A method for developing a wellbore configuration design

Abstract

The application provides a wellbore structure design method for developing a well, comprising the following steps: (1) establishing a probability database of block risk occurrence, wherein the probability database comprises a complex occurrence depth ratio, a complex occurrence probability and a complex treatment cycle; (2) establishing a design well complex risk database, wherein the risk database comprises a design well occurrence depth, a complex occurrence probability and a complex treatment cycle; and (3) establishing a wellbore structure design optimization method, wherein the product of an investment rate of a to-be-selected scheme, a total complex occurrence rate and a total complex treatment cycle is used as a method for judging a target scheme. In the application, the complex occurrence depth is more accurate, the scheme comparison is more comprehensive and accurate, a plurality of complex occurrence probabilities and complex treatment times of the same stratum are combined, one stratum position corresponds to one complex treatment time and one complex occurrence probability, and the calculation parameters are simplified.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of petroleum engineering, and particularly relates to a wellbore structure design method for a development well. BACKGROUND

[0002] Wellbore structure is a key parameter of well drilling design, and has a decisive role on the risk of well drilling construction. At present, there are several methods for designing wellbore structure: ① Through formation three-pressure profile, the well depth at which the formation is easy to lose stability is taken as a geologic must sealing point, the well depth at which the drilling fluid density is greater than the formation fracture pressure during drilling is taken as an engineering must sealing point, and then the wellbore structure is determined by considering the well kick allowance, whether the casing is stuck during casing running, and other factors. ② In the master's thesis "Research on risk evaluation method for deep wellbore structure design", proposed by Luo Jun et al., the possibility of accident complexity in the drilling process is classified into [0, 1] by using fuzzy membership function evaluation method, the risks of well leakage, overflow, collapse and differential pressure sticking are evaluated respectively, and a whole risk evaluation model for deep wellbore structure design is established, which can realize quantitative risk evaluation under different degrees of formation pressure error. According to the level of evaluation results, it is determined whether to optimize the wellbore structure or to prepare for treating accident complexity in advance during drilling, and meanwhile, it provides a reference for selecting drilling fluid density when improving wellbore structure. ③ In the paper "Wellbore structure optimization method based on pre-drilling risk prediction", proposed by Sheng Yanan et al., firstly, the formation pressure profile with confidence interval is obtained based on the data of adjacent wells, and then the wellbore structure design scheme of the target well to be drilled is evaluated by using drilling risk evaluation method, the possible engineering risks are predicted before drilling, and the wellbore structure design scheme is optimized based on the prediction results to avoid the occurrence of drilling risks. ④ In the paper "Research on drilling design risk assessment method based on formation information uncertainty", proposed by Li Yingying et al., firstly, the drilled formation is processed and analyzed through the data of drilled wells, the formation pressure longitudinal profile with confidence interval is quantitatively described, the classification and distribution probability of the complexity of un-drilled wells are evaluated, and finally the possible risks of the target well to be drilled in the actual drilling process are obtained, and the wellbore structure design scheme is optimized based on the prediction results to control the possibility of drilling risk occurrence to the lowest degree. The above methods are very complex, and do not consider the investment problem, and also do not consider that the complexity occurrence probability will change during the treatment process, if the time is very long, the complexity occurrence probability may increase greatly, and the complexity of different layers may occur at the same time, and the complexity occurrence period may also change, which will lead to the change of investment; the complexity may have mutual influence, if the complexity occurrence probability is too large, even if the treatment period is very short, the complexity of other layers will also occur, thereby leading to the change of complexity occurrence probability and treatment period, which will lead to the change of investment. The above methods will produce errors, and affect the optimization of wellbore structure.

[0003] Patent CN202010776936.9 "A deep well complex formation wellbore structure design method based on multi-objective optimization", discloses a deep well complex formation wellbore structure design method based on multi-objective optimization, comprising: step one, quantitative description of uncertainty of formation pressure of the well to be analyzed; step two, establishment of safe drilling fluid density window of the well to be analyzed; step three, risk quantitative evaluation of a specific wellbore structure scheme of the well to be analyzed; if the risk quantitative evaluation result is less than the risk preset value, the specific wellbore structure scheme is selected; if the risk quantitative evaluation result is greater than or equal to the risk preset value, the wellbore structure scheme is adjusted again. The casing level and potential risk assessment method based on reliability theory is used to evaluate the risk of different wellbore structure schemes, so as to select the scheme with the smallest risk; at the same time, the risk occurrence probability can be reduced by optimizing the construction parameters, and the drilling safety is maximized in the design stage. It does not consider that the complexity occurrence probability will change in the process of dealing with risk, if the time is very long, the complexity occurrence probability may increase greatly, and the complexity of different horizons may appear at the same time, the complexity occurrence period will also change, which will lead to the change of investment; the complexity will have mutual influence, if the complexity occurrence probability is too large, even if the processing period is very short, the complexity of other horizons will also appear, which will lead to the change of complexity occurrence probability and processing period, and will lead to the change of investment.

[0004] Patent CN202120043045.2 "Wellbore structure suitable for complex formation conditions", discloses a wellbore structure suitable for complex formation conditions, which has first, second and third sealing points distributed in sequence and interval from top to bottom, and first and second risk points distributed in interval from top to bottom between the second and third sealing points. The wellbore structure suitable for complex formation conditions includes first, second, third, fourth, fifth and sixth open-time casings, which are respectively lowered into the first, second, first risk, second risk, third sealing points and oil and gas target layer. It can reasonably increase the casing level, expand the safe drilling to the target layer through the wellbore structure, and realize the exploration and development purpose. It does not consider that the complexity occurrence probability will change in the process of dealing with risk, if the time is very long, the complexity occurrence probability may increase greatly, and the complexity of different horizons may appear at the same time, the complexity occurrence period will also change, which will lead to the change of investment; the complexity will have mutual influence, if the complexity occurrence probability is too large, even if the processing period is very short, the complexity of other horizons will also appear, which will lead to the change of complexity occurrence probability and processing period, and will lead to the change of investment. SUMMARY

[0005] The determination of wellbore structure should comprehensively consider investment and engineering risks, and using the depth at which complexities occur in adjacent wells as the depth at which complexities occur in the well to be optimized is prone to error. Even at the same depth as adjacent wells, the geological strata may differ, and the probability of complexities occurring will also differ. Therefore, statistically determining the probability of complexities based on well depth results in significant errors. To address this problem, this invention uses the proportion of the depth at which complexities occur in adjacent wells within the formation, representing the well depth parameter for complexity occurrence based on geological stratification, which is more accurate.

[0006] This invention provides a method for designing the structure of a wellbore, comprising:

[0007] (1) Establish a probability database for the occurrence of block risks. The probability database includes the well depth ratio of complex occurrences, the probability of complex occurrences, and the cycle of handling complex occurrences.

[0008] (2) Establish a complex risk database for the design well. The risk database includes the well depth where the design well occurs, the probability of complex occurrence, and the cycle of complex handling.

[0009] (3) Establish a wellbore structure design optimization method, and use the product of the investment rate of the candidate scheme, the total complexity occurrence rate, and the total complexity processing cycle as the method to judge the target scheme.

[0010] Step (1) includes:

[0011] The depth of adjacent wells with complex occurrences is converted into the proportion of their location in each formation; the probability of complex occurrence is the sum of the number of times complex occurrences occur at the same formation location divided by the number of samples; the processing cycle for complex occurrences is the sum of the processing cycles for complex occurrences at the same formation location.

[0012] Step (2) includes:

[0013] The well depth ratio in the complex database is converted to the well depth at which the design well will occur; the probability of complex occurrence and the cycle of complex processing are taken according to the complex database.

[0014] Step (3) includes: the option with the smallest product of the investment rate, total complexity occurrence rate and total complexity processing cycle of the candidate options is the target option.

[0015] Step (1) includes:

[0016] Statistical and computational analysis of drilled wells with complex occurrences, including well number, well depth, and processing time data, including: Well No. A i , Ibuka H j Complex processing time T j The number of non-human-caused complex events, S j The probability of a complex event occurring is F. i, the time of complex processing is T i , the number of relevant sample wells is P, the top of the geological horizon where the complexity occurs is C j , the bottom of the geological horizon where the complexity occurs is C j+1 ;

[0017] A database matrix X of drilled well conditions is established: (A i , H j , T j , S j , C j , C j+1 );

[0018] The C j position of the complexity occurrence in the stratum:

[0019] The position of the complexity occurrence stratum is initialized as bili j , and is represented as n+bili j , where n is the stratum sequence, the first layer from the ground is 0, the second layer is recorded as 1, and so on, and is recorded as bili k ; if bili k is the same, it is considered to be the same position in the same stratum, and the number of the same position in the same stratum is m;

[0020] The probability of the occurrence of the comprehensive risk of different complexity types in the same position in the same stratum is calculated:

[0021]

[0022] The time of the comprehensive risk processing of different complexity types in the same position in the same stratum is calculated:

[0023]

[0024] A database Y matrix of the probability of complexity occurrence is established: (bili k , F k , T k );

[0025] Wherein, A i is the well number of the target block; H j is the well depth where the complexity occurs in the well number A i ; T j is the time of complexity processing at the well depth H j in the well number A i ; S j is the number of non-human complexity occurrences at the well depth H j in the well number A i ; bili j is the position of the complexity occurrence in the horizon.

[0026] wherein, the step (2) comprises:

[0027] establishing a design well B database matrix Z(H b , C vb , C vb+1 , Y(b,2), Y(b,3));

[0028] the design well is at a well depth H b , the top inclined depth of the geological horizon is C vb , the bottom inclined depth of the geological horizon is C vb+1 , and H b =[z(b,3)-z(b,2)]·[Y(b,1)-n]+z(b-2), which is expressed as z(b,1)=H b ;

[0029] n is a stratum sequence, the first layer from the ground is 0, the second layer is recorded as 1, and the like;

[0030] at this time, the complexity of the design well H b occurs with a probability of Y(k,2), and the processing period is Y(k,3), so that z(b,2)=Y(k,2), and z(b,3)=Y(k,3) by analogy;

[0031] establishing a database of complexity probability and complexity processing time:

[0032] V[Z(b,1),Z(b,4),Z(b,5)].

[0033] wherein, the step (3) comprises:

[0034] let the bottom hole depth be M0, the wellbore diameter of the current drilling is Q s , the wellbore diameter of the next drilling is Q x , the casing outer diameter of the current drilling is φ1, and the casing outer diameter of the next drilling is φ2;

[0035] the casing is lowered to M0, which is taken as a reference scheme, and the investment is taken as a reference investment U;

[0036] the casing of the scheme K is lowered to M0-kΔh, in the database V, if M0-kΔh≤V(b,1)≤M0, the corresponding complexity occurrence probability v(b,2) and complexity processing period v(b,3) are selected, and there are m points; the period of the scheme K is D;

[0037] the investment rate of the scheme is expressed as the investment U k of the scheme K and the reference investment U;

[0038]

[0039] Where KΔh is the step size for wellbore structure optimization, zj is the cost per cubic meter of drilling fluid, gj is the cost per cubic meter of cement slurry, and V is the cost per cubic meter of cementing slurry. s This is the mechanical drilling rate of this well opening, in m / h; V x is the mechanical drilling rate for the next well opening, in m / h; shixiao is the pure drilling time; rf is the cost related to the drilling cycle; tg is the price difference between the casing for this opening and the casing for the next opening, in yuan / t.

[0040] Total complexity occurrence rate F of scheme K k :

[0041]

[0042] Scheme K: Total complexity occurrence processing cycle ratio T k :

[0043]

[0044] Establish coordinate axes at 120° angles to each other: OA, OB, OC; ray OA represents the investment rate of the proposed scheme. k , where ray 0B represents the total complexity occurrence rate F k The ray OC represents the total complex processing cycle T. k Using the area S of a triangle ΔABC As a comparison parameter, if S ΔABC If the value is small, the solution is the optimal solution considering the three factors of comprehensive investment, complexity occurrence rate, and complexity processing cycle; if there is no complexity, that is, the occurrence rate and complexity processing cycle are 0, then S ΔABC The investment rate of the plan;

[0045]

[0046] The wellbore structure design method developed in this application has the following beneficial effects:

[0047] ① The determination of wellbore structure should comprehensively consider investment and engineering risks, using the depth at which complexities occur in adjacent wells as the depth at which complexities occur in the well to be optimized. This method has errors; even at the same depth as adjacent wells, the geological strata may differ, and the probability of complexity occurrence will also differ. Therefore, statistically calculating the probability of complexity occurrence based on well depth has a large error. To address this problem, this invention uses the proportion of the depth at which complexities occur in adjacent wells within the formation, describing the well depth parameter for complexity occurrence based on geological stratification, which is more accurate. ② During risk management, the probability of complexity occurrence will change. If the time is long, it may cause a significant increase in the probability of complexity occurrence, and complexities in different strata may occur simultaneously, changing their occurrence cycle and leading to changes in investment. The occurrence of complexities can also be mutually influential. If the probability of complexity occurrence is too high, even if the processing cycle is very short, it may lead to the occurrence of complexities in other strata, thus changing the probability of complexity occurrence and the processing cycle, leading to changes in investment. To address these issues, this invention uses the product of investment rate and total probability of occurrence as the impact of complex occurrence probability on investment; the product of investment rate and complex processing cycle as the impact of complex processing cycle on investment; and the product of total complex occurrence rate and complex processing cycle as the overall impact of complex processing cycle and probability of occurrence on investment. These three factors are summed as a quantitative evaluation standard for risk management and occurrence costs, resulting in a more comprehensive and accurate comparison of solutions. ③ It simplifies the design method and facilitates implementation using computer programming. Attached Figure Description

[0048] Fig. 1 This is a schematic diagram illustrating the investment rate, total complexity occurrence rate, and total complexity processing cycle of the scheme in the embodiments of this application;

[0049] Fig. 2 This is a schematic diagram of the wellbore structure design method for an embodiment of this application. Detailed Implementation

[0050] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0051] Example 1

[0052] like Figs. 1-2 As shown, the wellbore structure design method of this application includes: (1) establishing a probability database of block risk occurrence, which includes the proportion of well depths where complex occurrences occur, the probability of complex occurrences, and the cycle of handling complex occurrences; (2) establishing a complex risk database for the design well, which includes the well depth where the design well occurs, the probability of complex occurrences, and the cycle of handling complex occurrences; (3) establishing a wellbore structure design optimization method, which uses the product of the investment rate of the candidate scheme, the total complexity occurrence rate, and the total complexity handling cycle as the method for judging the target scheme.

[0053] This invention uses the proportion of the well depth where complex events occur in adjacent wells within the formation, which is based on geological stratification to describe the well depth parameters of complex events, making it more accurate.

[0054] Example 2

[0055] like Figs. 1-2 As shown, this invention discloses a method for optimizing the wellbore structure of development wells in the field of oil and gas drilling, comprising: 1) establishing a probability database of block risk occurrence, which mainly includes the proportion of well depths where complex events occur, the probability of complex events occurring, and the cycle of handling complex events. The well depths where complex events occur in adjacent wells are converted into the proportion of their locations in each formation; the probability of complex events occurring is the sum of the number of times complex events occur at the same formation location divided by the number of samples; the cycle of handling complex events is the sum of the cycle of handling complex events occurring at the same formation location. 2) establishing a complex risk database for design wells, which includes the well depths where complex events occur in design wells, the probability of complex events occurring, and the cycle of handling complex events. The proportion of well depths in the complex database is converted into the well depths where complex events occur; the probability of complex events occurring and the cycle of handling complex events are taken from the values ​​in the complex database. 3) establishing a wellbore structure design optimization method, which uses the product of the investment rate of the candidate scheme, the total probability of complex events occurring, and the total cycle of handling complex events as the method for judging the optimal scheme, that is, the scheme with the smallest product is the optimal scheme. This method is also easy to implement using computer programming.

[0056] (1) Establish a probability database for the occurrence of block risks

[0057] Statistical analysis and calculation of data on drilled wells with complex occurrences, including well number, well depth, and processing time, including: Well number A i , Ibuka H j (Vertical depth), complex processing time T j The number of non-human-caused complex events, S j The probability of a complex event occurring is F. i The time for complex processing is T. i (If more than one complex event occurs at the same depth, the processing time will be combined; all costs, including material consumption and other expenses for handling complex events, will be converted into cycle time.) The number of adjacent wells in the relevant block is P, and the top of the geological stratum where the complex event occurs is C. j (Vertical depth), the bottom of the geological stratum where the complex formation occurs is C. j+1 (Vertical depth).

[0058] Establish a database matrix X of drilled well information: (A i H j T j S j C j C j+1 ).

[0059] Complex C-type formations in strataj Position:

[0060] The position of the complex occurrence formation is bili j Initialization processing, denoted as n + bili j , n is the formation sequence, the first layer from the ground is 0, the second layer position is recorded as 1, and so on, recorded as bili k If bili k The same is considered to be the same position of the same formation, and the number of the same position of the same formation is m.

[0061] Calculate the probability of occurrence of the comprehensive risk of different complex types in the same position of the same formation:

[0062]

[0063] Calculate the time of comprehensive risk processing of different complex types in the same position of the same formation:

[0064]

[0065] Establish the database Y matrix of the probability of complex occurrence: (bili k , F k , T k ).

[0066] Where, A i is the well number of the target block; H j is the well depth of the complex occurrence in well number A i ; T j is the time of complex occurrence processing at well depth H i in well number A j ; S j is the number of non-human complex occurrences at well depth H i in well number A j ; bili j is the position of the complex occurrence in the layer position.

[0067] (2) Establish a complex risk database for design wells

[0068] Establish the database matrix Z(H b , C vb , C vb+1 , Y(b,2), Y(b,3))

[0069] The complex occurs at well depth H b of the design well, the top of the geological layer is C vb , the bottom of the geological layer is C vb+1 , and H b= [z(b,3) - z(b,2)] · [Y(b,1) - n] + z(b - 2), expressed as z(b,1) = H b .

[0070] n is the sequence of strata, the first layer from the ground is 0, the second layer is recorded as 1, and so on.

[0071] At this time, the well H b is designed, the probability of the complexity occurring at the location is Y(k,2), and the processing period is Y(k,3), then let z(b,2) = Y(k,2), and let z(b,3) = Y(k,3) by analogy;

[0072] A database of complexity probability and complexity processing time is established:

[0073] V[z(b,1), z(b,4), z(b,5)]

[0074] (3) Establishing a wellbore structure design optimization method

[0075] Let the bottom hole depth be M0, the wellbore diameter of the current drilling is Q s , the wellbore diameter of the next drilling is Q x , the casing outer diameter of the current drilling is φ1, and the casing outer diameter of the next drilling is φ2.

[0076] Take the casing down to M0 as the reference scheme, and its investment as the reference investment U.

[0077] The casing of scheme K is lowered to M0-kΔh, and in the database V, if M0-kΔh≤V(b,1)≤M0 exists, then select the corresponding complexity occurrence probability v(b,2), complexity processing period v(b,3), and there are m points. The period of scheme K is D.

[0078] The investment rate of the scheme is expressed as the investment U k of scheme k divided by the investment U of the reference scheme.

[0079]

[0080] where KΔh is the step length of the wellbore structure optimization, zj is the cost of each cubic meter of drilling fluid, gj is the cost of each cubic meter of cement slurry, V s is the mechanical drilling speed of the current wellbore, m / h; V x is the mechanical drilling speed of the next wellbore, m / h; shixiao is the pure drilling time efficiency; rf is the cost related to the drilling period (including rig daily fee, technical service fee, well control device usage fee, etc.); tg is the price difference between the casing of the current drilling and the next drilling, with the unit being yuan / t.

[0081] The total complexity occurrence rate F k of scheme K:

[0082]

[0083] The total complex occurrence processing cycle proportion T of the scheme K k :

[0084]

[0085] Coordinate axes OA, OB and OC which are mutually at an angle of 120 degrees are established, the ray OA is the investment rate of the scheme k , the ray OB is the total complex occurrence rate F k , and the ray OC is the total complex processing cycle T k . The triangular area S ΔABC is used as a comparison parameter, if the value of S ΔABC is small, the scheme is the optimal scheme which comprehensively considers the investment, the complex occurrence rate and the complex processing cycle, if there is no complex, i.e. the complex occurrence rate and the complex processing cycle are 0, then S ΔABC is the investment rate of the scheme.

[0086]

[0087] The determination of the wellbore structure should comprehensively consider the investment and the engineering risk, and the depth of the complex occurrence of the adjacent well is used as the depth of the complex occurrence of the to-be-optimized well. This method has an error, i.e. even if the depth is the same as that of the adjacent well, the geological stratification can be different, and the complex occurrence probability is also different, therefore, the error is great based on the depth statistics of the complex occurrence probability. In view of this problem, the application uses the proportion of the depth of the complex occurrence of the adjacent well in the position of the stratum, which is a depth parameter of the complex occurrence based on the geological stratification, and is more accurate.

[0088] In the process of risk treatment, the complex occurrence probability will change, if the time is long, the complex occurrence probability can greatly increase, and the complex of different layers can simultaneously occur, and the complex occurrence cycle can also change, which can cause the investment to change; the complex occurrence can have mutual influences, if the complex occurrence probability is too large, even if the treatment cycle is very short, the complex of other layers can also occur, thereby causing the complex occurrence probability and the treatment cycle to change, which can cause the investment to change. In view of these problems, the application uses the product of the investment rate and the total complex occurrence probability as the influence of the complex occurrence probability on the investment, uses the product of the investment rate and the complex processing cycle as the influence of the complex processing cycle on the investment, and uses the product of the total complex occurrence rate and the complex processing cycle as the influence of the complex processing cycle and the occurrence probability on the investment, and the three are added together as a quantitative evaluation standard of the risk treatment and the generation cost, and the scheme comparison is more comprehensive and accurate.

[0089] The application simplifies the design method and is convenient for computer programming.

[0090] Example Three

[0091] There are four adjacent wells A1, A2, A3, A4 in a certain block, and the designed well is B well. The complex occurrence conditions of A1, A2, A3 wells are shown in Table 1.

[0092] Table 1: Complex table of adjacent wells

[0093]

[0094] 1. Establish a complex database matrix X: (A i , H j , T j , S j , C j , C j+1 ):

[0095]

[0096] 2. Establish a database Y matrix of the probability of complex occurrence: (bili k , F k , T k )

[0097] Assume that ES is the uppermost formation, n takes 0; ED is the second formation, n takes 1; EF is the third formation, n takes 2.

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105] Since there are four adjacent wells, P takes 4. Since Y(1,1) and Y(3,1) have the same value, they are considered to be the same formation at the same location, and are combined into Y(1,1); Y(2,1) remains unchanged, and Y(4,1) is changed to Y(3,1); Y(5,1) and Y(6,1) have the same value, so they are considered to be the same formation at the same location, and are combined into Y(4,1); Y(7,1) is changed to Y(5,1). The probability of complex occurrence is:

[0106]

[0107]

[0108]

[0109]

[0110]

[0111] Complex occurrence time, as described above, the same formation same location, combined processing.

[0112] Form a database matrix Y:

[0113]

[0114]

[0115]

[0116]

[0117]

[0118]

[0119] 3, to carry out the optimization of well structure

[0120] Design well B well geology stratification for table 2

[0121] Table 2 design well geology stratification depth (inclined depth)

[0122]

[0123] Establish the design well complex probability data matrix Z(H b , C vb , C vb+1 , gailv b , zhouqi b )

[0124]

[0125] Z(1,1) = H1 = [z(1,3)-z(1,2)]·[Y(1,1)-0]+z(1,2) = 1160

[0126] Z(1,2) = H2 = [z(2,3)-z(2,2)]·[Y(2,1)-1]+z(2,2) = 1285

[0127] Z(1,3) = H3 = [z(3,3) - z(3,2)] - [Y(3,1) - 1] + z(3,2) = 1320

[0128] Z(1,4) = H4 = [z(4,3) - z(4,2)] - [Y(4,1) - 1] + z(4,2) = 1390

[0129] Z(1,5) = H5 = [z(5,3) - z(5,2)] - [Y(5,1) - 2] + z(5,2) = 1700

[0130] Database of complex probability and complex processing time: V[Z(b,1), Z(b,4), Z(b,5)]

[0131]

[0132] The well bottom depth of well B is 1800 m, the wellbore diameter of the current spud is 0.311 m, the wellbore diameter of the next spud is 0.2159 m, the casing outer diameter of the current spud is 244.5, the drilling speed of the current spud is 16 m / h, the drilling speed of the next spud is 22 m / h, the drilling fluid is 0.2 ten thousand / m3, the cementing slurry cost is 0.5 ten thousand / m3; is the mechanical drilling speed of the current spud, m / h; is the mechanical drilling speed of the next spud, m / h; the pure drilling time is 40%; is the cost related to the drilling cycle (including rig daily fee, technical service fee, well control device usage fee, etc.), taking 8 million / day for 30 rigs; is the price difference of the casing of the current spud and the casing of the next spud, taking 0.02 yuan / m, taking 300 m. The benchmark investment is 3 million.

[0133] Scheme one: K takes 1, the casing is lowered to 1800 m-300 m=1400 m, and the cycle D is 12 days. In the database V, there is 1800>v(5,1)≥1400. Therefore, scheme one exists the probability of complex occurrence, then the corresponding complex occurrence probability v(5,2)=0.25, the complex processing cycle v(5,3)=1 is selected, participates in the calculation of scheme two, because there is only one point, so w=1.

[0134] The investment rate of scheme one is represented as investment U k The ratio of the investment of the benchmark scheme U.

[0135]

[0136] The total complex occurrence rate F1 of scheme one is:

[0137] F1=0.25

[0138] The total complex occurrence processing cycle ratio T1 of scheme one is:

[0139]

[0140]

[0141] Scheme two: K is 2, the casing is under deep and down to 1800m-600m=1200m, and the period D is 12 days.In database V, there are 1800>v(5,1), v(4,1), v(3,1), v(2,1)≥1200.Therefore, the probability of occurrence of complexity between scheme one is, then the corresponding complex occurrence probability v(5,2)=0.25, v(4,2)=0.75, v(3,2)=0.5, v(2,2)=0.5 is selected, the complex processing period v(5,3)=1, v(4,3)=1.3, v(3,3)=1, v(2,3)=1 is participated in the calculation of scheme two, because there are only four points, so w=1.

[0142] The investment rate of scheme two is represented as the investment U of scheme k The ratio of the investment U of the base scheme.

[0143]

[0144] The total complex occurrence rate F2 of scheme two is:

[0145] 0.25+0.75+0.5+0.5=3

[0146] The total complex occurrence processing period ratio T2 of scheme two is:

[0147]

[0148]

[0149] S Δ方案一 <S Δ方案二

[0150] Therefore, scheme one is the preferred scheme.

[0151] In the application, before the implementation of the drilling scheme of petroleum engineering, the well structure is optimized in the design stage, so as to ensure that the investment cost of the well to be drilled is low and the construction risk is low.

[0152] In the application, the depth of complexity occurrence is more accurate.The ratio of the depth of complexity occurrence of adjacent wells in the formation is based on the geological stratification to express the well depth parameter of complexity occurrence, and is more accurate.

[0153] The present application is more comprehensive and accurate. The product of the investment rate and the total probability of occurrence is used as the influence of the complex occurrence probability on investment; the product of the investment rate and the complex processing period is used as the influence of the complex processing period on investment; the product of the complex total occurrence rate and the complex processing period is used as the influence of the complex processing period and the occurrence probability on investment, and the three are added together as the quantitative evaluation standard of risk processing and generation cost, which is more comprehensive and accurate.

[0154] The present application is more convenient. The present application combines multiple complex occurrence probabilities and complex processing times in the same stratum, and one stratum position corresponds to one complex processing time and complex occurrence probability, which simplifies the calculation parameters.

[0155] The above introduction is only the preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for designing the structure of a wellbore, characterized in that, include: (1) Establish a probability database for the occurrence of block risks. The probability database includes the well depth ratio of complex occurrences, the probability of complex occurrences, and the cycle of handling complex occurrences; including: The depths of adjacent wells where complexities occur are converted into their proportions within each formation; the probability of a complexity occurring is the sum of the number of times a complexity occurs at the same formation location divided by the number of samples; the processing cycle for complexities is the sum of the processing cycles for complexities occurring at the same formation location. Statistical and computational analysis of drilled wells with complex occurrences, including well number, well depth, and processing time data, including: Well No. A i , Ibuka H j Complex processing time T j The number of non-human-caused complex events, S j The probability of a complex event occurring is F. i The time for complex processing is T. i The number of relevant sample wells, P, and the top of the complex geological stratum, C. j The bottom of the complex geological stratum is C. j+1 ; Establish a database matrix X of drilled well information: (A i H j T j S j C j C j+1 ); Complex C-type formations in strata j Location: The location of complex geological formations (bili) j Initialization processing, represented as n+bili j Let n be the stratigraphic sequence, starting from the surface, the first layer is 0, the second layer is 1, and so on, denoted as bili. k If bili k If they are the same, they are considered to be in the same stratum and at the same location. Let the number of the same location in the same stratum be m. Calculate the probability of the occurrence of combined risks of different complex types at the same location in the same stratum: Calculate the time required for comprehensive risk management of different complexity types at the same location in the same stratum: Establish a database Y matrix representing the probability of complex events occurring: (bili) k F k T k ); Among them, A i H is the hash number of the target block. j For the well number A i Complex well depths; T j At hash A i Nakai Deep H j The time required to handle complex situations; S j For the well number A i Nakai Deep H j The number of times non-human-caused complex events occur; bili j The location where the complexity occurs within the layer; (2) Establish a complex risk database for the design well. The risk database includes the well depth where the design well occurs, the probability of complex occurrence, and the cycle of complex handling. (3) Establish a wellbore structure design optimization method, and use the product of the investment rate of the candidate scheme, the total complexity occurrence rate, and the total complexity processing cycle as the method to judge the target scheme.

2. The wellbore structure design method according to claim 1, characterized in that, Step (2) includes: The well depth ratio in the complex database is converted to the well depth at which the design well will occur; the probability of complex occurrence and the cycle of complex processing are taken according to the complex database.

3. The wellbore structure design method according to any one of claims 1-2, characterized in that, Step (3) includes: the option with the smallest product of the investment rate, total complexity occurrence rate and total complexity processing cycle of the candidate options is the target option.

4. The wellbore structure design method according to any one of claims 1-2, characterized in that, Step (2) includes: Establish the design well B database matrix Z(H) b C vb C vb+1 ,Y(b,2),Y(b,3)); The design well is at a depth of H. b The geological formation is complex; the top of this geological stratum has a slope depth of C. vb The bottom of this geological stratum has a slope depth of C. vb+1 H b =[z(b,3)-z(b,2)]·[Y(b,1)-n]+z(b-2), which can be expressed as z(b,1)=H b ; n is the stratigraphic sequence, starting from the ground surface, the first layer is 0, the second layer is 1, and so on; At this time, design well H b If the probability of a complex event occurring at a given location is Y(K,2) and the processing period is Y(k,3), then let z(b,2) = Y(k,2), and similarly let z(b,3) = Y(k,3). Establish a database of complex probabilities and complex processing times: V[Z(b,1),Z(b,4),Z(b,5)].

5. The wellbore structure design method according to any one of claims 1-2, characterized in that, Step (3) includes: Let the bottom depth be M0, and the borehole diameter for this drilling operation be Q. s The diameter of the next well opening is Q. x The outer diameter of the casing in this opening is φ1, and the outer diameter of the casing in the next opening is φ2; Using the casing down to M0 as the benchmark scheme, its investment is taken as the benchmark investment U; In scheme K, the casing depth is M0-kΔh. In database V, if there exists M0-kΔh≤V(b,1)≤M0, then the corresponding probability of complex occurrence v(b,2) and the complex processing period v(b,3) are selected, and there are m points; the period of scheme K is D. The investment rate of the project is expressed as the investment U of project k. k The ratio of the investment U to the benchmark plan; Where KΔh is the step size for wellbore structure optimization, zj is the cost per cubic meter of drilling fluid, gj is the cost per cubic meter of cement slurry, and V is the cost per cubic meter of cementing slurry. s This is the mechanical drilling rate of this well opening, in m / h; V x is the mechanical drilling rate for the next well opening, in m / h; shixiao is the pure drilling time; rf is the cost related to the drilling cycle; tg is the price difference between the casing for this opening and the casing for the next opening, in yuan / t. Total complexity occurrence rate F of scheme K k : Scheme K: Total complexity occurrence processing cycle ratio T k : Establish coordinate axes at 120° angles to each other: OA, OB, OC; ray OA represents the investment rate of the proposed scheme. k , where ray 0B represents the total complexity occurrence rate F k The ray OC represents the total complex processing cycle T. k Using the area S of a triangle ΔABC As a comparison parameter, if S ΔABC If the value is small, the solution is the optimal solution considering the three factors of comprehensive investment, complexity occurrence rate, and complexity processing cycle; if there is no complexity, that is, the occurrence rate and complexity processing cycle are 0, then S ΔABC The investment rate of the plan;

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