Horizontal well type structure for thin oil layer and guiding method

Abstract

The invention relates to a horizontal well type structure for a thin oil layer and a guiding method. Acquiring a thin oil layer top boundary line, a thin oil layer bottom boundary line, geologic survey features above the thin oil layer, geologic survey features below the thin oil layer, geologic survey features of the thin oil layer and remote exploration data within a normal distance from a central axis of a well track of the detection section by using data acquired during drilling of the detection section; a production section is drilled, a window entering point of the production section is determined according to the thin oil layer top boundary line, the thin oil layer bottom boundary line and the thin oil layer geological survey characteristics, geological logging data of the production section in front of the window entering point are compared with remote exploration data, and then the while-drilling geosteering tool is calibrated; and according to the geologic survey features above the thin oil layer and the geologic survey features below the thin oil layer, the drilling well is guided and adjusted, so that the horizontal section behind the window entering point extends in the thin oil layer. The detection section is used for detecting the position of the thin oil layer and the geological information of the reservoir and calibrating the while-drilling instrument, so that the borehole is prevented from penetrating through the upper and lower boundaries of the hydrocarbon reservoir.

Description

Technical Field

[0001] The present invention belongs to the technical field of drilling, and particularly relates to a horizontal well type structure and a guiding method for thin oil layers. Background Art

[0002] Most of the horizontal wells implemented in oil and gas fields at home and abroad are conventional horizontal wells. The thickness of the oil layer is generally not less than 5m, and the reserves developed and utilized are reservoirs with relatively thick and good abundance. They have the advantages of large reserves, wide area, and good oil quality. In recent years, due to long-term deep injection and production in each oil field, there are a large number of thin layers, thin interbeds, and interlayer reservoirs, and the thickness of their reservoirs is generally 1 - 2m. When using vertical wells to exploit thin oil layers, the single-well controlled reserves are small, the production is low, and the economic benefits are poor. When using vertical wells to co-produce with other layers, the degree of utilization is low and the benefits are not obvious. With the rapid development of horizontal well technology, especially the application of high-precision geological evaluation wireless measurement-while-drilling technology, the combination of horizontal well drilling technology and high-precision LWD forms geological steering drilling technology, making it possible to efficiently exploit thin oil layers.

[0003] The purpose of geological steering is to control the trajectory of the wellbore through the gas field according to the hydrocarbon content in the formation, and change the conventional geometric control method. During geological steering construction, it is necessary to use geological evaluation instruments, and the measurement points need to lag behind the drill bit by a certain distance. It is easy to have situations such as inaccurate determination of the reservoir entry point and failure to avoid the oil / gas section in time, which easily leads to the wellbore crossing the upper and lower boundaries of the oil and gas layer, resulting in a decrease in its exposure degree, and further affecting the engineering construction benefits. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a horizontal well type structure and a guiding method for thin oil layers. The horizontal well type structure uses a detection section to detect the position and reservoir geological information of the thin oil layer and calibrate the measurement-while-drilling instrument, which can prevent the wellbore from crossing the upper and lower boundaries of the oil and gas layer, improve the reservoir encounter rate, and reduce the construction cost.

[0005] The technical solution of the present invention lies in: (1) The present invention provides a guiding method for a horizontal well type structure for thin oil layers.

[0006] A guiding method for a horizontal well type structure for thin oil layers. Before drilling into the thin oil layer, first drill a detection section, and obtain the top boundary line and bottom boundary line of the thin oil layer, the geological measurement characteristics above the thin oil layer, the geological measurement characteristics below the thin oil layer, the geological measurement characteristics of the thin oil layer, and the far exploration data within the normal distance from the center axis of the wellbore trajectory of the detection section by using the data obtained during the drilling of the detection section; Start drilling the production section from the starting position of the detection section. Determine the entry point of the production section based on the top boundary line, bottom boundary line of the thin oil layer, and the geological survey characteristics of the thin oil layer. Compare the geological logging data of the production section before the entry point with the far exploration data, and then calibrate the geosteering tool while drilling; adjust the drilling guidance according to the geological survey characteristics above and below the thin oil layer to ensure that the horizontal section after the entry point extends within the thin oil layer.

[0007] A guiding method for the horizontal well type structure of a thin oil layer is as follows: S1: Start drilling the vertical section, the first build section, and the first holding section in sequence from the ground. After drilling the first holding section, add a geosteering tool while drilling into the measurement tool string, and continue to drill the detection section. Through the geological logging data during the drilling of the detection section and the wellbore trajectory geometric parameter data and geological parameter data around the wellbore trajectory obtained in real time by the measurement tool string while drilling and the geosteering tool while drilling, obtain the top boundary line, bottom boundary line of the thin oil layer, and the thickness of the thin oil layer, the geological survey characteristics above the thin oil layer, the geological survey characteristics below the thin oil layer, the geological survey characteristics of the thin oil layer, and the far exploration data within the normal distance from the central axis of the wellbore trajectory of the detection section. S2: After drilling the detection section, backfill the detection section 30 m into the first holding section, and start drilling the production section. The measurement tool string while drilling and the geosteering tool while drilling obtain the data while drilling in real time, and determine the entry point of the production section according to the top boundary line, bottom boundary line of the thin oil layer, and the geological survey characteristics of the thin oil layer. Compare the geological logging data of the second build section with the far exploration data, and then calibrate the geosteering tool while drilling. S3: After calibrating the geosteering tool while drilling, adjust the drilling guidance according to the geological survey characteristics above the thin oil layer and the geological survey characteristics below the thin oil layer to ensure that the horizontal section after the entry point extends within the thin oil layer.

[0008] The wellbore trajectory geometric parameter data includes well depth, well inclination angle, and azimuth angle. The geological parameter data around the wellbore trajectory includes gamma, acoustic wave, and resistivity. The acoustic wave includes acoustic wave transit time logging data and far exploration acoustic wave data while drilling. The resistivity includes deep and shallow lateral resistivity logging data and far exploration electromagnetic wave resistivity data while drilling.

[0009] The geological survey characteristics above the thin oil layer, the geological survey characteristics below the thin oil layer, and the geological survey characteristics of the thin oil layer all include formation shale content, formation porosity, permeability, and oil saturation.

[0010] The calculation process of the formation shale content is as follows: V sh =(GR−GR min ) / (GR max −GR min ); In the formula: Vsh is the formation shale content, %; GR is the logging value of the natural gamma ray curve of the reservoir, API; GR min is the logging value of the natural gamma ray curve at the pure sandstone, API; GR max is the logging value of the natural gamma ray curve at the pure shale, API; The formation porosity is calculated by the relationship between the acoustic travel time and the formation porosity. The specific relationship is: Δ t = ϕ ⋅Δ t f +(1− ϕ )⋅Δ t m ; In the formula: Δ t is the acoustic travel time, μs / m; ϕ is the formation porosity, %; Δ t f is the acoustic travel time of the fluid, μs / m; Δ t m is the acoustic travel time of the rock skeleton, μs / m; The oil saturation is calculated from the deep and shallow lateral resistivity logging data; specifically, first determine the true formation resistivity R t ; R t = R d ( R s − R f ) / ( R d − R f ); In the formula, R t is the true formation resistivity, Ω·m; R d is the deep lateral resistivity, Ω·m; R s is the shallow lateral resistivity, Ω·m; R f is the mud resistivity, Ω·m; Then determine the formation oil saturation according to the true formation resistivity R t specifically: by R t = ϕ n ⋅ R w ⋅ F ( S w ) to obtain F (S w ), and then obtain the formation oil saturation; where: n is the cementation exponent, dimensionless; R w is the formation water resistivity, Ω·m; F ( S w ) is a function related to the water saturation.

[0011] (2) The present invention proposes a horizontal well well type structure for thin oil layers.

[0012] A horizontal well well type structure for thin oil layers, where the detection section and the production section have the same starting point. The detection section includes a descending section and a second constant inclination section connected in sequence. The production section includes a second deflecting section and a reservoir tracking section. The descending section and the second deflecting section are in the same plane and are both arc sections. The second constant inclination section includes an in-reservoir detection section and an out-of-reservoir detection section. The starting point of the in-reservoir detection section coincides with the top boundary line of the thin oil layer, and the end point coincides with the bottom boundary line of the thin oil layer. The reservoir tracking section extends entirely within the thin oil layer.

[0013] It also includes a vertical well section, a first deflecting section, and a first constant inclination section connected in sequence from the wellhead downward. The end of the first constant inclination section is respectively connected to the detection section and the production section. The descending section and the second deflecting section are both tangent to the end of the first constant inclination section.

[0014] The constant inclination angle of the first constant inclination section ranges from 30° to 60°, and the constant inclination angle of the second constant inclination section ranges from 80° to 90°.

[0015] The distance between the end point of the descending section and the window entry point is 20m to 50m. The length of the out-of-reservoir detection section is 10m to 30m.

[0016] The descending rate value of the descending section is higher than the deflecting rate value of the second deflecting section.

[0017] The technical effect of the present invention is as follows: The present invention uses the detection section to detect the position of the thin oil layer and reservoir geological information and calibrate the logging-while-drilling instrument, preventing the wellbore from crossing the upper and lower boundaries of the oil and gas layer, improving the reservoir encounter rate, and reducing the construction cost. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of a horizontal well well type structure for thin oil layers according to an embodiment of the present invention.

[0019] Figure 2 It is a guiding schematic diagram of the detection section NG according to an embodiment of the present invention.

[0020] Figure 3 It is a guiding schematic diagram of the production section NB according to an embodiment of the present invention.

[0021] Reference numerals: vertical well section OK, first build section KM, first tangent section MN, detection section NG, production section NB, dropping section NE, second tangent section EG, in-reservoir detection section EF, out-of-reservoir detection section FG, second build section NA, reservoir tracing section AB, window entry point A. Detailed implementation mode

[0022] Example 1 A horizontal well type structure for thin oil layers, the detection section NG and the production section NB have the same starting point. The detection section NG includes a dropping section NE and a second tangent section EG connected in sequence. The production section NB includes a second build section NA and a reservoir tracing section AB. The dropping section NE and the second build section NA are in the same plane and are both arc sections. The second tangent section EG includes an in-reservoir detection section EF and an out-of-reservoir detection section FG. The starting point of the in-reservoir detection section EF coincides with the top boundary line of the thin oil layer, and the end point coincides with the bottom boundary line of the thin oil layer. The reservoir tracing section AB extends entirely within the thin oil layer.

[0023] The specific implementation process of this example is as follows: Before drilling into the thin oil layer, first drill a detection section NG, and obtain the top boundary line and bottom boundary line of the thin oil layer, the geological survey characteristics above the thin oil layer, the geological survey characteristics below the thin oil layer, the geological survey characteristics of the thin oil layer, and the far exploration data within the normal distance from the central axis of the wellbore trajectory of the detection section NG by using the data obtained during the drilling of the detection section NG. Start drilling the production section NB from the starting position of the detection section NG, determine the window entry point A of the production section NB based on the top boundary line of the thin oil layer, the bottom boundary line of the thin oil layer, and the geological survey characteristics of the thin oil layer. Compare the geological logging data of the production section NB before the window entry point A with the far exploration data, and then calibrate the geosteering tool while drilling. Adjust the drilling guidance according to the geological survey characteristics above the thin oil layer and the geological survey characteristics below the thin oil layer to ensure that the horizontal section after the window entry point A extends within the thin oil layer.

[0024] Example 2 On the basis of Example 1, a vertical well section OK, a first build section KM, and a first tangent section MN are connected in sequence from the wellhead downwards. The ends of the first tangent section MN are respectively connected to a detection section NG and a production section NB. The dropping section NE and the second build section NA are both tangent to the ends of the first tangent section MN.

[0025] The specific implementation process of this example is as follows: Start drilling a vertical section OK, a first build section KM, and a first tangent section MN successively from the ground. After drilling the first tangent section MN, add a geosteering tool while drilling into the measurement-while-drilling (MWD) tool string, and continue drilling the detection section NG. Through the geological logging data during the drilling of the detection section NG and the wellbore trajectory geometric parameter data and geological parameter data around the wellbore trajectory obtained in real time by the MWD tool string and the geosteering tool, obtain the top boundary line, bottom boundary line, and thickness of the thin oil layer, the geological measurement characteristics above the thin oil layer, the geological measurement characteristics below the thin oil layer, the geological measurement characteristics of the thin oil layer, and the remote exploration data within the normal distance from the center axis of the wellbore trajectory of the detection section NG. S2: After drilling the detection section NG, backfill the detection section NG 30 m into the first tangent section MN, and start drilling the production section NB. The MWD tool string and the geosteering tool obtain the data while drilling in real time, and determine the entry window point A of the production section NB according to the top boundary line, bottom boundary line, and geological measurement characteristics of the thin oil layer. Compare the geological logging data of the second build section NA with the remote exploration data, and then calibrate the geosteering tool. S3: After calibrating the geosteering tool, adjust the drilling guidance according to the geological measurement characteristics above the thin oil layer and the geological measurement characteristics below the thin oil layer to ensure that the reservoir tracking section AB extends within the thin oil layer.

[0026] Embodiment 3 On the basis of Embodiment 2, it further includes: The tangent angle range of the first tangent section MN is 30° - 60°, and the tangent angle range of the second tangent section EG is 80° - 90°, which can quickly penetrate the thin oil layer and save the drilling footage. The distance between the end point of the angle reduction section NE and the entry window point A is 20 m - 50 m, so that the entry window point A is within the long-distance detection range of the geosteering tool. The length of the outer reservoir detection section FG is 10 m - 30 m, which is convenient for obtaining the geological measurement characteristics below the thin oil layer. The angle reduction rate value of the angle reduction section NE is higher than the build rate value of the second build section NA, which is convenient for quickly obtaining the top boundary line and bottom boundary line of the thin oil layer.

[0027] Embodiment 4 On the basis of Embodiment 3, it further includes: The wellbore trajectory geometric parameter data includes well depth, well inclination angle, and azimuth angle. The geological parameter data around the wellbore trajectory includes gamma, acoustic wave, and resistivity. The acoustic wave includes acoustic wave transit time logging data and while-drilling remote exploration acoustic wave data. The resistivity includes deep and shallow lateral resistivity logging data and while-drilling remote exploration electromagnetic wave resistivity data.

[0028] The geological measurement characteristics above the thin oil layer, the geological measurement characteristics below the thin oil layer, and the geological measurement characteristics of the thin oil layer all include formation shale content, formation porosity, permeability, and oil saturation.

[0029] The calculation process of the shale content in the formation is as follows: V sh =(GR−GR min ) / (GR max −GR min ); In the formula: V sh is the shale content in the formation, %; GR is the logging value of the natural gamma ray curve of the reservoir, API; GR min is the logging value of the natural gamma ray curve at the pure sandstone, API; GR max is the logging value of the natural gamma ray curve at the pure shale, API; The formation porosity is calculated through the relationship between the acoustic travel time and the formation porosity. The specific relationship is: Δ t = ϕ ⋅Δ t f +(1− ϕ )⋅Δ t m ; In the formula: Δ t is the acoustic travel time, μs / m; ϕ is the formation porosity, %; Δ t f is the acoustic travel time of the fluid, μs / m; Δ t m is the acoustic travel time of the rock skeleton, μs / m; The oil saturation is calculated from the deep and shallow lateral resistivity logging data; specifically, first determine the true resistivity of the formation R t ; R t = R d ( R s − R f ) / ( R d − R f ); In the formula, R t is the true resistivity of the formation, Ω·m; R d is the deep lateral resistivity, Ω·m; R s is the shallow lateral resistivity, Ω·m; R f is the mud resistivity, Ω·m; Then determine the oil saturation of the formation according to the true resistivity of the formation R t Specifically: through Rt = ϕ n ⋅ R w ⋅ F ( S w ) is obtained F ( S w ), and then the formation oil saturation is obtained; where: n is the cementation exponent, dimensionless; R w is the formation water resistivity, Ω·m; F ( S w ) is a function related to the water saturation.

Claims

1. A guiding method for the well type structure of horizontal wells in thin oil layers, characterized in that, Before drilling into the thin oil layer, first drill a detection section (NG), and obtain the top boundary line and bottom boundary line of the thin oil layer, the geological survey characteristics above the thin oil layer, the geological survey characteristics below the thin oil layer, the geological survey characteristics of the thin oil layer, and the remote exploration data within the normal distance from the center axis of the wellbore trajectory of the detection section (NG) by using the data obtained during the drilling of the detection section (NG). Start drilling the production section (NB) from the starting position of the detection section (NG), determine the entry window point (A) of the production section (NB) based on the top boundary line, bottom boundary line, and geological survey characteristics of the thin oil layer, compare the geological logging data of the production section (NB) before the entry window point (A) with the remote exploration data, and then calibrate the geological steering tool while drilling; adjust the drilling steering according to the geological survey characteristics above the thin oil layer and the geological survey characteristics below the thin oil layer to ensure that the horizontal section after the entry window point (A) extends within the thin oil layer.

2. The guiding method for the horizontal wellbore structure for thin oil layers according to claim 1, characterized in that, The method is as follows: S1: Start drilling the vertical section (OK), the first build section (KM), and the first holding section (MN) in sequence from the ground. After drilling the first holding section (MN), add a geological steering tool while drilling into the detection section (NG). By using the geological logging data during the drilling of the detection section (NG) and the wellbore trajectory geometric parameter data and geological parameter data around the wellbore trajectory obtained in real time by the measurement while drilling tool string and the geological steering tool while drilling, obtain the top boundary line, bottom boundary line, and thickness of the thin oil layer, the geological survey characteristics above the thin oil layer, the geological survey characteristics below the thin oil layer, the geological survey characteristics of the thin oil layer, and the remote exploration data within the normal distance from the center axis of the wellbore trajectory of the detection section (NG). S2: After drilling the detection section (NG), backfill the detection section (NG) 30 m into the first holding section (MN), and start drilling the production section (NB). The measurement while drilling tool string and the geological steering tool while drilling obtain the data while drilling in real time, and determine the entry window point (A) of the production section (NB) according to the top boundary line, bottom boundary line, and geological survey characteristics of the thin oil layer. Compare the geological logging data of the second build section (NA) with the remote exploration data, and then calibrate the geological steering tool while drilling. S3: After the geological steering tool while drilling is calibrated, adjust the drilling steering according to the geological survey characteristics above the thin oil layer and the geological survey characteristics below the thin oil layer to ensure that the horizontal section after the entry window point (A) extends within the thin oil layer.

3. The guiding method for the horizontal wellbore structure for thin oil layers according to claim 2, wherein The wellbore trajectory geometric parameter data includes well depth, well inclination angle, and azimuth angle. The geological parameter data around the wellbore trajectory includes gamma, acoustic wave, and resistivity. The acoustic wave includes acoustic wave transit time logging data and remote exploration acoustic wave data while drilling. The resistivity includes deep and shallow lateral resistivity logging data and remote exploration electromagnetic wave resistivity data while drilling.

4. The guiding method for the horizontal well type structure for thin oil layers according to claim 2, characterized in that, The geological survey characteristics above the thin oil layer, the geological survey characteristics below the thin oil layer, and the geological survey characteristics of the thin oil layer all include formation shale content, formation porosity, permeability, and oil saturation.

5. The guiding method for the horizontal well type structure for thin oil layers according to claim 4, characterized in that, The calculation process of the shale content in the formation is as follows: V sh =(GR−GR min ) / (GR max −GR min ); Where: V sh is the shale content of the formation, %; GR is the logging value of the reservoir natural gamma ray curve, API; GR min is the logging value of the natural gamma ray curve at the pure sandstone, API; GR max is the logging value of the natural gamma ray curve at the pure shale, API; The formation porosity is calculated through the relationship between the acoustic travel time and the formation porosity, and the specific relationship is: Δ t = ϕ ⋅Δ t f +(1− ϕ )⋅Δ t m ; where: Δ t is the acoustic travel time, μs / m; ϕ is the formation porosity, %; Δ t f is the acoustic travel time of the fluid, μs / m; Δ t m is the acoustic travel time of the rock matrix, μs / m; The oil saturation is calculated from the deep and shallow lateral resistivity logging data; specifically, the true formation resistivity is determined first based on the deep and shallow lateral resistivity logging data R t ; R t = R d ( R s − R f ) / ( R d − R f ); where R t is the true formation resistivity, Ω·m; R d is the deep lateral resistivity, Ω·m; R s is the shallow lateral resistivity, Ω·m; R f is the mud resistivity, Ω·m; Then, based on the true formation resistivity R t the formation oil saturation is determined, specifically: by R t = ϕ n ⋅ R w ⋅ F ( S w ) is obtained F ( S w ), and then the formation oil saturation is obtained; where: n is the cementation exponent, dimensionless; R w is the formation water resistivity, Ω·m; F ( S w ) is a function related to water saturation.

6. A horizontal well type structure for thin oil layers, characterized in that, The guiding method applied to the horizontal wellbore structure for thin oil layers described in claim 1, where the detection section (NG) and the production section (NB) have the same starting point. The detection section (NG) includes a descending section (NE) and a second constant inclination section (EG) connected in sequence. The production section (NB) includes a second deflecting section (NA) and a reservoir tracking section (AB). The descending section (NE) and the second deflecting section (NA) are in the same plane and are both circular arc sections. The second constant inclination section (EG) includes an in-reservoir detection section (EF) and an out-of-reservoir detection section (FG). The starting point of the in-reservoir detection section (EF) coincides with the top boundary line of the thin oil layer, and the end point coincides with the bottom boundary line of the thin oil layer. The reservoir tracking section (AB) extends entirely within the thin oil layer.

7. The horizontal well well type structure for thin oil layers according to claim 6, characterized in that, It further includes a vertical well section (OK), a first deflecting section (KM), and a first constant inclination section (MN) connected in sequence from the wellhead downward. The ends of the first constant inclination section (MN) are respectively connected to the detection section (NG) and the production section (NB). The descending section (NE) and the second deflecting section (NA) are both tangent to the end of the first constant inclination section (MN).

8. The horizontal well type structure for thin oil layers according to claim 7, characterized in that, The constant inclination angle of the first constant inclination section (MN) ranges from 30° to 60°, and the constant inclination angle of the second constant inclination section (EG) ranges from 80° to 90°.

9. The horizontal well type structure for thin oil layers according to claim 7, characterized in that, The distance between the end point of the descending section (NE) and the window entry point (A) is 20m to 50m; the length of the out-of-reservoir detection section (FG) is 10m to 30m.

10. The horizontal well type structure for thin oil layers according to claim 7, characterized in that, The descending slope value of the descending section (NE) is higher than the deflecting slope value of the second deflecting section (NA).

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