A horizontal well trajectory optimization design method based on a three-dimensional geological model

Abstract

The application discloses a horizontal well trajectory optimization design method based on a three-dimensional geological model, and the method comprises the following steps: slicing a reservoir sand body index model along a pre-designed initial horizontal well trajectory, mapping sand body indexes of a to-be-developed area on the slice, and calculating and statistically obtaining an initial sand body drilling rate of a to-be-designed well according to the initial horizontal well trajectory; optimizing and adjusting the initial horizontal well trajectory for several times, and correspondingly obtaining several optimized and adjusted horizontal well trajectories; slicing the reservoir sand body index model along each optimized and adjusted horizontal well trajectory, mapping the sand body indexes on the slice, and calculating and statistically obtaining an optimized and adjusted sand body drilling rate of the to-be-designed well in the to-be-developed area according to each optimized and adjusted horizontal well trajectory; comparing the initial sand body drilling rate and the several optimized and adjusted sand body drilling rates, and selecting a horizontal well trajectory corresponding to an optimal sand body drilling rate as a final horizontal well trajectory of the to-be-developed area. The application has higher optimization precision and better reliability.

Description

Technical Field

[0001] This invention relates to the field of petroleum development technology, and in particular to the design of three-dimensional horizontal well trajectories for large shale oil platforms, specifically to a method for optimizing the design of horizontal well trajectories based on a three-dimensional geological model. Background Technology

[0002] Traditional horizontal well trajectory design based on two-dimensional reservoir well-connection profiles reflects the distribution of sand bodies and oil layers along the line connecting adjacent wells. It only reflects connectivity and cannot characterize porosity, permeability, or oil saturation. Furthermore, there is a distance between adjacent wells and horizontal wells, especially in the approximately 3000m horizontal section where sand bodies exhibit strong heterogeneity and rapid changes, failing to accurately reflect the distribution of underground reservoir sand bodies.

[0003] Traditional horizontal well trajectory design based on two-dimensional reservoir well profiles has several limitations, mainly in the following aspects:

[0004] 1. It reflects the oil layer connectivity along the well-to-well profile of adjacent wells. It is a projection of the current design trajectory and not a true slice.

[0005] 2. It can only reflect the connectivity of the oil layer and the pinch-out of the sand body, but it cannot reflect the physical properties of the reservoir, such as porosity, permeability and oil saturation.

[0006] 3. The prediction of sand bodies is highly dependent on the work experience of technical personnel, which can easily lead to different results from different people.

[0007] 4. The correlation with actual drilling data is not strong, requiring continuous adjustments by the guidance engineer.

[0008] The horizontal well trajectory design based on the structural results of two-dimensional reservoir well profiles and seismic interpretation has poor correspondence with the results of actual drilling logging and gamma-ray interpretation while drilling. There is an urgent need for a horizontal well trajectory optimization method with higher accuracy and better reliability. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the two-dimensional reservoir profile projection used in conventional horizontal well trajectory design, and to provide a more accurate and reliable horizontal well trajectory optimization design method based on a three-dimensional geological model.

[0010] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0011] A method for optimizing the trajectory of horizontal wells based on a three-dimensional geological model includes:

[0012] Two-dimensional well profiles of the control wells in the area to be developed and a pre-constructed three-dimensional geological model of the reservoir in the area to be developed are obtained. The three-dimensional geological model of the reservoir includes a reservoir sand body index model.

[0013] The reservoir sand body index model is sliced ​​along the pre-designed initial horizontal well trajectory, and the sand body index of the area to be developed is mapped onto the slice. The initial sand body encounter rate of the well to be designed in the area to be developed is calculated and statistically obtained based on the initial horizontal well trajectory.

[0014] Using the reservoir two-dimensional well profile of the control well as a reference, the initial horizontal well trajectory is optimized and adjusted several times to obtain several optimized and adjusted horizontal well trajectories.

[0015] The reservoir sand body index model is sliced ​​along each of the optimized and adjusted horizontal well trajectories. The sand body index of the area to be developed is mapped onto the slice. The optimized and adjusted sand body drilling rate of the wells to be designed in the area to be developed is calculated and statistically obtained according to each of the optimized and adjusted horizontal well trajectories.

[0016] The initial sand body drilling rate and several optimized sand body drilling rates are compared, and the horizontal well trajectory corresponding to the optimal sand body drilling rate is selected as the final horizontal well trajectory for the area to be developed.

[0017] Furthermore, the method for constructing the three-dimensional geological model of the reservoir in the area to be developed includes:

[0018] Obtain the seismic data interpretation results of the undeveloped area and the well logging data interpretation results of the control wells in the undeveloped area;

[0019] Based on the interpretation results of the seismic data and the interpretation results of the logging data of the control well, a three-dimensional geological model of the reservoir is constructed using three-dimensional geological modeling software.

[0020] Furthermore, the seismic data interpretation results include the location, strike, and displacement of the top and bottom structures of the strata and faults.

[0021] Furthermore, the logging data interpretation results of the control well include clay content, porosity, permeability, and water saturation.

[0022] Furthermore, the control wells in the area to be developed are control wells within a 5km to 8km radius of the area to be developed.

[0023] Furthermore, the formula for calculating the sand body index is as follows:

[0024]

[0025] In the formula, PI is the sand body index; K is the permeability; Porosity; So is oil saturation, So = 1 - Sw; Sw is water saturation; Vsh is clay content.

[0026] Furthermore, the formula for calculating the sand body drilling rate is as follows:

[0027]

[0028] In the formula, F is the sand body encounter rate; a is the cumulative length of the horizontal well section with a PI value greater than 0.2; and b is the total length of the horizontal section of the well.

[0029] Furthermore, the initial horizontal well trajectory is designed based on the horizontal well trajectory of the two-dimensional reservoir profile projection map of the control well in the area to be developed.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects: Based on the traditional horizontal well trajectory design based on two-dimensional reservoir profile, the present invention applies three-dimensional geological modeling technology to establish a three-dimensional geological model of the reservoir in the area to be developed. The three-dimensional geological model of the reservoir includes a reservoir sand body index model. By slicing the reservoir sand body index model along the pre-designed initial horizontal well trajectory, the sand body index of the area to be developed is mapped onto the slice. The initial sand body encounter rate of the well to be designed in the area to be developed is calculated and statistically obtained according to the initial horizontal well trajectory. Using the two-dimensional well profile of the control well as a reference, the initial horizontal well trajectory is optimized and adjusted several times, resulting in several optimized and adjusted horizontal well trajectories. The reservoir sand body index model is sliced ​​along each optimized and adjusted horizontal well trajectory, and the sand body index of the area to be developed is mapped onto the slice. Based on each optimized and adjusted horizontal well trajectory, the optimized and adjusted sand body encounter rate of the well to be designed in the area to be developed is calculated and statistically obtained. In other words, this invention obtains the corresponding optimized and adjusted sand body encounter rate by continuously optimizing and adjusting the horizontal well trajectory. The initial sand body encounter rate and several optimized and adjusted sand body encounter rates are compared, and the horizontal well trajectory corresponding to the optimal sand body encounter rate is selected as the final horizontal well trajectory for the area to be developed, thus achieving optimized horizontal well trajectory design.

[0031] This invention utilizes logging data interpretation results from control wells with the highest formation resolution currently available for calibration and standardization. Simultaneously, it applies top and bottom stratigraphic structures from 3D seismic data interpretation results for structural constraints, establishing a high-precision 3D geological model for horizontal well trajectory optimization. Traditional horizontal well trajectories based on 2D reservoir profiles are actually projections along the strike of adjacent wells, failing to accurately reflect the structural features, sand body connectivity, and oil layer distribution near the horizontal well trajectory. Compared to traditional reservoir profile horizontal well trajectory design, this invention uses 3D geological model slices to more accurately reflect sand body and oil layer development along the horizontal well trajectory direction. Furthermore, by calculating and statistically analyzing sand body encounter rates, the horizontal well trajectory is continuously optimized and adjusted to achieve the goal of improving reservoir encounter rates.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a flowchart of a horizontal well trajectory optimization design method based on a three-dimensional geological model according to the present invention;

[0035] Figure 2 This is an embodiment of the present invention based on three-dimensional geological modeling to optimize the trajectory of well HH100-22. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions 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, 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.

[0037] This invention discloses a method for optimizing the trajectory of horizontal wells based on a three-dimensional geological model, which specifically includes the following steps:

[0038] Step 1: Obtain the two-dimensional well profile of the control well in the area to be developed and the pre-constructed three-dimensional geological model of the reservoir in the area to be developed. The three-dimensional geological model of the reservoir includes the reservoir sand body index model.

[0039] The preferred method for constructing a three-dimensional geological model of the reservoir in the area to be developed is as follows:

[0040] a: Obtain the seismic data interpretation results of the undeveloped area and the well logging data interpretation results of the control wells in the undeveloped area;

[0041] Specifically, the results of seismic data interpretation include the location, strike, and displacement of the top and bottom structures of strata and faults;

[0042] The logging data interpretation results of control wells include clay content, porosity, permeability, and water saturation.

[0043] b: Based on the interpretation results of seismic data and the interpretation results of logging data from control wells, a three-dimensional geological model of the reservoir is constructed using three-dimensional geological modeling software. In this embodiment, the three-dimensional geological modeling software used is Petrel 2019.

[0044] Preferably, the control wells in the area to be developed are control wells within a range of 5km to 8km around the area to be developed.

[0045] Step 2: Slice the reservoir sand body index model along the pre-designed initial horizontal well trajectory, map the sand body index of the area to be developed onto the slice, and calculate the initial sand body encounter rate of the well to be designed in the area to be developed based on the initial horizontal well trajectory.

[0046] Specifically, the initial horizontal well trajectory is designed based on the two-dimensional reservoir profile projection of the control well in the area to be developed; that is, the initial horizontal well trajectory is the horizontal well engineering design trajectory.

[0047] The formula for calculating the sand body index is:

[0048]

[0049] In the formula, PI is the sand body index; K is the permeability; Porosity; So is oil saturation; Vsh is clay content.

[0050] The formula for calculating the sand body encounter rate is:

[0051]

[0052] In the formula, F is the sand body encounter rate; a is the cumulative length of the horizontal well section with a PI value greater than 0.2; and b is the total length of the horizontal section of the well. Step 3: Using the two-dimensional interconnected well profile of the control well as a reference, the initial horizontal well trajectory is optimized and adjusted several times to obtain several optimized and adjusted horizontal well trajectories.

[0053] Step 4: Slice the reservoir sand body index model along each optimized and adjusted horizontal well trajectory, map the sand body index of the area to be developed onto the slice, and calculate and statistically obtain the optimized and adjusted sand body drilling rate of the wells to be designed in the area to be developed based on each optimized and adjusted horizontal well trajectory.

[0054] The formulas for calculating the sand body index and the sand body drilling rate in this step are the same as those in step 2.

[0055] Step 5: Compare the initial sand body drilling rate with several optimized sand body drilling rates, and select the horizontal well trajectory corresponding to the optimal sand body drilling rate as the final horizontal well trajectory for the area to be developed.

[0056] Example

[0057] To achieve economies of scale in the development of shale oil production in the Changqing Oilfield, particularly with its "small well sites, large well clusters" horizontal well platform, it is crucial to improve the sand body encounter rate of horizontal wells. Horizontal well trajectory design is one of the key factors for drilling success. Conventional horizontal well trajectory design is based on two-dimensional reservoir profiles, primarily utilizing adjacent wells and seismic profiles. However, there is a distance between adjacent wells and horizontal wells, especially in the approximately 3000m horizontal section where sand bodies exhibit strong heterogeneity and rapid changes, failing to accurately reflect the distribution of underground reservoir sand bodies.

[0058] This example demonstrates trajectory optimization for one well on the target platform, Hua H100. First, 32 control wells were selected, and their geological layers were stratified. Based on fine-grained sub-layer division and comparison, the top and bottom structures of the 3D geological model were obtained. Second, fault strike, dip, and dip angle data interpreted from seismic analysis were loaded into the model to establish a 3D structural model of the area to be developed. Third, porosity, permeability, clay content, and water saturation curves were imported into the 3D model to establish a 3D geological attribute model. Finally, the sand body index model was calculated using the sand body index formula.

[0059] Following previous geological statistics and analysis, a PI index greater than 1.5 was used as the dividing line to classify sand bodies. The engineering design trajectory was imported into a 3D model, and the sand body index curve along the trajectory was obtained using modeling software. The lengths of well sections with attributes greater than 1.5 were accumulated to obtain the cumulative length 'a'. 'a' was divided by the horizontal segment length 'b' to obtain the drilling encounter rate under the current trajectory. The trajectory was redesigned and adjusted to continuously improve the sand body drilling encounter rate 'F', ultimately obtaining a trajectory that meets both engineering construction requirements and has a high drilling encounter rate, which was then used as the final optimized trajectory.

[0060] well name Optimization times Sand body segment length Horizontal segment length Drilling rate HH100-22 1 2562 3000 85.4％ HH100-22 2 2676 3000 89.2％ HH100-22 3 2805 3000 93.5％

[0061] In this example, comparing the optimized drilling results and design of the target well HH100-22 with those of the optimized well, the horizontal well trajectory design using only two-dimensional reservoir well profiles resulted in a longer sandstone reservoir section encountered. After optimizing the horizontal well trajectory using high-precision three-dimensional geological modeling results, the success rate of encountering dominant sandstone bodies on the entire large platform was higher.

[0062] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for optimizing the trajectory design of horizontal wells based on a three-dimensional geological model, characterized in that, include: Two-dimensional well profiles of the control wells in the area to be developed and a pre-constructed three-dimensional geological model of the reservoir in the area to be developed are obtained. The three-dimensional geological model of the reservoir includes a reservoir sand body index model. The reservoir sand body index model is sliced ​​along the pre-designed initial horizontal well trajectory, and the sand body index of the area to be developed is mapped onto the slice. The initial sand body encounter rate of the well to be designed in the area to be developed is calculated and statistically obtained based on the initial horizontal well trajectory. Using the reservoir two-dimensional well profile of the control well as a reference, the initial horizontal well trajectory is optimized and adjusted several times to obtain several optimized and adjusted horizontal well trajectories. The reservoir sand body index model is sliced ​​along each of the optimized and adjusted horizontal well trajectories. The sand body index of the area to be developed is mapped onto the slice. The optimized and adjusted sand body drilling rate of the wells to be designed in the area to be developed is calculated and statistically obtained according to each of the optimized and adjusted horizontal well trajectories. The initial sand body drilling rate and several optimized sand body drilling rates are compared, and the horizontal well trajectory corresponding to the optimal sand body drilling rate is selected as the final horizontal well trajectory for the area to be developed. The method for constructing the three-dimensional geological model of the reservoir in the area to be developed includes: Obtain the seismic data interpretation results of the undeveloped area and the well logging data interpretation results of the control wells in the undeveloped area; The logging data interpretation results of the control well include clay content, porosity, permeability and water saturation. Based on the seismic data interpretation results and the well logging data interpretation results of the control well, a three-dimensional geological model of the reservoir is constructed using three-dimensional geological modeling software; The formula for calculating the sand body index is as follows: In the formula, Sand body index; For penetration rate; Porosity; Oil saturation =1-Sw; Sw is the water saturation level; The content of clay; The formula for calculating the sand body drilling rate is as follows: 100% In the formula, This refers to the sand body encounter rate. The cumulative length of horizontal well sections with a PI value greater than 0.2; This is the total length of the horizontal section of the well.

2. The method for optimizing the trajectory of a horizontal well based on a three-dimensional geological model according to claim 1, characterized in that, The earthquake data interpretation results include the location, strike, and displacement of the top and bottom structures of the strata and faults.

3. The method for optimizing the trajectory of horizontal wells based on a three-dimensional geological model according to claim 1, characterized in that, The control wells in the area to be developed are those within a 5km to 8km radius of the area to be developed.

4. The method for optimizing the trajectory of horizontal wells based on a three-dimensional geological model according to claim 1, characterized in that, The initial horizontal well trajectory is designed based on the two-dimensional reservoir profile projection of the control well in the area to be developed.

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