Method, device, equipment and medium for predicting effective lower limit depth of reservoir

Abstract

The invention relates to a method, device, equipment and medium for predicting the effective lower limit depth of a reservoir, in particular to the technical field of reservoir exploration, and the method comprises the following steps: recovering the evolution process of a target reservoir, and obtaining the densification temperature of the reservoir; recovering the thermal evolution history of the basin where the target reservoir is located, and obtaining a basin ground temperature field; and obtaining a linear fitting relationship between the temperature of the reservoir and the effective lower limit depth based on reservoir densification temperature and basin ground temperature field prediction, and predicting the effective lower limit depth of the target reservoir according to the temperature of the target reservoir. According to the method provided by the invention, the effective prediction of the effective lower limit depth of the reservoir is realized by designing the prediction process, determining the densification process and the densification time of the reservoir and combining the characteristics of the basin ground temperature field, and the exploration deployment of the reservoir in less-well and no-well areas is powerfully guided, so that the efficient and reasonable development of an oil field is ensured.

Description

Technical Field

[0001] The present invention relates to the field of reservoir exploration technology, and specifically to a method, device, equipment, and medium for predicting the effective lower limit depth of a reservoir, and in particular to a method, device, equipment, and medium for predicting the effective lower limit depth of a reservoir based on a geothermal field, and more particularly to a method, device, equipment, and medium for predicting the effective lower limit depth of a reservoir based on a geothermal field for reservoirs in areas with few or no wells in the early stages of exploration. Background Art

[0002] At present, the prediction method of the lower limit of the effective depth of clastic reservoirs is generally based on the evaluation of the lower limits of reservoir physical properties, thickness, and electrical properties based on a large amount of core test, logging parameter and other data.

[0003] For example, CN118330772A discloses a method for predicting clastic thin-layer lithologic oil reservoirs. First, based on the determination of the macroscopic boundaries of the single sand body distribution, the physical parameters are combined to predict the distribution range of the effective sandstone body with reservoir performance. Then, the oil-bearing sandstone is subjected to the lower limit parameter constraints of the lithology, physical properties, and electrical properties, and the oil-bearing sandstone is analyzed for the effective sandstone body with lithologic closure conditions, thereby finally realizing the prediction of the oil-bearing sandstone body.

[0004] However, there is still a lack of effective prediction depth for reservoirs in areas with few or no wells in the early stages of exploration, which is not conducive to the exploration of reservoirs in areas with few or no wells. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method, device, equipment and medium for predicting the effective lower limit depth of a reservoir, so as to solve the defect that there is still a lack of effective prediction depth for reservoirs in areas with few wells or no wells in the early stage of exploration, which is not conducive to the exploration of reservoirs in areas with few wells or no wells.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for predicting the effective lower limit depth of a reservoir, the method comprising:

[0008] Restore the evolution process of the target reservoir and obtain the reservoir densification temperature;

[0009] Restore the thermal evolution history of the basin where the target reservoir is located and obtain the basin geothermal field;

[0010] Based on the reservoir densification temperature and the basin geothermal field prediction, the linear fitting relationship between the reservoir temperature and the effective lower limit depth is obtained. According to the temperature of the target reservoir, the effective lower limit depth of the target reservoir is predicted.

[0011] The method provided by the present invention, through the design of the prediction process, clarifies the reservoir densification process and the densification time in combination with the geothermal field characteristics of the basin, realizes the effective prediction of the effective lower limit depth of the reservoir, and effectively guides the exploration and deployment of reservoirs in areas with few wells or no wells, thereby ensuring that the oil field can be developed efficiently and reasonably.

[0012] As a preferred technical solution of the present invention, the recovery of the evolution process of the target reservoir and obtaining the reservoir densification temperature include: reconstructing the reservoir water-rock reaction process with the help of microscopic analysis, isotope analysis and inclusion testing, determining the reservoir diagenetic environment and pore evolution characteristics at different temperatures, determining the type of dense minerals and analyzing the formation temperature of the corresponding dense minerals to obtain the reservoir densification temperature.

[0013] As a preferred technical solution of the present invention, the microscopic analysis includes: using a polarizing microscope to observe rock thin sections to obtain samples reflecting the diagenetic characteristics of the depth segment, and then performing cathode luminescence and scanning electron microscopy analysis on the samples reflecting the diagenetic characteristics of the depth segment to determine the type, occurrence state and occupancy relationship of the diagenetic minerals.

[0014] As a preferred technical solution of the present invention, the isotope analysis includes: performing C isotope analysis and O isotope analysis on the carbonate rock obtained by microscopic analysis, and calculating the K-Ar age of the authigenic illite.

[0015] As a preferred technical solution of the present invention, the inclusion test comprises: performing a phase transition test on the paleofluid in the gas-liquid two-phase inclusion to obtain a uniform temperature of the inclusion.

[0016] As a preferred technical solution of the present invention, the thermal evolution history of the basin where the target reservoir is located is restored and the geothermal field of the basin is obtained, including: using formation testing, basement heat flow value and formation thermal conductivity testing, and obtaining a plane distribution map of the temperature gradient of the entire basin based on the Mckenzie thermal history model.

[0017] Preferably, the formation test includes: temperature data from drill pipe formation testing during drilling and MDT testing.

[0018] Preferably, the base heat flow value comprises: calculating the earth heat flow using the thermal resistance method proposed by CHAPMAN.

[0019] Preferably, the formation conductivity test includes: testing the formation thermal conductivity value of the target layer.

[0020] As a preferred technical solution of the present invention, the effective lower limit depth of the reservoir is predicted based on the reservoir densification temperature and the basin geothermal field, including: establishing a linear relationship between geothermal gradient and burial depth with the help of the quantitative relationship between physical properties, geothermal field, and diagenetic evolution, and then calculating the effective lower limit depth of the target reservoir based on the temperature of the target reservoir.

[0021] In a second aspect, the present invention provides a device for predicting the effective lower limit depth of a reservoir, the device comprising:

[0022] A reservoir densification temperature acquisition module is used to restore the evolution process of the target reservoir and obtain the reservoir densification temperature;

[0023] The module for obtaining the basin geothermal field is used to restore the thermal evolution history of the basin where the target reservoir is located and obtain the basin geothermal field;

[0024] The effective lower limit depth prediction module is used to obtain the linear fitting relationship between the reservoir temperature and the effective lower limit depth based on the reservoir densification temperature and the basin geothermal field, and predict the effective lower limit depth of the target reservoir based on the temperature of the target reservoir.

[0025] In a third aspect, the present invention provides an electronic device, the electronic device comprising:

[0026] at least one processor; and a memory communicatively coupled to the at least one processor;

[0027] Wherein, the memory stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for predicting the effective lower limit depth of a reservoir as described in the first aspect.

[0028] In a fourth aspect, the present invention provides a computer storage medium having computer executable instructions stored therein, which, when executed by a processor, implements the method for predicting the effective lower limit depth of a reservoir as described in the first aspect.

[0029] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0030] (1) The method provided by the present invention identifies acid-base diagenetic minerals by means of thin sections, cathode luminescence, scanning electron microscopy and laser micro-area isotope analysis, and determines the influence of mineral morphology, occurrence state and combination mode on reservoir physical properties and the order of formation, thereby establishing the longitudinal evolution model of acid-base diagenesis, restoring the reservoir densification process, and determining the typical minerals and causes of reservoir densification.

[0031] (2) The present invention establishes a quantitative relationship between physical properties, geothermal field, and diagenetic evolution, and on the basis of restoring the geothermal gradient plane diagram, predicts the effective lower limit depth of the reservoir in the well-free area with few wells (less than 1 exploratory well / 100 square kilometers) by fitting the relationship between temperature and depth. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart of a method for predicting the effective lower limit depth of a reservoir provided by an embodiment of the present invention;

[0033] Figure 2 is a schematic diagram of a device for predicting the effective lower limit depth of a reservoir provided by an embodiment of the present invention;

[0034] Figure 3 is a schematic diagram of an electronic device provided by an embodiment of the present invention;

[0035] Figure 4 This is a diagram of the diagenetic environment evolution and pore evolution model of the reservoir in the Xihu Sag of the East China Sea obtained in Example 1 of the present invention;

[0036] Figure 5 This is a graph showing the relationship between the quartz inclusion temperature and the formation temperature in the range of 3000-4600 m in the formation depth in a typical structure of the Xihu Sag in the East China Sea obtained in Example 1 of the present invention;

[0037] Figure 6 This is a relationship diagram between the quartz inclusion temperature and the formation temperature in the typical structure of the Xihu Sag in the East China Sea in Example 1 of the present invention within the range of 4000-4900m in depth;

[0038] Figure 7 This is the temperature gradient plane diagram of the West Lake Depression in the East China Sea obtained in Example 1 of the present invention;

[0039] Figure 8 This is the effective lower limit depth map of the reservoir in the Xihu Sag of the East China Sea obtained in Example 1 of the present invention.

[0040] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0041] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0042] This embodiment provides a method for predicting the effective lower limit depth of a reservoir. Figure 1 As shown, the method includes:

[0043] Restore the evolution process of the target reservoir and obtain the reservoir densification temperature;

[0044] Restore the thermal evolution history of the basin where the target reservoir is located and obtain the basin geothermal field;

[0045] The effective lower limit depth of the reservoir is predicted based on the reservoir densification temperature and basin geothermal field.

[0046] Among them, the recovery of the evolution process of the target reservoir and obtaining the reservoir densification temperature include: reconstructing the reservoir water-rock reaction process with the help of microscopic analysis, isotope analysis and inclusion testing, determining the reservoir diagenetic environment and pore evolution characteristics at different temperatures, determining the type of dense minerals and analyzing the formation temperature of the corresponding dense minerals to obtain the reservoir densification temperature.

[0047] In the present invention, the equations used to reconstruct the reservoir water-rock reaction process are as follows:

[0048] 2KAlSi3O8(potassium feldspar)+2H + +H2O=Al2Si2O5(OH)4(kaolinite)+2K + +4SiO2(Quartz)

[0049] KAlSi3O8+CO2+1.5H2O=0.5Al2Si2O5(OH) 49 (Kaolinite)+2SiO2+K + +HCO3 -

[0050] (Ca 2+ +Mg 2+ +Fe 2+ )+CO3 2- →(Mg,Ca,Fe)CO3

[0051] KAlSi3O8+Al2Si2O5(OH)4=KAl3Si3O 10 9(OH)2(illite)+2SiO2+H2O

[0052] The microscopic analysis includes: observing rock thin sections with a polarizing microscope to obtain samples reflecting the diagenetic characteristics of the depth section, and then performing cathode luminescence and scanning electron microscopy analysis on the samples reflecting the diagenetic characteristics of the depth section to determine the type, occurrence state and occupancy relationship of the diagenetic minerals.

[0053] In the present invention, the rock slices used can be selected by selecting wells that are representative of the region, such as wells with abundant rock and wall core samples, which can cover all strata and have sufficient sample points in the depth section of the transformation of the diagenetic stage; then, dyed resin or liquid glue (using the internationally universal blue color) is poured into the pore space of the rock under vacuum, and the resin or liquid glue is solidified at a certain temperature and pressure, and then ground to obtain the rock slices. Furthermore, other rock slice preparation methods in the field can also be used for preparation.

[0054] In the present invention, in the scanning electron microscope analysis, a scanning electron microscope is used to scan the sample using a focused very narrow high-energy electron beam, and various physical information is stimulated through the interaction between the light beam and the material, and the microscopic morphology of the material is characterized by collection, amplification, and re-imaging. By combining the scanning electron microscope and the polarizing microscope, the microscopic morphology is observed while the micro-area composition analysis of the material is performed to further determine the occurrence state and the occupation relationship of the diagenetic minerals.

[0055] Wherein, the isotope analysis includes: performing C isotope analysis and O isotope analysis on the carbonate rock obtained by microscopic analysis, and calculating the K-Ar age of the authigenic illite.

[0056] Among them, isotope analysis is mainly about carbon and oxygen isotopes of carbonate minerals. The value of carbon isotope can be used to determine the source of the material and then determine its formation environment, while the oxygen isotope is based on the formula:

[0057] 1000lnα 白云石-水 =3.2×10 6 / T1 2 -1.5

[0058] 1000lnα 方解石-水 =2.78×10 6 / T2 2 -2.89

[0059] Where α 方解石-水 =(1+δ 18 O 方解石 / 1000) / (1+δ 18 O 水 / 1000); α 白云石-水 =(1+δ 18 O 白云石 / 1000) / (1+δ 18 O 水 / 1000);δ 18 O 白云石 —Measured dolomite oxygen isotope value; δ 18 O 方解石 —Measured calcite oxygen isotope value; δ 18 O 水 —oxygen isotope value of water medium; T1—dolomite precipitation temperature, °C; T2—calcite precipitation temperature, °C;

[0060] The specific temperatures at which different types of carbonates are formed are calculated, and finally the formation process of carbonates is comprehensively judged by referring to the analysis results of carbon and oxygen isotopes;

[0061] In the present invention, authigenic illite is often the latest cementing mineral formed before oil and gas injection. Since oil and gas replace formation water and thus cause the termination of silicate diagenesis, the authigenic illite K-Ar age will record the time of oil and gas injection events and represent the maximum age of the formation of the trap structure. In the calculation process, the sample is first washed with oil, then the characteristics of clay minerals in the sample are studied by scanning electron microscopy and X-ray diffraction technology, the authigenic illite is separated and purified, the K content is determined, the Ar isotope ratio is analyzed, and the XRD purity is detected, and then the age is calculated by K-Ar, the age result is re-evaluated, the data is processed, and finally the calculation of the "corrected age" is realized.

[0062] Wherein, the inclusion test comprises: performing a phase transition test on the paleofluid in the gas-liquid two-phase inclusion to obtain the uniform temperature of the inclusion.

[0063] In the present invention, various data and information are obtained by qualitative or quantitative analysis of the paleofluid in the inclusion, and various geological processes in the crust and mantle under study are further explained. A gas-liquid two-phase inclusion (an inclusion in a single phase when captured) is selected, and the gas-liquid two-phase is transformed into a single phase when heated to a certain temperature using a hot and cold stage, and the phase state (single phase) when the inclusion is formed is restored, and the instantaneous temperature when restored is the uniform temperature of the inclusion.

[0064] The method of restoring the thermal evolution history of the basin where the target reservoir is located and obtaining the geothermal field of the basin includes: obtaining a planar distribution map of the temperature gradient of the entire basin based on the Mckenzie thermal history model with the help of formation testing, basement heat flow value and formation thermal conductivity testing.

[0065] In the present invention, the planar distribution map of the temperature gradient of the entire basin can be generated by using commonly used software in the field, such as PetroMod software.

[0066] The formation test includes: drill pipe formation test during drilling and temperature data in MDT test.

[0067] The base heat flow value includes: using the thermal resistance method proposed by CHAPMAN to calculate the earth heat flow, and the calculation formula is:

[0068]

[0069] Where: q s is the earth heat flow, mW / m 2 ; ΔZi is the depth difference between adjacent structural layers, km; K i Z i Thermal conductivity of the formation at depth, W / (m·K); T s is the oil test temperature, ℃; T0 is the near-surface isothermal zone temperature, 18℃.

[0070] Wherein, the formation conductivity test includes: testing the formation thermal conductivity value of the target layer.

[0071] Among them, the effective lower limit depth of the reservoir predicted based on the reservoir densification temperature and the basin geothermal field includes: establishing a linear relationship between geothermal gradient and burial depth with the help of the quantitative relationship between physical properties, geothermal field, and diagenetic evolution, and then calculating the effective lower limit depth of the target reservoir based on the temperature of the target reservoir.

[0072] In the present invention, compaction is the main reason for the reduction of reservoir porosity. According to the sandstone compaction curve of Baldwin and Butler (1985), the curve of porosity variation with burial depth can be known. Affected by the later diagenesis, the trend of porosity variation with depth is actually also affected by cementation and dissolution. Cementation and dissolution are controlled by temperature. From the syngenetic stage (temperature near the surface) to the early diagenetic stage (surface temperature -65°C), the acidic fluid mainly comes from atmospheric fresh water and humic acid produced by plant decay, and the local distribution of early cementing materials has limited impact on porosity.

[0073] When entering the early diagenetic stage B (65℃-85℃), organic acids began to be gradually generated, some aluminosilicate minerals were dissolved, cementation occurred extensively, and chlorite, kaolinite and illite were common; when the local temperature was 85℃-140℃, the reservoir was in an acidic environment, the dissolution was strong, and secondary pores were widely developed; when the local temperature was 140℃-160℃, the cementation of iron-containing carbonates, secondary quartz enlargement and clay minerals was enhanced, and the reservoir gradually densified, among which authigenic quartz was the most common and the time of large-scale precipitation roughly corresponded to the time of reservoir densification. The homogenization temperature of the brine inclusions on the secondary enlargement of quartz continued to increase with depth, but when it was greater than 160℃, the temperature no longer increased with depth, the dissolution stopped and the silica precipitated. It is speculated that the effective lower limit of the porous reservoir is a geothermal temperature of less than 160℃.

[0074] In a second aspect, this embodiment provides a device for predicting the effective lower limit depth of a reservoir, such as Figure 2 As shown, the device comprises:

[0075] A reservoir densification temperature acquisition module is used to restore the evolution process of the target reservoir and obtain the reservoir densification temperature;

[0076] The module for obtaining the basin geothermal field is used to restore the thermal evolution history of the basin where the target reservoir is located and obtain the basin geothermal field;

[0077] The effective lower limit depth prediction module is used to predict the effective lower limit depth of the reservoir based on the reservoir densification temperature and the basin geothermal field.

[0078] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0079] Further, the present invention provides an electronic device, which is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0080] like Figure 3 As shown, the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. The I / O interface 15 is also connected to the bus 14.

[0081] A number of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0082] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as a method based on predicting the effective lower limit depth of a reservoir.

[0083] In some embodiments, the method based on predicting the effective lower limit depth of the reservoir can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the method for predicting the effective lower limit depth of the reservoir described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the method for predicting the effective lower limit depth of the reservoir in any other appropriate manner (for example, by means of firmware).

[0084] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0085] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0086] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0087] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0088] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0089] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0090] The server provided in this embodiment includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for predicting the effective lower limit depth of a reservoir is implemented.

[0091] Unless otherwise specifically stated, terms such as processing, computing, calculating, determining, displaying, etc. may refer to the actions and / or processes of one or more processing or computing systems, or similar devices, which operate and convert data represented as physical (e.g., electronic) quantities within registers or memories of a processing system into other data similarly represented as physical quantities within memories, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0092] Those skilled in the art will also appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments of the present invention may all be implemented as electronic hardware, computer software, or a combination thereof. In order to clearly illustrate the interchangeability between hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above around their functions. Whether such functions are implemented as hardware or software depends on the specific application and the design constraints imposed on the entire system. A skilled person may implement the described functions in an alternative manner for each specific application, but such implementation decisions should not be interpreted as departing from the scope of protection of the present invention.

[0093] The steps of the method or algorithm described in conjunction with the embodiments herein may be directly embodied as hardware, a software module executed by a processor, or a combination thereof. The software module may be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a mobile disk, a CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor so that the processor can read information from the storage medium and can write information to the storage medium. Of course, the storage medium may also be an integral part of the processor. The processor and the storage medium may be located in an ASIC. The ASIC may be located in a user terminal. Of course, the processor and the storage medium may also be present in a user terminal as discrete components.

[0094] For software implementation, the techniques described in the present invention can be implemented with modules (e.g., procedures, functions, etc.) that perform the functions described in the present application. These software codes can be stored in a memory unit and executed by a processor. The memory unit can be implemented within the processor or outside the processor. In the latter case, it is coupled to the processor in a communication manner via various means, which are well known in the art.

[0095] Further, in order to illustrate the prediction effect that can be achieved by the method for predicting the effective lower limit depth of a reservoir provided by the present invention, the following actual example is used for exemplary description, as follows:

[0096] Example 1

[0097] The present invention provides a reservoir for the Xihu Sag in the East China Sea. The distribution of exploration wells in the reservoir is 0.3 exploration wells / 100 square kilometers. The actual prediction process is as follows:

[0098] The water-rock reaction process of the reservoir is reconstructed using thin section identification, scanning electron microscopy, laser micro-area isotope, inclusion testing and other data, the reservoir diagenetic environment and pore evolution characteristics at different temperatures are clarified, the formation temperature of typical dense minerals is determined, and the lower limit of the effective reservoir is predicted based on the characteristics of the basin's geothermal field.

[0099] The specific steps are as follows:

[0100] 1. Select wells that are representative of the region, and take cores from the wellbore or well wall to cover as many strata as possible for sampling, especially designing more sample points for the transformation depth section of the diagenetic stage; then inject dyed resin or liquid glue (using the internationally accepted blue color) into the pore space of the rock under vacuum, solidify the resin or liquid glue at a certain temperature and pressure, and then grind it into rock slices for observation under a polarizing microscope.

[0101] 2. Based on the observation of cast thin sections, select samples that can reflect the diagenetic characteristics of the depth section, use a scanning electron microscope to scan the samples with a focused narrow high-energy electron beam, stimulate various physical information through the interaction between the beam and the material, collect, magnify, and re-image the material microscopic morphology to characterize it. The resolution of the new scanning electron microscope can reach 1nm; the magnification can reach 300,000 times and above and can be adjusted continuously; and the depth of field, field of view, and stereoscopic imaging effect are good. By combining a scanning electron microscope with a polarizing microscope, the microscopic morphology is observed while the material micro-area composition analysis is performed to further determine the occurrence state and occupation relationship of the diagenetic minerals.

[0102] 3. Carbonate is an important indicator mineral of diagenetic environment. Its formation temperature and time are helpful to judge the diagenetic environment and diagenetic stage, and affect the porosity evolution. Through the previous observation, the specific carbonate types (siderite, calcite, ferrocalcite, dolomite and ankerite, etc.) are identified. The laser micro-area sampling equipment is used to heat the carbonate rock samples with a high-energy focused laser beam (laser probe) to produce CO2 gas (CaCO3=CaO+CO2) at high temperature, and send it to the mass spectrometer for analysis and determination of its C and O isotope values, so as to achieve "micro-area" in-situ sampling to achieve high spatial resolution and comparable accuracy to conventional analysis methods for C and O isotope analysis.

[0103] 4. Authigenic illite is often the latest cementing mineral formed before oil and gas injection. Since oil and gas replace formation water and thus cause the termination of silicate diagenesis, the authigenic illite K-Ar age will record the time of oil and gas injection events and represent the maximum age of the formation of the trap structure. First, wash the sample with oil, then use scanning electron microscopy and X-ray diffraction technology to study the characteristics of the sample clay minerals, separate and purify the authigenic illite, determine the K content, analyze the Ar isotope ratio and XRD purity test, then calculate the age through K-Ar, re-evaluate the age results, process the data, and finally calculate the "corrected age".

[0104] 5. The fluid trapped by the mineral during its growth process preserves various geological and geochemical information of the geological environment at that time (such as temperature, pressure, composition, etc.). Therefore, various data and information can be obtained through qualitative or quantitative analysis of the paleofluid in the inclusion, and the various geological processes in the crust and mantle under study can be further explained. Select gas-liquid two-phase inclusions (inclusions that are single-phase when captured), and use a hot and cold stage to heat to a certain temperature, so that the gas-liquid two-phase is transformed into a single phase, and the phase state (single phase) when the inclusion is formed is restored. The instantaneous temperature at the time of restoration is the uniform temperature of the inclusion.

[0105] 6. Compaction is the main reason for the reduction of reservoir porosity. According to the sandstone compaction curve of Baldwin and Butler (1985), we can know the curve of porosity variation with burial depth. Influenced by the later diagenesis, the trend of porosity variation with depth is actually also affected by cementation and dissolution. Cementation and dissolution are controlled by temperature. From the syngenetic stage (temperature near the surface) to the early diagenetic stage (surface temperature -65°C), acidic fluids mainly come from atmospheric fresh water and humic acid produced by plant decay, and early cementing materials are locally distributed, with limited impact on porosity. Entering the early diagenetic B period (65°C-85°C), organic acids begin to be gradually generated, some aluminosilicate minerals are dissolved, cementation occurs extensively, and chlorite, kaolinite and illite are common. When the local temperature is 85°C-140°C, the reservoir is in an acidic environment, dissolution is strong, and secondary pores are widely developed. At 140°C-160°C, iron-containing carbonates and secondary quartz increase in size, and clay mineral cementation is enhanced, and the reservoir gradually densifies ( Figure 4 ), among which authigenic quartz is the most common and its large-scale precipitation time roughly corresponds to the reservoir densification time. The homogenization temperature of the brine inclusions in the secondary quartz enlargement continues to increase with depth, but when it reaches 160℃, the temperature no longer increases with depth, the dissolution stops and the silica precipitates ( Figure 5 and Figure 6 ), it is inferred that the effective lower limit of porous reservoirs is a ground temperature of <160℃.

[0106] 7. Most oil and gas exploration is aimed at potential reservoirs. The samples obtained have a certain burial depth and are generally in the middle diagenesis stage or later. The diagenetic phenomena observed by thin sections and scanning electron microscopes are all characteristics of the middle diagenesis or later stages. Water-rock reaction occurs during the diagenesis process, and the reaction products are historical witnesses of the diagenesis of the reservoir. It can not only study the diagenesis, but also the history, composition and properties of fluid activity in order to restore the complete dynamic process of diagenetic evolution. Samples are selected to simulate underground conditions in the laboratory, and water-rock reactions are carried out under different temperatures, pressures and acid-base conditions to restore the geological process. Through the chemical reaction process of the mutual exchange of material components between aqueous solutions and mineral rocks, the complete dynamic process of diagenetic evolution in the study area can be understood.

[0107] 8. On the basis of clarifying the factors affecting physical properties and the dynamic process of diagenetic evolution, we further established the quantitative relationship between physical properties, geothermal field and diagenetic evolution, and proposed the formula 160℃=T×H+18℃ (T is the geothermal gradient and H is the burial depth), which can accurately calculate the effective lower limit depth.

[0108] 9. From point to line and then to surface, from well-existing to well-free areas, the temperature gradient plane distribution map of the whole basin is restored by integrating the basement heat flow value, basin thermal simulation and formation testing (DST) data ( Figure 7), according to the formula 160℃=T×H+18℃ (T is the geothermal gradient, H is the burial depth), the effective lower limit depth of the whole basin is calculated and predicted ( Figure 8 ).

[0109] 10. Verify and calibrate in practice, and test the prediction lower limit prediction technology based on the actual drilling situation of new wells, which is in line with expectations.

[0110] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0111] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0112] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for predicting the effective lower limit depth of a reservoir, characterized in that: The method comprises: Restore the evolution process of the target reservoir and obtain the reservoir densification temperature; Restore the thermal evolution history of the basin where the target reservoir is located and obtain the basin geothermal field; Based on the reservoir densification temperature and the basin geothermal field prediction, the linear fitting relationship between the reservoir temperature and the effective lower limit depth is obtained. According to the temperature of the target reservoir, the effective lower limit depth of the target reservoir is predicted.

2. The method for predicting the effective lower limit depth of a reservoir as claimed in claim 1, characterized in that: The process of restoring the evolution of the target reservoir and obtaining the reservoir densification temperature includes: reconstructing the reservoir water-rock reaction process by means of microscopic analysis, isotope analysis and inclusion testing, determining the reservoir diagenetic environment and pore evolution characteristics at different temperatures, determining the type of dense minerals and analyzing the formation temperature of the corresponding dense minerals to obtain the reservoir densification temperature.

3. The method for predicting the effective lower limit depth of a reservoir as claimed in claim 2, characterized in that: The microscopic analysis includes: observing rock thin sections with a polarizing microscope to obtain samples reflecting the diagenetic characteristics of the depth section, and then performing cathode luminescence and scanning electron microscopy analysis on the samples reflecting the diagenetic characteristics of the depth section to determine the type, occurrence state and occupation relationship of the diagenetic minerals.

4. The method for predicting the effective lower limit depth of a reservoir as claimed in claim 2 or 3, characterized in that: The isotope analysis includes: performing C isotope analysis and O isotope analysis on the carbonate rock obtained by microscopic analysis, and calculating the K-Ar age of the authigenic illite.

5. The method for predicting the effective lower limit depth of a reservoir according to any one of claims 2 to 4, characterized in that: The inclusion test comprises: performing a phase transition test on the paleofluid in the gas-liquid two-phase inclusion to obtain a uniform temperature of the inclusion.

6. The method for predicting the effective lower limit depth of a reservoir according to any one of claims 1 to 5, characterized in that: The said restoring the thermal evolution history of the basin where the target reservoir is located and obtaining the geothermal field of the basin comprises: obtaining a plane distribution map of the temperature gradient of the whole basin based on the Mckenzie thermal history model by means of formation testing, basement heat flow value and formation thermal conductivity testing; Preferably, the formation test includes: temperature data from drill pipe formation test and MDT test during drilling; Preferably, the base heat flow value comprises: calculating the earth heat flow using the thermal resistance method proposed by CHAPMAN; Preferably, the formation conductivity test includes: testing the formation thermal conductivity value of the target layer.

7. The method for predicting the effective lower limit depth of a reservoir according to any one of claims 1 to 6, characterized in that: The method of predicting the effective lower limit depth of the reservoir based on the reservoir densification temperature and the basin geothermal field includes: establishing a linear relationship between geothermal gradient and burial depth by means of the quantitative relationship between physical properties, geothermal field, and diagenetic evolution, and then calculating the effective lower limit depth of the target reservoir based on the temperature of the target reservoir.

8. A device for predicting the effective lower limit depth of a reservoir, characterized in that: The device comprises: A reservoir densification temperature acquisition module is used to restore the evolution process of the target reservoir and obtain the reservoir densification temperature; The module for obtaining the basin geothermal field is used to restore the thermal evolution history of the basin where the target reservoir is located and obtain the basin geothermal field; The effective lower limit depth prediction module is used to obtain the linear fitting relationship between the reservoir temperature and the effective lower limit depth based on the reservoir densification temperature and the basin geothermal field, and predict the effective lower limit depth of the target reservoir based on the temperature of the target reservoir.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively coupled to the at least one processor; Wherein, the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for predicting the effective lower limit depth of a reservoir as described in any one of claims 1-7.

10. A computer storage medium, characterized in that: The computer storage medium stores computer executable instructions, which, when executed by a processor, implement the method for predicting the effective lower limit depth of a reservoir as described in any one of claims 1 to 7.

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