Active geosteering method for horizontal section of horizontal well

Abstract

The invention relates to the technical field of oilfield exploration, development and evaluation, in particular to an active geosteering method for a horizontal section of a horizontal well. The method comprises the steps that a target horizontal well and a reference well are determined, and the spatial relation between the initial actual drilling track of the target horizontal well and an initial actual drilling target layer is determined; a target actual drilling track is obtained, a target actual drilling target layer is determined, and the space relation between the target actual drilling track and the target actual drilling target layer is determined; based on the target horizontal well actual drilling track and the target actual drilling target stratum, comprehensively obtaining a predicted target stratum by means of multiple prediction methods; selecting at least two control points in the obtained prediction target layer; connecting the control points in sequence by taking the current well bottom as a starting point to obtain a pre-drilling track; drilling the target horizontal well according to the pre-drilling track; and the steps are executed circularly until the final target point is reached, and drilling is completed. According to the method provided by the invention, various information sources are comprehensively utilized, the well track is actively corrected, and the drilling rate, the recovery rate and the economic efficiency of the oil-containing sandstone are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield exploration, development and evaluation, and in particular to a horizontal well horizontal section active geosteering method. BACKGROUND

[0002] In the horizontal well horizontal section, the drilling purpose requires the horizontal well trajectory to be in the target formation to improve the oil sandstone drilling rate, recovery rate and economic efficiency. However, the understanding of the underground formation in the prior art is only an idealized model, which is more or less away from the real underground geological conditions, which leads to the fact that although the horizontal well design trajectory is described as being in the best and most appropriate position of the target formation, when the horizontal well actual drilling trajectory reaches the specified position and altitude according to the horizontal well design trajectory, it is found that the target layer is not here but in a position above or below.

[0003] In practical application, the value of geosteering in the horizontal well horizontal section is to combine the while-drilling data, on-site analysis and research, real-time correction of the well trajectory and upward or downward adjustment on the basis of fully understanding the design purpose, so that the idealized design model is closer to the real underground geological conditions, and the horizontal well actual drilling trajectory is as much as possible in the target formation to achieve the drilling purpose.

[0004] Chinese patent document publication No. CN 111260791 B discloses a method for updating a geosteering model, a three-dimensional steering model is established, new formation information obtained during drilling is taken as a new constraint point to update the three-dimensional steering model, and geosteering is performed based on the updated three-dimensional steering model. However, passive waiting for new constraint points, in some cases, when the new constraint point appears, the horizontal well actual drilling trajectory has reached the boundary of the target layer or even has penetrated out of the target layer, combined with the fact that all existing commercial steering tools have zero length, which inevitably leads to the fact that the horizontal well actual drilling trajectory travels tens or even hundreds of meters outside the target layer, and further leads to the fact that the oil sandstone drilling rate is reduced. Therefore, in view of the above problems, a horizontal well horizontal section active geosteering method is proposed. SUMMARY

[0005] (I) Technical problem to be solved

[0006] The present application provides a horizontal well horizontal section active geosteering method to overcome the technical problem that the understanding of the underground formation in the prior art is more or less away from the real underground geological conditions, and cannot improve the oil sandstone drilling rate, recovery rate and economic efficiency.

[0007] (II) Technical scheme

[0008] To solve the above problems, the present application provides a horizontal well horizontal section active geosteering method, which comprises:

[0009] Step S1: Determine the target horizontal well and reference well, collect basic data of the target horizontal well, collect reference data of the reference well, and determine the spatial relationship between the initial drilling trajectory of the target horizontal well and the initial drilling target layer based on the acquired basic data and reference data.

[0010] Step S2: Extend the initial actual drilling trajectory of the target horizontal well determined in step S1 forward to the current bottom of the target horizontal well, obtain the target actual drilling trajectory of the target horizontal well, obtain the measurement data of the target horizontal well, determine the target actual drilling target layer of the target horizontal well based on the measurement data, and determine the spatial relationship between the target actual drilling trajectory and the target actual drilling target layer.

[0011] Step S3: Based on the target horizontal well drilling trajectory and target drilling layer determined in Step S2, and in conjunction with the seismic data ahead of the target horizontal well and the reference data of the reference well determined in Step S1, the predicted target layer is obtained by comprehensively using multiple prediction methods.

[0012] Step S4: Within the prediction target layer obtained in step S3, select at least two control points from near to far;

[0013] Step S5: Starting from the current bottom of the target horizontal well determined in step S1, connect the control points obtained in step S4 in sequence to obtain the pre-drilling trajectory;

[0014] Step S6: Drill the target horizontal well determined in step S1 according to the pre-drilling trajectory obtained in step S5.

[0015] Step S7: Repeat steps S2 to S6 until the final target point is reached, and the drilling is complete.

[0016] Preferably, in step S1, the target horizontal well is a horizontal section of a horizontal well that has not been drilled, and the reference well is a vertically inclined well that has been drilled.

[0017] Preferably, the basic data of the target horizontal well includes the historical horizontal well drilling trajectory and the horizontal well logging-while-drilling curve; the reference basic data of the reference well includes the reference well drilling trajectory, the reference well logging curve, the reference well stratification data, and the reference well location target layer; by comparing the horizontal well logging-while-drilling curve and the reference well logging curve, a geological interpretation is made to determine the spatial relationship between the initial drilling trajectory of the target horizontal well and the initial drilling target layer.

[0018] Preferably, in step S2, the measurement data includes measurement while drilling data, logging while drilling data, cuttings logging data, gas logging while drilling data, other engineering parameter data, and regional data. The target drilling trajectory of the target horizontal well is determined based on the measurement while drilling data, and the target drilling layer is determined in the formation space. The other engineering parameter data includes drilling rate, drilling pressure, and mud density.

[0019] Preferably, in step S3, based on the actual drilling trajectory of the target horizontal well and the target drilling target layer, and in conjunction with the seismic data ahead of the target horizontal well and the target layer at the location of the reference well, the predicted target layer is obtained.

[0020] Preferably, in step S3, the multiple prediction methods for the target layer include trend prediction, correlation prediction, and seismic interpretation prediction, and the target layer is the overlapping area of ​​the target layer jointly predicted by the trend prediction, correlation prediction, and seismic interpretation prediction methods.

[0021] Preferably, the trend prediction method generates a trend prediction target layer by extending forward based on the target drilled layer, where the trend and dip angle remain unchanged; the correlation prediction method generates a correlation prediction target layer by selecting a reference well and connecting the target drilled layer with the reference well location target layer; the seismic interpretation prediction method generates a seismic prediction target layer by fitting the target drilled trajectory, a reference well, and seismically interpreted stratigraphic data.

[0022] Preferably, the reference well selected by the correlation prediction method and the reference well selected by the seismic interpretation prediction method are the same reference well, and the reference well is located on the horizontal projection line of the horizontal well design trajectory.

[0023] Preferably, in step S4, the beginning and end of the control point need to be defined. The control point at the beginning is 10 meters away from the current bottom of the target horizontal well, and the control point at the end is located at the maximum distance between the predicted target layer and the current bottom of the target horizontal well.

[0024] Preferably, during each execution of step S7, in step S6, during the process of determining the spatial relationship between the target drilling trajectory and the target drilling layer, the distance of the target drilling trajectory and the thickness of the target drilling layer are updated each time by extending forward, until drilling is completed.

[0025] (III) Beneficial Effects

[0026] The present invention provides an active geological steering method for horizontal well sections, which combines multiple information sources and uses multiple prediction methods to actively predict the target layer ahead based on the actual drilling situation. This can avoid the passive adjustment of the horizontal well trajectory after the actual drilling trajectory reaches the edge of the target layer or even penetrates the target layer, thereby reducing the probability of the actual drilling trajectory penetrating the target layer and improving the drilling encounter rate, recovery rate and economic efficiency of oil-bearing sandstone. Attached Figure Description

[0027] Figure 1 This is a flowchart of an active geological steering method for horizontal sections of horizontal wells according to an embodiment of the present invention;

[0028] Figure 2 This is a logging-while-drilling curve diagram of an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of a well profile according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the target layer predicted by the trend prediction method in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the target layer predicted by the association prediction method in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the target layer predicted by the earthquake interpretation and prediction method in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram illustrating the intersection of three prediction methods in an embodiment of the present invention;

[0034] Figure 8 This is a schematic diagram of fitting a virtual reference well using two reference wells in an embodiment of the present invention;

[0035] Figure 9 This is a schematic diagram of fitting a virtual reference well using a single reference well, as shown in an embodiment of the present invention.

[0036] Legend:

[0037] 100 - Horizontal well design trajectory; 120 - Historical horizontal well actual drilling trajectory; 122 - Target horizontal well actual drilling trajectory; 140 - Horizontal well pre-drilling trajectory;

[0038] 200 - Design target layer; 202 - Reference well location target layer; 220 - Historical drilling target layer; 222 - Target drilling target layer; 242 - Trend prediction target layer; 244 - Correlation prediction target layer; 246 - Seismic prediction target layer; 248 - Predicted target layer;

[0039] B - Landing point; C - First target point; D - Current well bottom; E - First control point; F - Second control point; G - Third control point;

[0040] 300 - Reference well; 310 - First reference well; 320 - Second reference well; 330 - First virtual reference well; 340 - Third reference well; 350 - Second virtual reference well. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Figure 1 This is a flowchart of the active geological steering method for the horizontal section of a horizontal well, as described in an embodiment of the present invention. Figure 1 As shown, this invention provides an active geological steering method for the horizontal section of a horizontal well, specifically including:

[0043] Step S1: Determine the target horizontal well and reference well, collect basic data of the target horizontal well, collect reference data of the reference well, and determine the spatial relationship between the initial drilling trajectory of the target horizontal well and the initial drilling target layer based on the acquired basic data and reference data.

[0044] Step S2: Extend the initial actual drilling trajectory of the target horizontal well determined in step S1 forward to the current bottom of the target horizontal well, obtain the target actual drilling trajectory of the target horizontal well, obtain the measurement data of the target horizontal well, determine the target actual drilling target layer of the target horizontal well based on the measurement data, and determine the spatial relationship between the target actual drilling trajectory and the target actual drilling target layer.

[0045] Step S3: Based on the target horizontal well drilling trajectory and target drilling layer determined in Step S2, and in conjunction with the seismic data ahead of the target horizontal well and the reference data of the reference well determined in Step S1, the predicted target layer is obtained by comprehensively using multiple prediction methods.

[0046] Step S4: Within the prediction target layer obtained in step S3, select at least two control points from near to far;

[0047] Step S5: Starting from the current bottom of the target horizontal well determined in step S1, connect the control points obtained in step S4 in sequence to obtain the pre-drilling trajectory;

[0048] Step S6: Drill the target horizontal well determined in step S1 according to the pre-drilling trajectory obtained in step S5.

[0049] Step S7: Repeat steps S2 to S6 until the final target point is reached, and the drilling is complete.

[0050] In this method, in step S1, the target horizontal well is the horizontal section of a horizontal well that has not been drilled, and the reference well is a vertical and inclined well that has been drilled. The basic data of the target horizontal well includes the historical horizontal well drilling trajectory 120 and the horizontal well logging-while-drilling curve; the reference basic data of the reference well includes the reference well drilling trajectory, the reference well logging curve, the reference well layer data, and the reference well location target layer 202.

[0051] Specifically, by comparing the logging-while-drilling curves of the horizontal well with those of the reference well, a geological interpretation is made to determine the spatial relationship between the initial actual drilling trajectory of the target horizontal well and the initial actual drilling target layer.

[0052] It should be noted that the reference well location target layer 202 is actually drilled and is also part of the design target layer 200. It is also the basic information used to fit the design target layer 200. That is, the design target layer 200 is generated by fitting multiple control points and surface data, such as seismic interpretation stratigraphic data, based on geological data determined by the reference well and other vertical and deviated wells.

[0053] In practical applications, in step S2, the measurement data includes measurement while drilling data, logging while drilling data, cuttings logging data, gas logging data, other engineering parameter data, and regional data. Among them, the target actual drilling trajectory 122 of the target horizontal well is determined based on the measurement while drilling data, and the target actual drilling target layer 222 is determined in the formation space.

[0054] It is important to note that other engineering parameters include drilling speed, drilling pressure, and mud density.

[0055] In addition, well logging curves include GR (Gamma Ray While Drilling), LLD (Layered Least Resistivity), and LLS (Layered Least Resistivity). GR, or Natural Gamma Ray While Drilling, measures the intensity of naturally occurring gamma rays in the rock formation to determine lithology, stratigraphic correlation, and estimate clay content. LLD, or Deep Lateral Resistivity, and LLS, or Shallow Lateral Resistivity, are measured simultaneously to reflect changes in resistivity within the formation, determine the true resistivity, delineate lithological profiles, and quickly and intuitively identify oil and water layers. The combined use of GR, LLD, and LLS logging curves can determine the lithology around the actual drilling trajectory of a horizontal well, identify the formation, and geologically interpret the spatial relationship between the target horizontal well drilling trajectory 122 and the target drilling layer 222, thus identifying the target drilling layer.

[0056] In this method, in step S3, based on the actual drilling trajectory 122 of the target horizontal well and the target actual drilling target layer 222, and in conjunction with the seismic data ahead of the target horizontal well and the target layer 202 of the reference well location, the predicted target layer 248 is obtained.

[0057] In practical applications, the various prediction methods for predicting the target layer 248 include trend prediction, correlation prediction, and seismic interpretation prediction. The target layer 248 is the overlapping area of ​​the target layer predicted by the trend prediction, correlation prediction, and seismic interpretation prediction methods.

[0058] It should be noted that the trend prediction method generates the trend prediction target layer 242 by extending forward from the target actual drilled layer 222, with the trend and dip angle remaining unchanged; the correlation prediction method generates the correlation prediction target layer 244 by selecting a reference well and connecting the target actual drilled layer 222 with the reference well location target layer 202; and the seismic interpretation prediction method generates the seismic prediction target layer 246 by fitting the target actual drilled trajectory 122, a reference well, and seismically interpreted stratigraphic data.

[0059] In practical applications, the trend prediction method assumes that the target layer ahead has a continuous trend with the target layer 220 of the actual drilling trajectory 120 of the implemented horizontal well. The trend prediction method makes full use of the information and trend of the target layer 222, but does not take into account the changes in the geological conditions ahead. In most cases, the trend prediction method is reasonable, but in some cases, especially when the geological conditions ahead change significantly, the trend prediction method will deviate.

[0060] In addition, the correlation prediction method uses the information of the target drilled layer 222 and the reference well location target layer 202 interpreted by the target horizontal well actual drilling trajectory 122. The information is derived from real drilling data and is reliable. However, the correlation prediction method does not consider the changes in geological conditions of the formation between the target horizontal well actual drilling trajectory 122 and the reference well. In most cases, the correlation prediction method is reasonable, but in some cases, especially when the geological conditions change significantly, the correlation prediction method will have deviations.

[0061] Furthermore, the seismic interpretation prediction method predicts the changes in geological conditions of the stratigraphic section between the actual drilling trajectory 122 of the target horizontal well and the reference well based on seismic interpretation. In most cases, the seismic interpretation prediction method is reasonable, but the seismic interpretation itself is inaccurate and has large errors, which leads to the deviation of the prediction.

[0062] In practical applications, the trend prediction method, correlation prediction method, and seismic interpretation prediction method each combine three information sources from different perspectives to obtain the predicted target layer 248. In most cases, each of these three methods is reasonable, and their results even overlap. However, in some situations, especially when geological conditions change significantly ahead of the actual drilling trajectory of a horizontal well, the prediction results of the three methods will diverge. The divergence becomes more pronounced the further away from the current wellbore bottom (D), but at the current wellbore bottom (D), the results of the three methods always overlap. All three methods may exhibit deviations, and current technology cannot determine which method is deviating. This proposed solution uses the overlapping area as the final target layer for prediction, simultaneously satisfying all three prediction methods, thereby improving prediction accuracy compared to a single method and increasing the drilling rate of oil-bearing sandstone.

[0063] Among them, the reference well selected by the correlation prediction method and the reference well selected by the seismic interpretation prediction method are the same reference well, which is located on the horizontal projection line of the horizontal well design trajectory 100.

[0064] Therefore, when there is no reference well or the reference well is distorted on the horizontal projection line of the horizontal well design trajectory 100 ahead of the actual drilling trajectory 122 of the target horizontal well, a reference well is selected on each side of the horizontal projection line of the horizontal well design trajectory 100. The two reference wells are connected to the horizontal projection line of the horizontal well design trajectory at a point. A virtual reference well is set at the intersection point. The average value of the target layer elevation depth of the two reference wells is used as the target layer elevation depth of the virtual reference well.

[0065] Furthermore, when there is no reference well or the reference well is distorted on the horizontal projection line of the horizontal well design trajectory 100 ahead of the target horizontal well actual drilling trajectory 122, and other reference wells are only located on one side of the horizontal projection line of the horizontal well design trajectory 100, the reference well closest to the horizontal projection line of the horizontal well design trajectory 100 is selected, and the perpendicular lines from the reference well to the horizontal projection line of the horizontal well design trajectory 100 intersect at a point. A virtual reference well is set at the intersection point, and the target layer elevation depth of the reference well is used as the target layer elevation depth of the virtual reference well.

[0066] In practical applications, in step S4, the beginning and end of the control points need to be defined. The control point E at the beginning is 10 meters away from the current bottom D of the target horizontal well, and the control point G at the end is located at the maximum distance between the predicted target layer 248 and the current bottom D of the target horizontal well.

[0067] It is important to note that the control point should be selected in the middle or upper part of the elevation depth of the predicted target layer 248. For thin layers, selecting the middle of the elevation depth of the predicted target layer 248 will help the actual drilling trajectory of the target horizontal well to be more within the target layer, thus improving the drilling rate of oil-bearing sandstone. For relatively thick layers, selecting the upper part of the elevation depth of the predicted target layer 248 will help prolong the water breakthrough time.

[0068] In this method, in step S5, the horizontal well design trajectory 100 is the trajectory before the horizontal well is implemented. It is the trajectory designed at the most appropriate position within the design target layer 200, which is obtained by fitting regional data and reference well data.

[0069] However, due to the complexity of underground geological conditions, the designed target layer 200 is more or less different from the actual underground geological conditions, and the horizontal well design trajectory 100 is usually located above or below the actual target layer 200.

[0070] Among them, the historical horizontal well actual drilling trajectory 120 is the trajectory after the horizontal well is implemented. Because there is a deviation between the horizontal well design trajectory 100 and the actual target layer, the historical horizontal well actual drilling trajectory 120 is the wellbore trajectory that is corrected in real time during the implementation of the horizontal well by the geological steering based on a full understanding of the purpose of the design scheme, combined with drilling data, on-site analysis and research. Therefore, how much of the historical horizontal well actual drilling trajectory 120 is located in the target layer depends on the effectiveness of the geological steering.

[0071] It is important to note that the horizontal well pre-drilling trajectory 140 is the trajectory during the horizontal well's implementation; it represents a section of the trajectory that has not yet been implemented but is about to be implemented. At this point, the horizontal well has been partially implemented, becoming the historical horizontal well actual drilling trajectory 120. Based on the actual drilling conditions and the purpose of the design scheme, the geological steering is analyzed and studied on-site, and the design trajectory is revised in real time to obtain the horizontal well pre-drilling trajectory 140. The horizontal well pre-drilling trajectory 140 originates from the historical horizontal well actual drilling trajectory 120 and incorporates information from the historical horizontal well actual drilling trajectory 120, making it closer to the actual underground geological conditions than the design trajectory.

[0072] In this method, during each execution of step S7, in step S6, during the process of determining the spatial relationship between the target drilling trajectory 122 and the target drilling target layer 222, the distance of the target drilling trajectory 122 and the thickness of the target drilling target layer 222 are updated each time by extending forward, until drilling is completed.

[0073] This invention provides an active geological steering method for horizontal well sections. Based on actual drilling conditions, it actively predicts the target layer ahead, avoiding passive adjustments to the horizontal well trajectory after the actual drilling trajectory reaches or even penetrates the target layer. This reduces the probability of the actual drilling trajectory penetrating the target layer and improves the encounter rate with oil-bearing sandstone. Three different prediction methods are used to predict the target layer ahead, and the overlapping area predicted by these three methods is selected to obtain the final predicted target layer, increasing the probability that the control point is located in the actual target layer and improving the reliability of the prediction. When there are few or no effective reference wells at the horizontal projection line position of the designed trajectory ahead, virtual reference wells are used instead of reference wells, ensuring the implementation of correlation prediction and seismic interpretation prediction methods.

[0074] The following is combined with Figures 2 to 9 Taking a horizontal well in a certain block of an oilfield as an example, the working principle of this active geological steering method for the horizontal section of a horizontal well will be described in detail:

[0075] Step 1: Determine the target horizontal well and reference well, collect basic data of the target horizontal well, collect reference data of the reference well, and determine the spatial relationship between the initial drilling trajectory of the target horizontal well and the initial drilling target layer based on the acquired basic and reference data.

[0076] In this embodiment, as Figure 2The logging-while-drilling curves of the horizontal well's actual drilling trajectory 120 are described. The changes in the horizontal well logging curves are analyzed using the MD Measurement Depth scale. The logging-while-drilling curves include GR, LLD, and LLS. The spatial relationship between the historical horizontal well's actual drilling trajectory 120 and the historical actual drilling target layer 220 is described by the changes in the logging curves.

[0077] In practical applications, based on historical horizontal well drilling trajectory 120, horizontal well logging-while-drilling curves, reference well 300 drilling trajectory, reference well 300 logging curves, reference well 300 stratification data, and the target layer 202 at the reference well location, geological interpretation is made through logging curve comparison to determine the spatial relationship between historical horizontal well drilling trajectory 120 and historical target layer 220. Historical horizontal well drilling trajectory 120 and historical target layer 220 are marked on the profile. Based on the geological interpretation of the horizontal well logging-while-drilling curves, the intersection of historical horizontal well drilling trajectory 120 and historical target layer 220 is taken as landing point B and marked on the profile. Reference well 300 and the target layer 202 at the reference well location are also marked on the profile. Simultaneously, the reference well and the target layer 202 at the reference well location are also marked on the profile.

[0078] Step 2: Extend the initial drilling trajectory of the target horizontal well forward to the bottom of the current well of the target horizontal well, obtain the target drilling trajectory of the target horizontal well, obtain the measurement data of the target horizontal well, determine the target drilling layer of the target horizontal well based on the measurement data, and determine the spatial relationship between the target drilling trajectory and the target drilling layer.

[0079] In this embodiment, as Figure 3 As shown, for comparison, the horizontal well design target layer 200 and the historical horizontal well actual drilled target layer 220 are marked on the profile, as are the horizontal well design trajectory 100 and the historical horizontal well actual drilled trajectory 120. Reference well 300 and the reference well location target layer 202 are marked on the profile. Based on the comparison of logging-while-drilling curves and geological interpretation, the historical horizontal well actual drilled trajectory 120 identified and determined the landing point B and the first target point C, thus determining the historical actual drilled target layer 220. However, the historical actual drilled target layer 220 is not located at the design target layer 200, indicating a distance between the design target layer 200 and the actual underground geological conditions. Landing point B and the first target point C are marked on the profile.

[0080] In practical applications, the historical horizontal well drilling trajectory 120 continues to extend forward to generate the target horizontal well drilling trajectory 122, reaching the current well bottom D, and generating measurement-while-drilling data and logging-while-drilling data. By comparing the logging curves, a geological interpretation is made to determine the target drilling layer 222.

[0081] In this embodiment, the actual drilling trajectory 122 of the target horizontal well and the current well bottom D are marked on the cross-sectional view, and the target drilling layer 222 is marked on the cross-sectional view.

[0082] It should be noted that each cycle will generate a new target horizontal well drilling trajectory 122 and a new target drilling layer 222, until drilling is completed.

[0083] Step 3: Based on the actual drilling trajectory of the target horizontal well and the target drilling layer, combined with the seismic data ahead of the target horizontal well and the reference data of the reference well determined in step S1, the predicted target layer is obtained by comprehensively using multiple prediction methods.

[0084] like Figure 4 As shown, this describes the trend prediction target layer 242 obtained based on the trend prediction method. The actual drilling target layer is 222. The trend and the dip angle of the formation remain unchanged. Extending forward, the predicted target layer 242 is generated.

[0085] like Figure 5 As shown, the correlation prediction target layer 244 obtained by the correlation prediction method is described. The reference well 300 is selected ahead, and the target drilling target layer 222 in step two is connected with the reference well position target layer 202 to generate the correlation prediction target layer 244.

[0086] like Figure 6 As shown, the earthquake prediction target layer 246 obtained by the earthquake prediction method is described. The earthquake prediction target layer 246 is generated by fitting the actual drilling trajectory 122 of the target horizontal well, the reference well 300 ahead, and the seismically interpreted stratigraphic data.

[0087] like Figure 7 As shown, the overlapping areas of the three prediction target layers determined by the trend prediction method, correlation prediction method, and seismic interpretation prediction method are identified, forming prediction target layer 248.

[0088] Step 4: Within the target layer for prediction, select at least two control points from near to far.

[0089] In this embodiment, control points E, F, and G are selected from near to far within the predicted target layer 248 region. Control points E, F, and G are located at the midpoint of the elevation depth within the final predicted target layer 248 region. Control point E is 10 meters from the current wellbore bottom D, and control point G is located at the furthest point from the current wellbore bottom D within the predicted target layer 248 region.

[0090] like Figure 8This describes a method for constructing contour maps on the top surface of the target layer of a horizontal well, using two reference wells 310 and 320 to fit a virtual reference well 330 to replace reference well 300. The horizontal projection lines of the actual drilling trajectory 122 of the target horizontal well, the current well bottom D, and the horizontal projection lines of the designed trajectory 100 of the horizontal well are located in the map.

[0091] In practical applications, when there is no reference well 300 or the reference well 300 is distorted on the horizontal projection line of the horizontal well design trajectory 100 ahead of the actual drilling trajectory 122 of the target horizontal well, a reference well 310 and a reference well 320 are selected on each side of the horizontal projection line of the horizontal well design trajectory 100. The reference wells 310 and 320 are connected to intersect the horizontal projection line of the horizontal well design trajectory 100 at a point. A virtual reference well 330 is set at the intersection point. The average value of the target layer elevation depth of reference well 310 and the target layer elevation depth of reference well 320 is used as the target layer elevation depth of virtual reference well 330.

[0092] like Figure 9 This describes a method for fitting a virtual reference well 350 to replace reference well 300 in a contour map of the top surface of the target layer of a horizontal well. The horizontal projection lines of the actual drilling trajectory 122 of the target horizontal well, the bottom of the current well D, and the horizontal projection lines of the designed trajectory 100 of the horizontal well are located in the map.

[0093] In practical applications, when there is no reference well 300 or the reference well 300 is distorted on the horizontal projection line of the horizontal well design trajectory 100 ahead of the actual drilling trajectory 122 of the target horizontal well, and the reference well is only located on one side of the horizontal projection line of the horizontal well design trajectory 100, the reference well 340 closest to the horizontal projection line of the horizontal well design trajectory 100 is selected, and the perpendicular lines from the reference well 340 to the horizontal projection line of the horizontal well design trajectory 100 intersect at a point. A virtual reference well 350 is set at the intersection point, and the target layer elevation depth of the reference well 340 is the target layer elevation depth of the reference well 350.

[0094] Step 5: Starting from the current bottom of the target horizontal well, connect the control points sequentially to obtain the pre-drilling trajectory.

[0095] In this embodiment, a pre-drilling trajectory 140 is designed based on control points E, F, and G. Starting from the current well bottom D, control points E, F, and G are connected in sequence to form the pre-drilling trajectory 140.

[0096] Step Six: Drill the target horizontal well according to the pre-drilling trajectory.

[0097] In this embodiment, drilling proceeds according to the pre-drilling trajectory 140.

[0098] Step 7: Repeat steps 2 through 6 until the final target point is reached, and drilling is complete.

[0099] In this embodiment, steps two through six are executed cyclically to continuously extend the actual drilling trajectory forward, and the control point and the horizontal well pre-drilling trajectory 140 are also continuously updated until drilling is completed.

[0100] The present invention provides an active geological steering method for horizontal well sections, which combines multiple information sources and uses multiple prediction methods to actively predict the target layer ahead based on the actual drilling situation. This can avoid the passive adjustment of the horizontal well trajectory after the actual drilling trajectory reaches the edge of the target layer or even penetrates the target layer, thereby reducing the probability of the actual drilling trajectory penetrating the target layer and improving the drilling encounter rate, recovery rate and economic efficiency of oil-bearing sandstone.

[0101] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A method for active geosteering of a horizontal section of a horizontal well, c h a r a c t e r i s e d in that, The method comprises the following steps: Step S1: determining a target horizontal well and a reference well, collecting basic data of the target horizontal well, collecting reference data of the reference well, and determining an initial real drilling trajectory of the target horizontal well and a spatial relationship between the initial real drilling target layer of the target horizontal well according to the obtained basic data and reference data; Step S2: extending the initial real drilling trajectory of the target horizontal well determined in the step S1 to a present bottom hole of the target horizontal well, obtaining a target real drilling trajectory of the target horizontal well, obtaining measurement data of the target horizontal well, determining a target real drilling target layer of the target horizontal well according to the measurement data, and determining a spatial relationship between the target real drilling trajectory and the target real drilling target layer; Step S3: based on the target horizontal well real drilling trajectory and the target real drilling target layer determined in the step S2, in combination with forward seismic data of the target horizontal well and the reference data of the reference well determined in the step S1, and by means of a plurality of prediction methods, a predicted target layer is obtained; Step S4: at least two control points are selected from the predicted target layer obtained in the step S3 from near to far; Step S5: taking the present bottom hole of the target horizontal well determined in the step S1 as a starting point, connecting the control points obtained in the step S4 in sequence, and obtaining a pre-drilling trajectory; Step S6: drilling the target horizontal well according to the pre-drilling trajectory obtained in the step S5; Step S7: the steps S2 to S6 are executed cyclically until a terminal target point is reached and drilling is completed.

2. The horizontal well horizontal section proactive geosteering method of claim 1, wherein, In the step S1, the target horizontal well is a horizontal section of a horizontal well which has not been drilled, and the reference well is a straight and inclined well which has been drilled.

3. The horizontal well horizontal section proactive geosteering method of claim 2, wherein, In the step S1, the basic data of the target horizontal well comprises a historical horizontal well real drilling trajectory (120) and a horizontal well logging-while-drilling curve; the reference data of the reference well comprises a reference well real drilling trajectory, a reference well logging curve, reference well layering data and a reference well location target layer (202); by comparing the horizontal well logging-while-drilling curve and the reference well logging curve, geological interpretation is made, and the spatial relationship between the initial real drilling trajectory of the target horizontal well and the initial real drilling target layer is determined.

4. The horizontal well horizontal section proactive geosteering method of claim 1, wherein, In the step S2, the measurement data comprises measurement-while-drilling data, logging-while-drilling data, drilling-while-drilling rock cutting logging data, drilling-while-drilling gas logging data, other engineering parameter data and regional data; the target horizontal well target real drilling trajectory (122) is determined according to the measurement-while-drilling data, and the target real drilling target layer (222) is determined in the stratum space; the other engineering parameter data comprises drilling speed, drilling pressure and mud density.

5. The method of claim 3, wherein, In the step S3, based on the target horizontal well real drilling trajectory (122) and the target real drilling target layer (222), in combination with the forward seismic data of the target horizontal well and the reference well location target layer (202), the predicted target layer (248) is obtained.

6. The horizontal well horizontal section proactive geosteering method of claim 1, wherein, In the step S3, the plurality of prediction methods of the predicted target layer (248) comprise a trend prediction method, a correlation prediction method and a seismic interpretation prediction method, and the predicted target layer (248) is an overlapping area of the target layers predicted by the trend prediction method, the correlation prediction method and the seismic interpretation prediction method.

7. The horizontal well horizontal section proactive geosteering method of claim 6, wherein, The trend prediction method is to generate a trend predicted target layer (242) by extending the target drilled target layer (222) forward according to the same trend and the same dip angle.

8. The horizontal well horizontal section proactive geosteering method of claim 7, wherein, The reference well selected by the correlation prediction method and the reference well selected by the seismic interpretation prediction method are the same reference well, and the reference well is a reference well located on the horizontal projection line of the horizontal well design trajectory (100).

9. The horizontal well horizontal section proactive geosteering method of claim 1, wherein, In the step S4, the first and last control points need to be defined, the first control point (E) is 10 meters away from the current bottom hole (D) of the target horizontal well, and the last control point (G) is located at the maximum distance between the predicted target layer (248) and the current bottom hole (D) of the target horizontal well.

10. The horizontal well horizontal section proactive geosteering method of claim 1, wherein, In each execution of the step S7, in the determination process of the spatial relationship between the target drilled trajectory (122) and the target drilled target layer (222) in the step S6, the distance of the target drilled trajectory (122) and the thickness of the target drilled target layer (222) are updated by extending forward each time until drilling is completed.

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