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

Abstract

The invention discloses a method for improving the reservoir capacity achievement rate in the gas storage construction process. The method comprises the following steps that 1, logging while drilling information is collected and analyzed, and a fault is implemented; 2, when an unpredicted fault is drilled, establishing a fault geologic model, and calculating the fault displacement of the fault; step 3, determining the well section which encounters the unpredicted fault as a backfill well section; 4, establishing a horizontal section + fault model, and re-planning a well section with reduced out-of-layer footage; step 5, deducing and determining a proper out-of-layer position range of the reservoir I; step 6, designing a plurality of tracks according to different build-up rates; step 7, calculating drilling friction resistance of the track schemes; and 8, the optimal track scheme is determined by integrating the two factors of the track scheme and the drilling friction resistance. According to the method, after fault key parameters are implemented through seismic data and logging-while-drilling data, the feasibility that the trajectory passes through the reservoir to the maximum extent and trajectory construction is comprehensively considered, an optimization scheme of trajectory control is determined, and it is guaranteed that the planned reservoir capacity can be achieved after the gas storage is built.

Description

Technical Field

[0001] The invention relates to a construction scheme for drilling in complex geological faults during construction of a gas storage reservoir in a depleted complex fault block oil and gas reservoir, and in particular to a method for improving storage capacity achievement rate during gas storage reservoir construction, belonging to the technical field of underground engineering for gas storage reservoir construction. Background Art

[0002] During the planning and construction of gas storage, there are very few work areas that can be used for gas storage construction through screening by geological personnel. Compared with conventional oil and gas wells, the work areas that can meet the requirements of gas storage construction are "limited resources". Therefore, effective technical measures should be taken in the engineering field during the construction of gas storage to ensure that the planned storage capacity can be achieved after the completion of the gas storage. Taking a gas storage under construction as an example, during the drilling construction of the reservoir, the horizontal section of the horizontal well Z1P1 encountered a fault, and the reservoir drilling rate was only 73%, which directly led to a significant reduction in storage capacity and caused huge economic losses. This kind of problem is not an isolated case. Basically, it often occurs when using depleted complex fault block oil and gas reservoirs to build gas storage.

[0003] From the perspective of engineering construction, the difficulty is transformed into fault trajectory control. The current technical means are:

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

[0005] 2. Based on the seismic data, the depth of the target oil layer, the change in the formation dip of the target oil layer, the fault distance and the relative position of the fault disk are obtained. Starting from the development well location of the target oil layer, the drilling direction of the drill bit is adjusted successively to complete the drilling of the stepped horizontal well.

[0006] 3. Obtain the marker layer division data of the construction well area based on the comparison of the completed well formations, the target data given by the geological engineering design of the construction well, and the fault data; obtain the fault distance on the seismic profile along the trajectory; determine the well inclination and vertical depth corresponding to the apparent translation of the fault position by 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 a set of marker layers at the upper and lower parts of the stratum, and calculate the vertical thickness between the two sets of marker layers in the adjacent wells and the vertical thickness of the marker layer two from the target point; calculate the well inclination and inclination depth when drilling into the marker layer two; determine whether the trajectory is from the rising plate of the fault to the descending plate, or from the descending plate of the fault to the rising plate, and design different target entry processes according to different trajectories. The above methods provide a trajectory control method for efficient penetration in the reservoir, horizontal sections and faults encountered during target drilling. However, in actual construction, there are complex fault block oil and gas reservoirs with unpredictable development faults. When a horizontal section suddenly encounters a fault and then chases the layer, a large section footage is used to adjust the trajectory. It has little effect on the production capacity after the completion and fracturing of the oil well in the later stage, but it will cause the storage capacity of the gas storage well to be reduced and fail to reach the planned storage capacity.

[0007] The Chinese invention patent application with publication number CN 108625842A discloses a drilling trajectory control method and system, including the following steps: constructing a formation profile model, determining the formation line and trajectory line in the profile model; calculating the upper interface distance, lower interface distance, drilling interface distance and drill bit front interface distance respectively based on the formation profile model; displaying the upper interface distance, lower interface distance, drilling interface distance and drill bit front interface distance on the formation profile model, and controlling the drilling trajectory according to the respective distances. This technical solution is too dependent on the constructed formation profile model. The trajectory control method described uses the upper interface distance, lower interface distance, drilling interface distance and drill bit front interface distance to determine and adjust. It is a control method for the trajectory to pass through the formation profile model, but the actual formation changes are difficult to predict, and it does not involve the adjustment method of the trajectory after the layer is penetrated.

[0008] The Chinese invention patent with the announcement number CN 109184560B discloses a method and device for controlling the borehole trajectory of a stepped horizontal well. The depth of the target oil layer, the change of the formation dip angle of the target oil layer, the fault distance and the relative position of the fault plate are obtained based on seismic data. Starting from the development well position of the target oil layer, the drilling direction of the drill bit is adjusted in sequence to complete the drilling of the stepped horizontal well. The fault trajectory control method described in this technical solution is too theoretical. The fault dip angle comes from the seismic profile, and the drilling process must be corrected according to the actual formation changes; it is difficult to adjust the trajectory along the fault dip angle, and the key parameter dogleg degree is not involved, which cannot effectively guide the construction.

[0009] The Chinese invention patent with the announcement number CN 110644967B discloses a trajectory control method for horizontal well targeting through faults. The method comprises the following steps: obtaining the marker layer division data of the construction well area, the target point data given by the geological engineering design of the construction well, and the fault data based on the comparison of the completed well formations; obtaining the fault offset on the seismic profile along the trajectory direction; determining the well inclination and vertical depth corresponding to the apparent translation of the fault position based on the engineering design trajectory, and calculating the vertical depth of the fault from the target point; determining the layer where the fault is located, selecting a set of marker layers at the upper and lower parts of the layer, and calculating the vertical thickness between the two sets of marker layers in the adjacent well and the vertical thickness of the marker layer from the target point; calculating the well inclination and inclination depth when encountering the marker layer; determining whether the trajectory is drilled from the rising plate of the fault to the descending plate, or from the descending plate of the fault to the rising plate, and designing different targeting processes according to different trajectories. The method of trajectory control for drilling through faults described in this technical solution is different from the trajectory control for drilling through faults in horizontal sections. The former only considers the destination point after trajectory adjustment, while the latter takes into account both the entire trajectory adjustment process and the destination point. Summary of the invention

[0010] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification of this application and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present invention.

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

[0012] The purpose of the present invention is to provide a method for improving the storage capacity achievement rate during the construction of a gas storage reservoir in view of complex geological faults encountered during the construction of horizontal wells during the construction of a gas storage reservoir. After the key parameters of the fault are determined through seismic data and logging while drilling data, the trajectory travels through the reservoir to the maximum extent and the feasibility of trajectory construction are comprehensively considered to determine the optimization plan of trajectory control, so as to ensure that the planned storage capacity can be achieved after the gas storage is built.

[0013] In order to solve the above technical problems, the method for improving the storage capacity achievement rate during the construction process of the gas storage reservoir of the present invention comprises the following steps in sequence:

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

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

[0016] Step 3, determining the well section where the unpredicted fault is encountered as the backfill well section;

[0017] Step 4: Establish a horizontal section + fault model and re-plan the well section to reduce the out-of-layer footage;

[0018] Step 5, derive and determine the appropriate exit position range of reservoir I;

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

[0020] Step 7, calculating the drilling friction of the above trajectory schemes;

[0021] Step 8: Consider both trajectory plan and drilling friction to determine the optimal trajectory plan.

[0022] Furthermore, in step 1, the trajectory exits reservoir I at point A and passes through the cap rock to enter reservoir II at point B;

[0023] In step 2, the calculation formula of the fault distance is as follows:

[0024]

[0025] Where: h1 is the fault distance, m; D A is the oblique depth at point A, m; D B is the oblique depth at point B, m; α A is the well inclination at point A, °; α B is the well inclination at point B, °; θ A is the reservoir dip angle at point A, °; θ B is the reservoir inclination angle at point B, °.

[0026] Furthermore, in step 4, the A′B′ segment close to the fault is preliminarily planned, and only the out-of-layer footage of the A′B′ segment is generated. The position of point B′ entering reservoir II is first determined, and the height difference calculation formula of the B′ position is as follows:

[0027]

[0028] Where: h2 is the height difference of B′, m; h1 is the fault distance, m; h Ⅱ is the thickness of reservoir II where point B′ is located.

[0029] Furthermore, in step 5, the adjusted footage is calculated using the following formula to infer the A′ position of reservoir I, as follows:

[0030]

[0031] Where: D A′ is the oblique depth at point A′ in the model, m; D B′ is the oblique depth at point B′ in the model, m;

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

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

[0034] K is the slope rate of the trajectory profile, which is ﹡° / 30m; L W To adjust the height difference of the stable slope section of the track, m; α W is the fault tilt angle, °.

[0035] Furthermore, L W Calculated by the following formula:

[0036]

[0037] Where: R is the radius of curvature at different build rates, m.

[0038] Furthermore, in step 6, six trajectories are designed according to the trajectory profile slope of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m.

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

[0040] Furthermore, in step 7, by adjusting the horizontal section friction coefficient, the friction resistance calculated by the wellplan module is made consistent with the actual construction friction resistance, and the horizontal section friction coefficient that meets the actual working conditions is inferred; and then the drilling friction resistance of the above trajectory schemes is calculated using the horizontal section friction coefficient.

[0041] Furthermore, it also includes:

[0042] Step 9, backfilling the AB section of the detected layer;

[0043] Step 10: Calculate the additional storage capacity of the optimal trajectory compared with the conventional trajectory.

[0044] Furthermore, the calculation formula for the newly added library capacity is as follows:

[0045]

[0046] Where: Q1 is the newly added storage capacity of the trajectory scheme of the present invention, m 3 ; L1 is the reduction of the layer advance of the trajectory scheme of the present invention, m; K1 is the permeability at the trajectory scheme of the present invention, μ㎡; φ1 is the porosity at the trajectory scheme of the present invention; L 总 is the total footage of the reservoir section of the deployed well, m; - Average permeability of deployed wells, μ㎡; - Average porosity of deployed wells; Q 总 is the total storage capacity of the deployed wells, m 3.

[0047] Compared with the existing engineering fault trajectory control and wellbore trajectory control methods in the prior art, the present invention has achieved the following beneficial effects and advantages: 1. When an unpredicted fault is encountered in the horizontal section, the important fault parameter fault distance can be quickly determined by combining seismic data and logging while drilling data, which is convenient for the formulation of the next trajectory control plan;

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

[0049] 3. According to preliminary estimates, the gas storage wells have effectively controlled the trajectory of crossing the fault, significantly increased the storage capacity, and achieved good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use 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 ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work. The accompanying drawings are only provided for reference and explanation, and are not used to limit the present invention.

[0051] in:

[0052] Figure 1 A flow chart of a method for improving storage capacity achievement rate during gas storage construction of the present invention;

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

[0054] Figure 3 This is a schematic diagram of a conventional horizontal well trajectory passing through a fault;

[0055] Figure 4 A schematic diagram of a horizontal well trajectory passing through a fault after the trajectory is adjusted after backfilling in the present invention;

[0056] Figure 5 It is a schematic diagram of trajectory schemes under different build-up rates in the present invention;

[0057] Figure 6 The trajectory diagrams of different slope ratio schemes and conventional schemes for Z-P2 well;

[0058] Figure 7 Drilling friction diagrams for different slope rate schemes and conventional schemes. DETAILED DESCRIPTION

[0059] In the following description of the present invention, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "inside" and "outside" are based on the directions or positional relationships 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 direction.

[0060] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below in conjunction with specific diagrams. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

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

[0063] Step 1: Collect and analyze the logging data while drilling to confirm the fault. The starting point of this step is that the horizontal section encounters an unpredicted fault. The fault is analyzed and confirmed through seismic data, logging data of implemented wells, lithological characteristics and logging data while drilling of the wells being drilled. Analyze the gamma value of the logging while drilling and the change characteristics of the gamma curve of the implemented wells.

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

[0065] Table 1 Gamma curve characteristics and lithology reference table of cap rock and reservoir

[0066]

[0067] Step 2: When drilling into an unpredicted fault, adjust the geological model, establish a fault geological model, and calculate the fault distance. Figure 2 Establish a fault calculation model. The determination of points A and B in the model refers to the gamma value variation characteristics of the well logging data, and the formation dip angle θ A ,θ B Obtained from seismic data. After determining points A and B, calculate the fault distance h1 according to the model. The calculation formula for h1 is as follows:

[0068]

[0069] Where: h1 is the fault distance, m; D A is the oblique depth at point A, m; D B is the oblique depth at point B, m; αA is the well inclination at point A, °; α B is the well inclination at point B, °; θ A is the reservoir dip angle at point A, °; θ B is the reservoir inclination angle at point B, °.

[0070] The fault distance calculated through the above steps can quickly confirm the unpredicted faults encountered during drilling, which is beneficial to the formulation of subsequent trajectory control plans.

[0071] Step 3: Optimize the trajectory control plan. The purpose of this step is to avoid the impact of unpredicted faults as much as possible, reduce the waste of reservoir footage, and facilitate the implementation of the trajectory adjustment plan.

[0072] When drilling into an unpredicted fault, conventional trajectory control is as follows: Figure 3 As shown in the figure, the AB section + CD section has a large footage. The large footage is used to adjust the trajectory, which requires the well completion and fracturing to remedy the situation. However, for the gas storage well, the storage capacity will be reduced and cannot reach the planned storage capacity. Therefore, the AB well section is determined as the backfill well section.

[0073] Step 4: After the gas storage well is preferably backfilled, the trajectory is readjusted according to the fault. Figure 4 The figure shows the schematic diagram of the horizontal well trajectory through the fault after the trajectory adjustment after backfilling. That is, after the fault and reservoir II are explored through the AB section, the A′B′ section close to the fault is preliminarily planned again, resulting in only the out-of-layer footage of the A′B′ section. Figure 3 The trajectory control of the present invention greatly reduces the number of layer outages caused by conventional wells compared with the original ones.

[0074] To ensure that the trajectory passes through the reservoir, a horizontal segment + fault model is established. Figure 4 , mainly including reservoir I and position B'. This model needs to determine the height difference of position B' and reservoir dip. The reservoir dip is obtained from seismic data. The height difference calculation formula of position B' is as follows:

[0075]

[0076] Where: h2 is the height difference of B′, m; h1 is the fault distance, m; h Ⅱ is 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: Determine the appropriate exit position range of reservoir I to facilitate the trajectory control scheme. Figure 4 As shown in the model, the position of A' is determined by formula deduction. After the trajectory exits reservoir I and enters reservoir II, the adjustment requires trajectory footage. When the position of reservoir B' in reservoir II is determined, the adjusted footage is calculated using the formula to infer the position of reservoir A' in reservoir I. The specific formula is as follows:

[0078]

[0079] Where: D A′ is the oblique depth at point A′ in the model, m; D B′ is the oblique depth at point B′ in the model, m;

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

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

[0082] K is the slope rate of the trajectory profile, which is ﹡° / 30m; L W To adjust the height difference of the stable slope section of the track, m; α W is the fault tilt angle, °; where L W It is obtained by calculation using formula (4).

[0083]

[0084] Where: R is the radius of curvature at different build rates, m.

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

[0086] Step 6. The present invention starts from the actual construction and combines the tool deflection capability to establish a trajectory solution database. In the construction of fault-block oil and gas reservoirs, considering the difficulty of trajectory adjustment, the horizontal section is generally drilled with rotary guide drilling tools, and the tool deflection capability is 1-6° / 30m. Assuming that the deflection capability can meet the trajectory control requirements, six trajectories are designed according to different deflection rates of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m.

[0087] The range of the exit position A′ of reservoir I is obtained by calculation in step 5. The trajectory scheme of well section A′B′ is designed by combining the tool deflection capability, i.e., different trajectory profile deflection rates K. For detailed trajectory scheme, see Figure 5 .

[0088] Table 2 Statistics of each trajectory scheme

[0089]

[0090] Step 7: Use the wellplan module in the oil industry software Landmark to calculate the drilling friction of the above trajectory schemes. This allows the present invention to not only formulate trajectory schemes, but also refer to the drilling friction of different trajectory schemes, taking into account the construction difficulty during specific construction, so as to select the best trajectory scheme.

[0091] When calculating drilling friction through the wellplan module, the default value of the upper casing friction coefficient above reservoir I is generally 0.25; the horizontal section starts from reservoir I and ends at reservoir II, and the default value of the horizontal section friction coefficient is 0.35.

[0092] In order to make the friction coefficient of the horizontal section more in line with the actual working conditions, the calculated friction resistance is compared with the actual construction friction resistance and then inferred. For example: The friction coefficient of the AB section of the Z-P2 well is calculated to be 13t by using the conventional default value of 0.35, while the actual construction friction resistance of the AB section is 15t. The friction coefficient of the AB section is adjusted to 0.45 to make the drilling friction resistance of the AB section 15t. It is more accurate to infer that the friction coefficient of the horizontal section is 0.45.

[0093] Table 3 Drilling friction statistics of each trajectory scheme

[0094] plan Friction coefficient value Friction 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: Consider both trajectory plan and drilling friction to determine the optimal trajectory plan.

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

[0097] The backfilling construction requirements for the AB section of the detected layer are as follows: the well should be cleared before backfilling to ensure the smooth flow of the wellbore; the drilling fluid should be properly handled to ensure that the drilling fluid performance meets the requirements; various ground equipment should be checked before backfilling to ensure the smooth and continuous construction; the cement slurry performance should meet the construction safety and cement plug strength requirements. Use the balance method for backfilling. After replacing the cement slurry, do not lift the drill too fast to avoid mixing the slurry and affecting the strength of the cement plug; wait for 48 hours to solidify and repair the cement plug surface. Take measures to prevent the drilling fluid from being contaminated when drilling the cement plug.

[0098] The backfill cost of the AB section of the well where the detection has been made is: backfill construction work (120,000 yuan) + waiting drilling rig daily fee (calculated based on a 50ZJ drilling rig, with a daily fee of 127,000 yuan, 127,000 yuan / d*operation time 2.5 days = 317,500 yuan) = 437,500 yuan.

[0099] Step 10: Calculate the additional storage capacity of the optimal trajectory compared with the conventional trajectory. Select the important parameters of reserve control, permeability K and porosity φ, to calculate the simplified version of the controlled reserves, and form the result, which is the additional storage capacity of the trajectory scheme of the present invention.

[0100]

[0101] Where: Q1 is the newly added storage capacity of the trajectory scheme of the present invention, m 3 ; L1 is the reduction of the layer advance by the trajectory scheme of the present invention, m; K1 is the permeability at the trajectory scheme of the present invention, μm 2 ; φ1 is the porosity at the trajectory scheme of the present invention; L 总 is the total footage of the reservoir section of the deployed well, m; - Average permeability of deployed wells, μm 2 ; - Average porosity of deployed wells; Q 总 is the total storage capacity of the deployed wells, m 3 .

[0102] The economic value of the newly added storage capacity of the trajectory scheme of the present invention is estimated as follows: It is estimated that the effective working gas volume of the wells of the gas storage under construction is 36% of the total storage capacity; the peak-shaving time is about 4-6 months, and according to the current gas storage rules, there are about 4 rounds of injection and production; the natural gas is low in and high out, and the price difference is about 0.2-0.3 yuan / cubic meter, and 0.2 yuan / cubic meter is calculated; the annual benefit of the newly added storage capacity of the present invention is:

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

[0104] The present invention effectively controls the trajectory of crossing the fault during construction, which is beneficial to ensuring that the planned storage capacity can be achieved after the gas storage is built, improves the storage capacity achievement rate, and achieves good economic benefits.

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

[0106] 1. Well Z-P2 is a depleted complex fault-block oil and gas reservoir for gas storage construction. The horizontal section encountered an unpredicted fault at a depth of 4525m. According to the gamma of logging while drilling (see Table 4) and the gamma curve change characteristics of the implemented wells (see Table 1), it is determined that the trajectory exits the I reservoir at a depth of 4525m at point A and passes through the cap rock to enter the II reservoir at a depth of 4623m at point B.

[0107] Table 4. Gamma data of logging while drilling for points A and B in horizontal section

[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] 2. According to the seismic data, the dip angle of reservoir I θA is 11°, the dip angle of reservoir II θB is 15°, and the well depth D at points A and B of the current trajectory data is collected. A , D B The well inclination at points A and B is α A , αB According to the above data, the fault throw is calculated to be 24m, which is used for the next trajectory design:

[0110]

[0111] 3. Determine the backfill plan for the detected well section. Since the well encountered a fault at a depth of 4525m and drilled to 4635m after passing point B, backfilling 50m more would increase the possibility of trajectory design optimization, so the backfill section was determined to be 4475m-4635m.

[0112] 4. To ensure that the trajectory passes through the reservoir, a horizontal section + fault model is established, and the height difference of the target point B′ in the II reservoir is 29m.

[0113]

[0114] 5. Derivation and determination of the appropriate exit position range of reservoir I is beneficial to the trajectory control scheme. Figure 4 As shown in the model, the position of A′ is determined by formula deduction. First, calculate the height difference L of the stable slope section of the adjustment trajectory W , calculated according to different slope rates of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, 6° / 30m:

[0115]

[0116] Again, the trajectory is adjusted out of reservoir I and enters reservoir II. The adjustment requires trajectory footage. When the position of reservoir B' is determined, the adjusted footage is calculated using the formula to infer the position of reservoir A', where the positions of points A' and B' are 141° and 143°:

[0117]

[0118] Table 5Ⅰ Theoretical calculation statistics of reservoir outburst position

[0119] Slope <![CDATA[Inclination - holding section elevation difference L W > Estimate the well depth of 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 position of reservoir I obtained in this step is a theoretical calculation, which only provides a reference for the subsequent trajectory design. The specific design should also consider the smoothness and rationality of the trajectory. The position of reservoir I obtained by 1° / 30m in Table 5 is quite different from the others, and has little reference value.

[0121] 6. According to the tool deflection capability of 1-6° / 30m, six trajectories are designed with different deflection rates of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m. At the same time, the conventional trajectory control method is designed for comparison.

[0122] Table 6 Statistics of out-of-layer advances for different trajectory schemes

[0123]

[0124] Figure 6 Shown are the trajectories of different slope rate schemes and conventional schemes. From left to right, there are six trajectories designed at 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m, as well as the trajectory of the conventional scheme.

[0125] From the perspective of trajectory design, without considering the construction difficulty, the 1° / 30m design trajectory solution has a layer advance of 255m, which is larger than other solutions and can be optimized and discarded. In general, the trajectory control solution of the present invention greatly reduces the layer advance compared with the conventional trajectory control solution.

[0126] 7. According to different trajectory plans, use professional software in the petroleum industry to calculate the friction resistance of different trajectories and analyze the trend of friction resistance changes.

[0127] Table 7 Drilling friction statistics of different trajectory schemes

[0128] plan Drilling friction 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 slope rate schemes and conventional schemes.

[0130] 8. From Figure 7 It can be seen that the drilling friction of the 5° / 30m and 6° / 30m trajectory schemes increases significantly, the construction difficulty increases dramatically, and the excessive slope in actual construction is prone to complex occurrences such as keyways. Considering the trajectory scheme and drilling friction, the trajectory scheme recommends the 3° / 30m and 4° / 30m trajectory schemes, which can take into account both the layer footage and the construction difficulty.

[0131] 9. Backfill the well section where the layer has been detected. Backfilling construction requirements for the well section where the layer has been detected: the well should be cleared before backfilling to ensure the smooth flow of the wellbore; the drilling fluid should be properly handled to ensure that the drilling fluid performance meets the requirements; various ground equipment should be checked before backfilling to ensure the smooth and continuous construction; the cement slurry performance should meet the construction safety and cement plug strength requirements; the balance method should be used for backfilling. After replacing the cement slurry, the speed of lifting the drill bit should not be too fast to avoid mixing the slurry and affecting the strength of the cement plug; wait for 48 hours to solidify and repair the cement plug surface. Measures should be taken to prevent the drilling fluid from being contaminated when drilling the cement plug.

[0132] The backfill cost of the detected well section is:

[0133] Backfill construction work (120,000 yuan) + Hou Ning's daily fee for waiting for the drilling rig (calculated based on a 50ZJ drilling rig, with a daily fee of 127,000 yuan, 127,000 yuan / d*operation time 2.5 days = 317,500 yuan) = 437,500 yuan.

[0134] 10. Calculation of the new storage capacity of the trajectory of the present invention compared with the conventional method. According to the geological data of the developed depleted gas reservoirs, the average porosity is 14% and the average permeability is 118.7×10 -3 μm 2 Compared with the conventional scheme, the trajectory scheme of the present invention reduces the layer footage by 365-165=200m (3° / 30m scheme). According to the core test of the adjacent well, the porosity of the layer near the fault is 16%, and the permeability is 120.5×10 -3 μ㎡. Geological prediction shows that the total reservoir capacity after completion is 0.98×10 8 m 3 .

[0135]

[0136] The economic value of the newly added storage capacity of the trajectory scheme of the present invention is estimated. It is estimated that the effective working gas volume of the gas storage wells under construction is 36% of the total storage capacity; the peak-shaving time is about 4-6 months, and according to the current gas storage rules, there are about 4 rounds of injection and production; the natural gas is low in and high out, and the price difference is about 0.2-0.3 yuan / cubic meter, and 0.2 yuan / cubic meter is calculated; the annual benefits of the newly added storage capacity of the present invention are:

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

[0138] The present invention can effectively control the trajectory of the fault during construction, so that the storage capacity of the gas storage will increase by 0.19×10 8 m 3 , improving the reservoir capacity achievement rate. Achieving good economic benefits, compared with the additional backfill investment of 437,500 yuan in conventional oil well construction, it can generate 5.472 million yuan in economic benefits each year.

[0139] The above is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation modes without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. The technical features not described in the present invention can be realized by or using existing technologies, which will not be repeated here.

Claims

1. A method for improving storage capacity achievement rate during gas storage construction, characterized in that: The steps are as follows: Step 1: Collect and analyze the logging while drilling data to identify the faults; Step 2: When drilling into an unpredicted fault, establish a fault geological model and calculate the fault distance; Step 3, determining the well section where the unpredicted fault is encountered as the backfill well section; Step 4: Establish a horizontal section + fault model and re-plan the well section to reduce the out-of-layer footage; Step 5, derive and determine the appropriate exit position range of reservoir I; Step 6: Design multiple trajectories according to different slope rates; Step 7, calculating the drilling friction of the above trajectory schemes; Step 8: Consider both trajectory plan and drilling friction to determine the optimal trajectory plan.

2. The method for improving storage capacity achievement rate during gas storage construction according to claim 1, characterized in that: In step 1, the trajectory exits reservoir I at point A and passes through the cap rock into reservoir II at point B; In step 2, the calculation formula of the fault distance is as follows: Where: h1 is the fault distance, m; D A is the oblique depth at point A, m; D B is the oblique depth at point B, m; α A is the well inclination at point A, °; α B is the well inclination at point B, °; θ A is the reservoir dip angle at point A, °; θ B is the reservoir inclination angle at point B, °.

3. The method for improving storage capacity achievement rate during gas storage construction according to claim 2, characterized in that: In step 4, the A′B′ segment close to the fault is preliminarily planned, and only the out-of-layer footage of the A′B′ segment is generated. The position of point B′ entering reservoir II is first determined, and the height difference calculation formula of the B′ position is as follows: Where: h2 is the height difference of B′, m; h1 is the fault distance, m; h Ⅱ is the thickness of reservoir II where point B′ is located.

4. The method for improving storage capacity achievement rate during gas storage construction according to claim 2, characterized in that: In step 5, the adjusted footage is calculated using the following formula to infer the A′ position of reservoir I, as follows: Where: D A′ is the oblique depth at point A′ in the model, m; D B′ is the oblique depth at point B′ in the model, m; α A′ is the well inclination at point A′, °; α B′ is the well inclination at point B′, °; φ A′ is the orientation of point A′, °; φ B′ is the orientation of point B′, °; K is the slope rate of the trajectory profile, which is ﹡° / 30m; L W To adjust the height difference of the stable slope section of the track, m; α W is the fault tilt angle, °.

5. The method for improving storage capacity achievement rate during gas storage construction according to claim 4, characterized in that: Where L W Calculated by the following formula: Where: R is the radius of curvature at different build rates, m.

6. The method for improving storage capacity achievement rate during gas storage construction according to claim 1, characterized in that: In step 6, six trajectories are designed with trajectory profile slopes of 1° / 30m, 2° / 30m, 3° / 30m, 4° / 30m, 5° / 30m, and 6° / 30m.

7. The method for improving storage capacity achievement rate during gas storage construction according to claim 1, characterized in that: In step 7, the wellplan module in the oil industry software Landmark is used to calculate the drilling friction of the above trajectory schemes.

8. The method for improving storage capacity achievement rate during gas storage construction according to claim 7, characterized in that: In step 7, the friction coefficient of the horizontal section is adjusted so that the friction resistance calculated by the wellplan module is consistent with the actual construction friction resistance, and the friction coefficient of the horizontal section that meets the actual working conditions is inferred; the drilling friction resistance of the above trajectory schemes is then calculated using the friction coefficient of the horizontal section.

9. The method for improving storage capacity achievement rate during gas storage construction according to claim 1, characterized in that: Also includes: Step 9, backfilling the AB section of the detected layer; Step 10: Calculate the additional storage capacity of the optimal trajectory compared with the conventional trajectory.

10. The method for improving storage capacity achievement rate during gas storage construction according to claim 9, characterized in that: The calculation formula for the additional storage capacity is as follows: Where: Q1 is the newly added storage capacity of the trajectory scheme of the present invention, m 3 ; L1 is the reduction of the layer advance of the trajectory scheme of the present invention, m; K1 is the permeability at the trajectory scheme of the present invention, μ㎡; φ1 is the porosity at the trajectory scheme of the present invention; L 总 is the total footage of the reservoir section of the deployed well, m; - Average permeability of deployed wells, μ㎡; - Average porosity of deployed wells; Q 总 is the total storage capacity of the deployed wells, m 3 .

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