter correction.
In an alternative embodiment, the program 310 may be specifically configured to cause the processor 302 to perform the following operations:
establishing a functional relation between LOGNL _ BSC and a formation thermal neutron elastic scattering cross section; and
and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC, and performing porosity quantitative evaluation by using a volume model based on formation lithology profile information.
In an alternative embodiment, the program 310 may be specifically configured to cause the processor 302 to perform the following operations:
the corrected hole diameter LOGNL _ BSC is obtained based on the following formula:
LOGNL_BSC＝[1-C·(8-BS)]·LOGNL+D·(8-BS)
the LOGNL is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the LOGNL _ BSC is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the borehole diameter is corrected, the size 8 is the size of a standard borehole, the BS is the actual borehole diameter, and the C, D is a fitting parameter.
In an alternative embodiment, the program 310 may be specifically configured to cause the processor 302 to perform the following operations:
the porosity was quantitatively evaluated based on the following formula:
T＝ΦT 1 +(1-Φ)T 2
wherein, T 1 Is a thermal neutron elastic scattering cross section in unit volume of water, T 2 The thermal neutron elastic scattering cross section of the unit volume rock, T is the measured thermal neutron elastic scattering cross section of the unit volume stratum, and phi is the stratum porosity.
In an alternative embodiment, the source distance of the distal gamma detector is 75.9cm and the source distance of the proximal gamma detector is 36.5cm.
Therefore, according to the porosity measurement method of the embodiment, the influence of the mineralization on the porosity measurement can be eliminated by selecting a proper pulse emission time sequence and a proper energy spectrum measurement time window; the porosity is measured by the inelastic scattering total energy spectrum technology ratio and the capture energy spectrum counting ratio of the far and near gamma-ray detectors with different source distances, the influence of the well diameter on the porosity measurement can be eliminated, and the obtained result has higher conformity with the response of the traditional chemical source measurement method.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the embodiments of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
Those skilled in the art will appreciate that the modules in the devices in an embodiment may be adaptively changed and arranged in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names. The steps in the above embodiments should not be construed as limiting the order of execution unless specified otherwise.
Claims (10)
1. A method of porosity measurement, the method comprising:
emitting pulsed neutrons based on a pulsed neutron emitter;
gamma rays generated after fast neutrons emitted by the pulse neutron emitter react with the formation are respectively detected based on a far-side gamma detector and a near-side gamma detector;
respectively collecting an inelastic scattering total energy spectrum and a capturing energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measuring time window;
performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the borehole diameter correction and the far-near non-elastic count ratio correction; and
and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC to perform porosity quantitative evaluation.
2. The porosity measurement method according to claim 1, wherein the acquiring of the inelastic scattering total spectrum and the capturing spectrum respectively according to the pre-designed pulse emission timing and the energy spectrum measurement time window further comprises:
a first inelastic scattering total energy spectrum and a first capture energy spectrum are acquired by the distal gamma detector and a second inelastic scattering total energy spectrum and a second capture energy spectrum are acquired by the proximal gamma detector.
3. The porosity measurement method according to claim 2, wherein the performing a function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a near-far capture count ratio LOGNL _ BSC after the near-far non-elastic count ratio correction after the borehole diameter correction, further comprises:
acquiring a far-near non-elastic counting ratio based on the first inelastic scattering total energy spectrum and the second inelastic scattering total energy spectrum, and taking a natural logarithm of the far-near non-elastic counting ratio;
acquiring a far-near capture count ratio based on the first capture energy spectrum and the second capture energy spectrum, and taking a natural logarithm of the far-near capture count ratio;
acquiring a far-near capture count ratio LOGNL after correction of the far-near non-missile count ratio based on the far-near non-missile count ratio after natural logarithm and the far-near capture count ratio after natural logarithm; and
and correcting the LOGNL based on the borehole structure information to obtain a far-near capture count ratio LOGNL _ BSC after the far-near non-shot count ratio correction of the borehole diameter correction.
4. The porosity measurement method of claim 3, wherein the obtaining of formation thermal neutron elastic scattering cross-sections for quantitative porosity evaluation based on the LOGNL _ BSC further comprises:
establishing a functional relation between the LOGNL _ BSC and the elastic scattering cross section of the formation thermal neutrons; and
and acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC, and performing porosity quantitative evaluation by using a volume model based on formation lithology profile information.
5. The porosity measurement method of claim 3, wherein the correcting the LOGNL based on the borehole structure information to obtain a near-far capture count ratio LOGNL _ BSC after near-far non-shot count ratio correction after borehole diameter correction, further comprising:
LOGNL_BSC＝[1-C·(8-BS)]·LOGNL+D·(8-BS)
the LOGNL is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the LOGNL _ BSC is the ratio of the far and near capture counts after the correction of the far and near non-bullet count ratio, the borehole diameter is corrected, the size 8 is the size of a standard borehole, the BS is the actual borehole diameter, and the C, D is a fitting parameter.
6. The porosity measurement method according to claim 4, wherein the obtaining of the formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC and the quantitative evaluation of the porosity based on the formation lithology profile information by using a volume model further comprise:
T＝ΦT 1 +(1-Φ)T 2
wherein, T 1 Is a thermal neutron elastic scattering cross section in unit volume of water, T 2 The thermal neutron elastic scattering cross section of the unit volume rock, T is the measured thermal neutron elastic scattering cross section of the unit volume stratum, and phi is the stratum porosity.
7. The porosity measurement method of claim 1, wherein the source distance of the distal gamma detector is 75.9cm and the source distance of the proximal gamma detector is 36.5cm.
8. A porosity measurement device, comprising:
a pulsed neutron emitter adapted to emit pulsed neutrons;
the far-side gamma detector and the near-side gamma detector are suitable for respectively detecting gamma rays generated after fast neutrons emitted by the pulse neutron emitter react with the formation;
the acquisition module is suitable for respectively acquiring an inelastic scattering total energy spectrum and a capturing energy spectrum according to a pre-designed pulse emission time sequence and an energy spectrum measurement time window;
the calculation module is suitable for performing function calculation on the inelastic scattering total energy spectrum and the capture energy spectrum to obtain a far-near capture count ratio LOGNL _ BSC after the well diameter correction and the far-near non-elastic count ratio correction; and
and the evaluation module is suitable for acquiring a formation thermal neutron elastic scattering cross section based on the LOGNL _ BSC so as to perform porosity quantitative evaluation.
9. A computing device, comprising: the system comprises a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface complete mutual communication through the communication bus;
the memory is configured to store at least one executable instruction that causes the processor to perform operations corresponding to the porosity measurement method of any of claims 1-7.
10. A computer storage medium having stored therein at least one executable instruction that causes a processor to perform operations corresponding to the porosity measurement method of any of claims 1-7.
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| CN116500694B (en) * | 2023-06-28 | 2023-09-01 | 中海油田服务股份有限公司 | Post-sleeve physical quantity inversion method, post-sleeve physical quantity inversion device, computing equipment and storage medium |
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