A method for geosteering in a horizontal well in a tight sand gas reservoir

Abstract

This invention provides a geological steering method for horizontal wells in tight sandstone gas reservoirs. First, relevant data from the target well and adjacent wells are acquired. Then, using this data, the geological characteristics of the target sandstone body, its micro-structure, reservoir heterogeneity, and stratigraphic occurrence are determined. Next, using well logging interpretation from adjacent wells and geophysical channel characterization, a refined three-dimensional geological model based on seismic constraints is established to clarify the sandstone body distribution and interlayer development. A geological profile is established along the well trajectory to determine the location of the horizontal well trajectory. Finally, trajectory optimization is performed. This steering method effectively combines geological and seismic data, using three-dimensional geological modeling to reasonably predict the distribution of reservoir sandstone bodies and scientifically assess interlayer development. The geological steering method and its implementation effectiveness are effectively guaranteed, and it can meet the geological steering requirements of different gas reservoirs and well areas with significantly different geological characteristics.

Description

Technical Field

[0001] This invention relates to the field of geological steering technology for sandstone gas reservoirs, specifically to a geological steering method for horizontal wells in tight sandstone gas reservoirs. Background Technology

[0002] Natural gas, serving as a bridge in the energy structure transition from fossil fuels to clean energy and from high-carbon to zero-carbon energy, continues to play a vital role, with demand maintaining rapid growth. Domestic onshore natural gas development primarily focuses on tight sandstone gas, carbonate acid gas, and shale gas, with tight sandstone gas accounting for the largest share. In recent years, horizontal wells have gradually become the main well type for tight sandstone gas reservoir development due to their advantages such as increased venting area, avoidance of water cones, and connection of advantageous channels. The key to horizontal well drilling is ensuring that the horizontal section is drilled as close to the center of the sand body as possible, maximizing formation communication and achieving a high sandstone encounter rate. The drilling quality of the horizontal section directly determines the development effect of the gas well. Therefore, employing scientific and reasonable methods for horizontal well geological steering is of great significance for the exploration and development of tight sandstone gas reservoirs.

[0003] However, current methods for geological steering of horizontal wells in tight sandstone gas reservoirs are mainly based on formation dip calculation, lithology identification, or logging while drilling. These methods consider relatively few factors and have low accuracy, failing to meet the requirements for geological steering of different gas reservoirs and well areas with significantly different geological characteristics. Summary of the Invention

[0004] The purpose of this invention is to address the problems of existing technologies for geological steering of horizontal wells in tight sandstone gas reservoirs, which suffer from limited consideration of factors, low accuracy, and inability to meet the geological steering requirements of different gas reservoirs and well areas with significantly different geological characteristics. This invention provides a geological steering method for horizontal wells in tight sandstone gas reservoirs. This method effectively combines geological and seismic data, utilizes three-dimensional geological modeling to reasonably predict the distribution of reservoir sand bodies, and makes scientific predictions about the development of interlayers. The geological steering method and its implementation effects are effectively guaranteed, and it can meet the geological steering requirements of different gas reservoirs and well areas with significantly different geological characteristics, making it easy to promote.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A geological steering method for horizontal wells in tight sandstone gas reservoirs includes the following steps:

[0007] Step S1: Based on the sedimentary background of tight sandstone gas reservoirs, conduct well-seismic analysis of the target well area to clarify the seismic response characteristics and well logging response characteristics;

[0008] Obtain logging data, well logging interpretation data, and geophysical data from adjacent wells in the target well area;

[0009] Step S2: Using the adjacent well logging display, secondary logging interpretation and logging response characteristics obtained in Step S1, determine the geological characteristics of the target layer sand body, and clarify the lithological combination, sand body thickness, gas content and interlayer characteristics.

[0010] Step S3: Using the geophysical data of the adjacent wells obtained in Step S1, perform a comprehensive analysis in both horizontal and vertical directions. By extracting amplitude anomalies and wave impedance plane maps and establishing a seismic profile of the target well area using the seismic response characteristics of the target well area obtained in Step S1, analyze the micro-structure of the sand body and the heterogeneous development characteristics of the reservoir, and determine the formation attitude.

[0011] Step S4: Use the data obtained in steps S2 and S3 to delineate the river channel, establish a detailed three-dimensional geological model based on seismic constraints, clarify the distribution of sand bodies and the development of interlayers, establish a geological profile along the well trajectory, and determine the location of the horizontal well trajectory.

[0012] Step S5: Combining the logging lithological characteristics and total hydrocarbon display information of adjacent wells, predict the horizontal well direction, propose trajectory optimization for the geological profile established along the wellbore trajectory in Step S4, and complete the geological steering of the horizontal well in the tight sandstone gas reservoir.

[0013] This invention provides a geological steering method for horizontal wells in tight sandstone gas reservoirs. First, relevant data from the target well and adjacent wells are acquired, specifically the seismic and logging response characteristics of the target well, and the logging displays, interpretations, and geophysical data from adjacent wells. Then, using the acquired data from the target and adjacent wells, the geological characteristics of the target sandstone layer, its micro-structure, reservoir heterogeneity, and stratigraphic occurrence are determined. Next, using the logging interpretations from adjacent wells and geophysical channel characterization results, a refined three-dimensional geological model based on seismic constraints is established to clarify the sandstone distribution and interlayer development. A geological profile is established along the well trajectory to determine the location of the horizontal well trajectory. Finally, trajectory optimization is performed to complete the geological steering of the horizontal well in the tight sandstone gas reservoir. This steering method effectively combines geological and seismic data, uses three-dimensional geological modeling to reasonably predict the distribution of reservoir sandstone bodies, and makes scientific predictions about interlayer development. The geological steering method and its implementation effectiveness are effectively guaranteed. It can meet the geological steering needs of different gas reservoirs and well areas with significantly different geological characteristics, and is easy to promote.

[0014] Furthermore, in step S1, the sedimentary background of the tight sandstone gas reservoir is a sand body development background confirmed by surface outcrops, seismic, drilling, and logging data. Well-seismic analysis utilizes surface natural gamma, sonic, and resistivity logging data to obtain formation amplitude anomalies, wave impedance, and channel sand body information through well-seismic calibration. Adjacent wells refer to, but are not limited to, the nearest producing wells and transit wells in different azimuths of the target well area. The logging display includes logging lithological descriptions, drilling gamma, and total hydrocarbon display information; the logging interpretation includes natural gamma, sonic, resistivity, and logging interpretation porosity saturation information.

[0015] Furthermore, in step S1, the method for obtaining well logging response characteristics includes the following steps:

[0016] Step S11: Based on the sedimentary background of tight sandstone gas reservoirs, determine the seismic response characteristics of channel sand bodies according to the calibration of drilling and seismic composite records;

[0017] Step S12: Select specific attributes based on seismic response characteristics to perform sand body distribution characteristic analysis within a fixed time window, and clarify the sand body distribution;

[0018] Step S13: Based on vertical seismic profile logging, formation coring, and high-pressure physical property experiments, determine the reservoir logging response characteristics, clarify the response differences between reservoir sections and non-reservoir sections, and obtain the logging response characteristics.

[0019] Furthermore, in step S2, the adjacent well logging display and secondary logging interpretation information include logging lithological description, drilling gamma ray, total hydrocarbon display, natural gamma ray, acoustic wave, resistivity, and logging interpretation porosity saturation information. The geological characteristics of the target layer sand body refer to the lithological description characteristics of the target layer; lithological assemblage mainly refers to the physical characteristics of sandstone, mudstone, and the sand-mud combination relationship; sand body thickness refers to the vertical thickness of the sand body; gas content refers to the total hydrocarbon display and its variations; and the basic characteristics of interlayers refer to the physical characteristics, relative position, thickness, and variations of the interlayers.

[0020] Furthermore, in step S2, based on the logging data from adjacent wells and secondary interpretation, the lithological assemblage of the target layer is analyzed, mainly describing the relative positional relationship between sand and mud, and the lithological characteristics of the top and bottom of the sand body. Based on the logging interpretation from adjacent wells, the trend of sand body thickness variation in the vertical and horizontal directions is analyzed and clarified, along with a description of sand body cuttings from logging. The physical characteristics of sand body interlayers are also described, including information on color, thickness, and location, as well as the positional variations of the interlayers.

[0021] Furthermore, in step S3, geophysical data refers to the depth domain data volume formed after synthetic record calibration and time-depth conversion. Lateral analysis refers to analyzing planar heterogeneity using seismic plane maps under certain time window conditions. Vertical analysis refers to analyzing the intensity variations of the seismic response of the target sand body using seismic profiles. Micro-structures refer to structures formed by small undulations within the sand body itself within the overall tectonic context. Reservoir heterogeneity includes both planar and vertical heterogeneity. Stratigraphic attitude includes three elements: strike, dip, and dip angle.

[0022] Furthermore, in step S3, determining the stratigraphic attitude includes the following steps:

[0023] Step S31: Use well-seismic composite records for calibration to determine the seismic response characteristics of the target layer;

[0024] Step S32: Obtain the depth domain seismic volume of the target layer through time-depth conversion.

[0025] Step S33: Set a certain time window, extract the seismic plane map of the target layer, and use the seismic plane map to determine the planar heterogeneity of the sand body and the boundary range of the sand body;

[0026] Step S34: By establishing a seismic profile along the well structure, determine the location of the target horizontal well in the formation and the attribute changes at different locations in the horizontal section;

[0027] Step S35: Calculate the formation dip angle and clarify the formation attitude by using the time-domain seismic data volume and combining it with the actual drilling conditions of adjacent wells.

[0028] Furthermore, in step S31, the synthetic record calibration refers to calculating the reflection coefficient from the acoustic wave and density logging curves, convolving the reflection coefficient with the extracted seismic wavelet to obtain the initial synthetic seismic record, correcting the initial synthetic seismic record according to the velocity field, and then matching and adjusting it with the well-side seismic trace to obtain the final synthetic seismic record.

[0029] Furthermore, in step S32, time-depth conversion refers to the continuous iterative process of several processes, including seismic data processing, velocity analysis, and well logging data research, to optimize the conversion results and transform the seismic data volume under time domain conditions into a data volume under depth domain conditions.

[0030] Furthermore, in step S4, channel characterization refers to using geophysical methods to characterize the channel's direction, width, length, and boundary information. Seismic constraints refer to using the channel characterization boundaries for modeling constraints. A refined 3D geological model refers to simulating a 3D lithofacies model of the target layer using algorithms such as sequential indication. Sandbody distribution refers to information such as the extent and morphology of sandbody development. Interlayer development includes information such as the thickness, relative position, and extension of interlayers. The geological profile refers to a projected profile perpendicular to the wellbore plane. The horizontal well trajectory includes three elements: depth, azimuth, and inclination.

[0031] Furthermore, in step S4, the method for establishing a detailed three-dimensional geological model includes the following steps:

[0032] Step S41: Conduct single-well sub-layer comparison and division, achieve fine lithofacies division, identify sand body interlayers, and obtain the lithofacies distribution of single wells;

[0033] Step S42: Constraints are applied using the variation function method, and the sand body boundary characterized by seismic analysis is used as the model boundary. Sequential indicator simulation is employed to obtain the three-dimensional lithofacies model of the target layer.

[0034] Furthermore, in step S5, the logging lithological characteristics include rock color, grain size, type and lithological variation relationship, the horizontal well orientation refers to the current and future location of the horizontal section in the sand body, and the trajectory optimization parameters include information such as vertical depth and dip angle.

[0035] Furthermore, in step S5, trajectory optimization includes the following steps:

[0036] Step S51: Determine the design trajectory position, the deviation between the actual drilling trajectory and the design trajectory, and predict the well trajectory state after continuing drilling according to the current well inclination and azimuth;

[0037] Step S52: Optimize the trajectory based on the trajectory prediction and the effects of earthquake and geological profile.

[0038] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0039] 1. This invention provides a geological steering method for horizontal wells in tight sandstone gas reservoirs. First, relevant data from the target well and adjacent wells are acquired, specifically the seismic and logging response characteristics of the target well, and the logging displays, interpretations, and geophysical data from adjacent wells. Then, using the acquired data from the target and adjacent wells, the geological characteristics of the target sandstone layer, its micro-structure, reservoir heterogeneity, and stratigraphic occurrence are determined. Next, using the logging interpretations from adjacent wells and geophysical channel characterization results, a refined three-dimensional geological model based on seismic constraints is established to clarify the sandstone distribution and interlayer development. A geological profile is established along the well trajectory to determine the location of the horizontal well trajectory. Finally, trajectory optimization is performed to complete the geological steering of the horizontal well in the tight sandstone gas reservoir. This steering method effectively combines geological and seismic data, uses three-dimensional geological modeling to reasonably predict the distribution of reservoir sandstone bodies, and makes scientific predictions about interlayer development. The geological steering method and its implementation effectiveness are effectively guaranteed. It can meet the geological steering needs of different gas reservoirs and well areas with significantly different geological characteristics, and is easy to promote.

[0040] 2. Guided by theories of seismic sedimentology, sedimentary petrology, and 3D geological modeling, this invention starts from basic geology, drilling, seismic, and logging data. Targeting the geological steering process of horizontal wells in tight sandstone gas reservoirs, it employs a combination of seismic constraints and detailed 3D modeling to track horizontal well drilling. This overcomes the limited accuracy of vertical identification in seismic data while providing a detailed description and effective prediction of reservoir sand body distribution. It offers a technical model for improving the sandstone encounter rate in horizontal well drilling of tight sandstone gas reservoirs, enabling precise drilling and supporting high-quality tracking and deployment research.

[0041] 3. This invention solves the problem of the difficulty in effectively integrating seismic and geological data during the geological steering process of horizontal well drilling in tight sandstone gas reservoirs, thereby improving the quality of drilling tracking.

[0042] 4. The geological steering method for tight sandstone gas reservoirs established in this application comprehensively considers geophysical, logging display, and well logging interpretation parameters, and the data is comprehensive, scientific and reasonable.

[0043] 5. The guiding method disclosed in this application can intuitively display the drilling process of the horizontal section, effectively improve the sand body encounter rate of horizontal well drilling, and help gas wells achieve better production results. Attached Figure Description

[0044] Figure 1 This is a flowchart of Embodiment 1 of the present invention.

[0045] Figure 2 This is a well-seismic correlation diagram of a typical sand body in a tight sandstone gas reservoir.

[0046] Figure 3 This is a typical well logging interpretation result diagram.

[0047] Figure 4 It is a planar distribution map of the river channel depicted using the earthquake amplitude attribute.

[0048] Figure 5 It is a seismic profile of the horizontal section along the well trajectory.

[0049] Figure 6 It is a three-dimensional geological model.

[0050] Figure 7 This is a geological model profile of the horizontal section along the well trajectory. Detailed Implementation

[0051] The present invention will now be described in detail with reference to the accompanying drawings.

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0053] Example 1

[0054] like Figure 1 As shown, a quantitative comprehensive evaluation method for tight sandstone gas reservoirs includes the following steps:

[0055] Step S1: Based on the sedimentary geological background of tight sandstone gas reservoirs, conduct well seismic analysis of the target well area to clarify the seismic and logging response characteristics and obtain data such as well logging interpretation and geophysical data from adjacent wells.

[0056] The sedimentary background of the tight sandstone gas reservoir is a sand body development background confirmed by surface outcrops, seismic data, drilling data, and well logging data. The well-seismic analysis utilizes well logging data such as natural gamma ray, sonic logging, and resistivity logging to obtain information such as formation amplitude anomalies, wave impedance, and channel sand bodies through well-seismic calibration. Adjacent wells refer to, but are not limited to, the nearest producing wells and transit wells in different azimuths of the target well area. The logging interpretation includes logging displays and logging interpretation. The logging interpretation includes logging lithology descriptions, gamma ray while drilling, and total hydrocarbon displays. The logging interpretation includes information such as natural gamma ray, sonic logging, resistivity logging, and logging interpretation porosity saturation. Figures 2-3 As shown.

[0057] The method for obtaining well logging response characteristics includes the following steps:

[0058] Step S11: Based on the sedimentary background of tight sandstone gas reservoirs, determine the seismic response characteristics of channel sand bodies according to the calibration of drilling and seismic composite records;

[0059] Step S12: Select specific attributes based on seismic response characteristics to perform sand body distribution characteristic analysis within a fixed time window, and clarify the sand body distribution;

[0060] Step S13: Based on vertical seismic profile logging, formation coring, and high-pressure physical property experiments, determine the reservoir logging response characteristics, clarify the response differences between reservoir sections and non-reservoir sections, and obtain the logging response characteristics.

[0061] Step S2: Based on the logging data of adjacent wells in the well area and the secondary interpretation of the logging, determine the geological characteristics of the target layer sand body, and clarify the basic characteristics such as lithological combination, sand body thickness, gas content, and interlayers.

[0062] The adjacent well logging display and secondary logging interpretation include information such as logging lithology description, drilling gamma, total hydrocarbon display, natural gamma, sonic logging, resistivity, and logging interpretation pore saturation. The geological characteristics of the target layer refer to the lithological description characteristics of the target layer. The lithological assemblage mainly refers to the physical characteristics of sandstone, the physical characteristics of mudstone, and the sand-mud combination relationship. The sand body thickness refers to the vertical thickness of the sand body. The gas content refers to the total hydrocarbon display and its variation. The basic characteristics of the interlayers refer to the physical characteristics, relative position, thickness, and variation of the interlayers.

[0063] Step S3: Using geophysical data, conduct comprehensive horizontal and vertical analysis, extract amplitude anomalies and wave impedance plane maps, and establish well-area seismic cross-well profiles to analyze the micro-structures of sand bodies and the heterogeneous development characteristics of reservoirs, and determine the stratigraphic attitude.

[0064] The geophysical data refers to the depth domain data volume formed after synthetic record calibration and time-depth conversion. The lateral analysis refers to the analysis of planar heterogeneity using seismic plane maps under certain time window conditions. The longitudinal analysis refers to the analysis of the intensity variation of seismic response of the target sand body using seismic profiles. The micro-structure refers to the structure formed by small undulations of the sand body itself within the overall tectonic background. The reservoir heterogeneity includes planar heterogeneity and longitudinal heterogeneity. The stratigraphic attitude includes three elements: strike, dip, and dip angle. Figures 4-5 As shown.

[0065] In step S3, determining the stratigraphic attitude includes the following steps:

[0066] Step S31: Use well-seismic composite records for calibration to determine the seismic response characteristics of the target layer;

[0067] Step S32: Obtain the depth domain seismic volume of the target layer through time-depth conversion.

[0068] Step S33: Set a certain time window, extract the seismic plane map of the target layer, and use the seismic plane map to determine the planar heterogeneity of the sand body and the boundary range of the sand body;

[0069] Step S34: By establishing a seismic profile along the well structure, determine the location of the target horizontal well in the formation and the attribute changes at different locations in the horizontal section;

[0070] Step S35: Calculate the formation dip angle and clarify the formation attitude by using the time-domain seismic data volume and combining it with the actual drilling conditions of adjacent wells.

[0071] Furthermore, in step S31, the synthetic record calibration refers to calculating the reflection coefficient from the acoustic wave and density logging curves, convolving the reflection coefficient with the extracted seismic wavelet to obtain the initial synthetic seismic record, correcting the initial synthetic seismic record according to the velocity field, and then matching and adjusting it with the well-side seismic trace to obtain the final synthetic seismic record.

[0072] Furthermore, in step S32, time-depth conversion refers to the continuous iterative process of several processes, including seismic data processing, velocity analysis, and well logging data research, to optimize the conversion results and transform the seismic data volume under time domain conditions into a data volume under depth domain conditions.

[0073] Step S4: Make full use of the well logging interpretation results of adjacent wells in the well area and the geophysical channel characterization results to establish a fine three-dimensional geological model based on seismic constraints, clarify the distribution of sand bodies and the development of interlayers, establish a geological profile along the well trajectory, and determine the location of the horizontal well trajectory.

[0074] The term "channel characterization" refers to using geophysical methods to characterize information such as the channel's direction, width, length, and boundaries. "Seismic constraints" refers to using the boundaries of the channel characterization for modeling constraints. "Refined 3D geological model" refers to simulating a 3D lithofacies model of the target layer using algorithms such as sequential indication. "Sand body distribution" refers to information such as the extent and morphology of sand body development. "Interlayer development" includes information such as the thickness, relative position, and extension of the interlayers. "Geological profile" refers to a projected profile perpendicular to the wellbore plane. "Horizontal well trajectory" includes three elements: depth, azimuth, and inclination. Figures 6-7 As shown.

[0075] In step S4, the method for establishing a detailed three-dimensional geological model includes the following steps:

[0076] Step S41: Conduct single-well sub-layer comparison and division, achieve fine lithofacies division, identify sand body interlayers, and obtain the lithofacies distribution of single wells;

[0077] Step S42: Constraints are applied using the variation function method, and the sand body boundary characterized by seismic analysis is used as the model boundary. Sequential indicator simulation is employed to obtain the three-dimensional lithofacies model of the target layer.

[0078] Step S5: Based on logging lithological characteristics and total hydrocarbon display information, predict the horizontal well direction and propose trajectory optimization parameters.

[0079] The logging lithological characteristics include rock color, grain size, type, and lithological variation relationships. The horizontal well orientation refers to the current and future location of the horizontal section within the sand body. The trajectory optimization parameters include information such as vertical depth and dip angle.

[0080] Specifically, in step S5, trajectory optimization includes the following steps:

[0081] Step S51: Determine the design trajectory position, the deviation between the actual drilling trajectory and the design trajectory, and predict the well trajectory state after continuing drilling according to the current well inclination and azimuth;

[0082] Step S52: Optimize the trajectory based on the trajectory prediction and the effects of earthquake and geological profile.

[0083] This invention provides a geological steering method for horizontal wells in tight sandstone gas reservoirs. First, relevant data from the target well and adjacent wells are acquired, specifically the seismic and logging response characteristics of the target well, and the logging displays, interpretations, and geophysical data from adjacent wells. Then, using the acquired data from the target and adjacent wells, the geological characteristics of the target sandstone layer, its micro-structure, reservoir heterogeneity, and stratigraphic occurrence are determined. Next, using the logging interpretations from adjacent wells and geophysical channel characterization results, a refined three-dimensional geological model based on seismic constraints is established to clarify the sandstone distribution and interlayer development. A geological profile is established along the well trajectory to determine the location of the horizontal well trajectory. Finally, trajectory optimization is performed to complete the geological steering of the horizontal well in the tight sandstone gas reservoir. This steering method effectively combines geological and seismic data, uses three-dimensional geological modeling to reasonably predict the distribution of reservoir sandstone bodies, and makes scientific predictions about interlayer development. The geological steering method and its implementation effectiveness are effectively guaranteed. It can meet the geological steering needs of different gas reservoirs and well areas with significantly different geological characteristics, and is easy to promote.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for geosteering in a horizontal well in a tight sand gas reservoir, characterized in that, The method comprises the following steps: Step S1: on the basis of the sedimentary background of the tight sandstone gas reservoir, well-seismic analysis of the target well area is carried out to determine the seismic response characteristics and the logging response characteristics; Obtaining the logging display, logging interpretation and geophysical data of the adjacent well in the target well area; The method for obtaining the logging response characteristics comprises the following steps: Step S11: on the basis of the sedimentary background of the tight sandstone gas reservoir, the seismic response characteristics of the channel sand body are determined according to the drilling and seismic synthetic record calibration; Step S12: according to the seismic response characteristics, a specific attribute is selected to analyze the sand body distribution characteristics in the fixed time window, and the sand body distribution is determined; Step S13: on the basis of the vertical seismic profile logging, formation coring and high-pressure physical property experiment, the reservoir logging response characteristics are determined, the response difference between the reservoir section and the non-reservoir section is determined, and the logging response characteristics are obtained; Step S2: the sand body geological characteristics of the target layer are determined by using the logging display, logging secondary interpretation and logging response characteristics of the adjacent well obtained in step S1, and the lithological combination, sand body thickness, gas content and interlayer characteristics are determined; Step S3: the geophysical data of the adjacent well obtained in step S1 are used for horizontal and vertical comprehensive analysis, the sand body microstructure and the reservoir heterogeneity development characteristics are analyzed by extracting the amplitude anomaly and wave impedance plan and using the seismic response characteristics of the target well area obtained in step S1 to establish the well area seismic overhole profile, and the stratum occurrence is determined; wherein the geophysical data refer to the depth domain data volume formed after the synthetic record calibration and time-depth conversion; Step S4: the data obtained in steps S2 and S3 are used for channel description, a fine three-dimensional geological model based on seismic constraint is established, the sand body distribution and interlayer development are determined, the geological profile along the well trajectory is established, and the position of the horizontal well trajectory is determined; Step S5: the horizontal well direction is predicted by combining the logging lithological characteristics and full-hydrocarbon display information of the adjacent well, the trajectory optimization is proposed for the geological profile along the well trajectory established in step S4, and the tight sandstone gas reservoir horizontal well geological steering is completed.

2. The method of geosteering in a tight sand gas reservoir horizontal well of claim 1, wherein, In step S1, the sedimentary background of the tight sandstone gas reservoir is the sand body development background verified by the surface outcrop, seismic, drilling and logging data; or / and, the well-seismic analysis is to obtain the amplitude anomaly, wave impedance and channel sand body information of the stratum by using the natural gamma, acoustic and resistivity logging data on the well and through well-seismic calibration; or / and, the logging display includes logging lithological description, while-drilling gamma and full-hydrocarbon display information; or / and, the logging interpretation includes natural gamma, acoustic, resistivity and logging interpretation porosity and permeability information.

3. The method of claim 1, wherein, In step S2, the logging display, logging secondary interpretation of the adjacent well includes logging lithological description, while-drilling gamma, full-hydrocarbon display, natural gamma, acoustic, resistivity and logging interpretation porosity and permeability information.

4. The method of claim 1, wherein, The step S3, the lateral analysis refers to using the seismic planar graph under certain time window condition to analyze the planar heterogeneity; or / and, the longitudinal analysis refers to using the seismic profile to analyze the target sand body seismic response strength change; or / and, the microstructure refers to the structure formed by the small fluctuation change of the sand body itself under the overall structure background; or / and, the reservoir heterogeneity includes the planar heterogeneity and the longitudinal heterogeneity; or / and, the stratum occurrence includes the strike, the tendency and the dip angle.

5. The method of claim 4, wherein, The step S3, the stratum occurrence determination includes the following steps: Step S31: using the well-seismic synthetic record calibration to determine the target horizon seismic response characteristics; Step S32: obtaining the depth domain seismic body of the target horizon through the time-depth conversion; Step S33: setting certain time window, extracting the target horizon seismic planar graph, using the seismic planar graph to determine the sand body planar heterogeneity and the sand body boundary range; Step S34: establishing the seismic profile along the well structure to determine the position of the target horizontal well in the stratum and the attribute change of different positions of the horizontal section; Step S35: calculating the stratum dip angle through the time domain seismic data body, combining the adjacent well actual drilling situation to determine the stratum occurrence.

6. The method of geosteering in a tight sand gas reservoir horizontal well of claim 5, wherein, The step S31, the process of the synthetic record calibration is to calculate the reflection coefficient from the sonic and density logging curves, to fold the reflection coefficient with the extracted seismic wavelet to obtain the initial synthetic seismic record, then to correct the initial synthetic seismic record according to the velocity field, and to match and adjust the final synthetic seismic record with the well seismic trace.

7. The method of geosteering in a tight sand gas reservoir horizontal well according to claim 6, characterized in that, The step S32, the process of the time-depth conversion is to iterate back and forth among the processes of the seismic data processing, the velocity analysis and the logging data research to optimize the conversion result, and to convert the seismic data body under the time domain condition into the data body under the depth domain condition.

8. The method of claim 1, wherein, The step S4, the river channel depiction refers to using the geophysics to depict the river channel strike, width, length and boundary information; the seismic constraint refers to using the boundary of the river channel depiction to constrain the modeling.

9. The method of claim 1-8, wherein, The step S4, the establishment method of the fine three-dimensional geological model includes the following steps: Step S41: carrying out the single well sublayer correlation and division, the lithofacies division reaches the fine requirement, the sand body interlayer is identified, and the single well lithofacies distribution is obtained; Step S42: using the sand body boundary depicted by the geophysics as the model boundary, using the sequential indicator simulation to obtain the three-dimensional lithofacies model of the target layer through the constraint method of the variation function.

10. The tight sand gas reservoir horizontal well geosteering method according to claim 9, characterized in that, The step S5, the trajectory optimization includes the following steps: Step S51: determining the design trajectory position, the deviation between the actual drilling trajectory and the design trajectory, and the predicted state of the well trajectory after continuing to drill under the current inclination and azimuth; Step S52: optimizing the trajectory according to the trajectory prediction situation, combining the seismic and geological profile effect.

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