Horizontal well soft landing geosteering method

Abstract

The invention relates to a horizontal well soft landing geosteering method, and belongs to the technical field of petroleum and natural gas exploration and development. The horizontal well soft landing geosteering method which is simple and convenient to operate, scientific and rigorous is provided by fully utilizing the key influence factor of the stratum vertical thickness, climbing for looking for, searching for the soft landing point, anchoring the soft landing point and taking the soft landing point as the target as the guidance. The method has general applicability to whether the mark and the target layer have the same inclination and inclination angle in exploration and development mine field practice, namely whether the vertical thickness of the overlying stratum of the target layer changes in the three-dimensional space or not, the method is scientific and rigorous, easy to operate and accurate in result, soft landing of the horizontal well can be completely achieved, and the method has a wide application prospect. And powerful technical support is provided for high-efficiency passing of the horizontal section after soft landing and realization of two core key indexes of reservoir height drilling encounter rate and track smoothness of the horizontal well.

Description

Technical Field

[0001] This invention relates to a geological guidance method for soft landing of horizontal wells, belonging to the field of oil and gas exploration and development technology. Background Technology

[0002] In exploration and development practice, horizontal well trajectories typically consist of three segments: the vertical section, the build-up section, and the horizontal section. A horizontal well soft landing refers to the process where, at the end of the build-up section and before entering the target layer, the horizontal well trajectory, along the designed direction, enters the target layer at a small angle (the angle between the horizontal well trajectory and the top of the target layer) that matches the thickness of the target layer. Figure 1 As shown in the diagram. This process is similar to an aircraft making a soft landing along the runway at a small angle (the angle between the aircraft's descent trajectory and the runway) that matches passenger comfort, ensuring a smooth landing.

[0003] A soft landing in a horizontal well provides strong support for efficient horizontal trajectory movement after entering the target layer, and plays a decisive role in ensuring the smooth trajectory of the horizontal well and a high drilling rate in the reservoir.

[0004] The success of a horizontal well soft landing hinges on the accuracy of the designed vertical depth of the soft landing point. The smaller the absolute error between the designed and actual vertical depth, the higher the accuracy of the designed vertical depth. Conversely, the larger the absolute error, the lower the accuracy. Typically, the target layer thickness for horizontal wells is relatively small, generally 1-2 meters or 3-5 meters, rarely reaching 10 meters. Theoretically, to achieve a smooth trajectory during the horizontal well build-up and a soft landing, the absolute error between the designed and actual vertical depth of the soft landing point must be less than 0.5 meters; in other words, the accuracy of the designed vertical depth must be sufficiently high.

[0005] In mining practice, the absolute error between the designed vertical depth and the actual vertical depth of a horizontal well soft landing point is often quite large due to the influence of two factors: the inherent depth accuracy of seismic, drilling, logging, and well logging data, and the magnitude of errors between different depth measurement systems. This absolute error increases with the increasing vertical depth of the target layer. Typically, this absolute error is 0.05–0.1% or greater of the target layer's vertical depth. That is, when the target layer's vertical depth is 4000 meters, the absolute error is 2–4 meters or greater, indicating very low accuracy in the designed vertical depth of the horizontal well soft landing point.

[0006] In mining practice, when the absolute error between the designed vertical depth and the actual vertical depth of the soft landing point is relatively large, that is, when the accuracy of the designed vertical depth of the horizontal well soft landing point is very low and cannot meet the theoretically high accuracy requirements, the following two situations may occur:

[0007] (1) When the absolute error between the designed vertical depth and the actual vertical depth of the soft landing point of a horizontal well is relatively large, and the designed vertical depth of the soft landing point is smaller than the actual vertical depth, it will cause the horizontal well trajectory above the target layer (actual layer) in the horizontal section (actually drilled) after the soft landing point (designed) to exhibit a "layer drift" phenomenon. That is to say, above the target layer (actual layer), when the horizontal section (actually drilled) approaches the target layer (actual layer), if the angle between the horizontal section (actually drilled) and the top of the target layer (actual layer) is too small or the angle is 0, the horizontal section (actually drilled) and the top of the target layer (actual layer) will be in a state of almost parallel or completely parallel, resulting in a serious delay or failure of the horizontal well soft landing. Figure 2 As shown.

[0008] (2) When the absolute error between the designed vertical depth and the actual vertical depth of the soft landing point of a horizontal well is relatively large, and the designed vertical depth of the soft landing point is greater than the actual vertical depth, it will cause a "large-angle dive" phenomenon in the horizontal well trajectory when the build-up section before the soft landing point (design) directly drills through the target layer (actual). That is to say, above the target layer (actual), when the build-up section before the soft landing point (design) approaches the target layer (actual), the angle between the build-up section trajectory and the top of the target layer (actual) is too large, resulting in a "hard landing" and the subsequent drilling through the target layer (actual), such as... Figure 3 As shown.

[0009] In either of the above two scenarios, a soft landing of the horizontal well cannot be achieved.

[0010] Horizontal well geological steering refers to the process of using geological information obtained when a horizontal well encounters the overlying strata of the target layer to promptly correct the designed vertical depth of the horizontal well's soft landing point, and guiding the corresponding trajectory adjustments during the horizontal well's build-up section, thereby achieving a soft landing. In mining practice, drilling, logging, and well logging data obtained during the actual drilling process are used to promptly identify multiple markers encountered sequentially in the overlying strata of the target layer. It should be noted that these markers are crucial geological information for horizontal well geological steering. Then, by sequentially identifying these markers, the designed vertical depth of the horizontal well's soft landing point is corrected, guiding the corresponding trajectory adjustments during the horizontal well's build-up section, thus achieving a soft landing. If the horizontal well's soft landing point is likened to a travel destination, these markers are like road signs on a highway. These road signs clearly indicate the distance between the current location and the destination, allowing for timely adjustments to travel plans, thereby achieving a timely and accurate arrival at the destination.

[0011] Therefore, it is essential and crucial to adopt a scientific and rigorous horizontal well geological steering method to make early and accurate corrections to the designed vertical depth of the horizontal well soft landing point, and to guide the corresponding trajectory correction of the horizontal well build-up section to achieve a soft landing of the horizontal well.

[0012] In mining practice, due to the influence of tectonic and sedimentary factors, the marker and target layers are usually not parallel to each other in three-dimensional space. That is to say, in three-dimensional space, the vertical thickness of the strata between each marker and the vertical thickness of the strata between each marker and the target layer are variable, rather than a fixed value.

[0013] In the horizontal well trajectory drilling direction, the interrelationships between various markers and target layers can be divided into the following six cases (such as...). Figure 4 As shown):

[0014] (1) Parallel lines: They are parallel to each other and have the same dip angle. The vertical thickness of the strata between each marker and the vertical thickness of the strata between each marker and the target layer are constant and are fixed values.

[0015] (2) Parallel curves: They are parallel to each other, but the dip angle is different. The vertical thickness of the strata between each marker and the vertical thickness of the strata between each marker and the target layer are different, that is, they gradually increase or decrease.

[0016] (3) Straight line divergence: It is divergent, and the vertical thickness of the strata between each marker and the vertical thickness of the strata between each marker and the target layer are all different, that is, they gradually increase.

[0017] (4) Curve divergence: It is divergent, and the vertical thickness of the strata between each marker and the vertical thickness of the strata between each marker and the target layer are all different, that is, they gradually increase.

[0018] (5) Linear convergence: It is in a convergent state. The vertical thickness of the strata between each marker and the vertical thickness of the strata between each marker and the target layer are all changing, that is, gradually decreasing.

[0019] (6) Curve convergence: It is in a convergent state. The vertical thickness of the strata between each marker and the vertical thickness of the strata between each marker and the target layer are all changing, that is, gradually decreasing.

[0020] Currently, there are two main types of geological steering methods commonly used in the industry for horizontal wells:

[0021] Method 1: Taking Chinese patent document CN109209229A as a typical example, the specific steps are as follows: First, multiple markers are determined in the overlying strata of the target layer, and it is assumed that each marker is parallel to the others, that is, each marker has the same dip and dip angle; then, each time a set of markers is encountered, the next set of markers is treated as a virtual target layer, and a trajectory is designed; finally, by continuously correcting the trajectory to reach the virtual target layer, the drilling is gradually approached, guiding the drilling to the real target layer.

[0022] In layman's terms, Method 1 assumes that all markers and target layers have the same dip and dip angle, and adopts a tentative approach, taking one step at a time to gradually approach the target layer. In mining practice, however, markers and target layers often do not have the same dip and dip angle, so this method is not rigorous or scientific, and cannot achieve a soft landing in horizontal wells.

[0023] Method 2: Taking Chinese patent document CN116025281A as a typical example, the specific steps are as follows: First, establish an initial formation model and an initial three-dimensional GR attribute model; then, when drilling reaches the first marker, collect the drilling GR curve, extract the corresponding pseudo-GR curve from the initial three-dimensional GR attribute model. If there is an error between the drilling GR curve and the pseudo-GR curve of the first marker's depth data, determine the actual drilling coordinates of the first marker, establish a first virtual vertical well under these coordinates, and combine the first virtual vertical well with the initial formation model to obtain the design vertical depth of the first marker; simultaneously, calculate the actual drilling vertical depth of the first marker based on the actual drilling depth measurement of the first marker combined with the corresponding well inclination data; The first vertical correction is calculated based on the designed vertical depth and the actual drilling depth of the first marker. The stratigraphic data of all markers below the first marker in the initial formation model are corrected according to the first vertical correction, resulting in the first corrected formation model and the first corrected three-dimensional GR attribute model. The vertical depth of the target point is predicted according to the first corrected formation model, and the well inclination angle is adjusted according to the vertical depth of the target point. Finally, this process is repeated until the nth marker is encountered, at which point the nth corrected formation model and the nth corrected three-dimensional GR attribute model are obtained. The vertical depth of the target point is predicted according to the nth corrected formation model, and the well inclination angle is adjusted according to the vertical depth of the target point. This process continues until all markers are encountered. The well then enters the target layer at the target point according to the final adjusted well inclination angle, completing the horizontal well landing.

[0024] Method 2 utilizes multiple markers in the overlying strata of the target layer. First, a virtual vertical well is established, and the vertical correction is calculated. Then, using this identical vertical correction value, the formation model is sequentially corrected, the target depth is predicted, and the well inclination angle is adjusted until a horizontal well landing is achieved. Theoretically, Method 2 is also flawed and unscientific. The main reason for this flaw is that, objectively speaking, the vertical correction calculated in the formation model using the virtual vertical well should be correlated with the vertical thickness of the formation between markers. That is, as the vertical thickness of the formation between markers and between markers and the target layer increases or decreases, the corresponding vertical correction will also increase or decrease proportionally. Method 2 uses a fixed vertical correction value when a marker is encountered to correct all subsequent marker positions and the formation model, which is flawed and unscientific. Furthermore, the target depth predicted by the formation model based on this is also flawed and unscientific, thus failing to achieve a horizontal well landing.

[0025] In summary, in mining practice, methods 1 and 2 are generally applicable when the relationships between markers and target layers along the horizontal well drilling direction are linear and parallel. However, methods 1 and 2 are not applicable for the five scenarios where the relationships between markers and target layers along the horizontal well drilling direction are curved and parallel, linear and divergent, linear and convergent, respectively, and neither can achieve a soft landing for the horizontal well. Specifically:

[0026] For horizontal wells where the relationships between markers and target layers along the drilling direction exhibit either linear or curvilinear divergence, if Method 1 or Method 2 is used for geological steering, the increasing vertical thickness of the formation will result in an uneven trajectory during the build-up section of the horizontal well, despite multiple adjustments. This leads to a "layer-drifting" phenomenon, preventing a soft landing of the horizontal well. Figure 5 As shown.

[0027] Conversely, for the two cases where the relationship between the markers and target layers in the drilling direction of the horizontal well trajectory is linear convergence or curvilinear convergence, if Method 1 or Method 2 is used for horizontal well geological steering, due to the gradual decrease in the vertical thickness of the formation, even after multiple adjustments to the horizontal well build-up trajectory, the build-up trajectory will still be uneven, and the horizontal well trajectory will exhibit a "large-angle dive" phenomenon, making it impossible to achieve a soft landing of the horizontal well.

[0028] In addition, for cases where the relationship between various markers and target layers in the drilling direction of a horizontal well trajectory is that the curves are parallel, if Method 1 or Method 2 is used for geological steering of the horizontal well, due to the gradual increase or decrease in the vertical thickness of the formation, even after multiple adjustments to the trajectory of the horizontal well build-up section, the trajectory of the build-up section will still be uneven, and the horizontal well trajectory will exhibit phenomena such as "floating above the layer" or "sinking at a large angle," making it impossible to achieve a soft landing of the horizontal well.

[0029] Therefore, it is very important and necessary to invent a geological guidance method for soft landing of horizontal wells that is applicable to different situations where the relationships between various markers and target layers in the drilling direction of the horizontal well trajectory are different. Summary of the Invention

[0030] The purpose of this invention is to provide a geological guidance method for soft landing of horizontal wells, which can solve the problem that current geological guidance methods for soft landing of horizontal wells cannot achieve soft landing of horizontal wells.

[0031] To achieve the above objectives, the technical solution adopted by the horizontal well soft landing geological steering method of the present invention is as follows:

[0032] A geological guidance method for soft landing in horizontal wells includes the following steps: identifying multiple markers in the overlying strata of the target layer of the horizontal well, drilling along the designed well trajectory, correcting the structural map of each marker encountered using drilling data, correcting the projection points of the designed soft landing point on the top and bottom of the target layer along the vertical direction, correcting the structural maps of the top and bottom of the target layer using the corrected projection points, and finally correcting the drilling trajectory using the corrected projection points of the designed soft landing point on the top of the target layer, the corrected marker structural map, and the structural maps of the top and bottom of the target layer.

[0033] This invention fully utilizes the key influencing factor of formation vertical thickness, employing a high-altitude, long-range approach to search for and anchor soft landing points. Guided by this target, it provides a simple yet scientifically rigorous geological guidance method for soft landing in horizontal wells. This invention is universally applicable to determining whether marker and target layers share the same dip and dip angle in exploration and development practices, i.e., whether the vertical thickness of the overlying strata of the target layer varies in three-dimensional space. The method is scientifically rigorous, easy to operate, and yields accurate results, fully capable of achieving soft landing in horizontal wells. It also provides strong technical support for efficient horizontal well traversal after soft landing, achieving the two core key indicators of high reservoir encounter rate and smooth trajectory in horizontal wells.

[0034] Preferably, multiple markers are identified and determined in the overlying strata of the target layer using seismic, drilling, logging, and well logging data.

[0035] Preferably, multiple indicators are identified and determined using the characteristics of well logging gamma curves.

[0036] Preferably, the data while drilling includes well logging gamma data and well deviation data.

[0037] Preferably, the method for correcting the construction diagram of the drilling mark is as follows: determine the actual drilling location and vertical depth of the horizontal well drilling mark, and then correct the construction diagram of the mark.

[0038] Preferably, the trajectory correction method is as follows: along the drilling direction of the drilled trajectory, passing through the actual drilling point of the marker and the projected point of the designed soft landing point on the top of the target layer after correction, within the range allowed by the drilling directional drilling capability, the trajectory of the well to be drilled after the drilling marker is corrected. Attached Figure Description

[0039] Figure 1 A schematic diagram illustrating a "soft landing" by entering the target layer at a small angle that matches the target layer thickness;

[0040] Figure 2 A schematic diagram showing the phenomenon of "layer drift" in which the horizontal well trajectory is above the target layer (actual layer) when the designed vertical depth for the soft landing point of the horizontal well is less than the actual vertical depth.

[0041] Figure 3 A schematic diagram illustrating how a horizontal well trajectory can "dive at a large angle" and "hard land" at the target layer (actual) when the designed vertical depth for the soft landing point of a horizontal well is greater than the actual vertical depth.

[0042] Figure 4 A schematic diagram illustrating six scenarios of the relationships between various markers and target layers along the drilling direction of a horizontal well trajectory;

[0043] Figure 5 This diagram illustrates how, in cases where the relationships between markers and target layers along the drilling direction of a horizontal well trajectory diverge linearly, using Method 1 or Method 2 for geological steering of the horizontal well results in a "layer drift" phenomenon in the horizontal well trajectory, making a soft landing of the horizontal well impossible.

[0044] Figure 6 This is a schematic diagram of the horizontal well soft landing geological guidance method according to an embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram illustrating how the gamma ray logging features are used to identify and determine three markers in an embodiment of the present invention.

[0046] Figure 8 This is a structural diagram of symbol 1 in an embodiment of the present invention;

[0047] Figure 9 This is a structural diagram of the top of the target layer in an embodiment of the present invention;

[0048] Figure 10 This is a cross-sectional view of the horizontal well trajectory including each marker, the top of the target layer, and the bottom of the target layer, according to an embodiment of the present invention.

[0049] Figure 11 This is a gamma curve diagram of well P4H1 encountering marker 1 in an embodiment of the present invention;

[0050] Figure 12 This is a modified diagram of marker 1 in an embodiment of the present invention;

[0051] Figure 13 This is the first corrected diagram of the target layer top structure in an embodiment of the present invention;

[0052] Figure 14 This is a cross-sectional view of the horizontal well trajectory after trajectory correction of the drilling trajectory after encountering marker 1 in an embodiment of the present invention. Detailed Implementation

[0053] The horizontal well soft landing geology guidance method of the present invention is a pioneering invention. The horizontal well soft landing geology guidance method of the present invention includes the following steps: identifying multiple markers in the overlying strata of the target layer of the horizontal well; then drilling along the designed well trajectory; each time a marker is encountered, the structural map of the encountered marker is corrected using drilling data; and the projection points of the soft landing point on the top and bottom of the target layer are corrected based on the principle of constant formation vertical thickness; then, the structural maps of the top and bottom of the target layer are corrected using the corrected projection points of the designed soft landing point on the top of the target layer, as well as the corrected marker structural map and the structural maps of the top and bottom of the target layer; and finally, within the range allowed by the drilling directional drilling capability, the trajectory of the well to be drilled after encountering the marker is corrected.

[0054] This invention fully utilizes the key influencing factor of formation vertical thickness, employing a high-altitude, long-range approach to search for and anchor soft landing points. Guided by this target, it provides a simple yet scientifically rigorous geological guidance method for soft landing in horizontal wells. This invention is universally applicable to determining whether marker and target layers share the same dip and dip angle in exploration and development practices, i.e., whether the vertical thickness of the overlying strata of the target layer varies in three-dimensional space. The method is scientifically rigorous, easy to operate, and yields accurate results, fully capable of achieving soft landing in horizontal wells. It also provides strong technical support for efficient horizontal well traversal after soft landing, achieving the two core key indicators of high reservoir encounter rate and smooth trajectory in horizontal wells.

[0055] In some preferred embodiments, multiple markers are identified and determined in the overlying strata of the target layer using seismic, drilling, logging, and well logging data.

[0056] In some preferred embodiments, multiple markers are identified and determined using well logging gamma curve features.

[0057] In this invention, A 设计 The intersection of the designed well trajectory and design marker 1, i.e., the location and vertical depth of design drilling encounter marker 1; B 设计 Design soft landing point C 设计 Along the vertical direction, the projection point on design mark 1; C 设计 h1 represents the intersection of the designed well trajectory and the top of the target layer, i.e., the location and vertical depth of the soft landing point in the target layer; b is B. 设计 With C 设计 The distance between them, i.e., the vertical thickness of the strata between marker 1 at the designed soft landing point and the top of the target layer; A 实钻 B is the intersection of the actual drilling trajectory and actual marker 1, i.e., the position and vertical depth of actual drilling marker 1; 修正1 C 设计 Along the vertical direction, the projection point on the actual drill mark 1; C 修正1B is obtained based on h1 and actual drill mark 1. 修正1 For the soft landing point C of the design target layer 设计 The vertical depth is corrected for the first time.

[0058] Theoretically, the more markers identified and determined, the better the results. However, in mining practice, generally, the distance from the target layer allows for slightly more flexibility in trajectory correction; conversely, the closer to the target layer, the smaller the flexibility. To meet the practical needs of horizontal well trajectory correction, in the overlying strata of the target layer, the farther away from the target layer, the sparser the markers need to be identified and determined; conversely, the closer to the target layer, the denser the markers need to be identified and determined. For example, markers need to be identified and determined near 100 meters, 50 meters, 30 meters, and 20 meters above the target layer.

[0059] In some preferred embodiments, the adjusted drilling trajectory passes through the drilling encounter point marked by the drilling mark.

[0060] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0061] Example

[0062] The horizontal well soft landing geological guidance method of this embodiment, such as Figure 6 As shown, the specific steps include:

[0063] (1) Using seismic, drilling and logging data, identify multiple markers of adjacent wells (JH1, JH2) in the overlying strata of the target layer, and mark them as marker 1, marker 2, marker 3, ... respectively. Using a combination of well and seismic data, compile structural maps of each marker (marker 1, marker 2, marker 3, ...), the top of the target layer and the bottom of the target layer in sequence.

[0064] Specifically, using the well logging gamma data from adjacent wells (JH1, JH2), three markers (such as...) are identified and determined in the overlying formation of the target layer by utilizing the characteristics of the well logging gamma curves. Figure 7 As shown, JH1 and JH2 are the well numbers of nearby drilled wells, and the three markers are labeled Mark 1, Mark 2, and Mark 3 respectively. Through well-seismic analysis, structural diagrams of Mark 1, Mark 2, Mark 3, the top of the target layer, and the bottom of the target layer are sequentially compiled; among them, the structural diagram (design) of Mark 1 and the top of the target layer is as follows. Figure 8 , Figure 9 As shown; where the distances between marker 1, marker 2, and marker 3 and the target layer decrease sequentially; the horizontal and vertical coordinates of the structural map refer to the east-west and north-south directions in the geodetic coordinate system, respectively, where the horizontal coordinate values ​​gradually increase from west to east, and the vertical coordinate values ​​gradually increase from south to north;

[0065] (2) Calculate the vertical thickness (h1, h2, h3...) of the strata between the projection points of the designed soft landing point on each marker along the vertical direction and the projection point on the top of the target layer, and the vertical thickness h between the projection points of the designed soft landing point on the top of the target layer and the projection point on the bottom of the target layer. 顶底 And obtain a horizontal well trajectory profile (design) including each marker, the top of the target layer, and the bottom of the target layer;

[0066] Specifically, based on the vertical and horizontal coordinates of the designed soft landing point, the designed soft landing point is projected vertically onto the structural diagrams (designs) of markers 1, 2, 3, the top of the target layer, and the bottom of the target layer obtained in step (1). The vertical depth of the soft landing point at the corresponding projection point on each structural diagram (design) is calculated. The absolute value of the difference between the projection point of the designed soft landing point on each marker and the projection point on the top of the target layer is the vertical thickness of the strata between markers 1, 2, 3 above the designed soft landing point and the top of the target layer (denoted as h1, h2, h3 respectively). The absolute value of the difference between the projection point of the designed soft landing point on the top of the target layer and the projection point on the bottom of the target layer is the vertical thickness of the strata between the top of the target layer and the bottom of the target layer below the designed soft landing point, denoted as h. 顶底 The designed soft landing point is the intersection of the designed well trajectory and the top of the target layer, i.e., located at the top of the target layer itself.

[0067] like Figure 8 As shown, the projection point of the designed soft landing point onto the construction diagram of marker 1 along the vertical direction is denoted as B. 设计 Then, its vertical depth is calculated to be -3425.0m; for example... Figure 9 As shown, the projection point of the designed soft landing point onto the top of the target layer on the structural diagram along the vertical direction is denoted as C. 设计 Then, its vertical depth is calculated to be -3488.7m; Figure 8 and Figure 9 P in 设计 and P' 设计 P represents the left and right endpoints of the designed well trajectory profile line, respectively. 设计 ~P' 设计 Represents the name of the section line;

[0068] like Figure 10 As shown, following the designed drilling direction along the well trajectory, passing through the designed drilling points and designed soft landing points marked 1, 2, and 3, a horizontal well trajectory profile (design) including each marker, the top of the target layer, and the bottom of the target layer is obtained; using point B... 设计 The vertical depth (-3425.0m) and point C 设计 The vertical depth (-3488.7m) is calculated by subtracting the two values ​​to obtain the vertical thickness h1 of the stratum between marker 1 and the top of the target layer, which is 63.7m.

[0069] Similarly, such as Figure 10 As shown, the projection point of the designed soft landing point onto the target layer bottom structure diagram along the vertical direction is denoted as D. 设计 Using point C 设计 Vertical depth and point D 设计 Subtract the vertical depth from the vertical depth to obtain the vertical thickness h of the stratum between the top and bottom of the target layer. 顶底 ;

[0070] (3) Drill along the designed drilling direction along the well trajectory to the designed horizontal well (P4H1 well). Using the logging-while-drilling gamma data and well inclination data of the designed horizontal well (P4H1 well), compare them with the gamma curve characteristics of marker 1 in the P4H1 well area identified in step (1) to determine the actual drilling location and vertical depth of marker 1 encountered by the horizontal well. Correct the marker 1 construction diagram (design) to obtain the marker 1 construction correction diagram (e.g., Figure 12 (As shown), and calculate the vertical depth B at the projection of the designed soft landing point onto the modified diagram of marker 1. 修正1 ;

[0071] Specifically, using the logging-while-drilling gamma ray data and wellbore deviation data of the designed horizontal well (P4H1 well), the actual drilling location and vertical depth of the horizontal well encountering the marker 1 within the P4H1 well area identified in step (1) are determined by comparing them with the gamma ray curve characteristics of marker 1; for example, Figure 11 As shown, the actual depth of the drilling point encountered by marker 1 in the horizontal well is -3367.8m, and the actual drilling point is denoted as A. 实钻 (Vertical depth is -3367.8m); using point A 实钻 (Vertical depth -3367.8m) The construction drawing (design) of marker 1 is revised to obtain the revised construction drawing of marker 1, as follows. Figure 12 As shown; project the designed soft landing point vertically onto the modified diagram of marker 1, and calculate the vertical depth of the projection of the designed soft landing point onto the modified diagram of marker 1, marked as B. 修正1 (3421.5m);

[0072] Using point A 实钻 The specific method for correcting the construction diagram of marker 1 (with a vertical depth of -3367.8m) is as follows: Based on the obtained point A 实钻 The ordinates and vertical depths of point A are determined, and point A is assigned a vertical coordinate. 实钻 Projecting onto the construction drawing (design) of mark 1, point A... 实钻 The vertical depth is used as a newly added well data point. The vertical depth contour lines of the structural map (design) of Mark 1 are corrected by using a combination of well and seismic methods to obtain the structural correction map of Mark 1.

[0073] (4) Using the vertical thickness h1 of the stratum between marker 1 and the top of the target layer, and the vertical thickness h between the top of the target layer and the bottom of the target layer obtained in step (2), 顶底 Step (3) The vertical depth B at the projection of the designed soft landing point onto the modified map of marker 1 is obtained. 修正1 The vertical depth of the projected soft landing point on the structural maps of the target layer top and bottom along the vertical direction is corrected respectively. Then the structural maps of the target layer top and bottom are corrected to obtain the first corrected structural map of the target layer top and the first corrected structural map of the target layer bottom.

[0074] Specifically, firstly, using the vertical thickness h1 (63.7m) of the strata between marker 1 and the top of the target layer obtained in step (2) and the design soft landing point obtained in step (3) on the modified structure diagram of marker 1 (see... Figure 12 Vertical depth B at the projection point on the surface 修正1 (-3421.5m), by passing B 修正1 The design soft landing point is adjusted by moving the vertical angle (-3421.5m) down by h1 (63.7m). In other words, using B... 修正1 Subtracting h1 (63.7m) from (-3421.5m) yields the first correction point C for the designed soft landing point. 修正1 (-3485.2m).

[0075] Then, using the first correction point C of the designed soft landing point... 修正1 The longitudinal and transverse coordinates and their vertical depth (with a vertical depth of -3485.2m) are given, and C is also given. 修正1 (Vertical depth -3485.2m) Projected onto the top structural drawing (design) of the target layer, C 修正1 The vertical depth (-3485.2m) was used as data from a newly added well. A combined well-seismic approach was employed to revise the target layer top structure map (design), resulting in the first revised target layer top structure map (see...). Figure 13 Similarly, using the first correction point C of the designed soft landing point... 修正1 (-3485.2m), vertical thickness h of the strata between the top and bottom of the target layer. 顶底 , will C 修正1 (Vertical depth -3485.2m) Move downwards along the vertical direction by h 顶底 The first correction point D is obtained by projecting the designed soft landing point vertically onto the target layer bottom structure diagram (design). 修正1 Similarly, using D 修正1 The vertical and horizontal coordinates and their vertical depth, and D 修正1 Projecting onto the target layer bottom structure drawing (design), D 修正1The vertical depth was used as newly added well data. A well-seismic combination method was used to correct the target layer bottom structure map (design) to obtain the first corrected target layer bottom structure map. Figure 12 and Figure 13 P in 修正 and P' 修正 They represent A respectively 实钻 B 修正1 The actual drilling trajectory of these two points plus the left and right endpoints of the corrected trajectory profile;

[0076] (5) Construct a correction map using the flag 1 obtained in step (3) (see Figure 12 The first revised map of the target layer top structure, the first revised map of the target layer bottom structure, and the projection point of the revised design soft landing point along the vertical direction onto the target layer top structure map obtained in steps (4) and (5) are the first revised design soft landing point C. 修正1 The trajectory of the well to be drilled after encountering marker 1 is corrected to obtain the corrected horizontal well trajectory profile (actual drilling + optimization).

[0077] Specifically, such as Figure 14 As shown, using the well inclination data of marker 1 encountered by the designed horizontal well (P4H1 well), the modified structure diagram of marker 1 obtained in step (3), the first modified structure diagram of the top of the target layer obtained in step (4), the first modified structure diagram of the bottom of the target layer, and the projection point of the modified designed soft landing point along the vertical direction on the top structure diagram of the target layer, the first modified point C of the designed soft landing point is used. 修正1 (Vertical depth -3485.2m), within the allowable range of drilling directional control capacity, the trajectory of the well to be drilled after encountering marker 1 is corrected, and the well is drilled along the corrected trajectory direction, passing through the actual encounter point A of actual marker 1. 实钻 (Vertical depth -3367.8m), the revised design soft landing point is projected vertically onto the top structure of the target layer, the first revised design soft landing point C. 修正1 (Vertical depth -3485.2m), including A 设计 (Vertical depth of -3389.5m), A 实钻 (Vertical depth is -3367.8m), C 设计 (Vertical depth of -3488.7m), C 修正1 (Vertical depth is -3485.2m), D 设计 D 修正1 By drilling into A 实钻 Previous drilling trajectory profile and drilling encounter A 实钻 The subsequent modified trajectory profiles are combined to obtain the horizontal well trajectory profile. Figure 1 (Solid diamond + optimization);

[0078] The corrected well trajectory must pass through A simultaneously.实钻 and C 修正1 Objectively speaking, the well trajectory of the build-up section consists of two parts: one is from the build-up point (the transition point between the vertical section and the build-up section) to point A. 实钻 That is, the point of inclination ~ A 实钻 This belongs to the drilled portion, that is, the drilled well trajectory; from A 实钻 Start, until C 修正1 This belongs to the part to be drilled, which is the correction trajectory;

[0079] In mining practice, A 设计 The design trajectory profile, A 实钻 In three-dimensional space, the two actual drilling trajectory profiles may or may not completely overlap; if the two profiles completely overlap, A 设计 It is possible in A 实钻 Above or below, A 设计 It is also possible that it is related to A 实钻 Complete overlap; if the two sections do not completely overlap, A 设计 It is possible in A 实钻 Above or below the side; Figure 14 In the middle, it shows that it passes through point A. 设计 This is a special case, one of several possibilities (the designed trajectory profile and the actual drilling trajectory profile completely overlap, and A...). 设计 In A 实钻 (below)

[0080] If A 设计 In A 实钻 Above, the actual drilling trajectory does not need to pass through A. 设计 The corrected well trajectory refers to the trajectory from A. 实钻 Start, until C 修正1 The section to be drilled between;

[0081] (6) After correcting the trajectory of the well to be drilled after encountering marker 1, continue drilling along the corrected trajectory to the designed horizontal well (P4H1 well). When encountering marker 2, use the drilling data of marker 2 to correct the structural diagram of marker 2 to obtain the corrected structural diagram of marker 2. Then, obtain the vertical depth B at the projection of the first corrected point of the designed soft landing point on the corrected structural diagram of marker 2. 修正2 Then, using the vertical thickness h2 of the strata between marker 2 and the top of the target layer, and the vertical thickness h between the top of the target layer and the bottom of the target layer... 顶底 The vertical depth B at the projection of the first corrected soft landing point onto the modified construction drawing of marker 2. 修正2 The design soft landing point and its vertical depth, the top structure map of the target layer, and the bottom structure map of the target layer were revised a second time to obtain the second revised soft landing point C.修正2 The target layer top structure and the target layer bottom structure are revised twice. Then, within the limits of the drilling directional drilling capability, the drilling trajectory after drilling mark 2 is corrected, and along the corrected trajectory direction, the actual drilling point of drilling mark 2 and the second corrected point C of the designed soft landing point are passed. 修正2 The horizontal well trajectory profile is obtained by combining the actual well trajectory profile before the actual drilling point of drilling mark 2 and the corrected trajectory profile after the actual drilling point of drilling mark 2. Figure 2 (Solid diamond + optimization);

[0082] Similarly, after correcting the drilling trajectory after encountering marker 2, drilling continues along the corrected trajectory to the designed horizontal well (P4H1 well). When marker 3 is encountered, the drilling data of marker 3 is used to correct the structural diagram of marker 3, resulting in the corrected structural diagram of marker 3. Then, the vertical depth B at the projection of the second corrected point of the designed soft landing point onto the corrected structural diagram of marker 3 is obtained. 修正3 Then, using the vertical thickness h3 of the strata between marker 3 and the top of the target layer, and the vertical thickness h between the top of the target layer and the bottom of the target layer... 顶底 The vertical depth of the designed soft landing point, the top structure map of the target layer, and the bottom structure map of the target layer were revised for the third time, resulting in the third revised point C of the designed soft landing point. 修正3 The third revised diagram of the target layer top structure and the third revised diagram of the target layer bottom structure; within the range allowed by the drilling directional drilling capability, the trajectory of the well to be drilled after drilling mark 3 is corrected, and along the corrected trajectory direction, the actual drilling point passing through drilling mark 3 and the projected point of the corrected design soft landing point along the vertical direction on the target layer top structure diagram are used to design the third revised point C of the soft landing point. 修正3 The horizontal well trajectory profile is obtained by combining the actual well trajectory profile before the actual drilling point of drilling mark 3 and the corrected trajectory profile after the actual drilling point of drilling mark 3. Figure 3 (Solid diamond + optimization);

[0083] After correcting the trajectory of the well to be drilled after encountering marker 3, the driller continues to drill the designed horizontal well (P4H1 well) along the corrected trajectory until the last marker is encountered. The driller then continues to drill along the corrected trajectory after the last marker, ultimately achieving a soft landing of the horizontal well.

Claims

1. A method of horizontal well soft landing geosteering, characterized in that, The method comprises the following steps: A plurality of marks are determined in the overlying strata of the target layer of the horizontal well, and drilling is performed along the designed well trajectory. When a mark is drilled, the structure map of the drilled mark is corrected by using the while-drilling data. The projection points of the designed soft landing point on the top and bottom of the target layer in the vertical direction are corrected. The structure maps of the top and bottom of the target layer are corrected by using the corrected projection points. Then, the well trajectory to be drilled is corrected by using the corrected projection points of the designed soft landing point on the top of the target layer, the corrected structure map of the mark, and the structure maps of the top and bottom of the target layer.

2. The method of claim 1, wherein, A plurality of marks are identified and determined in the overlying strata of the target layer by using seismic, drilling, logging, and well logging data.

3. The method of claim 2, wherein, The plurality of marks are identified and determined by using the characteristics of the well logging gamma curve.

4. The method of claim 1, wherein, The while-drilling data are well logging gamma data and inclination data.

5. The method of claim 4, wherein, The structure map of the drilled mark is corrected by determining the actual drilled position and the vertical depth of the mark drilled by the horizontal well, and then correcting the structure map of the mark.

6. The method of claim 1, wherein, The well trajectory to be drilled is corrected by passing through the actual drilled position of the mark and the corrected projection point of the designed soft landing point on the top of the target layer along the drilled well trajectory, and within the range allowed by the drilling directional build-up ability, the well trajectory to be drilled after the drilled mark is corrected.

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