Shale gas horizontal well geophysical prospecting guiding method and device

Abstract

The invention provides a shale gas horizontal well geophysical prospecting guiding method and device. Compared with the prior art, the method has the advantages that the problem that the subsequent stratum depth and occurrence of the horizontal well cannot be predicted completely by means of geosteering is solved, dynamic adjustment is achieved, high-speed drilling of the shale gas horizontal well can be guaranteed, the drilling rate of high-quality shale is increased, cost is saved, support is provided for high-quality exploration and development of shale gas, and the method is worthy of popularization and application. And the energy safety is ensured.

Description

Technical Field

[0001] The present invention relates to the field of shale gas exploration and development, and in particular to a shale gas horizontal well geophysical exploration guidance method and device. Background Art

[0002] Shale gas horizontal well guidance is a key link in shale gas development and an important guarantee for the economic benefits of shale gas exploration and development. High-quality horizontal well guidance can ensure that the horizontal well trajectory always passes through the target window in the high-quality shale section, so that high yield can be achieved in the later fracturing; if the horizontal well guidance quality is poor, the well trajectory is likely to pass through the non-high-quality shale section, resulting in the inability to achieve high yield after the horizontal well is drilled and fractured, and thus the inability to effectively develop shale gas.

[0003] At present, the guidance of shale gas horizontal wells is mainly based on the gamma, resistivity, and density measured by the rotary steering bit to infer the current shale formation occurrence and depth, thereby achieving guidance control. The rotary steering bit technology lacks predictability for subsequent formations after horizontal well drilling. It can only make backward corrections based on the current point information, reacts slowly to formation mutations, and cannot locate formation details and small faults, etc., and the guidance accuracy is limited. Even if the structural map of the study area is used as an aid, due to the complex and changeable structure, the actual drilling is very different from the initial structural map. For example, if the subsequent shale formation has a sudden occurrence and a small amplitude fold, it is very easy to cause the horizontal well trajectory to deviate from the target window of the high-quality shale section, resulting in poor fracturing effect of shale gas horizontal wells and no economic benefits for exploration and development. Summary of the invention

[0004] In view of this, the present invention aims to propose a shale gas horizontal well geophysical guidance scheme that can dynamically predict the subsequent stratum burial depth and production status of the horizontal well trajectory to adjust the horizontal well trajectory in real time, which can increase the drilling rate of high-quality shale sections in horizontal wells, improve drilling efficiency and save costs.

[0005] According to one aspect of the present invention, a shale gas horizontal well geophysical exploration guidance method is proposed, the method comprising:

[0006] Step 1, obtaining an initial velocity model of the study area, and using the initial velocity model to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain an initial shale stratigraphic structure map;

[0007] Step 2, designing an initial drilling plan based on the initial shale formation structure map;

[0008] Step 3, perform drilling operations and collect logging curves of drilling. After the drilling operation distance reaches the preset drilling length, compare the collected logging curves of drilling with the logging curves of adjacent wells to obtain the formation depth and occurrence of the drill bit position;

[0009] Step 4, adding the newly acquired formation depth and occurrence to the current velocity model, updating the velocity model, and updating the current shale formation structure map using the updated velocity model;

[0010] Step 5: predict whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure based on the updated shale formation structure map;

[0011] Step 6, based on the prediction, design the drill bit direction for further drilling operations.

[0012] In some embodiments, before step 1, the method further comprises establishing an initial velocity model by the following method:

[0013] Using seismic data, we can conduct detailed structural interpretation and obtain the fault characteristics and stratigraphic characteristics of shale storage;

[0014] The initial velocity model of time-to-depth conversion is established by combining well logging curves, logging layers, fault characteristics and stratigraphic characteristics.

[0015] In some embodiments, if it is predicted that there is a sudden change and / or special detailed structure in the formation of the horizontal well trajectory within the subsequent preset drilling length, then in step 6, the direction of the drill bit is adjusted based on the prediction.

[0016] In some embodiments, the method further comprises:

[0017] During the drilling operation, the velocity model and shale formation structure map are updated at every preset drilling length, and based on the updated shale formation structure map, it is predicted whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure. Based on the prediction, the drill bit direction for further drilling operations is designed.

[0018] In some embodiments, the preset drilling length ranges from 10 m to 30 m.

[0019] In some embodiments, the collected logging curves of the wellbore include a gamma curve, a resistivity curve, a sonic curve, and a density curve.

[0020] According to another aspect of the present invention, a shale gas horizontal well geophysical exploration guidance device is also proposed, the device comprising:

[0021] An initial model acquisition unit is used to obtain an initial velocity model of the study area, and use the initial velocity model to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain an initial shale stratigraphic structure map;

[0022] An initial plan design unit, used to design an initial drilling plan based on an initial shale formation structure map;

[0023] The drilling curve collection unit is used to perform drilling operations and collect logging curves of drilling. After the drilling operation distance reaches the preset drilling length, the collected logging curves of drilling are compared with the logging curves of adjacent wells to obtain the formation depth and occurrence of the drill bit position;

[0024] A model updating unit, used for adding the newly acquired formation depth and occurrence to the current velocity model, updating the velocity model, and updating the current shale formation structure map using the updated velocity model;

[0025] A trajectory prediction unit is used to predict whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure based on the updated shale formation structure map;

[0026] A steering design unit is used to design a drill bit direction for further drilling operations based on the prediction.

[0027] In some embodiments, the device further comprises:

[0028] Fine structural interpretation unit, used to use seismic data to conduct fine structural interpretation and obtain shale storage fault characteristics and stratigraphic characteristics;

[0029] The initial velocity model building unit is used to build an initial velocity model for time-depth conversion by combining well logging curves, well logging layers, fault characteristics and stratigraphic characteristics.

[0030] In some embodiments, if it is predicted that there is a sudden change and / or special detailed structure in the formation of the horizontal well trajectory within the subsequent preset drilling length, the guidance design unit adjusts the direction of the drill bit based on the prediction.

[0031] In some embodiments, during the drilling operation, the drilling curve collection unit, the model updating unit, the trajectory prediction unit, and the guidance design unit are repeatedly called.

[0032] In some embodiments, the preset drilling length ranges from 10 m to 30 m.

[0033] In some embodiments, the collected logging curves of the wellbore include a gamma curve, a resistivity curve, a sonic curve, and a density curve.

[0034] According to another aspect of the present invention, an electronic device is also provided, the electronic device comprising:

[0035] Memory, which stores executable instructions:

[0036] A processor runs the executable instructions in the memory to implement the shale gas horizontal well geophysical exploration guidance method described above.

[0037] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned shale gas horizontal well geophysical exploration guidance method is implemented.

[0038] The beneficial effects of the present invention include at least:

[0039] (1) The drilling rate of shale gas horizontal wells is improved, ensuring that the horizontal section trajectory is located in the high-quality production section;

[0040] (2) It realizes the dynamic prediction of the strata in the undrilled area, greatly improving the foresight of the guidance;

[0041] (3) Use multi-source information to enhance data constraints and make guidance results more accurate and reliable;

[0042] (4) It realizes an automated, intelligent, and refined guidance process, reducing the uncertainty caused by manual experience;

[0043] (5) The entire guidance system responds quickly and can achieve dynamic real-time adjustments, greatly improving guidance efficiency;

[0044] (6) Reduce or avoid rework and red-drilling caused by deviation from the target layer, thus reducing development costs;

[0045] (7) The guidance system is highly flexible and can adapt to complex geological conditions, reducing dependence on geological predictions;

[0046] (8) It is conducive to the efficient development of shale gas, increasing the production of single wells and reducing the overall development cost;

[0047] (9) The application of this guidance technology is conducive to promoting the rapid development of the shale gas industry;

[0048] (10) It is of great significance to ensure energy security and promote the unconventional oil and gas revolution.

[0049] The methods and apparatus of the present invention have other features and advantages that will be apparent from or will be described in detail in the accompanying drawings and subsequent detailed descriptions incorporated herein, which together serve to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0051] Figure 1 A flow chart of a shale gas horizontal well geophysical guidance method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0052] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0053] Example 1

[0054] In order to make the purpose, technical scheme and advantages of the present invention clearer, a shale gas horizontal well in a certain place is taken as an example. The research area is a favorable area for shale gas exploration. However, during the drilling of shale gas horizontal wells, the drilling speed of the horizontal well is affected due to the complex structure, the burial depth of the shale formation and the rapid change of the occurrence. Using the JY10 well in the area as a case, a detailed exemplary description of the present invention is first made.

[0055] Step 1: Conduct structural interpretation of the 3D seismic data in the area to confirm that the shale storage faults in the area are generally oriented in the northeast direction.

[0056] Step 2: Combine the well curves of JY194-3, JY195-2, SY1, NY1 and other wells drilled in the area, log the layers, interpret the faults, layers and process the velocity, and establish the initial velocity model of time-depth conversion.

[0057] Step 3: Use the time-depth conversion model to compile the initial shale stratigraphic structure map of the Longmaxi Formation and confirm that the overall burial depth of the high-quality shale in the Longmaxi Formation is between 900 and 6,500 meters.

[0058] Step 4: Design the target point of the shale gas horizontal well JY10HF according to the initial shale formation structure map and ground conditions. Design the target point A of the JY10HF well to be 3410 meters vertically, and start drilling.

[0059] Step 5: After the JY10HF horizontal well enters the designed target point, the gamma, resistivity, acoustic wave, density and other data of the well logging while drilling are collected. At this time, the vertical depth of the actual drilling target point is 3443 meters (the measured depth is 3662 meters), and the formation strike is 6.6° downward. There is a certain error between the design and the actual drilling.

[0060] Step 6: Add the obtained stratigraphic depth information and occurrence information to the initial velocity model, update the velocity model, use the new velocity model to perform time-depth conversion on the interpreted stratigraphic faults, and compile a new shale stratigraphic structure map.

[0061] Step 7: From the new shale formation structure map, it was found that the depth and occurrence of the formation in the subsequent 20-meter horizontal well trajectory changed. The vertical depth at the next 20-meter point was 3447.6 (measured depth 3682 meters), which was 1.3 meters deeper than the original design, and the formation was steeper than the original design.

[0062] Step 8: During the drilling of the JY10 well, the velocity model was updated every 20 meters, and the shale formation structure map was recompiled to predict the subsequent formation depth and production to ensure high-speed drilling of the horizontal well.

[0063] The JY10 well used a horizontal well guidance method combined with geophysical exploration. The horizontal section from target A to target B was 1,542 meters long, and the drilling time was 13 days at a cost of RMB 7.13 million. Compared with the JY207-1 well in the same structure but only using the geological guidance method, the horizontal section was 1,620 meters, and the drilling time was 19 days at a cost of RMB 9.35 million. The efficiency was significantly improved, and the drilling speed increased from 85 meters / day to 118 meters / day, an increase of about 38%. Due to the improvement in drilling efficiency, the cost has also been significantly reduced, from RMB 5,700 / meter to RMB 4,600 / meter.

[0064] For other detailed descriptions of this exemplary embodiment, reference may be made to the corresponding descriptions in the following embodiments, which will not be repeated here.

[0065] Example 2

[0066] Figure 1 A flow chart of a shale gas horizontal well geophysical guidance method according to an embodiment of the present invention is shown. The embodiment includes steps 1 to 6.

[0067] Step 1: obtain the initial velocity model of the study area, and use the initial velocity model to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain an initial shale stratigraphic structure map.

[0068] In some embodiments, the initial velocity model may be obtained by the following method:

[0069] Using seismic data, we can conduct detailed structural interpretation and obtain the fault characteristics and stratigraphic characteristics of shale storage;

[0070] The initial velocity model of time-to-depth conversion is established by combining well logging curves, logging layers, fault characteristics and stratigraphic characteristics.

[0071] Shale gas reservoirs are mainly located in shale formations. The inherent porosity and permeability of shale itself are very low, and it needs to rely on natural fractures for storage and migration. Among these natural fractures, fractures related to faults have better connectivity, so shale storage faults are faults developed in shale reservoirs or at their boundaries. The fracture network in these faults plays a key role in the accumulation and migration of shale gas.

[0072] Fault characteristics of shale reservoir faults can include:

[0073] Fault location and strike: confirm the location of the fault plane in space and the direction in which the fault extends;

[0074] Fault dip: the dip of the fault, whether it is vertical or oblique;

[0075] The nature of the fault: whether it is a normal fault, a reverse fault, or a transverse fault;

[0076] The distribution range of the fault: the length of the fault and whether it runs through the entire target layer;

[0077] Width of a fault zone: The extent of the fracture zone in a fault zone.

[0078] The stratigraphic characteristics of shale reservoir faults may include:

[0079] Upper and lower boundaries of the horizon: the top and bottom interfaces of the target reservoir horizon;

[0080] Layer thickness: statistics of the overall thickness of the reservoir;

[0081] Depth of the layer: determine the reservoir depth information;

[0082] The occurrence of the strata: the overall dip direction of the reservoir;

[0083] Detailed structure within the layer: small folds, small fault blocks and other structures within the layer.

[0084] The establishment of the initial velocity model for time-depth conversion usually includes the following steps:

[0085] (1) Collect the required data: well logging curves, well logging stratification results, fault characteristics and stratigraphic characteristics of the study area;

[0086] (2) Correlate and compare the logging curves to determine the comparative relationship between the logging curves.

[0087] (3) Based on the comparison, determine the time-depth relationship of stratigraphic boundaries.

[0088] (4) Collect or test the acoustic velocity parameters of each formation.

[0089] (5) The above data are digitized and input into a computer.

[0090] (6) Specific software, such as Petrel from Schlumberger, Hampson-Russell from CGG, and Kingdom from SMT, can be used to establish a speed model for time-to-depth conversion.

[0091] The velocity model may include information such as the top and bottom plate time or depth, velocity parameters, etc. of each layer. The velocity model is usually verified to ensure that the time-depth relationship of each layer is consistent.

[0092] Common algorithms used to establish velocity models for time-to-depth conversion include the grid method, velocity perturbation method, multi-parameter joint inversion, genetic algorithm, particle swarm algorithm and other intelligent algorithms.

[0093] According to the data source integration of this embodiment, multiple sources of information such as seismic data, well logging data, and geological data are organically combined, which enhances the constraints of velocity field simulation, is conducive to obtaining a high-quality velocity model, and lays the foundation for subsequent precise guidance calculations.

[0094] Using velocity models to convert the interpreted horizons into time and depth can include:

[0095] According to the velocity model, the corresponding actual depth of each layer interface in the measured depth is calculated;

[0096] By connecting the actual depth points of the same layer on different survey lines, we can obtain the depth structure diagram of the layer.

[0097] Time-depth conversion of faults using velocity models can include:

[0098] Based on the time position of the fault in the seismic section, the actual depth position is calculated;

[0099] By connecting the actual depths of the fault on different survey lines, the three-dimensional spatial position of the fault can be plotted.

[0100] Therefore, the initial velocity model can be used to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain the initial shale stratigraphic structure map.

[0101] The initial stratigraphic structure map obtained can contain the following information: the top and bottom interfaces of each stratum, as well as the absolute depth value; the inclination of the stratum, which expresses the occurrence of the stratum; the location and nature of the fault; the design of the drilling path; the distribution range of the profitable layer or target layer, etc., thus providing a basis for the subsequent design of the drilling plan.

[0102] Step 2: Design an initial drilling plan based on the initial shale formation structure map.

[0103] The target of the shale gas horizontal well can be designed according to the initial shale formation structure map obtained in step 1. The target of the horizontal well is the design target point of the horizontal section position, which is an area (such as a rectangular area) usually defined by a longitude and latitude range. When designing shale gas / oil horizontal well drilling, it is necessary to first determine the position of the horizontal section, that is, the target. According to the present invention, the most favorable production layer position can be selected as the target according to the formation structure map, and the block with large thickness and high porosity in the production layer shown in the formation structure map can be determined as the target, and drilling can be started.

[0104] Step 3, perform drilling operations and collect logging curves of drilling. After the drilling operation distance reaches the preset drilling length, compare the collected logging curves of drilling with the logging curves of adjacent wells to obtain the formation depth and occurrence of the drill bit position.

[0105] After the horizontal well is drilled into the target point, a logging curve while drilling can be collected. In some embodiments, the collected logging curves of the drilling include gamma curves, resistivity curves, sonic curves, and density curves.

[0106] After the drilling operation distance reaches the preset drilling length, for example, in one example, after the drilling operation distance reaches 20 meters, the collected logging curves of the drilling well and the logging curves of the adjacent wells can be compared to obtain the formation depth and occurrence at the drill bit position. The occurrence mainly refers to the strike and dip of the formation, reflecting the overall orientation of the formation. Determining the occurrence of the formation is very important for clarifying the spatial position of the formation and structural deformation.

[0107] Step 4: Add the newly acquired formation depth and occurrence to the current velocity model, update the velocity model, and use the updated velocity model to update the current shale formation structure map.

[0108] In this embodiment, when the drilling operation reaches a certain distance, the shale formation structure map is updated in time according to the formation depth and occurrence at the latest drill bit position, so as to realize dynamic prediction of the formation in the undrilled area, greatly improving the foresight of subsequent guidance.

[0109] Step 5: Based on the updated shale formation structure map, it is predicted whether there is a sudden change in the formation of the horizontal well trajectory within the subsequent preset drilling length and whether there is a special detailed structure.

[0110] The formation mutation may include the formation depth mutation and / or the formation occurrence mutation. The special detailed structure may include the micro-folds and / or small faults inside the formation.

[0111] If the subsequent horizontal well trajectory passes through an area with formation mutations and / or special detailed structures, it is very easy for the horizontal well to deviate from the target window of the high-quality shale section, resulting in poor fracturing effect of the shale gas horizontal well and no economic benefits for exploration and development.

[0112] The existing rotary guide drill bit technology can only perform backward correction based on the current point information, and is slow to respond to sudden changes in the formation, and cannot locate detailed formation structures and small faults, etc., and the guidance accuracy is limited. Even if the structural map of the study area is used as an aid, the actual drilling and the initial structural map are very different due to the complex and changeable structure. In this embodiment, the shale structural map is updated in time according to the drilled part, and the formation changes of the undrilled part can be accurately and dynamically predicted, so that the entire guidance system can respond quickly. Especially in a mining environment with complex geological conditions, the beneficial effects of this embodiment are more significant than those of the prior art.

[0113] Step 6, based on the prediction, design the drill bit direction for further drilling operations.

[0114] If the prediction results show that there are no sudden changes and / or special detailed structures in the horizontal well trajectory formation within the subsequent preset drilling length, drilling can continue along the originally designed drill direction.

[0115] If it is predicted that there are mutations and / or special detailed structures in the formation of the horizontal well trajectory within the subsequent preset drilling length, the drill bit direction can be adjusted to always ensure that the horizontal section trajectory is located in a high-quality production section, thereby increasing the drilling rate of shale gas horizontal wells, reducing costs and improving economic benefits.

[0116] In some embodiments, during the drilling operation, the velocity model and the shale formation structure map can be updated every preset drilling length, and based on the updated shale formation structure map, it can be predicted whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure, and based on the prediction results, a drilling plan for the subsequent preset drilling length can be designed.

[0117] That is, during the drilling operation, the above steps 3 to 6 are repeatedly executed, and the whole process realizes the dynamic prediction of the formation in the current undrilled area, so that the entire guidance system can respond quickly, significantly improve the guidance efficiency, and ensure that the horizontal section trajectory is always located in the high-quality production section.

[0118] If the preset drilling length is too long, the steering system may not be adjusted sensitively enough, and if it is too short, the drilling speed may be affected. After in-depth research, the inventor believes that in some examples, the preset drilling length may range from 10m to 30m. For example, the preset drilling length may be set to 20 meters (m).

[0119] To sum up, compared with the existing technology, the geophysical guidance method for shale gas horizontal wells provided in this embodiment solves the problem that the subsequent formation depth and occurrence of horizontal wells cannot be predicted by relying solely on geological guidance. In addition, this embodiment adopts dynamic adjustment to ensure high-speed drilling of shale gas horizontal wells, which not only improves the drilling rate of high-quality shale, but also saves costs, provides support for high-quality exploration and development of shale gas, and is conducive to ensuring national energy security.

[0120] Example 3

[0121] One embodiment of the present invention discloses a shale gas horizontal well geophysical exploration guidance device. The device comprises:

[0122] An initial model acquisition unit is used to obtain an initial velocity model of the study area, and use the initial velocity model to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain an initial shale stratigraphic structure map;

[0123] An initial plan design unit, used to design an initial drilling plan based on an initial shale formation structure map;

[0124] The drilling curve collection unit is used to perform drilling operations and collect logging curves of drilling. After the drilling operation distance reaches the preset drilling length, the collected logging curves of drilling are compared with the logging curves of adjacent wells to obtain the formation depth and occurrence of the drill bit position;

[0125] A model updating unit, used for adding the newly acquired formation depth and occurrence to the current velocity model, updating the velocity model, and updating the current shale formation structure map using the updated velocity model;

[0126] A trajectory prediction unit is used to predict whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure based on the updated shale formation structure map;

[0127] A steering design unit is used to design a drill bit direction for further drilling operations based on the prediction.

[0128] In the initial model acquisition unit, the time-depth conversion of the interpreted horizon using the velocity model may include:

[0129] According to the velocity model, the corresponding actual depth of each layer interface in the measured depth is calculated;

[0130] By connecting the actual depth points of the same layer on different survey lines, we can obtain the depth structure diagram of the layer.

[0131] Time-depth conversion of faults using velocity models can include:

[0132] Based on the time position of the fault in the seismic section, the actual depth position is calculated;

[0133] By connecting the actual depths of the fault on different survey lines, the three-dimensional spatial position of the fault can be plotted.

[0134] Therefore, the initial velocity model can be used to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain the initial shale stratigraphic structure map.

[0135] In the initial scheme design unit, the target of the shale gas horizontal well can be designed according to the initial shale formation structure map that has been obtained. The target of the horizontal well is the design target point of the horizontal section position, which is an area (such as a rectangular area) usually defined by a longitude and latitude range. When designing shale gas / oil horizontal well drilling, it is necessary to first determine the position of the horizontal section, that is, the target. According to the present invention, the most favorable production layer position can be selected as the target according to the formation structure map, and the block with large thickness and high porosity in the production layer shown in the formation structure map can be determined as the target, and drilling can begin.

[0136] After the horizontal well is drilled into the target point, the logging curve collection unit can collect the logging curve while drilling. In some embodiments, the collected logging curves of the drilling include gamma curves, resistivity curves, sonic curves, density curves, etc.

[0137] Through the model updating unit, after the drilling operation distance reaches the preset drilling length, for example, in one example, after the drilling operation distance reaches 20 meters, the collected logging curves of the drilling well and the logging curves of the adjacent wells can be compared to obtain the formation depth and occurrence at the drill bit position. The occurrence mainly refers to the strike and dip of the formation, reflecting the overall orientation of the formation. Determining the formation occurrence is very important for clarifying the spatial position of the formation and structural deformation.

[0138] When the drilling operation reaches a certain distance, the shale formation structure map is updated in time according to the formation depth and occurrence at the latest drill bit position, so as to realize the dynamic prediction of the formation in the undrilled area, greatly improving the foresight of subsequent guidance.

[0139] The formation mutations considered by the trajectory prediction unit may include formation depth mutations and / or formation occurrence mutations, and special detailed structures may include tiny folds and / or small faults inside the formation.

[0140] If the subsequent horizontal well trajectory passes through an area with formation mutations and / or special detailed structures, it is very easy for the horizontal well to deviate from the target window of the high-quality shale section, resulting in poor fracturing effect of the shale gas horizontal well and no economic benefits for exploration and development.

[0141] The existing rotary guide drill bit technology can only perform backward correction based on the current point information, and is slow to respond to sudden changes in the formation, and is unable to locate detailed formation structures and small faults, etc., and the guidance accuracy is limited. Even if the structural map of the study area is used as an aid, the actual drilling and the initial structural map are very different due to the complex and changeable structure. In this embodiment, the shale structure map is updated in time according to the drilled part, and the trajectory prediction unit can accurately and dynamically predict the formation changes of the undrilled part, so that the entire guidance system can respond quickly. Especially in a mining environment with complex geological conditions, the beneficial effects of this embodiment are more significant than those of the prior art.

[0142] In the guidance design unit, if the prediction results show that there are no mutations and / or special detailed structures in the formation of the horizontal well trajectory within the subsequent preset drilling length, drilling can continue along the originally designed drill bit direction; if it is predicted that there are mutations and / or special detailed structures in the formation of the horizontal well trajectory within the subsequent preset drilling length, the drill bit direction can be adjusted to always ensure that the horizontal section trajectory is located in a high-quality production section, thereby increasing the drilling rate of shale gas horizontal wells, reducing costs and improving economic benefits.

[0143] In some embodiments, the device further comprises:

[0144] Fine structural interpretation unit, used to use seismic data to conduct fine structural interpretation and obtain shale storage fault characteristics and stratigraphic characteristics;

[0145] The initial velocity model building unit is used to build an initial velocity model for time-depth conversion by combining well logging curves, well logging layers, fault characteristics and stratigraphic characteristics.

[0146] Fault characteristics of shale reservoir faults can include:

[0147] Fault location and strike: confirm the location of the fault plane in space and the direction in which the fault extends;

[0148] Fault dip: the dip of the fault, whether it is vertical or oblique;

[0149] The nature of the fault: whether it is a normal fault, a reverse fault, or a transverse fault;

[0150] The distribution range of the fault: the length of the fault and whether it runs through the entire target layer;

[0151] Width of a fault zone: The extent of the fracture zone in a fault zone.

[0152] The stratigraphic characteristics of shale reservoir faults may include:

[0153] Upper and lower boundaries of the horizon: the top and bottom interfaces of the target reservoir horizon;

[0154] Layer thickness: statistics of the overall thickness of the reservoir;

[0155] Depth of the layer: determine the reservoir depth information;

[0156] The occurrence of the strata: the overall dip direction of the reservoir;

[0157] Detailed structure within the layer: small folds, small fault blocks and other structures within the layer.

[0158] The establishment of the initial velocity model for time-depth conversion usually includes the following steps:

[0159] (1) Collect the required data: well logging curves, well logging stratification results, fault characteristics and stratigraphic characteristics of the study area;

[0160] (2) Correlate and compare the logging curves to determine the comparative relationship between the logging curves.

[0161] (3) Based on the comparison, determine the time-depth relationship of stratigraphic boundaries.

[0162] (4) Collect or test the acoustic velocity parameters of each formation.

[0163] (5) The above data are digitized and input into a computer.

[0164] (6) Specific software, such as Petrel from Schlumberger, Hampson-Russell from CGG, and Kingdom from SMT, can be used to establish a speed model for time-to-depth conversion.

[0165] The velocity model may include information such as the top and bottom plate time or depth, velocity parameters, etc. of each layer. The velocity model is usually verified to ensure that the time-depth relationship of each layer is consistent.

[0166] Common algorithms used to establish velocity models for time-to-depth conversion include the grid method, velocity perturbation method, multi-parameter joint inversion, genetic algorithm, particle swarm algorithm and other intelligent algorithms.

[0167] According to the data source integration of this embodiment, multiple sources of information such as seismic data, well logging data, and geological data are organically combined, which enhances the constraints of velocity field simulation, is conducive to obtaining a high-quality velocity model, and lays the foundation for subsequent precise guidance calculations.

[0168] In some embodiments, during the drilling operation, the drilling curve collection unit, the model updating unit, the trajectory prediction unit, and the guidance design unit are repeatedly called.

[0169] In some embodiments, the preset drilling length ranges from 10 m to 30 m.

[0170] Compared with the prior art, the shale gas horizontal well geophysical guidance device provided in this embodiment solves the problem that the subsequent stratum depth and occurrence of horizontal wells cannot be predicted by relying solely on geological guidance. In addition, this embodiment adopts dynamic adjustment to ensure high-speed drilling of shale gas horizontal wells, which not only improves the drilling rate of high-quality shale, but also saves costs, provides support for high-quality exploration and development of shale gas, and is conducive to ensuring national energy security.

[0171] For other detailed descriptions and advantages of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0172] Example 4

[0173] According to another aspect of the present invention, an electronic device is provided. The electronic device comprises:

[0174] Memory, which stores executable instructions:

[0175] A processor runs the executable instructions in the memory to implement the shale gas horizontal well geophysical exploration guidance method according to the present invention.

[0176] The method comprises the following steps:

[0177] Step 1, obtaining an initial velocity model of the study area, and using the initial velocity model to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain an initial shale stratigraphic structure map;

[0178] Step 2, designing an initial drilling plan based on the initial shale formation structure map;

[0179] Step 3, perform drilling operations and collect logging curves of drilling. After the drilling operation distance reaches the preset drilling length, compare the collected logging curves of drilling with the logging curves of adjacent wells to obtain the formation depth and occurrence of the drill bit position;

[0180] Step 4, adding the newly acquired formation depth and occurrence to the current velocity model, updating the velocity model, and updating the current shale formation structure map using the updated velocity model;

[0181] Step 5: predict whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure based on the updated shale formation structure map;

[0182] Step 6, based on the prediction, design the drill bit direction for further drilling operations.

[0183] In some embodiments, before step 1, the method further comprises establishing an initial velocity model by the following method:

[0184] Using seismic data, we can conduct detailed structural interpretation and obtain the fault characteristics and stratigraphic characteristics of shale storage;

[0185] The initial velocity model of time-to-depth conversion is established by combining well logging curves, logging layers, fault characteristics and stratigraphic characteristics.

[0186] In some embodiments, if it is predicted that there is a sudden change and / or special detailed structure in the formation of the horizontal well trajectory within the subsequent preset drilling length, then in step 6, the direction of the drill bit is adjusted based on the prediction.

[0187] In some embodiments, the method further comprises:

[0188] During the drilling operation, the velocity model and shale formation structure map are updated at every preset drilling length, and based on the updated shale formation structure map, it is predicted whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure. Based on the prediction, the drill bit direction for further drilling operations is designed.

[0189] In some embodiments, the preset drilling length ranges from 10 m to 30 m.

[0190] In some embodiments, the collected logging curves of the wellbore include a gamma curve, a resistivity curve, a sonic curve, and a density curve.

[0191] Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc.

[0192] The processor may be a central processing unit (CPU) or other forms of processing units with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of the present invention, the processor is used to run the computer-readable instructions stored in the memory.

[0193] The present embodiment discloses a volcanic rock porosity prediction device. The present embodiment establishes the relationship between porosity and lithofacies and conventional logging curves based on existing measured data through the LASSO algorithm. The present embodiment relies on the measured data of the study area rather than empirical parameters or core samples of a specific area in the past. In addition, the prediction process of the present embodiment has less human interference, and lithofacies information is added to the prediction, which can effectively improve the accuracy of porosity prediction in the study area.

[0194] For detailed description of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0195] Example 5

[0196] According to another aspect of the present invention, a computer-readable storage medium is provided, which stores a computer program. When the computer program is executed by a processor, the shale gas horizontal well geophysical exploration guidance method according to the present invention is implemented.

[0197] The method comprises the following steps:

[0198] Step 1, obtaining an initial velocity model of the study area, and using the initial velocity model to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain an initial shale stratigraphic structure map;

[0199] Step 2, designing an initial drilling plan based on the initial shale formation structure map;

[0200] Step 3, perform drilling operations and collect logging curves of drilling. After the drilling operation distance reaches the preset drilling length, compare the collected logging curves of drilling with the logging curves of adjacent wells to obtain the formation depth and occurrence of the drill bit position;

[0201] Step 4, adding the newly acquired formation depth and occurrence to the current velocity model, updating the velocity model, and updating the current shale formation structure map using the updated velocity model;

[0202] Step 5: predict whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure based on the updated shale formation structure map;

[0203] Step 6, based on the prediction, design the drill bit direction for further drilling operations.

[0204] In some embodiments, before step 1, the method further comprises establishing an initial velocity model by the following method:

[0205] Using seismic data, we can conduct detailed structural interpretation and obtain the fault characteristics and stratigraphic characteristics of shale storage;

[0206] The initial velocity model of time-to-depth conversion is established by combining well logging curves, logging layers, fault characteristics and stratigraphic characteristics.

[0207] In some embodiments, if it is predicted that there is a sudden change and / or special detailed structure in the formation of the horizontal well trajectory within the subsequent preset drilling length, then in step 6, the direction of the drill bit is adjusted based on the prediction.

[0208] In some embodiments, the method further comprises:

[0209] During the drilling operation, the velocity model and shale formation structure map are updated at every preset drilling length, and based on the updated shale formation structure map, it is predicted whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure. Based on the prediction, the drill bit direction for further drilling operations is designed.

[0210] In some embodiments, the preset drilling length ranges from 10 m to 30 m.

[0211] In some embodiments, the collected logging curves of the wellbore include a gamma curve, a resistivity curve, a sonic curve, and a density curve.

[0212] The present embodiment discloses a volcanic rock porosity prediction device. The present embodiment establishes the relationship between porosity and lithofacies and conventional logging curves based on existing measured data through the LASSO algorithm. The present embodiment relies on the measured data of the study area rather than empirical parameters or core samples of a specific area in the past. In addition, the prediction process of the present embodiment has less human interference, and lithofacies information is added to the prediction, which can effectively improve the accuracy of porosity prediction in the study area.

[0213] The computer-readable storage medium according to the embodiment of the present invention stores non-transitory computer-readable instructions, and when the non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the above-mentioned methods of the embodiments of the present invention are executed.

[0214] The above-mentioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or mobile hard disk), media with built-in rewritable non-volatile memory (e.g., memory card) and media with built-in ROM (e.g., ROM box).

[0215] Those skilled in the art should be able to understand that in order to solve the technical problem of how to obtain a good user experience, the present embodiment may also include well-known structures such as a communication bus and an interface, and these well-known structures should also be included in the protection scope of the present invention.

[0216] For detailed description of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0217] In summary, the beneficial effects of various embodiments of the present invention include at least:

[0218] (1) The drilling rate of shale gas horizontal wells is improved, ensuring that the horizontal section trajectory is located in the high-quality production section;

[0219] (2) It realizes the dynamic prediction of the strata in the undrilled area, greatly improving the foresight of the guidance;

[0220] (3) Use multi-source information to enhance data constraints and make guidance results more accurate and reliable;

[0221] (4) It realizes an automated, intelligent, and refined guidance process, reducing the uncertainty caused by manual experience;

[0222] (5) The entire guidance system responds quickly and can achieve dynamic real-time adjustments, greatly improving guidance efficiency;

[0223] (6) Reduce or avoid rework and red-drilling caused by deviation from the target layer, thus reducing development costs;

[0224] (7) The guidance system is highly flexible and can adapt to complex geological conditions, reducing dependence on geological predictions;

[0225] (8) It is conducive to the efficient development of shale gas, increasing the production of single wells and reducing the overall development cost;

[0226] (9) The application of this guidance technology is conducive to promoting the rapid development of the shale gas industry;

[0227] (10) It is of great significance to ensure energy security and promote the unconventional oil and gas revolution.

[0228] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications, or technical improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A shale gas horizontal well geophysical guidance method, characterized in that: The method comprises: Step 1, obtaining an initial velocity model of the study area, and using the initial velocity model to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain an initial shale stratigraphic structure map; Step 2, designing an initial drilling plan based on the initial shale formation structure map; Step 3, perform drilling operations and collect logging curves of drilling. After the drilling operation distance reaches the preset drilling length, compare the collected logging curves of drilling with the logging curves of adjacent wells to obtain the formation depth and occurrence of the drill bit position; Step 4, adding the newly acquired formation depth and occurrence to the current velocity model, updating the velocity model, and updating the current shale formation structure map using the updated velocity model; Step 5: predict whether there is a sudden change in the horizontal well trajectory and whether there is a special detailed structure within the subsequent preset drilling length based on the updated shale formation structure map; Step 6, based on the prediction, design the drill bit direction for further drilling operations.

2. The method according to claim 1, characterized in that Before step 1, the method further comprises establishing an initial velocity model by the following method: Using seismic data, we can conduct detailed structural interpretation and obtain the fault characteristics and stratigraphic characteristics of shale storage; The initial velocity model of time-to-depth conversion is established by combining well logging curves, logging layers, fault characteristics and stratigraphic characteristics.

3. The method according to claim 1, characterized in that: If it is predicted that there is a sudden change and / or special detailed structure in the formation of the horizontal well trajectory within the subsequent preset drilling length, then in step 6, the direction of the drill bit is adjusted based on the prediction.

4. The method according to claim 1, characterized in that: The method further comprises: During the drilling operation, the velocity model and shale formation structure map are updated at every preset drilling length, and based on the updated shale formation structure map, it is predicted whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure. Based on the prediction, the drill bit direction for further drilling operations is designed.

5. The method according to any one of claims 1 to 4, characterized in that: The preset drilling length ranges from 10m to 30m.

6. The method according to claim 1, characterized in that The collected logging curves of the drilling include gamma curve, resistivity curve, sonic curve and density curve.

7. A shale gas horizontal well geophysical exploration guidance device, characterized in that: The device comprises: An initial model acquisition unit is used to obtain an initial velocity model of the study area, and use the initial velocity model to perform time-depth conversion on fault characteristics and stratigraphic characteristics to obtain an initial shale stratigraphic structure map; An initial plan design unit, used to design an initial drilling plan based on an initial shale formation structure map; The drilling curve collection unit is used to perform drilling operations and collect logging curves of drilling. After the drilling operation distance reaches the preset drilling length, the collected logging curves of drilling are compared with the logging curves of adjacent wells to obtain the formation depth and occurrence of the drill bit position; A model updating unit, used for adding the newly acquired formation depth and occurrence to the current velocity model, updating the velocity model, and updating the current shale formation structure map using the updated velocity model; A trajectory prediction unit is used to predict whether there is a sudden change in the horizontal well trajectory formation within the subsequent preset drilling length and whether there is a special detailed structure based on the updated shale formation structure map; A steering design unit is used to design a drill bit direction for further drilling operations based on the prediction.

8. The device according to claim 7, characterized in that The device also includes: Fine structural interpretation unit, used to use seismic data to conduct fine structural interpretation and obtain shale storage fault characteristics and stratigraphic characteristics; The initial velocity model building unit is used to build an initial velocity model for time-depth conversion by combining well logging curves, well logging layers, fault characteristics and stratigraphic characteristics.

9. The device according to claim 7, characterized in that: If it is predicted that there is a sudden change and / or special detailed structure in the stratum of the horizontal well trajectory within the subsequent preset drilling length, the guidance design unit adjusts the direction of the drill bit based on the prediction.

10. An electronic device, characterized in that: The electronic device comprises: Memory, which stores executable instructions: A processor, wherein the processor runs the executable instructions in the memory to implement the method according to any one of claims 1 to 6.

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