Shale oil oiliness evaluation method and related equipment

Abstract

The invention provides a shale oil oiliness evaluation method and related equipment, and the method comprises the steps: extracting a nuclear magnetic interval porosity value through nuclear magnetic resonance logging result data, obtaining the interval porosity after a cut-off value, and obtaining a formation pressure coefficient through an equivalent depth method, the envelope size of the interval porosity and the pressure coefficient after the nuclear magnetism T2 cut-off value is calculated in an actual well and the envelope size of the nuclear magnetism interval porosity and the pressure coefficient can be used for directly evaluating the oil-gas content of shale oil. The method can solve the problem that the shale oil reservoir is not suitable for calculating the original oil saturation by using a capillary pressure curve based on a logging saturation interpretation model of a rock physics experiment because the saturation is measured by closed coring in a conventional reservoir oiliness evaluation method of the shale reservoir. And the oil-gas possibility of the shale oil is directly evaluated through the porosity of the nuclear magnetic interval and the envelope size of the pressure coefficient, so that the practical application effect is remarkable, and the popularization value is extremely high. No similar method is put forward and applied in publicly published literatures and commercial application software at present.

Description

Technical Field

[0001] The invention belongs to the field of petroleum and natural gas exploration, and specifically relates to a shale oil oil content evaluation method and related equipment. Background Art

[0002] In the current oilfield exploration and development, shale oil and gas has gradually become an important field for oil and gas replacement. Free hydrocarbons S1 are hydrocarbons that have been generated in rocks but still remain in the rocks and exist in a free state. Their size directly affects the production of the reservoir and is an important indicator for directly evaluating oil production capacity.

[0003] Conventional sandstone oil content evaluation methods mainly include closed coring to determine saturation, logging saturation interpretation model based on rock physics experiments, and calculation of oil saturation using capillary pressure curves. Due to the difficulty of shale sampling, difficulty in saturating with oil and water, and easy crushing by centrifugation, the above methods are not suitable for shale oil content evaluation.

[0004] Most of the existing methods for testing oil content based on free hydrocarbons require testing based on shale samples. Currently, the main evaluation methods for free hydrocarbons in shale oil are organic geochemical analysis methods based on rock pyrolysis. Organic geochemical analysis methods based on rock pyrolysis have the advantages of mature technology, high analysis accuracy, economy and speed, small sample usage, and easy acquisition. However, they can only be used to analyze specific rock samples. For wells without rock samples, free hydrocarbons S1 cannot be obtained. Therefore, this method is generally only used for systematic sampling and pyrolysis S1 measurement for key exploration wells. Summary of the invention

[0005] The present invention provides a shale oil oil content evaluation method and related equipment to solve the problem that free hydrocarbon S1 cannot be obtained for a well without a rock sample.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for evaluating the oil content of shale oil, comprising:

[0008] Extract interval porosity from NMR logging data;

[0009] According to the interval porosity value of the nuclear magnetic resonance logging data, the interval porosity after the cutoff value is obtained;

[0010] Obtain formation pressure coefficient;

[0011] Calculate the envelope area of ​​the interval porosity and formation pressure coefficient after the cutoff value;

[0012] The oil content of shale oil is evaluated based on the envelope size.

[0013] Preferably, extracting the porosity of the NMR logging data interval is specifically that the porosity of the NMR logging data interval is proportional to the total amount of hydrogen in the pores of the NMR logging data interval, and the porosity of the NMR logging data interval is extracted according to the total amount of hydrogen.

[0014] Preferably, the cutoff value is the relaxation time that correlates best with the pyrolysis S1.

[0015] Preferably, the relaxation times corresponding to the nuclear magnetic resonance logging T2 spectrum are arranged in order from small to large.

[0016] Preferably, the formation pressure coefficient is obtained according to the equivalent depth method.

[0017] Preferably, the envelope area of ​​the interval porosity and pressure coefficient after calculating the cutoff value is specifically:

[0018] The envelope size of the porosity and pressure coefficient after the cutoff value is calculated, the envelope size is characterized by the same scale, the two curves are normalized respectively, and then the envelope size is calculated.

[0019] Preferably, the oil content of shale oil is evaluated based on the envelope area. Specifically, the larger the envelope, the better the oil content of the shale oil and the higher the production capacity.

[0020] A shale oil oil content evaluation system, comprising:

[0021] Extraction module: extract interval porosity from NMR logging data;

[0022] Interval porosity acquisition module: according to the interval porosity of nuclear magnetic resonance logging data, the interval porosity after the cutoff value is obtained;

[0023] Formation pressure acquisition module: obtain formation pressure coefficient;

[0024] Calculation module: calculate the envelope size of the interval porosity and pressure coefficient after the cutoff value;

[0025] Evaluation module: Evaluate the oil content of shale oil according to the envelope size.

[0026] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of a shale oil oil content evaluation method when executing the computer program.

[0027] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a shale oil oil content evaluation method.

[0028] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a method for evaluating the oil content of shale oil, which extracts the porosity of the interval of nuclear magnetic resonance logging data to obtain the interval porosity after the cutoff value, and simultaneously uses the equivalent depth method to obtain the formation pressure coefficient, and calculates the envelope size of the porosity and pressure coefficient after the nuclear magnetic resonance T2 cutoff value in the actual well. The envelope size of the nuclear magnetic resonance interval porosity and pressure coefficient directly evaluates the oil and gas content of shale oil, has high accuracy, and has significant practical application effects, and therefore has great promotion value.

[0029] Furthermore, the porosity of the nuclear magnetic logging data interval is extracted by the total hydrogen content with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Correlation analysis between porosity and S1 in NMR logging intervals;

[0031] Figure 2 It is the correlation analysis between pressure coefficient and S1;

[0032] Figure 3 This is the envelope effect diagram of porosity and pressure coefficient when NMR T2 is greater than 8ms;

[0033] Figure 4 It is the full diameter two-dimensional nuclear magnetic T1-T2 spectrum fluid identification plate;

[0034] Figure 5 To calculate the correlation diagram between the envelope value and the test oil production;

[0035] Figure 6 This is a flow chart of a shale oil oil content evaluation method of the present invention;

[0036] Figure 7 This is a block diagram of a shale oil oil content evaluation system of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0040] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0041] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0044] The present invention is based on the interval porosity of nuclear magnetic resonance logging, analyzes the correlation between the interval nuclear magnetic resonance porosity (porosity after the T2 cutoff value) and S1, and clarifies the relationship between the spatial size of the shale oil and gas reservoir distribution and the oil content. At the same time, the correlation between the pressure coefficient and S1 is analyzed. After the organic matter generates hydrocarbons, the formation is overpressured, and the more overpressured the formation is, the higher the oil content index is. Therefore, the nuclear magnetic interval porosity and pressure coefficient are key parameters indicating the oil content of the shale oil reservoir. The larger the envelope (anti-intersection) size, the better the oil content. The interval porosity and pressure coefficient are normalized, and the envelope size of the interval porosity and pressure coefficient is calculated, so as to quantitatively characterize the oil content of the shale reservoir. And there is no similar method proposed and applied in the currently published literature and commercial application software. The present invention realizes the identification of shale oil sweet spot layers using logging data, and provides a new method for horizontal well target layer optimization and shale production capacity evaluation.

[0045] The horizontal axis of the T2 spectrum of nuclear magnetic resonance logging is T2 (ms); the vertical axis is the interval porosity, which reflects the contribution of different T2 components to the measured porosity. The entire T2 distribution area is the total porosity of the formation, and the interval porosity represents the porosity size after a certain T2 time (greater than 8ms means the porosity size after 8ms).

[0046] Rock pyrolysis analysis technology is a method that uses the principle of programmed temperature rise to quantitatively determine the content of hydrocarbons that can be thermally evaporated and pyrolyzed in rock samples; the main parameters detected are S0, S1, and S2. Among them, S0 is the mass fraction of gaseous hydrocarbon components of C1-C7 at 90°C, which exist in liquid hydrocarbons in the form of dissolved gas in pure oil layers; S1 is the mass fraction of light and medium liquid hydrocarbon components of C8-C29 at 300°C; S2 is the mass fraction of heavy crude oil, colloids, and asphaltene components greater than C29 at 300-600°C.

[0047] like Figure 6 As shown, the present invention provides a method for evaluating the oil content of shale oil, comprising:

[0048] S101 extracts the porosity of the NMR logging data interval;

[0049] S102 obtains the interval porosity after the cutoff value according to the porosity of the interval of the nuclear magnetic logging data;

[0050] S103 obtains formation pressure coefficient;

[0051] S104 calculates the envelope area of ​​the interval porosity and pressure coefficient after the cutoff value;

[0052] S105 evaluates the oil content of shale oil based on the envelope area.

[0053] The porosity of the NMR logging data interval is extracted specifically as follows: the porosity of the NMR logging data interval is proportional to the total hydrogen content in the pores of the NMR logging data interval, the porosity of the NMR logging data interval is extracted by the total hydrogen content, and the original data obtained by the NMR logging is subjected to the contribution of different T2 components obtained by multi-exponential fitting to the measured porosity.

[0054] The cut-off value is the relaxation time at which the correlation with free hydrocarbon S1 is best.

[0055] The relaxation times corresponding to nuclear magnetic resonance logging for shale reservoirs are 0.5ms, 1ms, 2ms, 4ms, 8ms, 16ms, 32ms and 64ms.

[0056] The formation pressure coefficient is calculated using the equivalent depth method.

[0057] The envelope area of ​​the interval porosity and pressure coefficient after calculating the cutoff value is specifically:

[0058] The envelope areas of the interval porosity and pressure coefficient after the cutoff value are calculated respectively, and the envelope size is characterized by the same scale. The two curves are normalized respectively, and then the envelope size is calculated.

[0059] The oil content of shale oil is evaluated based on the envelope area. Specifically, the larger the envelope area, the better the oil content of the shale oil.

[0060] The present invention can solve the problem that the conventional reservoir oil content evaluation methods such as closed coring to determine saturation, logging saturation interpretation model based on rock physics experiments, and calculation of original oil saturation using capillary pressure curves are not applicable to shale oil reservoirs. The oil and gas content of shale oil is directly evaluated by the porosity and pressure coefficient envelope size of the nuclear magnetic resonance interval, and the actual application effect is significant, so it is of great promotion value. There is no similar method proposed and applied in the currently published literature and commercial application software.

[0061] Example:

[0062] 1) Extracting interval porosity from NMR logging data:

[0063] The basis for determining formation porosity by NMR logging is the correspondence between the observed signal intensity and the hydrogen nucleus content in the pore fluid. Its value at time zero is proportional to the total amount of hydrogen in the formation pores. Therefore, after appropriate calibration, the signal intensity at time zero can be calibrated as the total porosity of the rock formation.

[0064] That is, φ=E(0)=(i=1,2,3,...n) (Formula 1)

[0065] The observed porosity can be decomposed into porosity in different relaxation time intervals. The relaxation times corresponding to NMR are 0.5ms, 1ms, 2ms, 4ms, 8ms, 16ms, 32ms, greater than 64ms, etc.

[0066] 2) Correlation analysis between the interval porosity after the extracted cutoff value and free hydrocarbon S1

[0067] The oil-bearing volume of shale is mainly composed of free hydrocarbons in the pores, organic matter, and hydrocarbons adsorbed on the clay surface. Free hydrocarbons are related to S0 and S1 in the pyrolysis data, and adsorbed hydrocarbons are related to S2. Since nuclear magnetic resonance logging detects fluids and hydrogen nuclei in the formation, the pore interval determined by calibration must be correlated with S1. The pore interval with a good correlation with S1 represents that this part of the pore interval has good oil content.

[0068] After analysis, it is clear that the pore space with T2 relaxation time greater than 8ms has the best correlation with S1. Figure 1shown.

[0069] 3) Determine the correlation between pressure coefficient and S1

[0070] The formation pressure coefficient was obtained by using the equivalent depth method, and the relationship between the pressure coefficient and the core S1 of wells with different burial depths and different maturities was statistically analyzed. The statistical analysis showed that as the pressure coefficient increases, the S1 value increases (see Figure 2 ).

[0071] 4) Calculate the envelope area of ​​porosity and pressure coefficient greater than 8ms by NMR

[0072] For the porosity and pressure coefficient of NMR logging greater than 8ms in different wells, the same scale is used to characterize the envelope size. The two curves are normalized respectively, and then the envelope size is calculated. The method is edited into a program and run for batch calculation in the study well area.

[0073] The two-dimensional nuclear magnetic resonance logging T1-T2 spectrum and cluster analysis results show that the shale in this area has a lot of movable oil signals and basically no movable water. Therefore, the size of the envelope area can be used to evaluate the oil content ( Figure 4 ).

[0074] 5) Effect verification

[0075] The shale reservoir well data in the study area were processed. Figure 3 For the processing result map, the first track is the lithology logging curve, including natural gamma and wellbore curve, the second track is the depth track, the third track is the deep and shallow resistivity, the fourth track is the three-porosity logging curve, including the compensated density, compensated neutron, and acoustic time difference curves, the fifth track is the interval porosity track of nuclear magnetic resonance logging, the sixth track is the envelope of porosity and pressure coefficient in the interval greater than 8ms of nuclear magnetic resonance logging, and the seventh track is the normalized envelope size. The envelope size can be used to determine that the sweet spot formation is Q8, Q9, Q1-Q3 oil layer group. Through the analysis of the oil test results of the same layer, the larger the envelope size, the higher the oil test capacity ( Figure 5 ), the result analysis proves the correctness of the method proposed in this paper and its adaptability in shale reservoirs.

[0076] like Figure 7 The present invention provides a shale oil oil content evaluation system, comprising:

[0077] Extraction module: extract the porosity of the NMR logging data interval;

[0078] Interval porosity acquisition module: according to the porosity of the interval of nuclear magnetic logging data, the interval porosity after the cutoff value is obtained;

[0079] Formation pressure acquisition module: obtain formation pressure coefficient;

[0080] Calculation module: calculate the envelope area of ​​the interval porosity and pressure coefficient after the cutoff value;

[0081] Evaluation module: Evaluate the oil content of shale oil based on the envelope area.

[0082] A terminal device is provided in one embodiment of the present invention. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned method embodiments are implemented. Alternatively, when the processor executes the computer program, the functions of the modules / units in the above-mentioned device embodiments are implemented.

[0083] The computer program may be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to accomplish the present invention.

[0084] The terminal device may be a computing device such as a desktop computer, a notebook, a palmtop computer, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0085] The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0086] The memory may be used to store the computer programs and / or modules, and the processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory.

[0087] If the module / unit integrated in the terminal device is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0088] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields, and the above-mentioned specific embodiments are only illustrative and instructive, rather than restrictive. Under the guidance of the specification, a person skilled in the art can also make many forms without departing from the scope of protection of the claims of the present invention, all of which belong to the scope of protection of the present invention.

Claims

1. A method for evaluating the oil content of shale oil, characterized in that: include: Extract interval porosity from NMR logging data; According to the interval porosity value of the nuclear magnetic resonance logging data, the interval porosity after the cutoff value is obtained; Obtain formation pressure coefficient; Calculate the envelope area of ​​the interval porosity and formation pressure coefficient after the cutoff value; The oil content of shale oil is evaluated based on the envelope size.

2. A shale oil oil content evaluation method according to claim 1, characterized in that: The porosity extraction of the NMR logging data interval is specifically that the porosity of the NMR logging data interval is proportional to the total amount of hydrogen in the pores of the NMR logging data interval, and the porosity of the NMR logging data interval is extracted according to the total amount of hydrogen.

3. A shale oil oil content evaluation method according to claim 1, characterized in that: The cutoff value is the relaxation time that correlates best with the pyrolysis S1.

4. A shale oil oil content evaluation method according to claim 3, characterized in that: The relaxation times corresponding to the nuclear magnetic resonance logging T2 spectra are arranged in order from small to large.

5. A shale oil oil content evaluation method according to claim 1, characterized in that: The formation pressure coefficient is obtained according to the equivalent depth method.

6. A shale oil oil content evaluation method according to claim 1, characterized in that: The envelope area of ​​the interval porosity and pressure coefficient after calculating the cutoff value is specifically: The envelope size of the porosity and pressure coefficient after the cutoff value is calculated, the envelope size is characterized by the same scale, the two curves are normalized respectively, and then the envelope size is calculated.

7. A shale oil oil content evaluation method according to claim 1, characterized in that: The evaluation of shale oil oil content based on the envelope area is specifically that the larger the envelope, the better the shale oil oil content and the higher the production capacity.

8. A shale oil oil content evaluation system, characterized in that: include: Extraction module: extract interval porosity from NMR logging data; Interval porosity acquisition module: according to the interval porosity of nuclear magnetic resonance logging data, the interval porosity after the cutoff value is obtained; Formation pressure acquisition module: obtain formation pressure coefficient; Calculation module: calculate the envelope size of the interval porosity and pressure coefficient after the cutoff value; Evaluation module: Evaluate the oil content of shale oil according to the envelope size.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of a shale oil oil content evaluation method as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of a shale oil oil content evaluation method as described in any one of claims 1 to 7 are implemented.

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