A multi-measurement mode lateral well log reconstruction method

Abstract

The application discloses a multi-measurement mode side logging curve reconstruction method, which is composed of 9 metal electrodes which are symmetrical in upper and lower parts, including a main electrode A0, inner and outer supervision electrodes M1, M1', M2 and M2', inner and outer shielding electrodes A1, A1', A2 and A2' in deep measurement mode, inner shielding electrodes A1, A1', loop electrodes A2 and A2' in shallow measurement mode, and the main electrode A0, the inner and outer shielding electrodes A1, A1', A2 and A2' emitting current in deep measurement operation, and the current flowing back to the far side of the instrument. The multi-measurement mode side logging curve reconstruction method, without changing the hardware circuit and mechanical structure of the existing deep and shallow measurement mode double side logging instrument, only through the deep and shallow measurement resistivity curve data collected by the instrument in the well, adopts a curve reconstruction algorithm to reconstruct the shallow measurement resistivity curve, obtains the reconstructed shallow resistivity curve reflecting the real resistivity information of the formation, and improves the qualified rate of the deep and shallow resistivity curves.

Description

Technical Field

[0001] This invention relates to the field of well logging technology in oil exploration and development, specifically to a method for reconstructing lateral logging curves using multiple measurement modes. Background Technology

[0002] Petroleum exploration aims to find and identify oil and gas resources. It utilizes various exploration methods to understand underground geological conditions, identify conditions related to oil generation, storage, migration, accumulation, and preservation, comprehensively evaluate oil and gas prospects, determine favorable areas for oil and gas accumulation, locate oil and gas traps, and determine the area of ​​oil and gas fields, clarifying the characteristics of oil and gas reservoirs and their production capacity. Petroleum development is an important stage following seismic exploration, drilling, completion, and delivery. Its main task is to extract crude oil from the formation and bring it into the oil and gas gathering and transportation system. This is a resource and energy industry that plays a vital role in the national economy. Crude oil exploration and development is a comprehensive process integrating seismic exploration, drilling, oil production, downhole operations, water injection, wastewater treatment, and gathering and transportation.

[0003] Well logging is an important measurement method used in underground oil and gas exploration. After identifying potentially oil-bearing geological blocks using methods such as seismic logging, exploratory wells need to be drilled first. Once the exploratory wells reach the designed depth, well logging, also known as completion logging, must be performed. The main purpose of well logging is to obtain various geological and engineering data. It uses instruments that reflect physical properties such as heat, sound, electricity, light, magnetism, and nuclear radioactivity to measure various physical information of the formation. Then, by processing and interpreting this information according to their respective physical principles and interrelationships, the porosity, permeability, and fluid properties and their distribution of underground rocks can be identified, thereby discovering oil and gas reservoirs and assessing oil and gas reserves and production. The purpose and tasks of oil logging vary at different stages of oil and gas field exploration and development. For example, the main purpose and task of open-hole logging is to discover and evaluate the reservoir performance and production capacity of oil and gas layers; while production logging is mainly used to observe and analyze the development dynamics and production status of oil and gas layers. In general, oil exploration logging is one of the most high-tech technologies in the petroleum industry and also one of the technologies that involves the most general disciplines. It occupies an important position in the upstream sector of the petroleum industry and plays an irreplaceable role in accurately determining the content and location of oil and gas reservoirs, as well as in engineering positioning and subsequent operations.

[0004] Multi-mode lateral logging is one of the mainstream methods for resistivity logging, especially suitable for measuring saline slurries and medium-to-high resistivity formations. It obtains formation resistivity information by measuring the voltage and current signals of the instrument's central main electrode, which is used for formation lithology identification, oil, gas, and water layer evaluation, and calculation of formation parameters such as oil saturation. Currently, commonly used multi-mode lateral logging instruments include dual-mode and array-mode lateral logging. Dual-mode lateral logging uses two measurement modes, while array-mode lateral logging uses more than two. Because different measurement modes have different radial depths, resistivity information at different radial depths of the formation can be obtained, which is crucial for evaluating formation permeability and identifying oil and gas reservoirs.

[0005] The "Well Logging Push-and-Move Device" disclosed in patent CN217270090U includes a main rod and a push-and-move arm. The main rod is hollow inside, with two or more arm mounting slots extending through its sidewalls. These slots gradually increase in size from the outside to the inside of the main rod, with one end suitable for housing a pushing part that contacts the push-and-move arm. The push-and-move arm is rotatably mounted within the arm mounting slot. By machining the arm mounting slots on the main rod parts, which gradually increase in size along the opening direction, the space between the push-and-move arm and the main body is increased, facilitating the flow of granular solid lubricant. The spherical support prevents the accumulation of solid lubricant. The arm has point-like contact points when closed, protecting the main rod and reducing wear while ensuring its support strength. The push-and-move arm is designed with a wedge-shaped structure, which facilitates the flow of round granular solid lubricant. A reasonable gap is designed between the push-and-move arm and the main rod to ensure reliable arm retraction.

[0006] The patent CN220415342U, entitled "A Density Push-to-Protect Structure and Natural Gamma Density Lateral Diameter Combined Logging Tool," includes an outer tube, a drive assembly, a piston, and a caliper arm. The outer tube is hollow inside, with a through-hole on its sidewall. The caliper arm is rotatably mounted at the measurement hole, with one end extending through the measurement hole into the outer tube. The piston is eccentrically mounted inside the outer tube and is drively connected to one end of the caliper arm. The drive assembly is mounted inside the outer tube and is drively connected to the piston via a transmission component. It drives the piston to slide back and forth along the axial direction of the outer tube and rotates the caliper arm so that its other end extends outside the outer tube or is stored in the measurement hole. The advantages of this invention are its simple structure, reasonable design, ability to quickly measure the caliper diameter, and ability to ensure close contact between the equipment and the well wall, making measurement very convenient.

[0007] The "Well Logging Tool" disclosed in patent CN220566068U includes: a segmented pipe body, within which a segmented magnetic core, a coil wound around the outside of the segmented magnetic core, and multiple sensors are disposed. The multiple sensors are used to measure the three components of magnetic flux, and the magnetic core and the coil wound around the outside of the magnetic core are used to measure magnetic susceptibility. The beneficial effect of this invention is that it achieves the measurement of the horizontal and vertical components of the magnetic field and the apex angle of the well inclination through the arrangement of multiple highly sensitive sensors. Based on the principle of magnetic susceptibility measurement, and the arrangement of the magnetic core and coil in the well logging tool, the eddy currents in the highly conductive medium cancel each other out. The measurement output directly reflects the change in formation magnetic susceptibility, and the measurement results can be processed by the built-in circuit board and uploaded digitally to the wellhead instrument for recording, facilitating subsequent analysis and processing.

[0008] In the "Dual Lateral and Micro Lateral Combined Logging Instrument" patent CN201428444Y, the technical solution consists of a dual lateral electrode system, a dual lateral electronic circuit section, a dual lateral insulating sub, a micro lateral electrode system, a micro lateral electronic circuit section, and a micro lateral insulating sub. The dual lateral electrode system includes a main electrode, centered on which are symmetrically arranged monitoring electrodes, shielding electrodes, auxiliary monitoring electrodes, and loop electrodes. The micro lateral electrode system also includes a main electrode, centered on which are symmetrically arranged monitoring electrodes, shielding electrodes, and loop electrodes. The key design feature of this invention is the structural layout of the electrode system. The dual lateral and micro lateral systems employ independent, fully symmetrical electrode structures, used for calculating formation oil saturation, permeability, drilling fluid invasion, and oil layer thickness. It is an important drilling geological steering and logging geological evaluation measurement instrument in oilfield exploration and development.

[0009] In practical multi-mode lateral logging operations, the shallow measurement mode has shorter shielding electrodes on both sides of the central main electrode, resulting in lower focusing capability compared to the deep measurement mode. In formations with low mud resistivity and drastic lithological changes, the focusing current in the shallow measurement mode may not be properly adjusted, leading to abnormal spikes in the shallow measurement resistivity curve. This results in substandard resistivity logging data that cannot be submitted as acceptable data. Due to the high timeliness requirements at the operation site, retesting is usually not permitted. Therefore, providing a multi-mode lateral logging curve reconstruction method is crucial. This method can effectively improve the pass rate of resistivity logging curve data, providing data assurance for data interpreters to submit qualified resistivity logging evaluation data.

[0010] Therefore, we propose a multi-measurement mode lateral logging curve reconstruction method to address the problems mentioned above. Summary of the Invention

[0011] The purpose of this invention is to propose a multi-measurement mode lateral logging curve reconstruction method. In the case of abnormal spikes in shallow measurement resistivity curves, shallow measurement resistivity curve reconstruction processing is performed to obtain resistivity curves that can reflect different radial depths of the reservoir, thereby improving the data quality of multi-measurement mode lateral logging curves.

[0012] To achieve the above objectives, the present invention provides the following technical solution: a method for reconstructing lateral logging curves in multiple measurement modes, which consists of nine symmetrical metal electrodes, including a main electrode A0 and inner and outer monitoring electrodes M1, M1', M2 and M2'.

[0013] In deep measurement mode, the inner and outer shielding electrodes are A1, A1', A2 and A2'. In shallow measurement mode, the inner shielding electrodes are A1 and A1', and the loop electrodes are A2 and A2'.

[0014] Preferably, during deep measurement, the emitted current from the main electrode A0 and the inner and outer shielding electrodes A1, A1', A2 and A2' flows back to the far sides of the instrument; during shallow measurement, the emitted current from the main electrode A0 and the inner shielding electrodes A1 and A1' flows back to the loop electrodes A2 and A2'.

[0015] Preferably, the automatic stratification results of the well logging curves are as follows: the first channel is the depth channel, the second channel is the original deep and shallow resistivity curves RD and RS obtained from the measurement, and the third channel is the shallow resistivity square wave curve RTCENG obtained by automatically stratifying the formation based on the shallow measured resistivity curve.

[0016] Preferably, the correlation between resistivity curves of different measurement modes is expressed. The first channel is the depth channel, the second channel is the original deep and shallow resistivity curves RD and RS obtained from the measurement, and the third channel is the similarity curve RTCCOEF obtained by automatically layering curves and calculating the correlation between deep and shallow resistivity curves layer by layer.

[0017] Preferably, the resistivity curve reconstruction processing steps are described. Based on the deep and shallow resistivity measurement device, the deep and shallow resistivity continuous logging curves of a certain formation depth are collected. The shallow resistivity curve of that depth is used to perform automatic formation layering calculation to obtain the shallow resistivity square wave layering curve of that depth.

[0018] Preferably, the multi-mode resistivity curve reconstruction results are given, with the first channel being the depth channel, the second channel being the original deep and shallow resistivity curves RD and RS obtained from the measurement, and the third channel being the original deep resistivity curve RD and the reconstructed shallow resistivity curve RSC.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] Without altering the hardware circuitry and mechanical structure of the existing dual-lateral logging instrument with its shallow and deep measurement modes, this method reconstructs shallow resistivity curves using only the resistivity curve data collected downhole by the instrument. This reconstructed shallow resistivity curves, reflecting the true resistivity information of the formation, improves the pass rate of shallow and deep resistivity curves and provides more reliable shallow and deep resistivity curve data for effective reservoir evaluation. Attached Figure Description

[0021] Figure 1a This is an external view of the multi-measurement mode lateral logging instrument of the present invention;

[0022] Figure 1b This is a diagram showing the distribution of lateral logging current lines in the multi-measurement mode of this invention.

[0023] Figure 2 This is a diagram showing the automatic stratification results of the well logging curves of this invention;

[0024] Figure 3 This is a graph showing the correlation between resistivity curves under different measurement modes of the present invention.

[0025] Figure 4 This is a schematic diagram of the resistivity curve reconstruction process of the present invention;

[0026] Figure 5 This is a schematic diagram of the resistivity curve reconstruction result of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides the following technical solution:

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other. Example

[0030] like Figure 1a and Figure 1bAs shown, the external structure and current line distribution diagram of a multi-measurement mode lateral logging instrument are presented. The instrument consists of nine symmetrical metal electrodes: a main electrode A0, inner and outer monitoring electrodes M1, M1', M2, and M2', inner and outer shielding electrodes A1, A1', A2, and A2' in deep measurement mode, and inner shielding electrodes A1 and A1', and loop electrodes A2 and A2' in shallow measurement mode. During deep measurement, the main electrode A0 and the inner and outer shielding electrodes A1, A1', A2, and A2' emit current, which flows back to the more distant sides of the instrument. During shallow measurement, the main electrode A0 and the inner shielding electrodes A1 and A1' emit current, which flows back to the loop electrodes A2 and A2'. The current line distribution diagram shows that the current lines in deep measurement flow radially further than those in shallow measurement; therefore, the detection depth in deep measurement is greater than that in shallow measurement. Based on the above electrode system structure and operating mode, deep and shallow resistivity measurements with different detection depths can be achieved.

[0031] like Figure 2 As shown, the results of automatic stratification of well logging curves are presented. The first channel is the depth channel, the second channel is the original deep and shallow resistivity curves RD and RS obtained from the measurement, and the third channel is the shallow resistivity square wave curve RTCENG obtained by automatic stratification of formation based on the shallow measured resistivity curve.

[0032] like Figure 3 As shown, the correlation between resistivity curves under different measurement modes is illustrated. The first channel is the depth channel, the second channel is the original deep and shallow resistivity curves RD and RS obtained from the measurement, and the third channel is the similarity curve RTCCOEF obtained by calculating the correlation between deep and shallow resistivity curves layer by layer based on the automatic layered curve.

[0033] like Figure 4 The diagram illustrates the resistivity curve reconstruction process. Based on a shallow and deep resistivity measurement device, continuous well logging curves of shallow and deep resistivity within a certain formation depth are acquired. Automatic formation layering is then performed using the shallow resistivity curve within that depth range to obtain the square-waveform layered curve of the shallow resistivity within that depth range. The automatic layering calculation method is as follows:

[0034] The activity of a shallow resistivity curve is defined as:

[0035] Formula 1

[0036] Formula 2

[0037] In the formula, Indicates depth The activity of the logging curve at the location; This indicates the length of the logging curve used in calculating activity; Indicates the values ​​of the well logging curve; Indicates the well logging curve at The average value within the range of L / 2 above and below.

[0038] Using the activity curve calculated by Formula 1, and taking the location of the activity maximum as the formation interface, a square wave curve for automatic stratification of shallow resistivity curves can be obtained. N represents the number of layers.

[0039] Based on the layered square wave curves, the resistivity similarity between shallow and deep layers is calculated layer by layer. The calculation formula is as follows:

[0040] Formula 3

[0041] In the formula, This represents the average deep resistivity of the i-th layer. This represents the average shallow resistivity of the i-th layer.

[0042] After calculating the layer correlation curve using Formula 3, a correlation coefficient threshold is set. If the current layer Then, the layer with the highest correlation is searched within a certain range above and below the current layer, and the linear fitting coefficients K and B of shallow and deep resistivity are calculated.

[0043] Finally, the shallow resistivity curve of the current layer can be reconstructed using the fitting coefficients K and B, calculated as follows:

[0044] Formula 4

[0045] In the formula, This represents the reconstruction of shallow resistivity data at different depth points. This represents the original measured deep resistivity data at different depth points.

[0046] like Figure 5 As shown, the results of multi-mode resistivity curve reconstruction are presented. The first channel is the depth channel, the second channel is the original deep and shallow resistivity curves RD and RS, and the third channel is the original deep resistivity curve RD and the reconstructed shallow resistivity curve RSC. From the shallow resistivity curves before and after reconstruction, it can be seen that the original shallow resistivity curve has a spike in the layer corresponding to the dashed box. Through reconstruction, the shallow resistivity curve is restored, the pass rate of deep and shallow resistivity curves is improved, and the deep and shallow resistivity curves have similar response relationships.

[0047] The working principle of this embodiment is as follows: When using the multi-measurement mode lateral logging curve reconstruction method, firstly, taking a dual lateral logging tool with both deep and shallow measurement modes as an example, the logging tool moves continuously downhole and simultaneously collects resistivity information at different radial depths of the reservoir, obtaining continuous resistivity response curves for both deep and shallow modes in the measurement depth segment. The shallow measurement resistivity curve is used as the basic data for formation layer division, and the formation in the measurement depth segment is automatically layered. In this measurement depth segment, the similarity of deep and shallow resistivity curve data is calculated layer by layer to obtain a similarity curve. Based on this similarity curve, each layer is judged. If the similarity value of the current layer is lower than the set similarity threshold, the adjacent layers above and below are searched to obtain the linear fitting coefficient of the deep and shallow resistivity curves of the layer with the highest similarity among the adjacent layers. Using this linear fitting coefficient and combined with the deep resistivity curve of the current layer, the shallow resistivity curve is recalculated, thereby completing a series of tasks.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0049] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reconstructing lateral logging curves using multiple measurement modes, the device consisting of nine symmetrically arranged metal electrodes, a main electrode A0, and inner and outer monitoring electrodes M1, M1', M2 and M2'; In deep measurement mode, the inner and outer shielding electrodes are A1, A1', A2 and A2'; in shallow measurement mode, the inner shielding electrodes are A1 and A1', and the loop electrodes are A2 and A2'. The logging tool moves continuously downhole and simultaneously collects resistivity information at different radial depths of the reservoir, obtaining continuous resistivity response curves for both shallow and deep modes within the measurement depth range. The shallow resistivity curve is used as the basis for formation layer division. The formation within the measurement depth range is automatically layered. Within this measurement depth range, the similarity of the shallow and deep resistivity curve data is calculated layer by layer to obtain a similarity curve. Based on this similarity curve, each layer is judged. If the similarity value of the current layer is lower than the set similarity threshold, the adjacent layers above and below are searched to obtain the linear fitting coefficient of the shallow and deep resistivity curves of the layer with the highest similarity among the adjacent layers. Using this linear fitting coefficient and combining it with the deep resistivity curve of the current layer, the shallow resistivity curve is recalculated.

2. The method for reconstructing lateral logging curves with multiple measurement modes according to claim 1, characterized in that: During deep measurements, the main electrode A0 and the inner and outer shielding electrodes A1, A1', A2 and A2' emit current, which flows back to the far sides of the instrument; during shallow measurements, the main electrode A0 and the inner shielding electrodes A1 and A1' emit current, which flows back to the loop electrodes A2 and A2'.

3. The method for reconstructing lateral logging curves with multiple measurement modes according to claim 1, characterized in that: The results of automatic stratification of well logging curves are as follows: the first channel is the depth channel; the second channel is the original deep and shallow resistivity curves RD and RS obtained from the measurement; and the third channel is the shallow resistivity square wave curve RTCENG obtained by automatic stratification of formation based on the shallow measured resistivity curve.

4. The method for reconstructing lateral logging curves with multiple measurement modes according to claim 1, characterized in that: The correlation between resistivity curves under different measurement modes is described. The first channel is the depth channel, the second channel is the original deep and shallow resistivity curves RD and RS obtained from the measurement, and the third channel is the similarity curve RTCCOEF obtained by calculating the correlation between deep and shallow resistivity curves layer by layer based on the automatic layered curve.

5. The method for reconstructing lateral logging curves with multiple measurement modes according to claim 1, characterized in that: The process of reconstructing resistivity curves is described. Based on a deep and shallow resistivity measurement device, continuous logging curves of deep and shallow resistivity in a certain formation depth are collected. The shallow resistivity curve in that depth range is used to perform automatic formation layering calculation to obtain the shallow resistivity square wave layering curve in that depth range.

6. The method for reconstructing lateral logging curves with multiple measurement modes according to claim 1, characterized in that: The results of multi-mode resistivity curve reconstruction are presented. The first channel is the depth channel, the second channel is the original deep and shallow resistivity curves RD and RS obtained from the measurement, and the third channel is the original deep resistivity curve RD and the reconstructed shallow resistivity curve RSC.

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