Well trajectory optimization method and device for fracture-developed areas in non-target layers

Abstract

The present invention provides a well trajectory optimization method for a fracture-developed area in a non-target layer, including: determining en echelon units in a strike-slip en echelon fault system; classifying the faults in the determined en echelon units according to the fracture strength to obtain I-level faults, II-level faults, and III-level faults in descending order of fracture strength; spatially segmenting the faults in the determined en echelon units to determine the dip-terminal segments and turning segments of the faults; predicting fractures for the faults in the determined en echelon units according to the classification of the faults; determining or adjusting a well trajectory extending through the strike-slip en echelon fault system based on the classification of the faults, the dip-terminal segments of the faults, and the predicted fracture-developed areas so as to keep away from the I-level faults, II-level faults, and the turning segments of the faults and the fracture-predicted developed areas. The present invention also provides a well trajectory optimization device for a fracture-developed area in a non-target layer.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, in particular to the drilling trajectory optimization technology in the fracture-developed area of non-target layers, and specifically relates to a well trajectory optimization method and device for the fracture-developed area of non-target layers. Background Art

[0002] Fault zones are crucial for key factors such as hydrocarbon migration, trap occlusion, and reservoir development and transformation during the formation of hydrocarbon reservoirs. However, fault zones are a "double-edged sword". Due to the differential inheritance activities of the Caledonian and early Hercynian in multiple strata such as the deep Cambrian, the target Ordovician, and the shallow Silurian, while the strike-slip faults control the formation of fault-karst reservoirs in the target Ordovician, in non-target layers, such as the Lower Paleozoic Silurian, it mainly shows complex en echelon characteristics. The en echelon faults control the fracture-developed area of the interbedded sandstone and mudstone, resulting in serious drilling losses during the drilling process to the Silurian. The inventor of the present invention found that the main controlling factor for the serious losses in the Silurian is the fracture development caused by fault activities. Therefore, the fine interpretation and evaluation of the strike-slip en echelon faults in the Silurian during the early Hercynian are important bases and references for reducing the serious losses in the Silurian. For example, the reservoir type in Shunbei Oilfield in the Tarim Basin is mainly fault-karst reservoirs, and the fault-karst reservoirs are dissolution holes and fractures controlled by large-scale strike-slip faults. Affected by fault inheritance, the fracture-developed area controlled by faults in the interbedded sandstone and mudstone of the Silurian has serious losses.

[0003] Currently, there is no corresponding fine interpretation of faults and targeted evaluation research for the serious drilling losses in the Silurian in other blocks, nor has a corresponding well trajectory optimization technology been formed.

[0004] Therefore, it is hoped to propose a well trajectory optimization method to reduce the probability of serious losses in the fracture-developed area of non-target layers.

[0005] The above description is only for understanding the background of the relevant technologies in this field and does not admit that it belongs to the prior art. Summary of the Invention

[0006] The present invention aims to provide a drilling trajectory optimization method and device that can at least solve some of the above technical problems.

[0007] In an embodiment of the present invention, a well trajectory optimization method for the fracture-developed area of non-target layers is provided, which includes:

[0008] Determine en echelon units in the strike-slip en echelon fault system;

[0009] Classify the faults in the determined en echelon units according to the fault strength to obtain class I faults, class II faults, and class III faults with decreasing fault strength;

[0010] Spatially segment the fractures in the determined en echelon units to determine the dip-terminal segments and turning segments of the fractures;

[0011] According to the classification of the fractures, predict the fractures within the fracture control range in the determined en echelon units;

[0012] Based on the classification of the fractures, the dip-terminal segments of the fractures, and the predicted fractures, determine or adjust the well trajectory extending through the strike-slip en echelon fracture system to keep it away from the Class I fractures, Class II fractures, the turning segments of the fractures, and the fracture prediction development areas.

[0013] In some embodiments of the present invention, the non-target layer is the Silurian system between the seismic reflection wave T 6 0 and the seismic reflection wave T 7 0 In the absence of corresponding fracture evaluation and well trajectory optimization techniques for severe leakage in the non-target layer, such as the Silurian system, the embodiments of the present invention creatively provide a five-step fracture evaluation and trajectory optimization technique for well trajectories to reduce severe leakage in the non-target layer, such as the Silurian system, namely "determine units, level classification, spatial segmentation, fracture prediction, and integrated analysis", which reduces the probability of severe leakage in the non-target layer, such as the Silurian system, especially reduces the probability of severe leakage caused by drilling in the fracture development area of the non-target layer, such as the Silurian system.

[0014] In some embodiments of the present invention, determining the en echelon units in the strike-slip en echelon fracture system includes:

[0015] Determine the fracture interpretation marker beds to delimit the strike-slip en echelon fracture system, and conduct three-dimensional closed fracture interpretation in space for the strike-slip en echelon fracture system;

[0016] Analyze the fracture properties in the strike-slip en echelon fracture system during the three-dimensional closed fracture interpretation in space to obtain the fracture dip, dip angle, and fracture contact relationship;

[0017] Based on the fracture dip, dip angle, and fracture contact relationship, determine the en echelon units in the strike-slip en echelon fracture system.

[0018] In some embodiments of the present invention, classifying the fractures in the determined en echelon units according to the fracture strength to obtain Class I fractures, Class II fractures, and Class III fractures with decreasing fracture strength includes:

[0019] Determine the Class I fractures, where the Class I fractures include the en echelon unit control fractures, and the control fractures are boundary fractures that extend to the top and bottom of the Silurian formation of the strike-slip en echelon fracture system;

[0020]

[0021] ​Identify Class II fractures, where the Class II fractures include fractures that extend to the top of the en echelon fracture system of the strike segment but do not break through to the bottom, and the fracture throw, vertical and planar extension lengths of the Class II fractures are less than those of the Class I fractures;

[0022] Identify Class III fractures, where the Class III fractures include fractures within the en echelon unit, and the fracture throw, vertical and planar extension lengths of the Class III fractures are less than those of the Class II fractures.

[0023] In some embodiments of the present invention, the spatially segmenting the fractures in the determined en echelon unit to determine the dip terminal segment and the turning segment of the fractures includes:

[0024] Determine the spatial characteristics of the fractures in the en echelon unit, where the spatial characteristics include the vertical extension length;

[0025] Based on the spatial characteristics, determine the dip terminal segment and the turning segment of the fractures in the en echelon unit, where the vertical extension length of the turning segment is greater than that of the dip terminal segment and is located in the middle of the fracture.

[0026] In some embodiments of the present invention, the determining the spatial characteristics of the fractures in the en echelon unit includes:

[0027] Obtain a detailed interpretation of the ribbon effect of the fractures in the en echelon unit;

[0028] Obtain the spatial characteristics of the fractures in the en echelon unit from the detailed interpretation of the ribbon effect of the fractures in the en echelon unit.

[0029] In some embodiments of the present invention, the predicting the fractures in the determined en echelon unit according to the classification of the fractures includes:

[0030] Predict the fracture density of the fractures in the en echelon unit based on the classification of the fractures and the spatial segmentation, where the fracture density of the Class I fractures is greater than that of the Class II fractures, and the fracture density of the Class II fractures is greater than that of the Class III fractures, and where the fracture density of the turning segment in the same fracture is greater than that of the dip terminal segment;

[0031] Based on the distribution of the fracture density, determine the internal area of the tensile-shear dropped block with a low fracture density.

[0032] In some embodiments of the present invention, the determining or adjusting the well trajectory passing through the strike-slip en echelon fracture system based on the classification of the fractures, the dip terminal segment of the fractures and the predicted fractures so as to keep away from the Class I fractures, Class II fractures and the turning segments of the fractures, and the fracture prediction development areas includes:

[0033] The determined or adjusted well trajectory is close to the dip end of the Class III fault and / or is located in the internal area of the strike-slip pull-apart block.

[0034] In some embodiments of the present invention, there is provided a well trajectory optimization device for a fracture-developed area of a non-target layer, which includes:

[0035] An en echelon unit determination module, configured to determine en echelon units in a strike-slip en echelon fault system;

[0036] A fault classification module, configured to classify the faults in the determined en echelon units according to the fault strength, so as to obtain Class I faults, Class II faults, and Class III faults in descending order of fault strength;

[0037] A spatial segmentation module, configured to perform spatial segmentation on the faults in the determined en echelon units to determine the dip end segments and turning segments of the faults;

[0038] A fracture prediction module, configured to perform fracture prediction on the faults in the determined en echelon units according to the classification of the faults;

[0039] A well trajectory optimization module, configured to determine or adjust the well trajectory passing through the strike-slip en echelon fault system based on the classification of the faults, the dip end segments of the faults, and the predicted fractures, so as to make it away from the Class I faults, Class II faults, and the turning segments of the faults and the fracture prediction development areas.

[0040] In some embodiments of the present invention, the non-target layer is the Silurian system between the T 6 0 seismic reflection wave and the T 7 0 seismic reflection wave.

[0041] Aiming at the serious leakage problem of the non-target layer, such as the Silurian system (in some embodiments of the present invention, it is the Silurian system of the Lower Paleozoic non-target layer section in Shunbei Oilfield, Tarim Basin), and combining that the main controlling factor of leakage is fracture development under the control of faults, the embodiments of the present invention carry out relative continuous seismic wave T 6 0 (the top of the Silurian system), T 7 0 (the bottom of the Silurian system) as marker beds, carry out three-dimensional fine interpretation of en echelon faults, combine fault properties and parameter statistics to determine en echelon units and Silurian system level classification; analyze the differences of en echelon faults spatially and perform fault segmentation; combine fracture prediction, consider the Ordovician geological target situation, and creatively propose a "five-step" seismic optimization technology for well trajectory to reduce the leakage of non-target layers, and reduce the probability of leakage of non-target layers during drilling.

[0042] Thus, the embodiments of the present invention achieve the following technical effects:

[0043] 1. Establish corresponding fine interpretation and evaluation techniques for fractures aiming at serious leakage in non-target intervals of drilling.

[0044] 2. Establish well trajectory optimization techniques for serious leakage in non-target intervals to reduce the probability of leakage.

[0045] Other features and advantages of the embodiments of the present invention can be learned from the following specific embodiments, and some can be deduced by those skilled in the art through the teachings herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings, where:

[0047] Figure 1 shows a flowchart of a method according to an embodiment of the present invention;

[0048] Figure 2 shows a flowchart of a method according to an embodiment of the present invention;

[0049] Figure 3 shows a flowchart of a method according to an embodiment of the present invention;

[0050] Figure 4 shows a flowchart of a method according to an embodiment of the present invention;

[0051] Figure 5 shows a flowchart of a method according to an embodiment of the present invention;

[0052] Figure 6 shows a flowchart of a method according to an embodiment of the present invention;

[0053] Figure 7 shows a structural diagram of device modules according to an embodiment of the present invention;

[0054] Figures 8A to 8C shows the spatial characteristics of en echelon units according to an embodiment of the present invention, where Figure 8A is a plan view of a strike-slip en echelon fracture system, Figure 8B is a sectional view, Figure 8C is a three-dimensional solid view for showing the demarcation of en echelon units;

[0055] Figure 9 shows the classification characteristics of en echelon fractures according to an embodiment of the present invention, showing Class I fractures, Class II fractures and Class III fractures;

[0056] Figures 10A to 10G shows the spatial segmentation characteristics of en echelon fractures according to an embodiment of the present invention, where Figure 10A and Figure 10B are plan views and show the "ribbon effect" of fine interpretation of 1Line×1Trace (25m×25m),Figures 10C to 10F It is a sectional view to show the inclined final section and the turning section, Figure 10G and it is a three-dimensional view;

[0057] Figures 11A to 11C It shows a schematic diagram of well trajectory optimization according to an embodiment of the present invention, wherein Figure 11A it shows a part of the en echelon fracture system at different depths in the form of a top view, Figure 11B and it is a sectional view, Figure 11C and it is a three-dimensional space interpretation diagram. Specific embodiments

[0058] To make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below in combination with specific embodiments and drawings. Herein, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but not to limit the present invention.

[0059] In some embodiments of the present invention, a well trajectory optimization method is provided, which has five steps of "determination unit, level classification, spatial segmentation, fracture prediction, and integrated analysis".

[0060] Further, in the embodiment as Figure 1 shown, a well trajectory optimization method for the fracture development area of non-target layers is provided, which may include the following steps S101 to S105.

[0061] In some embodiments, the non-target layer may be the Silurian system between the T 6 0 seismic reflection wave and the T 7 0 seismic reflection wave. However, it can be conceived that the non-target layer is other layers above the target layer.

[0062] S101: Determine the en echelon unit in the strike-slip en echelon fracture system;

[0063] In some embodiments, the step S101 may include steps such as fracture fine interpretation, fracture pattern analysis, and determination of fracture units.

[0064] Specifically, as Figure 2 shown, the determination of the en echelon unit in the strike-slip en echelon fracture system may include the following steps S201 to S203:

[0065] S201: Determine the fracture interpretation marker layer to delimit the strike-slip en echelon fracture system, and conduct three-dimensional closed interpretation of the fracture space of the strike-slip en echelon fracture system;

[0066] In some embodiments, the fine fracture interpretation can be carried out as follows: Taking the Sinian fault system in the early Hercynian period in the Shunbei Oilfield as an example, it is a strike-slip en echelon fault system. In some embodiments, it can be based on T 6 0 seismic reflection wave (top of the Sinian System), T 7 0 seismic reflection wave (bottom of the Sinian System) as the fault interpretation marker horizons. Preferably, for the top of the non-target formation, such as T 6 0 seismic reflection wave (top of the Sinian System), the bottom of the non-target formation, T 7 0 seismic reflection wave (bottom of the Sinian System), strengthen the coherence and discontinuity attributes along the formation, so as to carry out the three-dimensional spatial closed interpretation of the strike-slip en echelon fault system (for example, with the help of DSG software), and thereby determine the planar detected faults at the top of the non-target formation, such as T 6 0 seismic reflection wave (top of the Sinian System) and the corresponding relationship between the planar detected faults at the bottom of the non-target formation, T 7 0 seismic reflection wave (bottom of the Sinian System).

[0067] S202: Analyze the fracture properties in the strike-slip en echelon fault system during the three-dimensional spatial closed interpretation of the faults to obtain the fracture dip direction, dip angle and the contact relationship between the faults;

[0068] In some embodiments, the fracture property analysis can be carried out as follows: For the strike-slip en echelon fault system interpreted spatially based on the marker horizons T 6 0 seismic reflection wave (top of the Sinian System), T 7 0 seismic reflection wave (bottom of the Sinian System), conduct statistics on the fracture properties such as the fracture dip direction, dip angle, fault throw and the contact relationship between the faults in the strike-slip en echelon system, so as to provide a basis for determining the en echelon units.

[0069] S203: Determine the en echelon units in the strike-slip en echelon fault system based on the fracture dip direction, dip angle and the contact relationship between the faults.

[0070] In some embodiments, the determination of the en echelon units can be carried out as follows: The inventor found that the en echelon units formed by the tensional strike-slip en echelon faults are relatively independent, and the corresponding fracture characteristics of each en echelon unit have certain regularities; here, the inventor found that the boundary faults of the same en echelon unit are adjacent, dip towards each other, and both faults break to the top surface of the Yijianfang Formation of the Ordovician System; thus, by judging the fracture dip direction, dip angle and the contact relationship between the faults, those with such characteristics can be determined as the same en echelon unit.

[0071] S102: Classify the fractures in the determined en echelon units according to the fracture strength to obtain fractures with decreasing fracture strength as Class I fractures, Class II fractures, and Class III fractures;

[0072] In some embodiments, as Figure 3 shown, the step S102 may specifically include the following steps S301 to S303:

[0073] S301: Determine Class I fractures, where the Class I fractures include en echelon unit control fractures, and the control fractures are boundary fractures that extend to the fractures at the top and bottom of the strike-slip en echelon fracture system;

[0074] In some specific embodiments, Class I fractures can be determined as follows: Based on the fine interpretation of the fractures in the strike-slip en echelon system, the fracture throw, fracture vertical and planar extension lengths of the en echelon unit control fractures or boundary fractures are relatively larger than those of other fractures, and they can be defined as Class I fractures. They usually break through the top of the Silurian system upwards, such as T 6 0 seismic reflection wave (top of the Silurian system), and break through the top of the Yijianfang Formation of the Ordovician system downwards, such as breaking through T 7 0 seismic wave (bottom of the Silurian system). In some embodiments, only the boundary fractures of the en echelon unit (such as a pair of boundary fractures) are defined as Class I fractures.

[0075] S302: Determine Class II fractures, where the Class II fractures include fractures that extend to the top of the strike segment en echelon fracture system but do not break through to the bottom. The fracture throw, fracture vertical and planar extension lengths of the Class II fractures are smaller than those of the Class I fractures;

[0076] In some specific embodiments, Class II fractures can be determined as follows: For the internal fractures of the en echelon unit control fractures, they do not break through the top of the Silurian system upwards, such as seismic wave T 6 0 (top of the Silurian system), but break through the bottom of the non-target formation downwards, such as seismic wave T 7 0 (bottom of the Silurian system), or vice versa. The fracture throw, fracture vertical and planar extension lengths of such fractures are smaller than those of the Class I fractures and can be defined as Class II fractures.

[0077] S303: Determine Class III fractures, where the Class III fractures include fractures within the en echelon unit. The fracture throw, fracture vertical and planar extension lengths of the Class III fractures are smaller than those of the Class II fractures.

[0078] In some specific embodiments, Class III fractures can be determined as follows: For the associated adjustment fractures in the en echelon unit, they only develop within the Silurian strata, and the fracture throw and planar extension length are smaller than those of the Class II fractures. For example, they include or mainly include T6 3 The discontinuous detection results of the discontinuous attributes of the seismic reflection wave (top of the Kalpin Tagh Formation in the Silurian) are determined. Such faults can be defined as grade III faults, and their fault throw, vertical and planar extension lengths are smaller than those of grade II faults.

[0079] S103: Spatially segment the faults in the determined en echelon units to determine the distal and turning segments of the faults;

[0080] In some embodiments, the spatial segmentation may include steps of determining the spatial characteristics of the faults, determining the differential characteristics within the same fault, and the fault locations.

[0081] In a specific embodiment, as Figure 4 shown, the step S103 may include steps S401 and S402:

[0082] S401: Determine the spatial characteristics of the faults in the en echelon units, where the spatial characteristics include the vertical extension length;

[0083] In a specific embodiment, as Figure 5 shown, the step S401 may include the following steps S501 and S502:

[0084] S501: Obtain a fine interpretation of the ribbon effect of the faults in the en echelon units;

[0085] S502: Obtain the spatial characteristics of the faults in the en echelon units from the fine interpretation of the ribbon effect of the faults in the en echelon units.

[0086] In some embodiments, when determining the spatial characteristics of faults, the "ribbon effect" of en echelon faults can be considered. As an example, for instance, the Silurian faults in the Shunbei area in the early Hercynian period are mainly negative flower-shaped en echelon strike-slip faults under a tensile-shear background. Different en echelon units have consistencies and differences, and the en echelon faults have a strong "ribbon effect". The vertical extension length of the faults and optionally the size of the fault throw can be determined based on this "ribbon effect" or the negative flower-shaped characteristics.

[0087] S402: Based on the spatial characteristics, determine the distal and turning segments of the faults in the en echelon units, where the vertical extension length of the turning segment is greater than that of the distal segment and is located in the middle of the fault.

[0088] In some embodiments, the location of the faults can be determined by determining the differential characteristics. For example, the negative flower-shaped strike-slip faults with en echelon characteristics under a tensile-shear background have strong differences. Different positions of the same fault are divided into distal and turning segments. The fault throw size and vertical extension length at the turning segment are both greater than those at the distal segment.

[0089] S104: Predict the fractures in the identified en echelon units according to the classification of the fractures.

[0090] In some embodiments, as Figure 6 shown, step S104 may include steps S601 and S602:

[0091] S601: Predict the fracture density of the fractures in the en echelon units based on the classification of the fractures and the spatial segmentation.

[0092] In some embodiments, within the same distance from a fracture, the fracture density of grade I fractures is greater than that of grade II fractures, and the fracture density of grade II fractures is greater than that of grade III fractures. Among them, the fracture density of the turning segment in the same fracture is greater than that of the dipping end segment.

[0093] S602: Determine the internal area of the tensile-shear slump block with a low fracture density based on the distribution of the fracture density.

[0094] In some embodiments, the fracture prediction may have the following characteristics: Combining the strike-slip fracture level division and the spatial segmentation difference characteristics of the Silurian en echelon units, the inventors found that fractures of different levels control different fracture zone strengths (for example, control the fracture density of the slit zone), where the fracture zone strength controlled by grade I fractures > the fracture zone strength controlled by grade II fractures > the fracture zone strength controlled by grade III fractures. There are also differences in the fracture zone strength of the same fracture, and the fracture zone strength at the turning end is greater than that at the dipping end. By way of explanation and not limitation, the inventors found that based on the differential distribution law of fracture strength at different fracture levels, the seismic facies characteristics in the area with a large fracture density are manifested as strong energy anomalies. Thus, the internal area of the tensile-shear slump block in the low fracture density area can be obtained.

[0095] S105: Determine or adjust the well trajectory extending through the strike-slip en echelon fracture system based on the classification of the fractures, the dipping end segments of the fractures, and the predicted fractures, so as to keep it away from the grade I fractures, grade II fractures, the turning segments of the fractures, and the fracture prediction development areas.

[0096] In some embodiments, step S105 may include: making the determined or adjusted well trajectory close to the dipping end of the grade III fractures and / or located in the internal area of the tensile-shear slump block.

[0097] In some embodiments, such integrated analysis and well trajectory optimization can be carried out as follows: Combining the geological target of the Ordovician target layer-scale fault dissolution body, comprehensively considering the geological target of the fracture zone. If it is impossible to deploy the well trajectory outside the en echelon fault system (zone), it is preferably possible to optimize the trajectory in the areas without energy anomalies inside the en echelon unit III-level faults, the dip ends of en echelon faults, and strike-slip blocks, etc. Thus, the optimized well trajectory can be determined or the original well trajectory can be optimized and adjusted, so as to reduce the probability of severe leakage during drilling in non-target layers, such as the Silurian system.

[0098] such as Figure 7 As shown, the embodiment of the present invention also provides a well trajectory optimization device 700 for the fracture-developed area of non-target layers, which may include: an en echelon unit determination module 701 for determining en echelon units in the strike-slip en echelon fault system; a fracture classification module 702 for classifying the fractures in the determined en echelon units according to the fracture strength to obtain I-level fractures, II-level fractures, and III-level fractures with gradually decreasing fracture strength; a spatial segmentation module 703 for spatially segmenting the fractures in the determined en echelon units to determine the dip ends and turning segments of the fractures; a fracture prediction module 704 for predicting fractures in the determined en echelon units according to the classification of the fractures; a well trajectory optimization module 705 for determining or adjusting the well trajectory extending through the strike-slip en echelon fault system based on the classification of the fractures, the dip ends of the fractures, and the predicted fractures so that it is far away from the I-level fractures, II-level fractures, and the turning segments and fracture prediction-developed areas of the fractures.

[0099] To better understand the structure and function of the embodiments of the present invention, hereinafter, taking a certain 3D work area in the Tarim Basin (hereinafter referred to as S 3D for short) as an example with reference to FIGS. 8 to 11, a well trajectory optimization technology example for reducing severe leakage in the Silurian system will be further described in detail. It can be imagined that the following features can be combined with multiple embodiments of the present invention to obtain new embodiments.

[0100] Step S1: Determine the unit

[0101] such as Figures 8A to 8C As shown, S 3D is located on the north slope of the central Tarim Basin. During the first stage of the Middle Caledonian, under the action of the west Kunlun compressive stress in the southwest direction, multiple groups of NW-trending reverse strike-slip fault zones such as the No. I and No. II faults in the central Tarim were formed; during the third stage of the Middle Caledonian, superimposed by the Altun compressive stress in the southeast direction, with differential movement of blocks, while the NW-trending faults continued to move, a series of NE-trending strike-slip fault zones were formed. The main activity period of the NE-trending strike-slip fault zones was the Middle Caledonian and the Early Hercynian. The fault characteristics in the Early Hercynian were mainly negative flower-shaped en echelon characteristics under the background of strike-slip and torsion. The determination of en echelon units mainly includes three parts. First, carry out fine interpretation of en echelon faults, using T 6 0 seismic reflection wave (top of the Silurian system), T7 0 The seismic reflection wave (bottom of the Silurian System) is the fault interpretation marker bed, and T is preferred. 6 0 The seismic reflection wave (top of the Silurian System), T 7 0 The seismic reflection wave (bottom of the Silurian System) strengthens the coherence and discontinuity attributes along the layer, and conducts a three-dimensional closed interpretation of the strike-slip en echelon faults in space. At the same time, combined with T 6 3 The seismic reflection wave (top of the Kalpin Tagh Formation of the Silurian System) strengthens the coherence and discontinuity attributes, and conducts a fine three-dimensional interpretation of the internal faults of the Silurian System; secondly, conduct a fault property analysis, and conduct statistics on the fault properties such as the dip, dip angle, strike, fault throw and the contact relationship between faults of the strike-slip en echelon faults to provide a basis for determining the en echelon unit. Finally, further determine the en echelon unit. According to the adjacent and opposite dipping of the boundary faults of the same en echelon unit, the fault throw and the planar extension length are equivalent, and the two faults intersect in the strata below the Silurian System, these characteristics can be determined as the same en echelon unit.

[0102] Step S2: Level classification

[0103] Such as Figure 9 As shown, through the fine interpretation of the strike-slip en echelon faults, the level classification of the en echelon faults is carried out.

[0104] In the shown example, the fault throw, vertical and planar extension length of the faults controlling the boundary faults of the en echelon unit are the largest, and such faults are Class I faults. The internal faults of the en echelon unit are broken up to the T 6 0 seismic reflection wave (top of the Silurian System), and broken through the T 7 0 seismic reflection wave (bottom of the Silurian System). The fault throw, vertical and planar extension length of the faults are smaller than those of the Class I faults, and such faults are Class II faults. The associated adjustment faults in the en echelon unit are only developed within the Silurian System strata, and the fault throw and planar extension length are smaller than those of the Class II faults, mainly determined by the detection results of the discontinuity attributes of the T 6 3 seismic reflection wave (top of the Kalpin Tagh Formation of the Silurian System), but not broken up to the T 6 0 seismic reflection wave (top of the Silurian System), and not broken through the T 7 0 seismic reflection wave (bottom of the Silurian System), and such faults are Class III faults.

[0105] Step S3: Spatial segmentation

[0106] Such as Figures 10A to 10GAs shown in the figure, the Early Hercynian Silurian faults in the Shunbei area are mainly negative flower-shaped en-echelon strike-slip faults under the background of extension-torsion. Different en-echelon units have consistencies and differences. Through the fine interpretation of faults with 1Line×1Trace (25m×25m), the fault dip properties of the same en-echelon fault will reverse, showing a strong "ribbon effect". At the same time, the fault throw and vertical extension length of the same fault vary at different positions. The fault throw and vertical extension length are smaller at the inclined end section; at the turning section, the fault throw and vertical extension length are larger.

[0107] Step S4: Fracture prediction

[0108] Combined with the reference Figure 9 and Figures 10A - 10G , forward modeling of the model shows that there are differences in fracture density within the control ranges of faults at different levels. Based on the fault level classification, the fracture density is the largest within the control range of Grade I faults, the smallest within the control range of Grade III faults, and the fracture density within the control range of Grade II faults is in the middle; there are also differences in the fracture zone density of the same fault. Combining the sectional characteristics of the spatial differences of the faults, the fracture density at the turning end is greater than that at the starting inclined end. The fracture intensity development is weaker inside the en-echelon unit's extension-torsion block compared to the fault area. Based on the distribution difference law of fracture density at different levels of faults and different positions of the same fault, energy-related attributes within the Silurian fault zone are predicted. The seismic facies characteristics in areas with a relatively large fracture density show strong energy anomalies.

[0109] Step S5: Integrated analysis

[0110] As Figures 11A to 11C shown in the figure, fracture development controlled by faults is the main reason for severe losses in the Silurian. Optimizing areas with a relatively small fracture density can effectively reduce severe losses in the Silurian. The fracture density within the control range of Grade III faults in the en-echelon faults is lower than that of Grade II and Grade I faults. The fracture density at the inclined end of the en-echelon fault is lower than that at the turning end. The fracture density inside the en-echelon unit's extension-torsion block is lower than that in the fault development area. The fracture development density in areas without energy anomalies in the Silurian en-echelon zone is lower than that in areas with strong energy anomalies. Considering the geological targets in the fault zone and a horizontal displacement of about 700m during drilling, the en-echelon faults in the Shunbei area are relatively wide. If it is not possible to deploy the well trajectory outside the en-echelon fault zone due to horizontal displacement reasons, it is preferable to optimize the trajectory in areas of Grade III faults in the en-echelon unit, the inclined end of the en-echelon fault, and areas without energy anomalies inside the extension-torsion block.

[0111] Here, this example of the present invention discloses a "five-step" well trajectory optimization method innovatively proposed for the serious drilling fluid loss problem caused by the development of faults and fractures in the Silurian system of the Shunbei Oilfield in the Tarim Basin. Through the establishment of a system of "determining units, level classification, spatial segmentation, fracture prediction, and integrated analysis", a fine interpretation and comprehensive evaluation technology for the strike-slip fault zone in the Silurian system is established, guiding the optimization of the well trajectory to avoid fluid loss in the Silurian system and reducing the probability of serious fluid loss in the Silurian system during drilling in the Shunbei area. Through the fine interpretation of the en echelon strike-slip fault zone in the Silurian system, en echelon units are determined. According to the differential characteristics of strike-slip faults, spatial segmentation is carried out. Combining the differences in fault levels, fault classification of grade I faults, grade II faults, and grade III faults is carried out; combining the forward modeling understanding of the model and the change in fracture prediction energy class, the fracture development intensity at different fracture positions and regions within the en echelon unit is predicted; combining the fracture prediction of different-level faults and the geological target of the Ordovician target layer, the integrated optimization of the well trajectory to avoid fluid loss in the Silurian system is carried out. Through the specific application of the entire set of method and technical processes of the present invention, the probability of serious fluid loss in the Silurian system is reduced.

[0112] In summary, the embodiment of the present invention fills the blank in the previous research on the optimization of well trajectories for the serious fluid loss problem in the Silurian system, and innovatively proposes a five-step "determining units, level classification, spatial segmentation, fracture prediction, and integrated analysis" fluid loss avoidance technology for non-target layers such as the Silurian system, such as the serious fluid loss in the Silurian system of the Shunbei Oilfield in the Tarim Basin, providing guidance for the optimization of well trajectories to reduce serious fluid loss in the Silurian system.

[0113] Therefore, the advantages of the en echelon fracture fine interpretation, evaluation, and trajectory optimization technology in the embodiment of the present invention are as follows:

[0114] 1) It realizes the three-dimensional spatial interpretation of strike-slip en echelon fractures under the extensional-torsional background of the Silurian system in the early Hercynian period, determines the en echelon units, the classification of strike-slip faults, and the characteristics of spatial segmentation, providing conditions for avoiding faults in the selection of favorable areas for well trajectories in the Silurian system.

[0115] 2) In view of the complex fracture characteristics in the Silurian system, combined with the classification of strike-slip faults and the characteristics of spatial segmentation, the prediction of fracture development intensity at different positions in the en echelon unit is carried out, providing a basis for determining well points in the optimization of well trajectories.

[0116] 3) Based on the geological target of large-scale fault-karst bodies in the Ordovician target layer, combined with the fracture intensity prediction in the Silurian system, a well trajectory optimization technology for avoiding fluid loss in the Silurian system is formed, reducing the probability of serious fluid loss in the Silurian system.

[0117] According to the technology of the embodiment of the present invention, it is not only applicable to the optimization of well trajectories with serious fluid loss in non-target layer sections during drilling in the Shunbei Oil and Gas Field and its adjacent areas in the Tarim Basin, but also has simple operation, good exploration and development effects, and broad application and promotion prospects.

[0118] In this document, multiple embodiments of the present invention are described. However, for the sake of brevity, the descriptions of each embodiment are not exhaustive, and the same or similar features or parts among the various embodiments may be omitted. In this document, the specific features, structures, materials, or characteristics of each embodiment may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0119] In this document, the terms "comprising", "including", or their variants are intended to be inclusive, not exclusive, such that a process, method, product, or device that includes a series of elements may include these elements and may also include other elements not expressly listed.

[0120] The exemplary systems and methods of the present invention have been specifically shown and described with reference to the above embodiments, which are only examples of the best mode for implementing the systems and methods. Those skilled in the art can understand that various changes can be made to the embodiments of the systems and methods described herein when implementing the systems and / or methods without departing from the spirit and scope of the present invention as defined in the appended claims. The appended claims are intended to define the scope of the systems and methods, so the systems and methods that fall within these claims and their equivalents may be covered. The above description of the systems and methods should be understood to include the combination of all the new and non-obvious elements described herein, and there may be claims in this application or subsequent applications that cover any combination of new and non-obvious elements. In addition, the above embodiments are exemplary, and no single feature or element is essential among all the possible combinations of features and elements that may be claimed in this application or subsequent applications.

Claims

1. A well trajectory optimization method for fracture-developed areas of non-target formations, characterized in that, it includes: Determine en echelon units in a strike-slip en echelon fault system; Classify the faults in the determined en echelon units according to fault strength to obtain Class I faults, Class II faults, and Class III faults with decreasing fault strength; Segment the faults in the determined en echelon units spatially to determine the dip-terminal segments and turning segments of the faults; Predict the fractures within the control range of the faults in the determined en echelon units according to the classification of the faults; Based on the classification of the faults, the dip-terminal segments of the faults, and the predicted fractures, determine or adjust the well trajectory passing through the strike-slip en echelon fault system to keep it away from Class I faults, Class II faults, and the turning segments and fracture prediction developed areas of the faults; Among them, segmenting the faults in the determined en echelon units spatially to determine the dip-terminal segments and turning segments of the faults includes: Determine the spatial characteristics of the faults in the en echelon units, and the spatial characteristics include vertical extension length and fault throw; Based on the spatial characteristics, determine the dip-terminal segments and turning segments of the faults in the en echelon units, where the vertical fault throw of the turning segment is greater than that of the dip-terminal segment and is located in the middle of the fault; Among them, determining the spatial characteristics of the faults in the en echelon units includes: Obtain a fine interpretation of the ribbon effect of the faults in the en echelon units; Obtain the spatial characteristics of the faults in the en echelon units from the fine interpretation of the ribbon effect of the faults in the en echelon units; Among them, predicting the fractures of the faults in the determined en echelon units according to the classification of the faults includes: Predict the fracture density of the faults in the en echelon units based on the classification of the faults and the spatial segmentation. At the same distance from the fault, the fracture density of Class I faults is greater than that of Class II faults, and the fracture density of Class II faults is greater than that of Class III faults. Among them, the fracture density of the turning segment in the same fault is greater than that of the dip-terminal segment; Based on the distribution of the fracture density, determine the internal area of the tensile-shear fault blocks with low fracture density; Among them, the non-target layer is the Silurian system between the seismic reflection wave and T 6 0 seismic reflection wave and T 7 0 seismic reflection waves.

2. The well trajectory optimization method according to claim 1, characterized in that, Determining en echelon units in a strike-slip en echelon fault system includes: Determine the fracture interpretation marker beds to delimit the strike-slip en echelon fault system, and conduct 3D spatial closed interpretation of the faults in the strike-slip en echelon fault system; Analyze the fault properties in the strike-slip en echelon fault system in the 3D spatial closed interpretation of the faults to obtain the fault dip, dip angle, and contact relationship between faults; Based on the fault dip, dip angle, and contact relationship between faults, determine en echelon units in the strike-slip en echelon fault system.

3. The well trajectory optimization method according to claim 1 or 2, characterized in that, Classifying the faults in the determined en echelon units according to fault strength to obtain Class I faults, Class II faults, and Class III faults with decreasing fault strength includes: Determine Class I faults, where the Class I faults include the en echelon unit control faults, and the control faults are boundary faults that extend to the top and bottom of the Silurian formation in the strike-slip en echelon fault system; Identify Class-II fractures, where the Class-II fractures include fractures that extend to the top of the strike-slip en echelon fracture system but do not reach the bottom, and the fracture throw and planar extension length of the Class-II fractures are less than those of the Class-I fractures; Identify Class-III fractures, where the Class-III fractures include fractures within the Silurian strata of the en echelon unit, and the fracture throw and planar extension length of the Class-III fractures are less than those of the Class-II fractures.

4. The well trajectory optimization method according to claim 1 or 2, characterized in that, based on the classification of the fractures, the dip terminal segments of the fractures, and the predicted fractures, determine or adjust the well trajectory passing through the strike-slip en echelon fracture system to keep it away from the Class-I fractures, Class-II fractures, the turning segments of the fractures, and the fracture prediction development areas, including: making the determined or adjusted well trajectory close to the dip terminal segments of the Class-III fractures and / or located within the internal area of the tensile-shear slump blocks.

5. A well trajectory optimization device for a fracture development area of a non-target formation, characterized in that, comprising: An en echelon unit determination module for determining en echelon units in a strike-slip en echelon fracture system; A fracture classification module for classifying the fractures in the determined en echelon units according to fracture strength to obtain Class-I fractures, Class-II fractures, and Class-III fractures with decreasing fracture strength; A spatial segmentation module for spatially segmenting the fractures in the determined en echelon units to determine the dip terminal segments and turning segments of the fractures; A fracture prediction module for predicting fractures in the determined en echelon units according to the classification of the fractures; A well trajectory optimization module for determining or adjusting the well trajectory passing through the strike-slip en echelon fracture system based on the classification of the fractures, the dip terminal segments of the fractures, and the predicted fractures to keep it away from the Class-I fractures, Class-II fractures, the turning segments of the fractures, and the fracture prediction development areas; wherein, the spatial segmentation module includes: A feature determination sub-module for determining the spatial features of the fractures in the en echelon unit, and the spatial features include vertical extension length and fracture throw; A fracture determination sub-module for determining the dip terminal segments and turning segments of the fractures in the en echelon unit based on the spatial features, where the vertical fracture throw of the turning segment is greater than that of the dip terminal segment and is located in the middle of the fracture; wherein, the feature determination sub-module includes: Obtain a detailed interpretation of the ribbon effect of the fractures in the en echelon unit; Obtain the spatial features of the fractures in the en echelon unit from the detailed interpretation of the ribbon effect of the fractures in the en echelon unit; wherein, the fracture prediction module includes: Predict the fracture density of the fractures in the en echelon unit based on the classification of the fractures and the spatial segmentation. At the same distance from the fracture, the fracture density of the Class-I fractures is greater than that of the Class-II fractures, and the fracture density of the Class-II fractures is greater than that of the Class-III fractures. Among them, the fracture density of the turning segment in the same fracture is greater than that of the dip terminal segment; Determine the internal area of the tensile-shear slump blocks with low fracture density based on the distribution of the fracture density; Among them, the non-target layer is the Silurian system between the seismic reflection wave and T 6 0 seismic reflection wave and T 7 0 seismic reflection wave.

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