Analysis method, device and equipment for in-situ formation fracture porosity of mixed rock

Abstract

The invention relates to a method, a device and equipment for analyzing in-situ formation fracture porosity of mixed rock. Comprising the steps of obtaining original data of a plurality of layers in a target block; taking out a first rock core sample from each layer of the target block, and performing experimental analysis on the first rock core sample of each layer to determine a target layer; taking out a second core sample from the target horizon, and performing a triaxial compression test on the second core sample to obtain a stress index; according to the original data and the stress index, the stratum fracture porosity of the target layer is calculated, the stratum fracture porosity is used for guiding workers to evaluate the real underground in-situ fracture porosity of the reservoir, and therefore an oil and gas reservoir exploitation plan of the target layer is made. The stratum fracture porosity calculated by the method represents the fracture porosity of the target horizon in the target block and represents in-situ characteristics in the stratum, so that the accuracy of reservoir evaluation is improved. A worker can formulate an oil and gas reservoir exploitation plan according to the formation fracture porosity, and the oil and gas reservoir yield is improved.

Description

Technical Field

[0001] The embodiments of this specification relate to the technical field of oil and gas reservoir development, and in particular to a method, device and equipment for analyzing the in-situ fracture porosity of mixed rock formations. Background Art

[0002] Mixed rock is the product of the mixing of terrigenous clastic components and carbonate rock components in the same stratum. It has the characteristics of variable particle size, diverse lithology, frequent alternation of thin and thick layers, and strong heterogeneity. Therefore, the reservoir development of mixed rock is very difficult. How to guide the exploitation of oil and gas reservoirs in mixed rock formations is a technical problem that needs to be solved urgently. Summary of the invention

[0003] To solve the problems existing in the prior art, the embodiments of this specification provide a method, device and equipment for analyzing the porosity of in-situ fractures in mixed rock formations, which guides the staff to formulate a mining plan for the in-situ mixed rock formations by calculating the porosity of in-situ fractures in the mixed rock.

[0004] The specific technical solutions of the embodiments of this specification are as follows:

[0005] On the one hand, an embodiment of this specification provides a method for analyzing the fracture porosity of an in-situ stratum of a mixed rock, the method comprising:

[0006] Obtain the original data of multiple layers in the target block;

[0007] Taking out at least one first core sample from each of the horizons of the target block, and performing experimental analysis on the first core sample of each of the horizons to determine the target horizon;

[0008] Taking out at least one second core sample from the target layer, and performing a triaxial compression test on the second core sample to obtain a stress index;

[0009] The formation fracture porosity of the target layer is calculated according to the original data and the stress index, and the formation fracture porosity is used to guide the staff to formulate the oil and gas reservoir exploitation plan of the target layer.

[0010] Further, taking out at least one second core sample from the target layer, and performing a triaxial compression test on the second core sample to obtain a stress index further comprises:

[0011] measuring a volume change of the second core sample during the triaxial compression test;

[0012] Calculating the porosity change of the second core sample during the triaxial compression test according to the volume change of the second core sample and the total porosity of the target layer calculated based on the original data;

[0013] Fit the porosity change and the pressure change in the triaxial compression test to obtain the stress index.

[0014] Further, the formula for calculating the total porosity is:

[0015]

[0016] Where, represents the total porosity, ρ 基质 represents the matrix density in the original data of the target horizon, ρ 体积 represents the bulk density in the original data of the target horizon, and the bulk density is the measured density logging data, ρ 流体 represents the fluid density in the original data of the target horizon.

[0017] Further, the formula for calculating the matrix density ρ 基质 in the original data of the target horizon is:

[0018]

[0019] Where, N represents the total number of cuttings types in the target horizon, ρ i represents the density of the i-th type of cuttings, p i represents the proportion of the i-th type of cuttings.

[0020] Further, the formula for calculating the porosity change of the second core sample during the triaxial compression test according to the volume change of the second core sample and the total porosity of the target horizon calculated based on the original data is:

[0021]

[0022] Where, represents the porosity change of the second core sample during the triaxial compression test, V0 represents the volume of the second core sample before the triaxial compression test, V represents the volume of the second core sample measured during the triaxial compression test, represents the total porosity.

[0023] Further, the formula for fitting the porosity change and the pressure change in the triaxial compression test to obtain the stress index is:

[0024]

[0025] Where, β represents the stress index, and σe represents the pressure applied during the triaxial compression test.

[0026] Further, the formula for calculating the formation fracture porosity of the target horizon based on the original data and the stress index is:

[0027]

[0028] Wherein, represents the initial porosity, Δt1 represents the acoustic transit time in the original data of the target horizon, Δt2 represents the matrix acoustic transit time of the target horizon, and Δt3 represents the fluid transit time in the original data of the target horizon;

[0029]

[0030] Wherein, represents the secondary porosity, represents the initial fracture porosity, represents the rigid porosity, R represents the resistivity logging data in the original data of the target horizon, and R0 represents the rock resistivity of the second core sample after saturation with water;

[0031]

[0032] Wherein, represents the formation fracture porosity.

[0033] Further, the formula for calculating the rock resistivity R0 of the second core sample after saturation with water is:

[0034]

[0035] Wherein, N represents the total number of cuttings types in the target horizon, R i represents the resistivity of the i-th type of cuttings, p i represents the proportion of the i-th type of cuttings, R 水 represents the resistivity of water, p 水 represents the proportion of water.

[0036] Further, the formula for calculating the matrix acoustic transit time Δt2 of the target horizon is:

[0037]

[0038] Wherein, N represents the total number of cuttings types in the target horizon, The acoustic transit time of the i-th type of cuttings.

[0039] Further, performing experimental analysis on each of the first core samples of each horizon to determine the target horizon further includes:

[0040] Perform thin section experiments, scanning electron microscope experiments, X-ray diffraction experiments, and computed tomography experiments on the first core samples of each of the said horizons to obtain the analysis results of each of the said first core samples of each horizon corresponding to each experiment;

[0041] Input the analysis results of each of the said first core samples of each horizon corresponding to each experiment into a pre-configured decision engine for analysis to determine the target horizon. Among them, discriminant rules for the test results of the thin section experiment, scanning electron microscope experiment, X-ray diffraction experiment, and computed tomography experiment are pre-configured in the decision engine, and the output result of the discriminant rule is whether the horizon is the target horizon.

[0042] Further, the discriminant rule of the computed tomography experiment includes:

[0043] Control the computed tomography experiment to scan the first cuttings samples at multiple sampling depths of the horizon to obtain the porosity scan values of the first cuttings samples at each sampling depth of this horizon;

[0044] Determine the sampling depth at which the difference between the porosity scan value and the total porosity of this horizon is less than the threshold as the target sampling depth, so as to take out at least one of the second core samples from the target sampling depth.

[0045] Further, taking out at least one of the second core samples from the target sampling depth further includes:

[0046] Take out at least one of the second core samples from within a predetermined depth range of the target sampling depth.

[0047] On the other hand, an embodiment of this specification also provides an analysis device for the in-situ formation fracture porosity of mixed sedimentary rocks. The device includes:

[0048] A data acquisition unit for acquiring the original data of multiple horizons in a target block;

[0049] A target horizon analysis unit for taking out at least one first core sample from each of the horizons of the target block and performing experimental analysis on the first core samples of each of the horizons to determine the target horizon;

[0050] A stress index calculation unit for taking out at least one second core sample from the target horizon, performing a triaxial compression test on the second core sample to obtain the stress index;

[0051] A formation fracture porosity calculation unit is used to calculate the formation fracture porosity of a target horizon based on the original data and the stress index. The formation fracture porosity is used to guide the staff in formulating an oil and gas reservoir exploitation plan for the target horizon.

[0052] On the other hand, an embodiment of this specification also provides a computer device, including a memory, a processor, and a computer program stored on the memory. When the processor executes the computer program, the above method is implemented.

[0053] On the other hand, an embodiment of this specification also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above method is implemented.

[0054] Using the embodiment of this specification, first, obtain the original data of multiple horizons in a target block, and take at least one first core sample from each horizon of the target block. The first core sample is used to determine the target horizon to be analyzed. Then, take at least one second core sample from the target horizon, perform a triaxial compression test on the second core sample to obtain the stress index, and finally calculate the formation fracture porosity of the target horizon according to the original data and the stress index. The formation fracture porosity represents the fracture porosity of the target horizon in the target block and characterizes the in-situ characteristics in the formation, thereby improving the accuracy of reservoir evaluation. The staff can formulate an oil and gas reservoir exploitation plan for the target horizon in the target block based on the formation fracture porosity, thereby increasing the production of the oil and gas reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the embodiments of this specification. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0056] Figure 1 The figure shows a schematic flow chart of a method for analyzing the in-situ formation fracture porosity of a mixed sedimentary rock in an embodiment of this specification;

[0057] Figure 2 The figure shows a schematic flow chart of determining the target horizon by performing experimental analysis on the first core sample of each horizon in an embodiment of this specification;

[0058] Figure 3 The figure shows a schematic diagram of well logging data in an embodiment of this specification;

[0059] Figure 4aThe figure shows a schematic diagram of the experimental results of the thin slice in the range of 3600 - 3610 in the embodiments of this specification;

[0060] Figure 4b The figure shows a schematic diagram of the experimental results of the thin slice in the range of 3630 - 3640 in the embodiments of this specification;

[0061] Figure 4c The figure shows a schematic diagram of the experimental results of the thin slice in the range of 3650 - 3660 in the embodiments of this specification;

[0062] Figure 5a The figure shows a schematic diagram of the experimental results of the scanning electron microscope in the range of 3600 - 3610 in the embodiments of this specification;

[0063] Figure 5b The figure shows a schematic diagram of the experimental results of the scanning electron microscope in the range of 3650 - 3660 in the embodiments of this specification;

[0064] Figure 6 The figure shows a schematic diagram of the results of CT scanning of the first core sample at 3600 - 3610 in the embodiments of this specification;

[0065] Figure 7 The figure shows a schematic diagram of the process of obtaining the stress index by performing a triaxial compression test on the second core sample in the embodiments of this specification;

[0066] Figure 8 The figure shows a covariation diagram of effective confining pressure and porosity in the embodiments of this specification;

[0067] Figure 9 The figure shows a schematic diagram of the structure of an analysis device for in - situ formation fracture porosity of a mixed - sedimentary rock in the embodiments of this specification;

[0068] Figure 10 The figure shows a schematic diagram of the structure of a computer device in the embodiments of this specification.

[0069]

Explanation of Reference Numerals

[0070] 901, data acquisition unit;

[0071] 902, target horizon analysis unit;

[0072] 903, stress index calculation unit;

[0073] 904, formation fracture porosity calculation unit;

[0074] 1002, computer device;

[0075] 1004, processing device;

[0076] 1006, storage resource;

[0077] 1008. Driving mechanism;

[0078] 1010. Input / output module;

[0079] 1012. Input device;

[0080] 1014. Output device;

[0081] 1016. Presentation device;

[0082] 1018. Graphical user interface;

[0083] 1020. Network interface;

[0084] 1022. Communication link;

[0085] 1024. Communication bus. Detailed implementation manners

[0086] Next, the technical solutions in the embodiments of this specification will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this specification. Obviously, the described embodiments are only a part of the embodiments of this specification, rather than all the embodiments. Based on the embodiments in this specification, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the embodiments of this specification.

[0087] It should be noted that the terms "first", "second", etc. in the specification, claims and the above-mentioned drawings of the embodiments of this specification are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the embodiments of this specification described here can be implemented in an order other than those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, device, product or equipment that includes a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.

[0088] It should be noted that in the technical solutions of the embodiments of this specification, the acquisition, storage, use, processing, etc. of data all comply with the relevant regulations of national laws and regulations.

[0089] It should be noted that in the embodiments of this specification, some industry-existing solutions such as certain software, components, models, etc. may be mentioned. They should be regarded as exemplary, and their purpose is only to illustrate the feasibility in the implementation of the technical solutions of this application, but it does not mean that the applicant has already or necessarily used this solution.

[0090] At present, the methods for characterizing the porosity of mixed sedimentary rock reservoirs all draw on the reservoir characteristics of shale, sandstone, and carbonate rock. For example: 1) Drawing on the pore characteristics of shale reservoirs, conducting a trinity characterization experiment of CO2-N2-high-pressure mercury injection, making a fitting graph of pore diameter-pore volume, and quantitatively characterizing the pore volume of the entire pore diameter; 2) Drawing on the pore characteristics of sandstone reservoirs, identifying the pore types and distributions in combination with the thin section and SEM identification results, statistically analyzing the development ratio and distribution scale of different types of pores, determining the development type of the pore-throat system of mixed sedimentary rock, and qualitatively evaluating the reservoir in combination with the geological, sedimentary, and diagenetic backgrounds; 3) Drawing on the pore characteristics of carbonate rock reservoirs, considering the characteristics of the rock matrix, focusing on the biogenic framework structure, and restoring the initial porosity during deposition.

[0091] However, the traditional methods for characterizing the porosity of mixed sedimentary rock have the following problems:

[0092] 1) The existing characterization processes mostly classify by pore diameter size, without separating fractures and pores, resulting in a fuzzy overall understanding of the pore-throat structure;

[0093] 2) The characterization experiments are all completed in the surface environment and cannot truly represent their in-situ characteristics in the formation, thus reducing the accuracy of reservoir evaluation;

[0094] 3) Geological laboratory experiments and well logging data calculation methods are often used separately. The repetitive work not only wastes time but also reduces the accuracy of reservoir evaluation.

[0095] Based on this, the embodiments of this specification provide a method for characterizing in-situ fractures of mixed sedimentary rock based on geological laboratory experiments and well logging data, and based on this method, an analysis method for the in-situ formation fracture porosity of mixed sedimentary rock is provided. As Figure 1 shown, the method includes:

[0096] Step 101: Obtain the original data of multiple horizons in the target block;

[0097] Step 102: Take at least one first core sample from each horizon of the target block, and conduct experimental analysis on the first core sample of each horizon to determine the target horizon;

[0098] Step 103: Take at least one second core sample from the target horizon, conduct a triaxial compression test on the second core sample, and obtain the stress index;

[0099] Step 104: Calculate the formation fracture porosity of the target horizon according to the original data and the stress index, and the formation fracture porosity is used to guide the staff to formulate the oil and gas reservoir exploitation plan for the target horizon.

[0100] In the embodiments of this specification, the original data of multiple horizons within the target block includes regional geological background information, drilling data, and logging data within multiple depth segments of the target block. The regional geological background information includes data such as the paleotectonic characteristics, sedimentary environment, and paleogeographic features of the target block and horizons. The drilling data includes cuttings logging data, formation water saturation, formation oil and gas saturation data, well test interpretation and analysis reports. The logging data includes conventional logging data and imaging logging data. The conventional logging data includes neutron porosity logging data (NPHI), acoustic velocity logging data (AC), density logging data (RHOB), saturation logging data (SNP), gamma logging data (GR), and rock mineral logging. The imaging logging data includes formation microresistivity scanning imaging logging data (FMI).

[0101] Then, at least one first core sample is taken from each horizon of the target block, and the first core samples of each horizon are experimentally analyzed to determine the target horizon.

[0102] In the embodiments of this specification, a high-speed precision cutting machine can be used to cut the mixed sedimentary rock core of the target block and horizon into small cylinders with a length of 10 - 15 cm and a diameter of 5 cm, and the long axis direction of the small cylinders is parallel to the drilling direction.

[0103] After obtaining the first core samples, as Figure 2 shown, experimentally analyzing the first core samples of each of the said horizons to determine the target horizon further includes:

[0104] Step 201: Conduct thin section experiments, scanning electron microscope experiments, X-ray diffraction experiments, and computed tomography experiments on the first core samples of each of the said horizons to obtain the analysis results of each of the first core samples of each of the said horizons corresponding to each experiment;

[0105] Step 202: Input the analysis results of each of the first core samples of each of the said horizons corresponding to each experiment into a pre-configured decision engine for analysis to determine the target horizon. Among them, discriminant rules for the test results of the thin section experiment, scanning electron microscope experiment, X-ray diffraction experiment, and computed tomography experiment are pre-configured in the decision engine, and the output result of the discriminant rule is whether the horizon is the target horizon.

[0106] In the embodiments of this specification, for the thin section experiment, an epoxy resin AB glue with a ratio of (1:1 - 2:1) can be prepared to bond the rock slices corresponding to the small cylinders, dried at different temperatures (20°C - 90°C), and the thin sections are polished to a standard thickness of about 30 μm to produce cast thin sections. The thin sections can show different types of porosities, including microfractures, within biogenic fossils, intragranular, and intergranular porosities.

[0107] For the scanning electron microscopy experiment (SEM), the rock slice corresponding to the small cylinder can be cut into 1×1 cm, cleaned with an ultrasonic cleaner, ion sputtered to deposit a carbon film, with the coating thickness controlled within 1 - 10 nanometers, to fabricate an SEM sample and determine the main pore types.

[0108] For the X-ray diffraction experiment (XRD), the powder corresponding to the small cylinder can be analyzed by a PW 1840 X-ray diffractometer (X'Pert PRO MPD instrument) at 40 kV and 30 mA to obtain the mineral types and contents.

[0109] For the computed tomography experiment (CT), X-ray computed tomography (CT) scanning imaging can be carried out using a Zeiss industrial CT - METROTOM 6scout Metrology CT (GOM CT) instrument to study the fracture conditions of the small rock cylinder.

[0110] Exemplarily, in Well X1, the thickness of the Wulalik Formation is 100 m, the depth ranges from 3580 to 3680 m, and the core recovery rate is 100%.

[0111] The in-situ stress analysis in Area AB shows that under the hydrostatic pore pressure, for every 0.1 km increase in depth, the effective stress increases by 1.30 MPa. Therefore, the effective confining pressure of the selected core is (47.8 - 46.5 MPa).

[0112] The cored interval of 3580 - 3680 m is segmented (3580 - 3590, 3590 - 3600, 3600 - 3610, 3610 - 3620, 3620 - 3630, 3630 - 3640, 3640 - 3650, 3650 - 3660, 3660 - 3670, 3670 - 3680) for identification, and samples are selected:

[0113] The logging data of Well X1 is as Figure 3 shown, including bulk density (RHOB), acoustic transit time (AC), resistivity logging (Ra), mineral logging data, and formation microimager logging data (FMI).

[0114] For each segment, the first core sample is taken for thin section experiments, and the experimental results are as Figure 4a 、 4b and 4c shown, Figure 4a which is the thin section experimental result of the 3600 - 3610 segment, Figure 4b which is the thin section experimental result of the 3630 - 3640 segment, Figure 4c which is the thin section experimental result of the 3650 - 3660 segment.

[0115] From Figures 4a - 4cIt can be concluded that the reservoir spaces in the 3600 - 3610 section are mainly composed of intragranular dissolution pores and intergranular pores; those in the 3630 - 3640 section are mainly composed of microfractures and intergranular pores; and those in the 3650 - 3660 section are mainly composed of microfractures. This indicates that subsequent drill string sampling can be carried out in these three sections.

[0116] However, the 3580 - 3590, 3590 - 3600, 3610 - 3620, 3620 - 3630, 3640 - 3650, 3660 - 3670, and 3670 - 3680 sections are severely fragmented; this shows that these 7 sections are severely affected by the outside world during coring, with induced fractures being overly developed, which is not conducive to subsequent drill string sampling.

[0117] Scanning electron microscopy (SEM) experiments were conducted on the 3600 - 3610, 3630 - 3640, and 3650 - 3660 sections that can undergo subsequent drill string sampling obtained from thin section experiments, and the results are as Figure 5a and Figure 5b shown. Figure 5a is the SEM experimental result of the 3600 - 3610 section, Figure 5b is the SEM experimental result of the 3650 - 3660 section.

[0118] From Figure 5a and Figure 5b it can be seen that intergranular pores and intragranular dissolution pores are the main pore types in the 3600 - 3610 section. In the 3630 - 3640 and 3650 - 3660 sections, the intergranular pores and intragranular dissolution pores are basically filled and blocked by clay, which may indicate that the 3630 - 3640 and 3650 - 3660 sections are severely affected by late diagenesis or drilling mud and may be affected during subsequent oil washing and hydrocarbon injection experiments. Therefore, the 3630 - 3640 and 3650 - 3660 sections are not conducive to subsequent drill string sampling.

[0119] The XRD analysis results further show that the samples taken from the 3600 - 3610 section are mainly composed of 30 - 50% quartz, 20 - 30% calcite, 20 - 30% clay, and 0 - 10% feldspar, with little overall change. The clay content in the samples is mainly kaolinite and illite, with a small amount of montmorillonite, indicating that the rock itself has a low maturity and there will be no phenomenon of montmorillonite swelling and dispersing to block pores during diagenesis. Therefore, the 3630 - 3640 and 3650 - 3660 sections are contaminated by mud, and the 3600 - 3610 section is the best experimental sample. Therefore, the target interval is the 3600 - 3610 section.

[0120] In actual implementation, an analysis function module for thin section experiment results, SEM results, and XRD results can be constructed by combining an image recognition algorithm and a decision engine algorithm, so as to analyze the thin section experiment results, SEM results, and XRD results of each layer using the analysis function module for thin section experiment results, SEM results, and XRD results, and output the target layer for subsequent drilling and sampling.

[0121] In the embodiments of this specification, the CT experiment is mainly used to obtain the porosity scan values of the first cuttings samples at various sampling depths of the layer. For example, the results of CT scanning of the first core sample at 3600 - 3610 are as Figure 6 shown, where green represents fractures and red represents pores. If the CT results show that the fracture development degree of the first core sample at 3600 - 3610 is medium, the CT results indicate that the microfracture development degree is medium, and the porosity is 8.6%. If the total porosity of the target layer calculated based on well logging data is also 8.6%, it indicates that the well logging and core of the first core sample have a high degree of coincidence, and the layer corresponding to the first core sample is the target layer.

[0122] According to an embodiment of this specification, the porosity distribution of the layer may be uneven. Therefore, in order to obtain the optimal second core sample, in the computerized tomography experiment of the embodiments of this specification, the first cuttings samples at multiple sampling depths of the layer are also scanned to obtain the porosity scan values of the first cuttings samples at various sampling depths of the layer;

[0123] Determine the sampling depth at which the difference between the porosity scan value and the total porosity of the layer is less than the threshold as the target sampling depth, so as to take out at least one of the second core samples from the target sampling depth. Preferably, at least one of the second core samples is taken out from a predetermined depth range of the target sampling depth.

[0124] In the embodiments of this specification, the total porosity of the layer is calculated based on the well logging data of the layer, and the formula is:

[0125]

[0126] where, represents the total porosity, ρ 基质 represents the matrix density in the original data of the target layer, ρ 体积 represents the bulk density (measured density logging data) in the original data of the target layer, ρ 流体 represents the fluid density in the original data of the target layer.

[0127] Furthermore, the formula for calculating the matrix density ρ 基质 in the original data of the target layer is:

[0128]

[0129] Among them, N represents the total number of cuttings types in the target horizon, ρ i represents the density of the i-th type of cuttings, and p i represents the proportion of the i-th type of cuttings.

[0130] In the embodiments of the specification, the bulk density and fluid density can be obtained through logging, the types of cuttings can be obtained by analyzing drilling data, and then density measurements are carried out on various types of cuttings to obtain the densities of various types of cuttings.

[0131] According to an embodiment of the present specification, as Figure 7 shown, taking out at least one second core sample from the target horizon and performing a triaxial compression test on the second core sample to obtain the stress index further includes:

[0132] Step 701: Measuring the volume change of the second core sample during the triaxial compression test;

[0133] Step 702: Calculating the porosity change of the second core sample during the triaxial compression test according to the volume change of the second core sample and the total porosity of the target horizon calculated based on the original data;

[0134] Step 703: Fitting the porosity change and the pressure change of the triaxial compression test to obtain the stress index.

[0135] In the embodiments of the present specification, first, the second core sample needs to be saturated, for example, by carrying out a deformation hydrostatic pressure test using a standard triaxial test system. After the equipment is set up, the second core sample is placed in the loading box, and at a temperature of 100 °C, uniform hydrostatic loading is carried out at a rate of 0.5 MPa / min until a confining pressure of 60 MPa is reached to simulate reservoir conditions.

[0136] In the embodiments of the present specification, it is considered that the main reason for the volume reduction of the second core sample caused by applying the confining pressure is the reduction of the porosity of the second core sample. Therefore, the present specification constructs a relationship between porosity and volume:

[0137]

[0138] Among them, represents the porosity change of the second core sample during the triaxial compression test, V0 represents the volume of the second core sample before the triaxial compression test, V represents the volume of the second core sample measured during the triaxial compression test, represents the total porosity.

[0139] Then, according to the formula:

[0140]

[0141] Fit the porosity change and the pressure change in the triaxial compression test to obtain the stress index. Wherein, β represents the stress index, and σe represents the pressure applied during the triaxial compression test.

[0142] It should be noted that during the triaxial compression test, the pressure is applied starting from 0 and gradually increased to the actual formation pressure.

[0143] Taking the 3600M core as an example:

[0144] When the effective confining pressure is 0, the volume V0 of the second core sample is 196 cm 3 The corresponding porosity is That is, at this time With the change of confining pressure and volume, calculate the corresponding porosity change according to the above formula The results are as Figure 8 shown.

[0145] In the initial stage of loading (10 - 30 MPa), the sample has a relatively large decrease, about 0.15% - 0.2%, which is related to the closure of induced fractures and the decrease in porosity, corresponding roughly to the removal effect of the overlying strata. After 30 MPa, it becomes stable. 46.8 MPa corresponds to the formation state of the rock, and the fracture porosity of the sample at this time is the in-situ fracture porosity to be obtained.

[0146] Make a regression index trend line for the fitting graph of the applied stress and porosity, and perform fitting according to the above formula, then the stress index β = 0.0013 can be obtained.

[0147] In the embodiments of this specification, calculate the formation fracture porosity of the target horizon according to the original data and the stress index β. Specifically, first construct the relationship among the total porosity initial porosity and secondary porosity among the three:

[0148]

[0149] And:

[0150]

[0151] Wherein, It represents the initial porosity, Δt1 represents the acoustic wave transit time in the original data of the target horizon, Δt2 represents the matrix acoustic wave transit time of the target horizon, and Δt3 represents the fluid transit time in the original data of the target horizon;

[0152] The formula for calculating the rock resistivity R0 of the second core sample after saturation with water is:

[0153]

[0154] Where, N represents the total number of cuttings types in the target horizon, R i represents the resistivity of the i-th type of cuttings, p i represents the proportion of the i-th type of cuttings, R 水 represents the resistivity of water, p 水 represents the proportion of water.

[0155] The relationship between the initial fracture porosity and the secondary porosity is constructed as follows:

[0156]

[0157] Where, represents the rigid porosity.

[0158] The calculation formula for the rigid porosity is constructed as:

[0159]

[0160] Where, R represents the resistivity logging data in the original data of the target horizon, and R0 represents the rock resistivity of the second core sample after saturation with water;

[0161] The formula for calculating the matrix acoustic wave transit time Δt2 of the target horizon is:

[0162]

[0163] Where, N represents the total number of cuttings types in the target horizon, the acoustic wave transit time of the i-th type of cuttings.

[0164] Finally, according to the formula:

[0165]

[0166] calculate the formation fracture porosity

[0167] Exemplarily, the logging data at 3600m:

[0168] Density logging data: 2.5 g / cm 3;

[0169] Acoustic travel time log data: 65 μs / ft;

[0170] Resistivity log data: 100 Ω.m;

[0171] Dolomite % = 0%, limestone % = 50%, sandstone % = 30%, mudstone % = 20%;

[0172] Resistivity R: R 白云岩 = 120 Ω.m; R 灰岩 = 100 Ω.m; R 砂岩 = 80 Ω.m; R 泥岩 = 60 Ω.m; R 水 = 1 Ω.m;

[0173] Matrix density: ρ 白云岩 = 2.87 g / cm 3 ; ρ 灰岩 = 2.71 g / cm 3 ; ρ 砂岩 = 2.65 g / cm 3 ; ρ 泥岩 = 2.4 g / cm 3 ;

[0174] ρ bulk density is the measured density log data, and the ρ fluid density is taken as 1.12 g / cm 3 ;

[0175] Acoustic travel time: Δt 白云岩 = 41.52 μs / ft; Δt 灰岩 = 45.90 μs / ft; Δt 砂岩 = 55.5 μs / ft; Δt 泥岩 = 150 μs / ft;

[0176] The Δt fluid travel time is taken as 183 μs / ft.

[0177] The formation fracture porosity can be calculated through the above formula Formation fracture porosity reflects the fracture porosity of the in-situ environment, thereby improving the accuracy of reservoir evaluation, facilitating the staff to evaluate the true situation of the underground reservoir according to the fracture porosity of the in-situ environment, formulate the exploitation plan of the oil and gas reservoir in the in-situ formation, and improve the recovery rate.

[0178] Based on the same inventive concept, the embodiment of this specification also provides an analysis device for the fracture porosity of the mixed sedimentary rock in-situ formation, as Figure 9 shown, including:

[0179] A data acquisition unit 901, configured to acquire original data of multiple horizons within a target block;

[0180] A target horizon analysis unit 902, configured to extract at least one first core sample from each horizon of the target block, and perform experimental analysis on the first core sample of each horizon to determine the target horizon;

[0181] A stress index calculation unit 903, configured to extract at least one second core sample from the target horizon, and perform a triaxial compression test on the second core sample to obtain a stress index;

[0182] A formation fracture porosity calculation unit 904, configured to calculate the formation fracture porosity of the target horizon according to the original data and the stress index, and the formation fracture porosity is used to guide the staff to formulate an oil and gas reservoir exploitation plan for the target horizon.

[0183] The beneficial effects obtained by the above device are the same as those obtained by the above method, and the embodiments of this specification will not elaborate.

[0184] As Figure 10 shown is a schematic structural diagram of a computer device according to an embodiment of this specification. The device in the embodiment of this specification may be the computer device in this embodiment and execute the method of the embodiment of this specification. The computer device 1002 may include one or more processing devices 1004, such as one or more central processing units (CPUs), and each processing unit may implement one or more hardware threads. The computer device 1002 may also include any storage resource 1006, which is used to store any type of information such as code, settings, data, etc. Non-limiting, for example, the storage resource 1006 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory devices, hard disks, optical discs, etc. More generally, any storage resource may use any technology to store information. Further, any storage resource may provide volatile or non-volatile retention of information. Further, any storage resource may represent a fixed or removable component of the computer device 1002. In one case, when the processing device 1004 executes the associated instructions stored in any storage resource or combination of storage resources, the computer device 1002 may perform any operation of the associated instructions. The computer device 1002 also includes one or more drive mechanisms 1008 for interacting with any storage resource, such as a hard disk drive mechanism, an optical disc drive mechanism, etc.

[0185] The computer device 1002 may also include an input / output module 1010 (I / O) for receiving various inputs (via the input device 1012) and for providing various outputs (via the output device 1014). One specific output mechanism may include a presentation device 1016 and an associated graphical user interface (GUI) 1018. In other embodiments, the input / output module 1010 (I / O), the input device 1012, and the output device 1014 may not be included, and it may only be a computer device in a network. The computer device 1002 may also include one or more network interfaces 1020 for exchanging data with other devices via one or more communication links 1022. One or more communication buses 1024 couple the components described above together.

[0186] The communication link 1022 may be implemented in any manner, for example, via a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 1022 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc. governed by any protocol or combination of protocols.

[0187] The embodiments of this specification also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above method.

[0188] The embodiments of this specification also provide a computer-readable instruction, where when the processor executes the instruction, the program therein causes the processor to execute the above method.

[0189] It should be understood that in various embodiments of the embodiments of this specification, the magnitudes of the sequence numbers of the above processes do not mean the order of execution is prior or posterior. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this specification.

[0190] It should also be understood that in the embodiments of this specification, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the embodiments of this specification generally represents an "or" relationship between the associated objects before and after.

[0191] Those of ordinary skill in the art will realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed in this specification can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this specification's embodiments.

[0192] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated here.

[0193] In the several embodiments provided in this specification's embodiments, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Additionally, the displayed or discussed couplings or direct couplings or communication connections to each other can be indirect couplings or communication connections through some interfaces, devices, or units, or can also be electrical, mechanical, or other forms of connection.

[0194] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or can also be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this specification's embodiments.

[0195] Furthermore, in each of the embodiments of this specification's embodiments, the functional units can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-integrated units can be implemented in the form of hardware or in the form of software functional units.

[0196] When the integrated unit 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 such an understanding, the technical solution of the embodiments of this specification, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this specification. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0197] In the embodiments of this specification, specific embodiments are used to elaborate on the principles and implementation manners of the embodiments of this specification. The descriptions of the above embodiments are only used to help understand the methods and their core ideas of the embodiments of this specification; at the same time, for those of ordinary skill in the art, according to the ideas of the embodiments of this specification, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the embodiments of this specification.

Claims

1. A method for analyzing the in-situ fracture porosity of mixed rock formations, characterized in that: The method comprises: Obtain the original data of multiple layers in the target block; Taking out at least one first core sample from each of the horizons of the target block, and performing experimental analysis on the first core sample of each of the horizons to determine the target horizon; Taking out at least one second core sample from the target layer, and performing a triaxial compression test on the second core sample to obtain a stress index; The formation fracture porosity of the target layer is calculated according to the original data and the stress index, and the formation fracture porosity is used to guide the staff to formulate the oil and gas reservoir exploitation plan of the target layer.

2. The method according to claim 1, characterized in that Taking out at least one second core sample from the target layer, performing a triaxial compression test on the second core sample, and obtaining a stress index further comprises: measuring a volume change of the second core sample during the triaxial compression test; Calculating the porosity change of the second core sample during the triaxial compression test according to the volume change of the second core sample and the total porosity of the target layer calculated based on the original data; The porosity change and the pressure change of the triaxial compression test are fitted to obtain the stress index.

3. The method according to claim 2, characterized in that The formula for calculating the total porosity is: in, represents the total porosity, ρ 基质 Represents the matrix density in the original data of the target layer, ρ 体积 represents the volume density in the original data of the target layer, the volume density is the measured density logging data, ρ 流体 Represents the fluid density in the original data of the target layer.

4. The method according to claim 3, characterized in that Calculate the matrix density ρ in the original data of the target layer 基质 The formula is: Where N represents the total number of rock cuttings types in the target layer, ρ i represents the density of the i-th type of rock cuttings, p i represents the proportion of the i-th type of rock fragments.

5. The method according to claim 3, characterized in that: The formula for calculating the porosity change of the second core sample during the triaxial compression test according to the volume change of the second core sample and the total porosity of the target layer calculated based on the original data is: in, represents the porosity change of the second core sample during the triaxial compression test, V0 represents the volume of the second core sample before the triaxial compression test, V represents the volume of the second core sample measured during the triaxial compression test, Represents the total porosity.

6. The method according to claim 5, characterized in that The porosity change and the pressure change of the triaxial compression test are fitted to obtain the formula of the stress index: Here, β represents the stress exponent and σe represents the pressure applied during the triaxial compression test.

7. The method according to claim 3, characterized in that The formula for calculating the formation fracture porosity of the target layer according to the original data and the stress index is: in, represents the initial porosity, Δt1 represents the acoustic wave transmission time in the original data of the target layer, Δt2 represents the matrix acoustic wave transmission time of the target layer, and Δt3 represents the fluid transmission time in the original data of the target layer; in, represents the secondary porosity, represents the initial fracture porosity, represents the rigid porosity, R represents the resistivity logging data in the original data of the target layer, and R0 represents the rock resistivity of the second core sample after saturation with water; in, Indicates the porosity of formation fractures.

8. The method according to claim 7, characterized in that The formula for calculating the rock resistivity R0 of the second core sample after saturation with water is: Where N represents the total number of rock cuttings types in the target layer, R i represents the resistivity of the i-th rock cuttings, p i represents the proportion of the i-th type of rock fragments, R 水 represents the resistivity of water, p 水 Indicates the proportion of water.

9. The method according to claim 7, characterized in that: The formula for calculating the matrix acoustic wave transmission time Δt2 of the target layer is: Where N represents the total number of rock cuttings types in the target layer, The acoustic wave transmission time of the i-th type of rock cuttings.

10. The method according to claim 2, characterized in that Performing experimental analysis on the first core sample of each of the horizons to determine the target horizon further includes: Performing a thin section experiment, a scanning electron microscope experiment, an X-ray diffraction experiment, and a computer tomography experiment on the first core sample of each of the layers, and obtaining analysis results corresponding to each experiment of the first core sample of each of the layers; The analysis results of each experiment corresponding to the first core sample of each of the layers are respectively input into a pre-configured decision engine for analysis to determine the target layer, wherein the decision engine is pre-configured with discrimination rules for the respective test results of the thin section experiment, the scanning electron microscope experiment, the X-ray diffraction experiment and the computer tomography experiment, and the output result of the discrimination rule is whether the layer is the target layer.

11. The method according to claim 10, characterized in that The discrimination rules of the computer tomography experiment include: Controlling the computer tomography experiment to scan the first rock cutting samples at multiple sampling depths of the horizon to obtain porosity scanning values ​​of the first rock cutting samples at each sampling depth of the horizon; A sampling depth at which the difference between the porosity scan value and the total porosity of the layer is less than a threshold is determined as a target sampling depth, so as to take at least one of the second core samples from the target sampling depth.

12. The method according to claim 11, characterized in that Retrieving at least one of the second core samples from the target sampling depth further comprises: At least one of the second core samples is taken from a predetermined depth range of the target sampling depth.

13. An analytical device for in-situ fracture porosity of mixed rock formations, characterized in that: The device comprises: A data acquisition unit, used to acquire original data of multiple layers in the target block; A target layer analysis unit is used to take out at least one first core sample from each layer of the target block, and perform experimental analysis on the first core sample of each layer to determine the target layer; A stress index calculation unit, used for taking out at least one second core sample from the target layer, performing a triaxial compression test on the second core sample, and obtaining a stress index; The formation fracture porosity calculation unit is used to calculate the formation fracture porosity of the target layer according to the original data and the stress index. The formation fracture porosity is used to guide the staff to formulate the oil and gas reservoir exploitation plan of the target layer.

14. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 12 is implemented.

15. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 12 is implemented.

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