Method for improving reservoir capacity achievement rate during gas storage construction process

Abstract

The application discloses a method for improving the reservoir capacity achievement rate in gas storage construction process, and steps are as follows: step 1, collecting and analyzing the logging-while-drilling data to determine the fault; step 2, when an unexpected fault is drilled, a fault geological model is established to calculate the fault throw; step 3, the well section of the unexpected fault is determined as a backfill well section; step 4, a horizontal section + fault model is established to re-plan the well section with reduced out-layer footage; step 5, the suitable out-layer position range of the I reservoir is determined; step 6, a plurality of trajectories are designed according to different build-up rates; step 7, the drilling friction of the above trajectory schemes is calculated; step 8, the optimal trajectory scheme is determined by comprehensively considering the trajectory scheme and the drilling friction. After the key parameters of the fault are determined by the seismic data and the logging-while-drilling data, the trajectory control optimization scheme is determined by comprehensively considering that the trajectory passes through the reservoir to the maximum extent and the trajectory construction feasibility, so that the planned reservoir capacity can be achieved after the gas storage is built.

Description

Technical Field

[0001] This invention relates to a construction scheme for encountering complex geological faults during the construction of gas storage facilities in depleted complex fault-block oil and gas reservoirs, and particularly to a method for improving the storage capacity achievement rate during the construction of gas storage facilities, belonging to the field of underground engineering technology for gas storage facility construction. Background Technology

[0002] During the planning and construction of gas storage facilities, the number of suitable work areas selected by geologists is extremely limited. Compared to conventional oil and gas wells, suitable work areas are considered "limited resources." Therefore, effective technical measures must be taken during the construction of gas storage facilities to ensure that the planned storage capacity is achieved after completion. For example, during the drilling of a gas storage facility under construction, the horizontal well Z1P1 encountered a fault in its horizontal section, resulting in a reservoir encounter rate of only 73%. This directly led to a significant reduction in storage capacity and caused substantial economic losses. Such difficulties are not isolated incidents; they frequently occur when constructing gas storage facilities using depleted, complex fault-block oil and gas reservoirs.

[0003] From an engineering construction perspective, the difficulty lies in controlling the trajectory across the fault. Currently available technologies include:

[0004] 1. Construct a formation profile model and determine the formation lines and trajectory lines in the profile model; based on the formation profile model, calculate the distances to the upper interface, lower interface, drill-intercept interface, and drill bit front interface respectively; display the distances to the upper interface, lower interface, drill-intercept interface, and drill bit front interface on the formation profile model, and control the drilling trajectory according to the aforementioned distances.

[0005] 2. Based on the seismic data, obtain the depth of the target oil layer, the change of the dip angle of the target oil layer, the fault displacement and the relative position of the fault plate. Starting from the development well position of the target oil layer, continuously adjust the drilling direction of the drill bit to complete the drilling of the stepped horizontal well.

[0006] 3. Based on the stratigraphic correlation of completed wells, obtain the marker layer delineation data of the area where the drilling well is located, the target point data given by the geological engineering design of the drilling well, and the fault data; obtain the fault displacement on the seismic profile along the trajectory direction; determine the well inclination and vertical depth corresponding to the apparent translation of the fault location from the engineering design trajectory, and calculate the vertical depth of the fault from the target point; determine the stratum where the fault is located, select one set of marker layers above and one set below the stratum, and calculate the vertical thickness between the two sets of marker layers in adjacent wells and the vertical thickness of marker layer two from the target point; calculate the well inclination and depth when the second marker layer is encountered; determine whether the trajectory is from the ascending side of the fault to the descending side or from the descending side of the fault to the ascending side, and design different target entry procedures according to different trajectories. The above methods provide efficient trajectory control for drilling through reservoirs, horizontal sections, and faults encountered during target drilling. However, in actual construction, there are complex fault-block oil and gas reservoirs where faults are unpredictable. When a fault is suddenly encountered during horizontal drilling, subsequent drilling is required to follow the fault. Large sections of drilling are used to adjust the trajectory. This has little impact on production capacity after well completion and fracturing in oil wells, but it can lead to a reduction in storage capacity for gas storage wells, preventing them from reaching the planned storage capacity.

[0007] Chinese invention patent application CN 108625842A discloses a drilling trajectory control method and system, including the following steps: constructing a formation profile model and determining the formation lines and trajectory lines in the profile model; based on the formation profile model, calculating the distances to the upper interface, lower interface, drill-intercept interface, and drill bit front interface; displaying the upper interface, lower interface, drill-intercept interface, and drill bit front interface distances on the formation profile model, and controlling the drilling trajectory according to these distances. This technical solution relies too heavily on the constructed formation profile model. The trajectory control method described, which uses the upper interface, lower interface, drill-intercept interface, and drill bit front interface distances for adjustment, is a method for controlling the trajectory as it travels through the formation profile model. However, actual formation changes are difficult to predict, and this method does not address adjustments after the trajectory crosses layers.

[0008] Chinese invention patent CN 109184560B discloses a method and device for wellbore trajectory control in a stepped horizontal well. Based on seismic data, it obtains the depth of the target oil layer, the change in the formation dip angle of the target oil layer, the fault displacement, and the relative position of the fault plate. Starting from the development well location of the target oil layer, the drilling direction of the drill bit is continuously adjusted to complete the drilling of the stepped horizontal well. However, the fault trajectory control method described in this technical solution is too theoretical. The fault dip angle is derived from seismic profiles, and corrections must be made based on actual formation changes during the drilling process. Trajectory adjustment along the fault dip angle is difficult to achieve, and the key parameter dogleg is not addressed, thus failing to effectively guide construction.

[0009] Chinese invention patent CN 110644967B discloses a trajectory control method for horizontal well drilling through faults. The method involves obtaining marker layer data for the drilling well area, target point data from the geological engineering design of the drilling well, and fault data based on the stratigraphic comparison of completed wells. Fault displacement is obtained on a seismic profile along the trajectory direction. The well inclination and vertical depth corresponding to the apparent translation of the fault location are determined from the engineering design trajectory, and the vertical depth of the fault from the target point is calculated. The fault stratum is determined, and a set of marker layers is selected above and below that stratum. The vertical thickness between the two sets of marker layers in adjacent wells and the vertical thickness of marker layer two from the target point are calculated. The well inclination and depth when encountering marker layer two are calculated. The method determines whether the trajectory is from the ascending side of the fault to the descending side, or from the descending side to the ascending side, and designs different target entry processes based on different trajectories. The target entry trajectory control method described in this technical solution differs from the trajectory control method for drilling through faults in horizontal sections. The former only considers the target point after trajectory adjustment, while the latter takes into account both the entire trajectory adjustment process and the target point. Summary of the Invention

[0010] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the invention.

[0011] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0012] The purpose of this invention is to provide a method to improve the storage capacity achievement rate during the construction of gas storage facilities by addressing complex geological faults encountered during horizontal well drilling. After determining the key fault parameters through seismic data and logging-while-drilling data, the method comprehensively considers the maximum extent to which the trajectory can traverse the reservoir and the feasibility of trajectory construction to determine an optimized trajectory control scheme, ensuring that the gas storage facility can achieve the planned storage capacity after completion.

[0013] To solve the above technical problems, the method for improving the storage capacity achievement rate during the construction process of a gas storage facility according to the present invention includes the following steps in sequence:

[0014] Step 1: Collect and analyze logging-while-drilling data to identify faults;

[0015] Step 2: When encountering an unpredicted fault, establish a geological model of the fault and calculate the fault displacement;

[0016] Step 3: Identify the well section where an unpredicted fault is encountered as the backfill section;

[0017] Step 4: Establish a horizontal section + fault model and replan the well section to reduce the footage of the exposed layers;

[0018] Step 5: Derive and determine the suitable range of emergence locations for reservoir I;

[0019] Step 6: Design multiple trajectories according to different inclination rates;

[0020] Step 7: Calculate the drilling friction for the above trajectory schemes;

[0021] Step 8: Take into account both the trajectory scheme and drilling friction factors to determine the optimal trajectory scheme.

[0022] Furthermore, in step 1, the trajectory exits reservoir I at point A and enters reservoir II by passing through the caprock at point B;

[0023] In step 2, the formula for calculating the fault displacement is as follows:

[0024]

[0025] In the formula: h1 is the fault displacement, in meters; D A Let D be the slope depth at point A, in meters; B The slope depth at point B is m; α A The well inclination at point A is °; α B The well inclination at point B is °; θ A Let θ be the dip angle of the reservoir where point A is located, in °; B Let be the dip angle of the reservoir where point B is located, in °.

[0026] Furthermore, in step 4, the A′B′ segment close to the fault is initially planned, and only the footage of the A′B′ segment is made. The location of point B′ entering the II reservoir is first determined, and the formula for calculating the elevation difference at point B′ is as follows:

[0027]

[0028] Where: h2 is the elevation difference at location B′, in meters; h1 is the fault displacement, in meters; h Ⅱ The thickness of reservoir II where point B′ is located.

[0029] Furthermore, in step 5, the adjusted footage is calculated using the following formula, and the location of reservoir I, A′, is deduced from it, as follows:

[0030]

[0031] In the formula: D A′ Let D be the slope depth at point A′ in the model, in meters; B′ Let B′ be the slope depth in the model, in meters.

[0032] α A′ The well inclination at point A′ is °; α B′ The well inclination at point B′ is °;

[0033] φ A′The orientation of point A′ is °; φ B′ The orientation of point B′ is °;

[0034] K is the slope of the trajectory profile, taken as *° / 30m; L W To adjust the elevation difference of the steady slope section of the trajectory, m; α W θ is the fault dip angle, in °.

[0035] Furthermore, among which L W It is obtained by calculation using the following formula:

[0036]

[0037] In the formula: R is the radius of curvature under different slopes, in meters.

[0038] Furthermore, in step 6, six trajectories are designed with slopes of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m.

[0039] Furthermore, in step 7, the wellplan module in the petroleum industry software Landmark is used to calculate the drilling friction of the above trajectory schemes.

[0040] Furthermore, in step 7, by adjusting the friction coefficient of the horizontal section, the friction calculated by the Wellplan module is made to match the actual construction friction, and the friction coefficient of the horizontal section that conforms to the actual working conditions is derived; then, the drilling friction of the above trajectory schemes is calculated using the friction coefficient of the horizontal section.

[0041] Furthermore, it also includes:

[0042] Step 9: Backfill the AB section of the explored layer;

[0043] Step 10: Calculate the new library capacity by comparing the optimal trajectory with the conventional trajectory.

[0044] Furthermore, the formula for calculating the increased storage capacity is as follows:

[0045]

[0046] In the formula: Q1 is the newly added library capacity of the trajectory scheme of the present invention, m 3 L1 represents the reduced excavation depth of the trajectory scheme of the present invention, in meters; K1 represents the permeability at the trajectory scheme of the present invention, in μm²; φ1 represents the porosity at the trajectory scheme of the present invention; L 总 Total footage (m) of the reservoir section of the deployment well; - Average permeability of deployed wells, μm²; - Average porosity of deployed wells; Q 总 To deploy the total reservoir capacity of the well, m 3.

[0047] Compared with existing engineering fault trajectory control and existing wellbore trajectory control methods, this invention achieves the following beneficial effects and advantages: 1. When encountering an unpredicted fault in the horizontal section, the important fault parameter, fault displacement, can be quickly determined by combining seismic data and logging-while-drilling data, which facilitates the formulation of the next trajectory control scheme.

[0048] 2. The trajectory control scheme comprehensively considers the capabilities of the tilting tool and the construction difficulty, and selects the optimal trajectory scheme under the two-factor conditions;

[0049] 3. Preliminary estimates indicate that the gas storage wells effectively control the trajectory across faults, significantly increasing storage capacity and achieving good economic benefits. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit the present invention.

[0051] in:

[0052] Figure 1 This is a flowchart of a method for improving the storage capacity achievement rate during the construction process of a gas storage facility according to the present invention;

[0053] Figure 2 This is a diagram of the horizontal well trajectory crossing fault calculation model in this invention;

[0054] Figure 3 A schematic diagram of a conventional horizontal well trajectory crossing a fault;

[0055] Figure 4 This is a schematic diagram of the horizontal well trajectory crossing the fault after backfilling and trajectory adjustment in this invention;

[0056] Figure 5 This is a schematic diagram of trajectory schemes under different inclination rates in this invention;

[0057] Figure 6 Trajectory diagrams for well Z-P2 with different build-up rates and the conventional approach;

[0058] Figure 7 Drilling friction diagrams for different build-up rates and conventional drilling methods. Detailed Implementation

[0059] In the following description of the present invention, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific orientation.

[0060] To make the technical means, creative features, objectives, and effects of this invention easier to understand, the invention is further described below with reference to specific illustrations. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0062] like Figure 1 As shown, the method for improving the storage capacity achievement rate during the construction of a gas storage facility according to the present invention includes the following steps in sequence:

[0063] Step 1: Acquire and analyze logging-while-drilling data to identify the fault. This step begins with the encounter of an unpredicted fault in the horizontal section. The fault is identified through a combination of seismic data, logging data from existing wells, lithological characteristics, and logging-while-drilling data. The variation characteristics of the logging-while-drilling gamma values ​​and the gamma curves from existing wells are analyzed.

[0064] Table 1 shows the gamma curve characteristics and lithology of the gas storage facility under construction. The trajectory is determined to start from point A in reservoir I, pass through the caprock at point B and enter reservoir II, thus determining points A and B.

[0065] Table 1. Gamma curve characteristics and lithological reference of caprock and reservoir.

[0066]

[0067] Step 2: When encountering an unpredicted fault during drilling, adjust the geological model, establish a fault geological model, and calculate the fault displacement. For example... Figure 2 A fault calculation model was established. The determination of points A and B in this model referenced the gamma value variation characteristics in well logging data and the formation dip angle θ. A θ B Obtained from seismic data. After determining points A and B, the fault displacement h1 is calculated based on the model. The formula for calculating h1 is as follows:

[0068]

[0069] In the formula: h1 is the fault displacement, in meters; D A Let D be the slope depth at point A, in meters; B The slope depth at point B is m; αA The well inclination at point A is °; α B The well inclination at point B is °; θ A Let θ be the dip angle of the reservoir where point A is located, in °; B Let be the dip angle of the reservoir where point B is located, in °.

[0070] The fault displacement calculated through the above steps can quickly identify unpredictable faults encountered during drilling, which is beneficial for the formulation of subsequent trajectory control schemes.

[0071] Step 3: Optimize the trajectory control scheme. The purpose of this step is to minimize the impact of encountering unpredictable faults, reduce the waste of reservoir footage, and facilitate the implementation of the trajectory adjustment scheme.

[0072] When drilling encounters an unpredictable fault, conventional trajectory control is as follows: Figure 3 As shown, this resulted in the AB+CD section having excessive footage. This significant footage was used to adjust the trajectory, requiring subsequent well completion and fracturing to remedy the situation in oil wells. However, for gas storage wells, this would lead to a reduction in storage capacity, failing to reach the planned capacity. Therefore, the AB section was designated as a backfill section.

[0073] Step 4: After backfilling, the trajectory of the gas storage well in this invention is readjusted according to the fault. Figure 4 The diagram shows the horizontal well trajectory after backfilling and trajectory adjustment, crossing the fault. Specifically, after backfilling following the discovery of the fault and reservoir II in section AB, the A′B′ section, which is closer to the fault, was initially re-planned, resulting only in the footage reaching the fault in section A′B′. (Comparison) Figure 3 The trajectory control of this invention for conventional wells significantly reduces the number of formation sections caused by previous methods.

[0074] To ensure the trajectory travels within the reservoir, a horizontal segment + fault model is established, which is shown in [reference needed]. Figure 4 The model mainly includes reservoir I and location B′. It needs to determine the elevation difference at location B′ and the reservoir dip angle. The reservoir dip angle is obtained from seismic data. The formula for calculating the elevation difference at location B′ is as follows:

[0075]

[0076] Where: h2 is the elevation difference at location B′, in meters; h1 is the fault displacement, in meters; h Ⅱ h2 represents the thickness of reservoir II where point B′ is located. Taking well Z-P2 as an example, the average value of h2 is 10m.

[0077] Step 5: Derive and determine the suitable range of emergence locations for reservoir I, which is beneficial for trajectory control schemes. For example... Figure 4 As shown in the model, the position A′ is determined through formula derivation. After the trajectory exits reservoir I and is adjusted, it enters reservoir II. Adjustment requires trajectory footage. Given that the position B′ of reservoir II is determined, the adjusted footage is calculated using the formula, and the position A′ of reservoir I is deduced from this. The specific formula is as follows:

[0078]

[0079] In the formula: D A′ Let D be the slope depth at point A′ in the model, in meters; B′ Let B′ be the slope depth in the model, in meters.

[0080] α A′ The well inclination at point A′ is °; α B′ The well inclination at point B′ is °;

[0081] φ A′ The orientation of point A′ is °; φ B′ The orientation of point B′ is °;

[0082] K is the slope of the trajectory profile, taken as *° / 30m; L W To adjust the elevation difference of the steady slope section of the trajectory, m; α W L is the fault dip angle, in °; where L W It is obtained by calculation using formula (4).

[0083]

[0084] In the formula: R is the radius of curvature under different slopes, in meters.

[0085] The well depth of reservoir I calculated in this step is a theoretical calculation and is only for reference in the subsequent trajectory design. The specific design also needs to consider the smoothness and rationality of the trajectory, and further trajectory design is required in step 6.

[0086] Step 6: Based on actual construction practices and considering the tool's directional drilling capability, this invention establishes a trajectory scheme database. For fault-block oil and gas reservoir construction, given the difficulty of trajectory adjustment, horizontal sections are generally drilled using rotary drilling tools. The tool's directional drilling capability is 1-6° / 30m. Assuming that the directional drilling capability can meet the trajectory control requirements, six trajectories are designed according to different directional drilling rates: 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m.

[0087] Step 5 calculates the range of the emergence location A′ in reservoir I. Based on the tool's build-up capability (i.e., the build-up rate K for different trajectory profiles), a trajectory scheme for the A′B′ well section is designed. Detailed trajectory schemes can be found in [link to relevant documentation]. Figure 5 .

[0088] Table 2. Statistical Table of Trajectory Schemes

[0089]

[0090] Step 7: Using the Wellplan module in the petroleum industry software Landmark, calculate the drilling friction for the above trajectory schemes. This invention not only formulates trajectory schemes but also considers the drilling friction magnitudes of different trajectory schemes, taking into account the construction difficulties during specific operations, thereby selecting the optimal trajectory scheme.

[0091] When calculating drilling friction using the Wellplan module, the default value for the friction coefficient of the upper casing above reservoir I is generally 0.25; the horizontal section from reservoir I to reservoir II is the horizontal section, and the default value for the friction coefficient of the horizontal section is 0.35.

[0092] To ensure the friction coefficient of the horizontal section better reflects actual working conditions, the calculated friction resistance is compared with the actual construction friction resistance, and then deduced in reverse. For example, in well Z-P2, the friction coefficient of section AB, calculated using the conventional default value of 0.35, yields a drilling friction resistance of 13t. However, the actual construction friction resistance of section AB is 15t. Adjusting the friction coefficient of section AB to 0.45 is necessary to achieve the drilling friction resistance of 15t. This leads to the conclusion that a friction coefficient of 0.45 for the horizontal section is more accurate.

[0093] Table 3. Drilling friction statistics for each trajectory scheme

[0094] plan Friction coefficient value Friction t C1′ 0.25 / 0.45 … C2′ 0.25 / 0.45 … C3′ 0.25 / 0.45 … C4′ 0.25 / 0.45 … C5′ 0.25 / 0.45 … C6′ 0.25 / 0.45 … .

[0095] Step 8: Take into account both the trajectory scheme and drilling friction factors to determine the optimal trajectory scheme.

[0096] Step 9: Backfill the AB section of the explored layer.

[0097] Backfilling requirements for the identified AB well section: The well should be dredged before backfilling to ensure unobstructed flow; the drilling fluid should be properly treated to meet performance requirements; all surface equipment should be inspected before backfilling to ensure continuous and smooth construction; the cement slurry properties should meet construction safety and cement plug strength requirements. A balanced backfilling method should be used. After replacing the cement slurry, the drill string should not be pulled up too quickly to avoid mixing the slurry and affecting the strength of the cement plug; allow 48 hours for setting before inspecting the cement plug surface. Measures should be taken to prevent drilling fluid contamination during cement plug drilling.

[0098] The backfilling cost for the detected AB well section is: backfilling operation (120,000 yuan) + waiting time for drilling rig (calculated based on 50ZJ drilling rig, daily cost is 127,000 yuan, 127,000 yuan / day * operation time 2.5 days = 317,500 yuan) = 437,500 yuan.

[0099] Step 10: Calculate the new reservoir capacity by comparing the optimal trajectory with the conventional trajectory. A simplified version of the reservoir control calculation is performed using key parameters for reservoir control, namely permeability K and porosity φ. The result represents the new reservoir capacity of the trajectory scheme of this invention.

[0100]

[0101] In the formula: Q1 is the newly added library capacity of the trajectory scheme of the present invention, m 3 L1 represents the reduced excavation depth of the trajectory scheme of this invention, in meters; K1 represents the permeability at the trajectory scheme of this invention, in μm. 2 ; φ1 represents the porosity at the trajectory scheme of this invention; L 总 Total footage (m) of the reservoir section of the deployment well; - Average permeability of deployed wells, μm 2 ; - Average porosity of deployed wells; Q 总 To deploy the total reservoir capacity of the well, m 3 .

[0102] The economic value estimate of the increased storage capacity based on the trajectory scheme of this invention is as follows: It is estimated that the effective working gas volume of the wells in the gas storage facility under construction is 36% of the total storage capacity; the peak shaving period is approximately 4-6 months, and based on the current gas storage facility's pattern, approximately 4 injection and extraction cycles are required; the price difference between natural gas entering at a lower price and exiting at a higher price is approximately 0.2-0.3 yuan / cubic meter, which is calculated to be 0.2 yuan / cubic meter; the annual benefit generated by the increased storage capacity of this invention is:

[0103] E = Q1 * 36% * 4 * 0.2 (6)

[0104] This invention effectively controls the trajectory of the gas storage facility across faults during construction, which helps ensure that the gas storage facility can reach the planned capacity after completion, improves the capacity achievement rate, and achieves good economic benefits.

[0105] The following section uses the Z-P2 well as an example to introduce the construction process of the gas storage facility:

[0106] I. Well Z-P2 is a gas storage facility constructed for a depleted complex fault-block oil and gas reservoir. An unpredicted fault was encountered at a depth of 4525m in the horizontal section. Based on the gamma ray logging data (see Table 4) and the gamma ray curve variation characteristics of the wells already drilled (see Table 1), the trajectory was determined to be from point A at a depth of 4525m, exiting reservoir I, and then passing through the caprock at point B at a depth of 4623m to enter reservoir II.

[0107] Table 4. Gamma data from logging-while-drilling of the trajectory at points A and B in the horizontal segment.

[0108] Serial Number well deep GR Serial Number well deep GR 1 4520 70.6 11 4617 126.06 2 4521 92.46 12 4618 105.53 3 4522 91.02 13 4619 103.58 4 4523 79.88 14 4620 108.81 5 4524 76.29 15 4621 109.2 6 4525 89.77 16 4622 85 7 4526 92.71 17 4623 70.22 8 4527 101.67 18 4624 80.2 9 4528 105.96 19 4625 78.64 10 4529 118 20 4626 70.76 .

[0109] II. Based on seismic data, the dip angle of reservoir I (θA) is 11°, and the dip angle of reservoir II (θB) is 15°. The current trajectory data is collected at well depths D at points A and B. A D B The well inclinations at points A and B are 4525m and 4623m, respectively. A αB The angles are 91° and 86°. Based on the above data, the fault displacement is calculated to be 24m, which will be used for the next trajectory design.

[0110]

[0111] III. Determine the backfilling plan for the well section where the strata have been detected. Since a fault was encountered at a depth of 4525m and drilling continued to 4635m after passing point B, backfilling an additional 50m would improve the possibility of trajectory design optimization. Therefore, the backfilling section was determined to be 4475m-4635m.

[0112] IV. To ensure that the trajectory travels within the reservoir, a horizontal segment + fault model is established, with an elevation difference of 29m between the target point B′ in reservoir II.

[0113]

[0114] V. The derivation and determination of a suitable range of emergence locations in reservoir I facilitates trajectory control schemes. For example... Figure 4 As shown in the model, the position of A′ is determined through formula derivation. First, the elevation difference L of the steady section of the adjustment trajectory is calculated. W Calculations were performed based on different slope inclinations of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m:

[0115]

[0116] Secondly, after the trajectory is adjusted from reservoir I to reservoir II, the adjustment requires trajectory footage. Given that the position of B′ in reservoir II is determined, the adjusted footage is calculated using a formula, and the position of A′ in reservoir I is deduced from this. The azimuths of points A′ and B′ are 141° and 143°, respectively.

[0117]

[0118] Table 5. Statistical Table of Theoretical Estimation of Reservoir Exit Location

[0119] Slope rate <![CDATA[Inclination - holding section height difference L W > Estimating the depth of wells emerging from reservoir I K m m 1° / 30m 15.87 4255 2° / 30m 7.93 4460 3° / 30m 5.29 4528 4° / 30m 3.97 4562 5° / 30m 3.17 4583 6° / 30m 2.64 4596

[0120] The emergence location of reservoir I obtained in this step is a theoretical calculation and is only for reference in the subsequent trajectory design. The specific design should also consider the smoothness and rationality of the trajectory. The emergence location of reservoir I calculated at 1° / 30m in Table 5 differs significantly from the others and has little reference value.

[0121] VI. Based on the tool's tilting capability of 1-6° / 30m, six trajectories were designed with different tilting rates of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m. Conventional trajectory control methods were also designed and compared.

[0122] Table 6. Statistics on Exit Progress under Different Trajectory Schemes

[0123]

[0124] Figure 6 The diagram shows the trajectory diagrams for different slope schemes and the conventional scheme. From left to right, they represent six design trajectories for 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m, as well as the trajectory diagram for the conventional scheme.

[0125] Comparing solely from the perspective of trajectory design, and temporarily disregarding construction difficulty, the 1° / 30m trajectory design results in a floor clearance of 255m, which is larger than other designs and can be optimized and discarded. Overall, the trajectory control scheme according to this invention significantly reduces the floor clearance compared to conventional trajectory control schemes.

[0126] 7. Based on different trajectory schemes, use professional software in the petroleum industry to calculate the friction resistance of different trajectories, and analyze the trend of friction resistance change.

[0127] Table 7. Statistics on Drilling Friction under Different Trajectory Schemes

[0128] plan Drilling friction t conventional 18.7 2° / 30m 13.6 3° / 30m 14.9 4° / 30m 1 5.3 5° / 30m 18.2 6° / 30m 19.8

[0129] Figure 7 Drilling friction diagrams for different build-up rates and conventional drilling methods.

[0130] 8. From Figure 7 It can be seen that the drilling friction increases significantly with the 5° / 30m and 6° / 30m trajectory schemes, greatly increasing the construction difficulty. Moreover, excessive build-up rates in actual construction can easily lead to complex issues such as keyways. Considering both the trajectory scheme and drilling friction, the recommended trajectory schemes are 3° / 30m and 4° / 30m, which can simultaneously balance the depth of drilling and the difficulty of construction.

[0131] 9. Backfilling of the detected well sections. Backfilling requirements for detected well sections: The well should be dredged before backfilling to ensure unobstructed flow; the drilling fluid should be properly treated to meet performance requirements; all surface equipment should be inspected before backfilling to ensure continuous and smooth construction; the cement slurry properties should meet construction safety and cement plug strength requirements; a balanced backfilling method should be used; after replacing the cement slurry, the drill string should not be pulled up too quickly to avoid mixing the slurry and affecting the strength of the cement plug; allow 48 hours for setting before inspecting and repairing the cement plug surface. Measures should be taken to prevent drilling fluid contamination during cement plug drilling.

[0132] The backfilling cost for the detected well section is:

[0133] Backfilling work (120,000 yuan) + Hou Ning waiting for drilling rig daily fee (calculated based on 50ZJ drilling rig, daily fee of 127,000 yuan, 127,000 yuan / day * working time 2.5 days = 317,500 yuan) = 437,500 yuan.

[0134] 10. Calculate the increased reservoir capacity by comparing the trajectory of this invention with conventional methods. Based on geological data of developed and depleted gas reservoirs, the average porosity is 14%, and the average permeability is 118.7 × 10⁻⁶. -3 μm 2 The trajectory scheme of this invention reduces the depth of the fault zone by 365-165=200m compared to the conventional scheme (3° / 30m scheme). According to core experiments from nearby wells, the porosity of the strata near the fault is 16%, and the permeability is 120.5×10⁻⁶. -3 μm². Geological prediction indicates the total reservoir capacity after completion will be 0.98 × 10⁻⁶. 8 m 3 .

[0135]

[0136] The economic value estimate of the increased storage capacity based on the trajectory scheme of this invention. It is estimated that the effective working gas volume of the wells in the gas storage facility under construction is 36% of the total storage capacity; the peak shaving period is approximately 4-6 months, and based on the current gas storage pattern, approximately 4 injection and extraction cycles are required; the price difference between inflow and outflow of natural gas is approximately 0.2-0.3 yuan / cubic meter, which is calculated to be 0.2 yuan / cubic meter; the annual benefit of the increased storage capacity of this invention is:

[0137] E = Q1 * 36% * 4 * 0.2 = 0.19 * 10 8 *36%*4*0.2=547.2*10 4

[0138] This invention effectively controls the trajectory across faults during construction, increasing the storage capacity of the gas storage facility by 0.19 × 10⁻⁶ after completion. 8 m 3 This improved the reservoir capacity achievement rate and resulted in good economic benefits. Compared with the additional investment of 437,500 yuan in backfilling required for conventional oil well construction, it can generate an annual economic benefit of 5,472,000 yuan.

[0139] The above description is merely a preferred embodiment of the present invention, showing and describing the basic principles, main features, and advantages of the present invention. It is not intended to limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. In addition to the above embodiments, the present invention may have other implementations without departing from the spirit and scope of the invention. Various changes and modifications to the present invention are possible, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents. Technical features not described in the present invention can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A method for improving the reservoir capacity achievement ratio in a gas storage construction process, characterized by, Comprise the following steps in turn: Step 1, collecting and analyzing logging-while-drilling data to identify faults; Step 2, when an unexpected fault is drilled, establish a fault geologic model and calculate the fault throw; Step 3, determine the drilled section of the unexpected fault as the backfill section; Step 4, establish a horizontal section + fault model and re-plan the well section to reduce the out-layer footage; Step 5, determine the appropriate out-layer position range of the I reservoir; Step 6, design multiple trajectories according to different build-up rates; Step 7, calculate the drilling friction of the above trajectory schemes; Step 8, determine the optimal trajectory scheme by comprehensively considering the trajectory scheme and drilling friction; 2. The method of claim 1, wherein, In step 1, the trajectory is out of the I reservoir from point A and into the II reservoir through the cap rock at point B; In step 2, the fault throw calculation formula is as follows: （1） In the formula: h1 is the fault displacement, in meters; D A Let D be the sloping depth at point A, in meters. B The slope depth at point B is m; α A The well inclination at point A is °; α B The well inclination at point B is °; θ A Let θ be the dip angle of the reservoir where point A is located, in °; B Let be the dip angle of the reservoir where point B is located, in °.

3. The method of claim 2, wherein the method is characterized by: In step 4, the A'B' section close to the fault is preliminarily planned, and only the out-layer footage of the A'B' section is caused, the B' point position into the II reservoir is determined first, and the B' position height difference calculation formula is as follows: （2） where: h2 is the height difference at position B', m; hi is the fault throw, m; h Ⅱ is the thickness of the II reservoir at point B'.

4. The method for improving the reservoir capacity achievement ratio of a gas storage construction process according to claim 2, characterized by, In step 5, the adjusted footage is calculated using the following formula, and the A' position of the I reservoir is back calculated, as follows: （3） where: D A′ is the draft at point A' in the model, m; D B′ is the draft at point B' in the model, m; α A′ is the inclination at point A', °; α B′ is the inclination at point B', °; φ A′ is the azimuth at point A', °; φ B′ is the azimuth at point B', °; K is the trajectory profile build-up rate, ° / 30 m; L W m is the adjustment trajectory build-up rate, ° / 30 m; α W is the fault dip angle, °.

5. The method of claim 4, wherein the method is characterized by: where L W The value is obtained by calculation with the following formula: （4） In step 6, six trajectories are designed according to the trajectory profile build-up rate of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m.

6. The method of claim 1, wherein the method is used to improve the reservoir capacity achievement ratio of a gas storage construction process, characterized by, In step 7, the wellplan module in the Landmark software in the petroleum industry is used to calculate the drilling friction of the above trajectory schemes.

7. The method of claim 1, wherein the method is used to improve the reservoir capacity achievement ratio of a gas storage construction process, characterized by, In step 7, the horizontal section friction coefficient is adjusted to make the friction calculated by the wellplan module consistent with the actual construction friction, and the horizontal section friction coefficient that meets the actual working condition is back calculated; then the horizontal section friction coefficient is used to calculate the drilling friction of the above trajectory schemes.

8. The method of claim 7, wherein the method is characterized by: Also include:

9. The method of claim 1, wherein the method further comprises: Step 9, backfill the AB well section of the detected layer; Step 10, calculate the new storage capacity of the optimal trajectory compared with the conventional trajectory. The calculation formula of the new storage capacity is as follows:

10. The method of claim 9, wherein the method is characterized by: ​ （5） wherein: Q1 is the incremental reservoir capacity of the trajectory solution, m3; L1 is the incremental footage of the trajectory solution, m; K1 is the permeability of the trajectory solution, μm2; Φ1 is the porosity of the trajectory solution; L 总 is the total footage of the deployment well, m; - the average permeability of the deployment well, μm2; - the average porosity of the deployment well; Q 总 is the total reservoir capacity of the deployment well, m3.

Images