Method for designing geologically constrained borehole trajectory of directional well

Abstract

The invention relates to a directional well geological constraint borehole trajectory design method, and belongs to the technical field of drilling engineering design. The method comprises the following specific steps: for a multi-target stratum with a complex structure, calibrating the accurate position of each target body in space by applying a three-dimensional seismic technology, accurately explaining target stratum and fracture space distribution, and further establishing a target stratum and fracture model in a three-dimensional space; for a multi-target directional well with an immovable well mouth, a multi-target five-section track design is adopted; the method comprises the following steps: calculating constraint borehole trajectory data by using a five-section borehole trajectory model according to a target point position, fusing three-dimensional seismic data with a drilling target, positioning the target on a three-dimensional seismic data volume in space, and carrying out multi-target five-section borehole trajectory design on a plurality of targets to be drilled from top to bottom. According to the method, fracture space forms accurately recognized in three-dimensional seismic data are effectively avoided, well tracks are set for target bodies one by one, and fracture influences are avoided.

Description

Technical Field

[0001] The invention relates to a method for designing a directional wellbore trajectory with geological constraints, and belongs to the technical field of drilling engineering design. Background Art

[0002] Directional drilling is becoming an extremely important means of oilfield exploration and development. The borehole trajectory measurement and control technology has undergone a development process from experience to science, and from qualitative to quantitative. At present, directional drilling technology is developing rapidly, and measurement while drilling technology is widely used, which provides a basis for geologists to determine underground drilling targets from qualitative to three-dimensional quantitative. The borehole trajectory design method for directional wells in conventional fault formations is that the geology provides the wellhead location and the location of the main underground geological target to be drilled, and drilling engineers use analytical methods to design the drilling borehole trajectory. This design method has little effect under the conditions of simple structure and single target layer, but when there are several sets of target layer sections and cross complex fault formations, this method is prone to cause loss of oil layer sections or difficulties in later transformation of oil and gas reservoirs due to proximity to faults. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention discloses a method for designing a directional wellbore trajectory with geological constraints. Firstly, on the basis of determining the wellhead position on the surface, three-dimensional seismic data is innovatively introduced to guide the drilling positions of target bodies in different layers, and the target bodies to be drilled are located in layers to form a geologically controlled drilling trajectory.

[0004] The technical solution adopted by the present invention is a directional wellbore trajectory design method with geological constraints, and the specific steps are as follows:

[0005] Step 1: For complex multi-target strata, 3D seismic technology is used to spatially mark the exact location of each target body, accurately interpret the spatial distribution of target strata and faults, and then establish target strata and fault models in 3D space;

[0006] Step 2: For multi-target directional wells whose wellheads cannot be moved, a multi-target five-segment track design is adopted;

[0007] Step three: According to the position of the target point, the constrained wellbore trajectory data is calculated using the five-segment wellbore trajectory model, and the three-dimensional seismic data is integrated with the drilling target to spatially locate the target on the three-dimensional seismic data volume. The multiple targets that need to be drilled are designed according to the multi-target five-segment wellbore trajectory from top to bottom.

[0008] Furthermore, in the step 1, the model is used to effectively avoid the spatial morphology of the fracture accurately identified in the three-dimensional seismic data during the well location design process, and the wellbore trajectory is reasonably set for each target body from the surface downward, mainly based on the main layer.

[0009] Furthermore, the step 2, multi-target five-segment track design specifically includes:

[0010] S1, the vertical depth D of the known target point or the starting point of the target segment t , the horizontal displacement S of the target point or the starting point of the target segment t , target segment length △D mm 、Target section well inclination angle α t ; Vertical depth D t , horizontal displacement S t and target segment length △D mm The unit is m, the target section well inclination angle α t The unit of is °;

[0011] S2, determine the vertical depth D of the deflection point kop , unit is m; the slope rate of the slope section K z , the unit is ° / 30m; the slope of the descending section is K n , in degrees / 30m; the radius of curvature R is calculated according to formula (1), in meters:

[0012] R=30 / (K*π / 180) Formula (1)

[0013] Where K is the slope rate of any segment; when K = K z When the curvature radius R of the deflection section is obtained Z ; When K = K n When the curvature radius R of the descending slope is obtained n ;

[0014] S3, according to formula (2-4), calculate D e , S e and R e ;

[0015] D e =D t -D kop +R n *sinα t ; Formula (2)

[0016] S e =S t +R n *(1-cosα t ); Formula (3)

[0017] R e =R z +R n ; Formula (4)

[0018] S4, calculate key parameters: replace D in S3 e , S e and Re Substitute into formula (5-6) and find

[0019] Obtain the inclination angle α of the stable inclined section b , the length of the stable slope section △D mw ;

[0020]

[0021] α b =2*arctan[(D e -ΔD mw ) / (2*R e -S e )] Formula (6)

[0022] Furthermore, in the step three, the wellbore trajectory data includes depth, well inclination, azimuth, etc.

[0023] Furthermore, in the step three, the borehole trajectory design needs to comprehensively consider the drilling capacity, and continuously adjust the vertical depth of the inclination point, the inclination rate, the slope reduction rate and other parameters, so as to try to achieve the design trajectory that meets the geological purpose and realize the borehole trajectory design under geological constraints.

[0024] The invention discloses a method for designing a borehole trajectory with geological constraints for directional wells. Compared with the prior art, the method breaks through the fixed mode of traditional single borehole trajectory design. For complex multi-target strata, the method uses three-dimensional seismic technology to spatially calibrate the accurate positions of multiple target bodies, effectively avoiding the spatial form of fractures accurately identified in three-dimensional seismic data, and setting the borehole trajectory for each target body from the surface downward with the main layer as the main body to avoid the influence of fractures. Under the premise of meeting the purpose of drilling, a relatively simple profile type should be selected as much as possible, and the well deviation section should be minimized, which is conducive to safe and rapid drilling and reducing drilling costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 Shown is a schematic diagram of the wellbore trajectory design in Example 1;

[0027] Figure 2 Shown is a schematic diagram of the geologically constrained wellbore trajectory in Example 1.

[0028] Specific implementation methods

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to further understand the content of the present invention, the present invention is further described below in conjunction with specific implementation methods.

[0031] Example 1: Figures 1-2 As shown, the directional wellbore trajectory design method with geological constraints specifically includes:

[0032] Step 1: For complex multi-target strata, 3D seismic technology is used to spatially calibrate the exact position of each target body, accurately interpret the target strata and fracture spatial distribution, and then establish the target strata and fracture model in 3D space; the model is used to effectively avoid the fracture spatial morphology accurately identified in the 3D seismic data during the well site design process, and the wellbore trajectory is reasonably set for each target body from the surface downward, with the main layer as the main layer.

[0033] Step 2: For multi-target directional wells with immovable wellheads, a multi-target five-segment track design is adopted; specifically, it includes:

[0034] S1, the vertical depth D of the known target point or the starting point of the target segment t , the horizontal displacement S of the target point or the starting point of the target segment t , target segment length △D mm 、Target section well inclination angle α t ; Vertical depth D t , horizontal displacement S t and target segment length △D mm The unit is m, the target section well inclination angle α t The unit of is °;

[0035] S2, determine the vertical depth D of the deflection point kop , unit is m; the slope rate of the slope section K z , the unit is ° / 30m; the slope of the descending section is K n , in degrees / 30m; the radius of curvature R is calculated according to formula (1), in meters:

[0036] R=30 / (K*π / 180) Formula (1)

[0037] Where K is the slope rate of any segment; when K = K z When the curvature radius R of the deflection section is obtained Z ; When K = K n When the curvature radius R of the descending slope is obtained n ;

[0038] S3, according to formula (2-4), calculate D e , S e and R e ;

[0039] D e =D t -D kop +R n *sinα t ; Formula (2)

[0040] S e =S t +R n *(1-cosα t ); Formula (3)

[0041] R e =R z +R n ; Formula (4)

[0042] S4, calculate key parameters: replace D in S3 e , S e and R e Substitute into formula (5-6) and find

[0043] Obtain the inclination angle α of the stable inclined section b , the length of the stable slope section △D mw ;

[0044]

[0045] α b =2*arctan[(D e -ΔD mw ) / (2*R e -S e )] Formula (6)

[0046] Step 3: According to the position of the target point, the constrained wellbore trajectory data is calculated using the five-segment wellbore trajectory model, as shown in Table 1. The wellbore trajectory data includes depth measurement, well inclination, azimuth, ordinate and abscissa. The three-dimensional seismic data is integrated with the drilling target to spatially locate the target on the three-dimensional seismic data volume. The multiple targets to be drilled are designed according to the multi-target five-segment wellbore trajectory from top to bottom. Draw the geological constraint wellbore trajectory diagram as shown in Table 1. Figure 2, the borehole trajectory design needs to comprehensively consider the premise that the drilling capacity allows, and continuously adjust the vertical depth of the inclination point, the inclination rate, the slope reduction rate and other parameters to try to achieve the design trajectory that meets the geological purpose and realize the borehole trajectory design under geological constraints. The vertical depth refers to the distance from a point on the trajectory to the horizontal plane where the wellhead is located. Sounding refers to measuring the well depth, that is, the length of the wellbore from the wellhead to the measuring point. The well inclination angle refers to the angle between the tangent line and the vertical line at a point on the axis of the wellbore. The azimuth refers to the angle between the projection of the tangent line at a point on the axis of the wellbore and the due north direction.

[0047] This method breaks through the fixed mode of traditional single borehole trajectory design. For complex multi-target strata, 3D seismic technology is used to spatially mark the accurate positions of multiple target bodies, effectively avoiding the spatial form of fractures accurately identified in 3D seismic data. From the surface downward, the main layer is used as the main layer, and the borehole trajectory is set for each target body to avoid the influence of fractures. Under the premise of meeting the drilling purpose, a relatively simple profile type should be selected as much as possible, and the well deviation section should be minimized, which is conducive to safe and fast drilling and reducing drilling costs.

[0048] Table 1: Wellbore trajectory data

[0049]

[0050]

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for designing a directional well trajectory with geological constraints, characterized in that: The specific steps are as follows: Step 1: For complex multi-target strata, 3D seismic technology is used to spatially mark the exact location of each target body, accurately interpret the spatial distribution of target strata and faults, and then establish target strata and fault models in 3D space; Step 2: For multi-target directional wells whose wellheads cannot be moved, a multi-target five-segment track design is adopted; Step three: According to the position of the target point, the constrained wellbore trajectory data is calculated using the five-segment wellbore trajectory model, and the three-dimensional seismic data is integrated with the drilling target to spatially locate the target on the three-dimensional seismic data volume. The multiple targets that need to be drilled are designed according to the multi-target five-segment wellbore trajectory from top to bottom.

2. The method for designing directional wellbore trajectory with geological constraints according to claim 1, characterized in that: Step 1: Use the model to avoid the spatial morphology of the fault accurately identified in the 3D seismic data during the well location design process, and reasonably set the wellbore trajectory for each target body from the surface downward, mainly based on the main layer.

3. The method for designing directional wellbore trajectory with geological constraints according to claim 1, characterized in that: The multi-target five-segment track design in step 2 specifically includes: S1, the vertical depth D of the known target point or the starting point of the target segment t , the horizontal displacement S of the target point or the starting point of the target segment t , target segment length △D mm 、Target section well inclination angle α t ; Vertical depth D t , horizontal displacement S t and target segment length △D mm The unit is m, the target section well inclination angle α t The unit of is °; S2, determine the vertical depth D of the deflection point kop , unit is m; the slope rate of the slope section K z , the unit is ° / 30m; the slope of the descending section is K n , in degrees / 30m; the radius of curvature R is calculated according to formula (1), in meters: R=30 / (K*π / 180) Formula (1) Where K is the slope rate of any segment; when K = K z When the curvature radius R of the deflection section is obtained Z ; When K = K n When the curvature radius R of the descending slope is obtained n ; S3, according to formula (2-4), calculate D e , S e and R e ; D e =D t -D kop +R n *sinα t ; Formula (2) S e =S t +R n *(1-cosα t ); Formula (3) R e =R z +R n ; Formula (4) S4, calculate key parameters: replace D in S3 e , S e and R e Substitute into formula (5-6) to obtain the well inclination angle α in the stable inclination section b , the length of the stable slope section △D mw ; α b = 2 * arctan[(D e - ΔD mw ) / (2 * R e - S e )] Formula (6).

4. The method for designing directional wellbore trajectory with geological constraints according to claim 1, characterized in that: Step 3: The wellbore trajectory data includes depth, well inclination, azimuth, horizontal coordinate and vertical coordinate.

5. The method for designing directional wellbore trajectory with geological constraints according to claim 1, characterized in that: Step three: The borehole trajectory design needs to comprehensively consider the drilling capacity, continuously adjust the parameters of the vertical depth of the inclination point, the inclination rate, and the slope reduction rate, complete the design trajectory to meet the geological purpose, and carry out the borehole trajectory design under geological constraints.

6. The method for designing directional wellbore trajectory with geological constraints according to claim 4, characterized in that: Sounding refers to measuring the well depth, that is, the length of the wellbore from the wellhead to the measuring point.

7. The method for designing directional wellbore trajectory with geological constraints according to claim 4, characterized in that: Well inclination refers to the angle between the tangent and the vertical line at a point on the wellbore axis.

8. The method for designing directional wellbore trajectory with geological constraints according to claim 4, characterized in that: The azimuth refers to the angle between the projection of the tangent line at a point on the wellbore axis and the true north direction.

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