A method and system for determining the structure parameters of a PDC bit based on rock drilling resistance characteristics

Abstract

The present application relates to the technical field of petroleum and natural gas drilling tool design and drilling engineering data processing, and discloses a PDC bit structure parameter determination method and system based on rock drilling resistance characteristics. The method obtains existing well geological interpretation, rock experiment, drilling conditions, PDC bit structure and bit use effect data, divides the single bit use scene according to the stratigraphic interface and the lithologic interface, eliminates abnormal conditions and invalid scenes, calculates the effective sample weight and the bit use effect evaluation value, and determines the optimized PDC bit structure combination of each stratigraphic-lithologic unit; taking the rock drillability level value, uniaxial compressive strength, internal friction angle, hardness and plasticity coefficient as the drilling resistance characteristic parameters, the prediction and mapping relationship between the parameters and the cutting tooth size, cutting tooth shape, number of blades, crown characteristics and gauge protection level is established; and the PDC bit structure parameter determination result is output according to the rock drilling resistance characteristic parameters of the target well.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling engineering technology, and more specifically, to a method and system for determining the structural parameters of a PDC drill bit. Background Technology

[0002] PDC drill bits are characterized by high mechanical drilling speed, long service life, and wide applicability to various formations, and have been widely used in oil and gas drilling projects. In deep, hard, brittle, highly abrasive formations, and multi-lithological interbedded formations, the structural parameters of PDC drill bits directly affect the bit's rock-breaking efficiency, single-bit footage, cutting tooth damage, mud bag risk, drilling stability, and caliper retention capability. Inappropriate selection of structural parameters such as cutting tooth size, cutting tooth profile, number of blades, crown characteristics, and caliper retention rating can easily lead to problems such as reduced mechanical drilling speed, abnormal cutting tooth damage, mud bagging, caliper enlargement, or premature bit failure.

[0003] Chinese invention patent application CN107944169A discloses a method for selecting drill bits for oil and gas drilling. This method obtains formation rock mechanics parameters and stratifies them. Based on the drill bit usage requirements of each layer, it determines drill bit structural parameters such as crown profile shape, cutter wings, cutting teeth, and back rake angle. The determined structural parameters are then compared with stock drill bits to select a matching bit. While this method can guide drill bit structure selection from the perspective of rock mechanics parameters and formation stratification, it primarily relies on layer judgment, structural requirement determination, and comparison with stock drill bits. It does not specifically disclose the use of historical drill bit usage results to calibrate the quantitative mapping relationship between multiple rock drill resistance parameters and multiple drill bit structural parameters. Therefore, when updated formation, lithology, or rock drill resistance parameters are obtained during the drilling of the target well, it is difficult to promptly generate specific structural parameter recommendations for subsequent well sections or the next drilling run. Summary of the Invention

[0004] This invention provides a method and system for determining the structural parameters of PDC drill bits based on the rock's anti-drilling properties. Its main purpose is to solve the problems in existing PDC drill bit selection methods, such as scattered historical data, unclear correspondence between formation conditions and drill bit structural parameters, significant impact of abnormal working conditions on the evaluation of performance, the inability to directly determine specific structural parameters while only being able to determine the drill bit model, and the difficulty in updating the determination results during drilling.

[0005] To achieve the above objectives, the present invention provides a method and system for determining the structural parameters of a PDC drill bit based on the rock's anti-drilling properties, comprising: acquiring geological interpretation data, rock test data, drilling condition data, PDC drill bit structural data, and drill bit usage effect data of existing wells in the same or adjacent blocks; and determining the drill bit usage scenario corresponding to a single PDC drill bit based on the PDC drill bit number, drill bit type, entry time, exit time, entry depth, and exit depth. Based on the top and bottom boundary depths of the stratigraphic unit and the lithological interface depth, the drill bit usage scenarios are assigned to the corresponding stratigraphic units and lithologies. Drill bit usage scenarios spanning different stratigraphic units or lithologies are further divided into multiple sub-use scenarios. A table of rock drillability parameters is established, and based on the well number, sampling depth, stratigraphic unit, and lithology of the sample source, rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient are added to the corresponding drill bit usage scenario or sub-use scenario. The stratigraphic unit, lithology, rock drillability parameters, drilling condition parameters, PDC drill bit structural parameters, and drill bit usage effect data corresponding to the drill bit usage scenario are correlated to construct a historical drill bit usage scenario database. Abnormal drilling records, abnormal working condition records, and invalid usage scenarios in the historical drill bit usage scenario database are identified and removed. The effective sample weights are calculated based on the ratio of normal drilling footage to total new footage to obtain effective historical drill bit usage scenarios. These effective historical drill bit usage scenarios are grouped according to stratigraphy and lithology. Drill bit performance evaluation values ​​are calculated based on the effective drilling footage, average mechanical drilling speed, drill bit wear, cutting tooth damage, and frequency of abnormal events per unit footage for each effective historical drill bit usage scenario. Effective historical drill bit usage scenarios under the same stratigraphy and lithology are classified into structural combinations based on combinations of cutting tooth size, cutting tooth type, number of blades, crown characteristics, and gauge protection level. Combining the drill bit performance evaluation values ​​and effective sample weights, the optimal PDC drill bit structural combination for each stratigraphy and lithology is determined, establishing a stratigraphy-lithology optimal PDC drill bit structure database. Each stratum-lithology unit in the optimal PDC drill bit structure database is used as a modeling sample. The rock drill resistance parameters are standardized, and the rock drill resistance input parameters corresponding to each PDC drill bit structure parameter are selected. The relationship between the rock drill resistance parameters and the cutting tooth size, cutting tooth type, number of blades, crown features and diameter protection level is established using all modeling samples. During the drilling of the target well, the stratigraphy, lithology and rock drill resistance parameters of the subsequent well sections of the target well are acquired or updated. The rock drill resistance parameters are standardized and the corresponding formulas are input to obtain the continuous predicted values ​​of various PDC drill bit structural parameters. The continuous predicted values ​​are mapped to a preset set of standard structural parameters for PDC drill bits, and the results of determining the cutting tooth size, cutting tooth type, number of blades, crown features, and gauge protection level for subsequent well sections or the next drilling run of the target well are output.

[0006] Optionally, the acquisition of geological interpretation data, rock test data, drilling condition data, PDC drill bit structure data, and drill bit performance data from existing wells in the same or adjacent blocks is included. The geological interpretation data includes well logging interpretation results, well logging lithological profiles, and geological stratification data, used to obtain stratigraphic names, top and bottom boundary depths, lithological names, and lithological interface depths. The rock test data originates from laboratory tests on cores, cuttings, or rock samples, used to obtain rock drillability grades, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient. The drilling condition data originates from logging-while-drilling data, daily drilling reports, or surface engineering parameter acquisition, used to obtain well depth, drilling pressure, rotational speed, torque, displacement, riser pressure, and mechanical strength. Drilling rate, drilling time, and drilling fluid density; the PDC drill bit structure data comes from drill bit usage records, drill bit manuals, or drill bit structure parameter tables, and is used to obtain drill bit diameter, cutting tooth size, cutting tooth type, number of blades, crown characteristics, and gauge protection grade; the drill bit performance data comes from drill bit pull-out inspection records, daily drilling reports, logging records, or downhole complex situation records, and is used to obtain single drill bit footage, average mechanical drilling rate, drill bit wear degree, cutting tooth damage, and records of unplanned reaming, pressure buildup, stuck pipe, and severe mud packing.

[0007] Optionally, the step of assigning the drill bit usage scenario to the corresponding stratum and lithology based on geological interpretation data includes: reading the stratum name, top boundary depth, and bottom boundary depth of each stratum from geological stratification data, well logging interpretation results, or well logging interpretation results; and reading the lithology name, top boundary depth, and bottom boundary depth of each lithological segment; taking the entry depth to exit depth corresponding to the drill bit usage scenario as the well section to be matched, and comparing it with the depth range corresponding to each stratum and the depth range corresponding to each lithological segment; when the entry depth and exit depth of the well section to be matched are both located at the top boundary depth and bottom boundary depth of the same stratum... When the depths of the drill bit are between the boundary depths, the drill bit usage scenario is assigned to the stratigraphic level. When the entry and exit depths of the well section to be matched are both between the top and bottom boundary depths of the same lithological segment, the drill bit usage scenario is assigned to the lithology. When the drill bit usage scenario crosses one or more stratigraphic interfaces or lithological change interfaces, all stratigraphic interface depths and lithological change interface depths located between the entry and exit depths are summarized and arranged in ascending order of depth. Using each interface depth as a dividing point, the drill bit usage scenario is divided into multiple continuous and non-overlapping sub-use scenarios. Based on the start and end depths of each sub-use scenario, its corresponding stratigraphy and lithology are determined, and the sub-use scenario is associated and stored with the original drill bit use scenario identifier, stratigraphy name, lithology name, start depth, and end depth. Specifically, when the depth range of the drill bit use scenario is [Din, Dout]... The interface depths within this interval, including the stratigraphic interface depth and the lithological variation interface depth, are d1, d2, ..., dn, respectively, and satisfy the following: The application scenarios for this drill bit are then divided into: Multiple sub-use scenarios are corresponding to this. For sampling records located at stratigraphic boundaries or lithological change boundaries, they are assigned to the corresponding sub-use scenarios according to the preset depth interval left-closed and right-open rule to avoid the same sampling record being assigned repeatedly.

[0008] Optionally, establishing a rock drill resistance parameter table and attaching the rock drill resistance parameter to the corresponding drill bit usage scenario according to the stratigraphic and lithological matching relationship includes: collecting the laboratory test results of cores, cuttings, or other rock samples from existing wells in the same or adjacent blocks, and establishing a rock drill resistance parameter table; the rock drill resistance parameter table includes at least the sample number, the well number from which the sample originated, the sampling depth or sampling well section, the stratigraphic position, the lithology, the rock drillability grade, the uniaxial compressive strength, the internal friction angle, the hardness, the plasticity coefficient, the test method, and the data source.

[0009] Units and test calibers were standardized for rock drillability parameters from different data. Specifically, rock drillability grade values ​​were dimensionless, uniaxial compressive strength was standardized to MPa, internal friction angle was standardized to degrees, and hardness and plasticity coefficients were recorded in dimensional or dimensionless form according to the corresponding rock mechanics test methods. For the same type of parameters obtained using different test methods, the corresponding test method identifiers were saved, and data with consistent test methods were prioritized for matching.

[0010] Based on the well number and sampling depth or sampling section, the rock test sample is assigned to the corresponding stratum and lithology. When the stratum and lithology of the rock test sample are consistent with the stratum and lithology of the drill bit usage scenario or the sub-use scenario after stratum and lithology division, the rock drillability grade, uniaxial compressive strength, internal friction angle, hardness and plasticity coefficient corresponding to the rock test sample are added to the corresponding drill bit usage scenario or sub-use scenario.

[0011] When multiple rock test samples correspond to the same well, the same stratigraphy, and the same lithology, the arithmetic mean of each rock drill resistance parameter is calculated, and the arithmetic mean is used as the representative value of the rock drill resistance parameter of the corresponding stratigraphy-lithology unit for that well; the representative value of the m-th rock drill resistance parameter in the g-th stratigraphy-lithology unit is calculated according to the following formula:

[0012] In the formula, x g,m Let x be the representative value of the m-th rock drill resistance parameter in the g-th stratigraphic-lithological unit. g,k,m is the m-th rock drill resistance parameter of the k-th rock experimental sample in the g-th stratigraphic-lithological unit, and ng is the number of valid rock experimental samples in the g-th stratigraphic-lithological unit.

[0013] When existing wells lack rock drill resistance parameters of the same well, same stratigraphy, and same lithology, alternative data are selected in the order of adjacent wells of the same stratigraphy and lithology in the same block, and adjacent wells of the same stratigraphy and lithology in adjacent blocks. When there are multiple adjacent wells that meet the conditions, the arithmetic mean of the corresponding rock drill resistance parameters of each adjacent well is calculated, and the obtained average value is added to the corresponding drill bit usage scenario. At the same time, the source well number and matching method of the alternative data are saved.

[0014] When any one of the following parameters is missing from the rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient in the rock drillability parameter table, and cannot be supplemented from adjacent well data that meets the criteria, the corresponding parameter will be marked as a missing value and processed in the subsequent historical drill bit usage scenario validity assessment process.

[0015] Optionally, the historical drill bit usage scenario database uses a single PDC drill bit usage scenario or a sub-use scenario after stratigraphic and lithological segmentation as a database record, and sets a usage scenario identifier for each database record; when the database record is a sub-use scenario after stratigraphic and lithological segmentation, its corresponding original drill bit usage scenario identifier is also saved. Each database record includes at least scenario attribute data, geological attribute data, rock drill resistance characteristic data, drilling condition data, PDC drill bit structure data, and drill bit usage effect data.

[0016] The scenario attribute data includes at least the well number, drill bit number, drill bit type, entry time, pull-out time, entry depth, pull-out depth, usage scenario identifier, and original drill bit usage scenario identifier; The geological attribute data includes at least the stratigraphic name, the top boundary depth of the stratigraphic unit, the bottom boundary depth of the stratigraphic unit, the lithology name, the top boundary depth of the lithology section, the bottom boundary depth of the lithology section, and the wellbore size; The rock drillability data include at least the rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient. The drilling condition data includes at least drilling time, drilling pressure, rotational speed, torque, displacement, standpipe pressure, mechanical drilling speed, and drilling fluid density; The PDC drill bit structure data includes at least the drill bit diameter, cutting tooth size, cutting tooth type, number of blades, crown features, and gauge protection rating. The drill bit performance data includes at least the total footage per drill bit, effective drilling footage, normal drilling time, average mechanical drilling speed, drill bit wear, number of damaged cutting teeth, total number of cutting teeth included in the inspection, and records of unplanned reaming, pressure buildup, stuck drill bit, and severe mud packing. The drill bit diameter is used to determine the fit between the PDC drill bit and the designed wellbore size, and serves as a constraint parameter for screening historical drill bit usage scenarios. The cutting tooth size, cutting tooth type, number of blades, crown features, and gauge protection level are the structural parameters of the PDC drill bit to be determined.

[0017] The scenario attribute data comes from the drill bit log sheet and the daily drilling report; the geological attribute data comes from geological stratification data, well logging interpretation results, and well logging lithology interpretation results; the rock drill resistance characteristic data comes from laboratory test results of cores, cuttings, or other rock samples; the drilling condition data comes from logging while drilling, surface engineering parameter acquisition, or the daily drilling report; the PDC drill bit structure data comes from the drill bit usage record, drill bit instruction manual, drill bit design drawings, or drill bit structure parameter table; the drill bit usage effect data comes from the daily drilling report, drill bit pull-out inspection record, drill bit wear evaluation record, well logging event record, and downhole complex situation record.

[0018] Optionally, the process of identifying and removing abnormal drilling records, abnormal operating condition records, and invalid usage scenarios from the historical drill bit usage scenario database, and calculating the weight of valid samples, includes: calculating the well depth increment between adjacent drilling operating condition records according to the sampling time sequence; when the well depth increment between adjacent drilling operating condition records is less than or equal to 0, or when the drilling daily report, logging record, or operation status record shows that the corresponding period is in the operation status of stopping drilling, tripping, circulating, connecting a single bit, changing drill bit, or other operation statuses that have not formed new wellbore footage, the corresponding record is marked as an abnormal drilling record.

[0019] When unplanned reaming, pressure buildup, stuck pipe, or severe mud bagging occurs in the daily drilling report, logging event record, or downhole complex situation record, the drilling condition record during the duration of the abnormal condition is marked as an abnormal condition record based on the occurrence time, end time, or corresponding depth range of the abnormal condition. When the same abnormal condition occurs repeatedly in multiple consecutive records, they are merged into one abnormal condition event based on the type of abnormal condition and the continuity of time, and the occurrence count of each type of abnormal condition is retained.

[0020] When a drill bit usage scenario lacks any of the required data, such as stratum, lithology, rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, plasticity coefficient, PDC drill bit structural parameters, or drill bit usage performance data, and cannot be supplemented with data from the same block or adjacent blocks that meet the matching conditions, the drill bit usage scenario is determined to be an invalid usage scenario.

[0021] The abnormal drilling records and abnormal working condition records are removed from the calculation data of average mechanical drilling speed, average drilling pressure, average rotation speed, average torque, average displacement, and average standpipe pressure. The normal drilling footage and normal drilling time for the corresponding drill bit usage scenario are calculated based on the retained normal drilling records. At the same time, the number of occurrences of unplanned reaming, pressure buildup, stuck drill, and severe mud packing are retained as the basic data for drilling stability evaluation.

[0022] The effective sample weights for the i-th drill bit usage scenario are calculated according to the following formula:

[0023] In the formula, L i This represents the total footage (in meters) corresponding to the usage scenario of the i-th drill bit. ; M i The effective drilling footage for the i-th historical drill bit usage scenario is expressed in meters. ; q i The effective sample weights for the i-th historical drill bit usage scenario are dimensionless. ; The effective drilling footage is obtained by accumulating the positive well depth increments from the remaining normal drilling records after further removing abnormal operating condition records such as pressure buildup, stuck pipe, abnormal drilling pressure, abnormal torque, severe mud packing, and missing data, based on the Li-forming records. When, the i-th drill bit usage scenario is retained as a valid historical drill bit usage scenario; when When the i-th drill bit usage scenario is removed from the comprehensive score calculation, 0.6 is a preset engineering screening threshold and should not be expressed as a general physical constant; when The scene will be marked as invalid, and division will not be performed.

[0024] Optionally, the drill bit performance evaluation value is obtained by comprehensively considering the rock breaking efficiency evaluation value, wear resistance evaluation value, and drilling stability evaluation value. For effective historical drill bit usage scenarios within the same stratigraphic unit, the effective drilling footage Mi, normal drilling time Ti, drill bit wear degree Ai, and number of damaged cutting teeth n for the i-th effective historical drill bit usage scenario are obtained. d,i The total number of cutting teeth included in the inspection, n c,i The number of unplanned drilling, pressure buildup, stuck drills, and severe mud blisters.

[0025] The effective drilling footage Mi is obtained by accumulating the remaining positive well depth increments after removing abnormal drilling records and abnormal operating condition records; the average mechanical drilling rate vi is calculated according to the following formula:

[0026] In the formula, Let be the average mechanical drilling rate (m / h) for the i-th valid historical drill bit usage scenario. ; Effective drilling footage, meters. ; Ti represents the cumulative time (in hours) for generating a normal drilling record of effective drilling footage Mi. .

[0027] This formula belongs to the engineering definition of mechanical drilling rate, which is the effective new footage formed within a unit of normal drilling time. Mi and Ti must come from the same batch of normal drilling records; abnormal records cannot be removed from the footage while the corresponding abnormal time period is retained in the time.

[0028] The effective drilling footage Mi and the average mechanical drilling rate vi are subjected to positive range normalization to obtain the normalized effective drilling footage M. i and normalized average mechanical drilling rate v i :

[0029]

[0030] In the formula, M g,max and M g,min These are the maximum and minimum effective drilling footage (in meters) within the g-th stratum-lithological unit; v g,max and v g,min These are the maximum and minimum average mechanical drilling rates within the g-th stratum-lithological unit, respectively, in m / h.

[0031] A higher normalized value indicates higher rock-breaking efficiency in the corresponding drill bit usage scenario. The drill bit wear degree Ai is obtained from the drill bit pull-out inspection record or drill bit wear evaluation record, and then reverse-normalized to obtain the normalized drill bit wear evaluation value Ai. :

[0032] In the formula, A g,max and A g,min These represent the maximum and minimum values ​​of drill bit wear within the g-th stratum-lithological unit, respectively. A i The higher the value, the lower the degree of drill bit wear. The drill bit wear level Ai is determined according to the drill bit pull-out inspection record, wear evaluation record, or drill bit photographs, according to a preset unified grading rule of 0 to 8 levels. Wherein, level 0 indicates no obvious wear, level 1-2 indicates slight wear and the cutting teeth are basically intact, level 3-4 indicates moderate wear with some cutting teeth worn flat or locally damaged, level 5-6 indicates severe wear and many cutting teeth showing obvious wear or damage, level 7 indicates severe damage to the cutting structure and the drill bit is close to failure, and level 8 indicates severe failure of the drill bit and cannot continue to be used normally. The higher the wear level value, the more severe the degree of drill bit wear.

[0033] Based on the number n of damaged cutting teeth in the drill bit retrieval inspection record. d,i and the total number of cutting teeth included in the inspection, n c,i The proportion of damaged cutting teeth, C, is calculated according to the following formula. i :

[0034] In the formula, Let be the proportion of cutter teeth damaged in the drill bit corresponding to the i-th scenario, dimensionless. ; The number of cutting teeth that have suffered damage such as chipping, severe wear, or localized breakage; The total number of cutting teeth included in the inspection is [number] pieces.

[0035] The proportion of damaged cutting teeth is then subjected to reverse range normalization to obtain a normalized cutting tooth integrity evaluation value C. i :

[0036] In the formula, C g,max and C g,min C represents the maximum and minimum values ​​of the proportion of cutter tooth damage within the g-th stratum-lithological unit, respectively, and is dimensionless; i The larger the value, the better the integrity of the cutting teeth.

[0037] Based on daily drilling reports, logging event records, or downhole complex situation records, calculate the total number Ni of unplanned reaming, pressure buildup, stuck pipe, and severe mud packing abnormal events in the i-th valid historical drill bit usage scenario, and calculate the frequency Fi of abnormal events per unit footage according to the following formula:

[0038] In the formula, M i Let m be the remaining effective drilling footage after removing abnormal drilling records and abnormal working condition records in the i-th effective historical drill bit usage scenario; N i The total number of unplanned abnormal events such as drill bit snagging, pressure buildup, drill jamming, and severe mud buildup in this usage scenario; F i This indicates the number of abnormal events occurring per 100 m of effective drilling footage, expressed as times per 100 m.

[0039] For multiple records that occur consecutively and belong to the same abnormal operating condition, they are merged into one abnormal event based on the abnormality type, start and end times, and start and end well depths to avoid duplicate counting. When Mi>0, Fi≥0; when Mi=0, the abnormal event frequency is not calculated, and the scenario is marked as an invalid scenario.

[0040] The drilling stability evaluation value E is obtained by performing reverse range normalization on the frequency of abnormal events per unit footage. s,i :

[0041] In the formula, F g,max and F g,min These represent the maximum and minimum frequencies of anomaly events per unit advance within the g-th lithological unit, respectively, in times / 100 m; E s,i The larger the value, the better the drilling stability in the corresponding drill bit application scenario; it is dimensionless.

[0042] When the maximum and minimum values ​​of the same evaluation index are equal within the corresponding stratigraphic-lithological unit, the normalized value of the evaluation index is uniformly set to 1, or the evaluation index is not included in the weight calculation of the stratigraphic-lithological unit.

[0043] Optionally, the entropy weight method is used to determine the corresponding weight coefficients based on the dispersion of each normalized evaluation index in the effective historical drill bit usage scenario database. For the r-th normalized evaluation index Z in any evaluation index group... i,r The percentage of the indicator is calculated according to the following formula:

[0044] In the formula: Let be the feature weight of the i-th scenario in the j-th indicator, which is dimensionless. ; Z i,r The five basic evaluation indicators are: normalized effective drilling footage, normalized average mechanical drilling rate, normalized drill bit wear evaluation value, normalized cutting tooth integrity evaluation value, and drilling stability evaluation value. , , , , .

[0045] The information entropy of the r-th evaluation index is calculated using the following formula:

[0046] In the formula, The information entropy of the r-th evaluation index is dimensionless. Let be the characteristic proportion of the i-th historical drill bit usage scenario in the r-th evaluation index, which is dimensionless; n represents the number of valid historical drill bit usage scenarios in the current stratigraphic-lithological comparable group; i = 1, 2, ..., n; r = 1, 2, ..., 5.

[0047] The difference coefficient of the r-th evaluation index is calculated according to the following formula:

[0048] The coefficient of difference for the r-th evaluation indicator is dimensionless. The weight coefficient of the r-th evaluation indicator is calculated according to the following formula:

[0049] In the formula, s represents the number of evaluation indicators in the current evaluation indicator group, and Z... i,r, Let p be the value of the r-th normalized evaluation index in the i-th valid historical drill bit usage scenario; when p i,r When =0, let p i,r lnp i,r =0, and .

[0050] Normalized effective drilling footage and normalized average mechanical drilling rate together constitute the rock breaking efficiency evaluation index. The intra-group weights λ1 and λ2 corresponding to effective drilling footage and average mechanical drilling rate are calculated according to the following formulas:

[0051]

[0052] and:

[0053] Where: λ1 is the normalized weight of effective drilling footage in rock breaking efficiency evaluation, dimensionless, 0≤λ1≤1; ω1 is the entropy weight of the effective drilling footage index, dimensionless, 0≤ω1≤1; The entropy weight of the average mechanical drilling rate index ω2 is dimensionless, 0≤ω2≤1; The normalized weight of λ2 average mechanical drilling rate in rock breaking efficiency evaluation is dimensionless, 0≤λ2≤1; The rock-breaking efficiency evaluation value E of the i-th effective historical drill bit usage scenario e,i Calculate according to the following formula:

[0054] The normalized drill bit wear evaluation value and the normalized cutting tooth integrity evaluation value together constitute the wear resistance performance evaluation index. The intra-group weights μ1 and μ2 corresponding to the degree of drill bit wear and the integrity of cutting teeth are calculated according to the following formulas:

[0055]

[0056] and: The wear resistance performance evaluation value E of the i-th effective historical drill bit usage scenario w,i Calculate according to the following formula:

[0057] In the formula: The entropy weight corresponding to the drill bit wear level index is dimensionless. The entropy weight corresponding to the integrity index of the cutting teeth is dimensionless. The wear grade represents the local weight in the wear resistance evaluation of the drill bit, and is dimensionless. The dimensionless value represents the local weight of cutting tooth integrity in the evaluation of wear resistance.

[0058] The weighting coefficients corresponding to the rock-breaking efficiency evaluation value, wear resistance evaluation value, and drilling stability evaluation value are obtained by combining the entropy weights of the five basic evaluation indicators, where: , , and The basic evaluation value S of the i-th valid historical drill bit usage scenario i Calculate according to the following formula:

[0059] After substituting and expanding the evaluation values ​​and corresponding weights of each dimension, the basic evaluation value S is... i Equivalent to the entropy-weighted sum of the five basic evaluation indicators:

[0060] In the formula: S i The evaluation value of the drill bit usage effect in the i-th historical drill bit usage scenario, which is dimensionless; E e,i Rock-breaking efficiency evaluation value, dimensionless; E w,iThis is a dimensionless value for evaluating wear resistance. E s,i This is a dimensionless value used to evaluate drilling stability. α represents the overall weight of the rock-breaking efficiency dimension; β represents the overall weight of the wear resistance dimension; γ is the overall weight of the drilling stability dimension; ω1 to ω5 are the entropy weights of the five basic evaluation indicators.

[0061] The basic evaluation value S of the drill bit usage scenario i The requirement is 0≤Si≤1. The larger the value, the better the overall performance of the corresponding PDC drill bit.

[0062] When the maximum and minimum values ​​of the same evaluation index are equal within the g-th stratigraphic-lithological unit, it indicates that the evaluation index cannot distinguish different drill bit usage scenarios within that stratigraphic-lithological unit. The normalized value of this evaluation index is then uniformly set to 1, and its entropy weight calculation result is 0. When the sum of the normalized values ​​of a certain basic evaluation index is 0, the index weight of that index is uniformly set to 1 / ng. When the sum of the difference coefficients of the five basic evaluation indicators is 0, the weights of the five basic evaluation indicators are all set to 1 / 5. When the number of effective historical drill bit usage scenarios in the g-th stratigraphic-lithological unit is less than 2, priority is given to supplementing effective historical drill bit usage scenarios of the same stratigraphic and lithological type in the same block or adjacent blocks. If, after supplementation, there are still fewer than 2 scenarios, entropy weight evaluation and optimal structure are not performed on that stratigraphic-lithological unit.

[0063] Considering the different proportions of abnormal operating condition records in different historical drill bit usage scenarios, the basic evaluation value S is... i With effective sample weights q i Multiply by each product to obtain the final evaluation value Ri for the i-th historical drill bit usage scenario:

[0064] In the formula: Ri is the final evaluation value, representing the overall performance of the corresponding PDC drill bit structure in this stratum-lithology scenario, and is dimensionless.

[0065] Optionally, establishing the relationship between rock drillability parameters and PDC drill bit structural parameters based on the optimal stratigraphic-lithological PDC drill bit structure database includes: treating each stratigraphic-lithological unit in the optimal stratigraphic-lithological PDC drill bit structure database as a modeling sample, and summarizing all modeling samples corresponding to different stratigraphic levels and different lithologies to uniformly establish the relationship between rock drillability parameters and PDC drill bit structural parameters; independent relationships are not established for each stratigraphic level. Assume there are G modeling samples in the optimal stratigraphic-lithological PDC drill bit structure database, and the rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient corresponding to the g-th modeling sample constitute a rock drillability parameter vector:

[0066] In the formula: X g K represents the rock drill resistance parameter vector for the g-th stratigraphic-lithological unit; d,g σ represents the rock drillability grade of the g-th stratum-lithological unit; c,g Uniaxial compressive strength, MPa; φ g H is the internal friction angle, in °; g Rock hardness (a higher normalized indentation hardness value indicates higher rock hardness), dimensionless; K p,g is the plasticity coefficient, a dimensionless quantity; g is the modeling sample number, also a dimensionless quantity.

[0067] The optimal cutting tooth size, optimal cutting tooth type, optimal number of blades, optimal crown features, and optimal gauge protection level corresponding to the g-th stratum-lithological unit are used to construct the PDC drill bit structural parameter vector:

[0068] In the formula, Dc,g is the historical best cutting tooth size in mm; Tc,g is the historical best cutting tooth type code; Nb,g is the historical best number of blades; Pc,g is the historical best crown feature code; and Gg is the historical best diameter preservation grade code.

[0069] The rock drill resistance parameters in each modeling sample are standardized. The standardized value of the m-th rock drill resistance parameter in the g-th stratigraphic-lithological unit is calculated according to the following formula:

[0070] In the formula, x g,m This refers to the m-th rock drill resistance parameter of the g-th stratigraphic-lithological unit. and s m Let z be the mean and standard deviation of the m-th rock drill resistance parameter in all modeling samples. g,m This corresponds to the dimensionless standardized value; The correlation between various standardized rock drill resistance parameters and cutting tooth size, cutting tooth type coding value, number of blades, crown feature coding value and gauge grade coding value were analyzed respectively. Based on the model prediction error, the set of input parameters corresponding to various PDC drill bit structural parameters was selected from the rock drill resistance parameters. For the r-th PDC drill bit structural parameter, the relationship between the standardized rock drill resistance parameter and the continuously predicted values ​​of the PDC drill bit structural parameter is established using all modeling samples according to the following formula:

[0071] In the formula, Let b be the continuously predicted value of the r-th PDC drill bit structural parameter corresponding to the g-th modeling sample, and Mr be the set of rock anti-drilling characteristic parameters obtained by screening the r-th PDC drill bit structural parameter. r,0 b is the intercept. r,m These are the coefficients of the corresponding relation. The intercept and relation coefficients are determined by multiple linear regression fitting from the modeling samples in the stratigraphic-lithological optimal PDC drill bit structure database. Establish the relationships between cutting tooth size, cutting tooth type, number of blades, crown characteristics, and diameter preservation grade.

[0072] Optionally, the relationship between the standardized rock drill resistance parameters and the PDC drill bit structural parameters includes the following five standardized rock parameters: The dimensions of the cutting teeth are as follows:

[0073] In the formula: , representing the standardized values ​​of rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient, respectively, dimensionless; b D,0 : Regression intercept, dimensionless; b D,1 -b D,4 The regression coefficients are obtained by fitting the historical best sample using multiple linear regression and are dimensionless.

[0074] After obtaining the calculated values, they are then mapped to a standard size set: The mapping relationship of cutting tooth dimensions is as follows:

[0075] Relationship between cutting tooth types:

[0076] Then map the calculated values ​​to the cutting tooth type category:

[0077] Among them, the cutting tooth type code 1 is planar tooth, 2 is composite tooth, and 3 is irregular tooth.

[0078] Formula for the number of blades:

[0079] Then map the calculated values ​​to the number of blades:

[0080] Coronal characteristic relationship:

[0081] Then map the calculated values ​​to crown features:

[0082] Among them, the crown feature codes are 1 for flat crown, 2 for short crown, 3 for medium crown, and 4 for long crown.

[0083] Relationship between diameter protection grades:

[0084] Then map the calculated values ​​to diameter preservation levels:

[0085] Among them, the diameter protection grade code is 1 for ordinary diameter protection, 2 for reinforced diameter protection, and 3 for super-strong diameter protection.

[0086] Optionally, determining the structural parameters of the PDC drill bit used in the subsequent well section of the target well or the next drilling run based on the rock drill resistance characteristics parameters of the subsequent well section of the target well and the established relationship between the PDC drill bit structural parameters includes: during the drilling of the target well, obtaining or updating the stratigraphy, lithology, rock drillability grade, uniaxial compressive strength, internal friction angle, hardness and plasticity coefficient of the subsequent well section of the target well based on logging-while-drilling data, logging data, geological stratification data, formation correlation results and rock test data of adjacent wells in the same block or adjacent blocks.

[0087] The subsequent well section of the target well refers to the predetermined well section beyond the current bottom depth that has not yet been drilled and requires determination of PDC bit structure parameters. This includes the well section between the current bottom depth and the predicted formation interface, the next designed drilling section, or the next planned drilling section. The determination while drilling (DWD) updates the required PDC bit structure parameters for the subsequent well section or the next drilling run based on formation and rock resistance information obtained or updated during drilling. It does not represent a real-time change to the PDC bit structure currently in use downhole.

[0088] When the subsequent well sections of the target well have laboratory test results of core samples, cuttings, or other rock samples from this well, the drill resistance parameters are input into the established standardized rock drill resistance parameters and the PDC drill bit structure parameters, and the optimal geometric structure is output according to the mapping relationship to guide the drilling process.

[0089] Optionally, the determination system includes a historical best database intelligent analysis and screening module, a standardized drill resistance characteristic parameter and drill bit geometry relationship intelligent analysis module, and a target well drilling determination module. The historical best database intelligent analysis and screening module is used to screen and determine the optimal PDC drill bit structure parameters corresponding to each stratigraphic-lithological unit based on geological interpretation data, rock test data, drilling condition data, PDC drill bit structure data, and drill bit usage effect data of historical wells in the same or adjacent blocks, forming a stratigraphic-lithological unit optimal PDC drill bit structure database.

[0090] The intelligent analysis module for the relationship between standardized anti-drilling characteristic parameters and drill bit geometry includes a standardization and parameter screening unit, a regression modeling unit, and a discrete mapping unit. The standardization and parameter screening unit is used to standardize rock drillability grade, uniaxial compressive strength, internal friction angle, hardness and plasticity coefficient and other rock drillability parameters, and to screen the input parameter set corresponding to each PDC drill bit structural parameter; the regression modeling unit is used to establish the regression relationship between the standardized rock drillability parameters and the continuous predicted values ​​of each PDC drill bit structural parameter. The discrete mapping unit is used to map the continuous predicted values ​​to a preset set of standard structural parameters to obtain PDC drill bit structural parameters that meet the engineering selection requirements. The target well drilling determination module includes a parameter acquisition unit, a standardization processing unit, a prediction calculation unit, and a result output unit. The parameter acquisition unit is used to acquire the rock drill resistance characteristics parameters of the current drilling layer of the target well. The standardization processing unit is used to process the rock drill resistance characteristics parameters of the target well according to the standardization rules determined by the standardization and parameter screening unit. The prediction calculation unit is used to input the standardized rock drill resistance characteristics parameters of the target well into the regression formula and generate a definite result after mapping by the discrete mapping unit. The result output unit is used to output the definite PDC drill bit structure parameters. Attached Figure Description

[0091] Figure 1 The above is a flowchart of the method and system for determining the structural parameters of PDC drill bits based on rock drill resistance characteristics as described in this invention. Figure 2 This is a diagram illustrating the overall steps of historical optimization for reservoir construction and determination of target well parameters in a specific embodiment of the present invention. Figure 3 This invention provides a flowchart for constructing a historical drill bit usage scenario in a specific implementation. Figure 4 This invention provides a flowchart for evaluating the performance of drill bits and screening historical preferred structures in a specific embodiment. Figure 5 This is a flowchart illustrating the establishment of the relationship between rock drill resistance parameters and PDC drill bit structural parameters, as well as the determination of target well structural parameters, in a specific embodiment of the present invention. Figure 6 This is a functional block diagram of a PDC drill bit structural parameter determination system in a specific embodiment of the present invention. Detailed Implementation

[0092] The following are several specific embodiments for verification implementation based on the method described in this invention.

[0093] Example 1: This embodiment selects existing well data from wells J1, J2, J3, J4, J5, and J6 in the Songliao Basin as historical data sources. Drill bit usage data is derived from drill bit log sheets and daily drilling reports; geological interpretation data is derived from geological stratification results tables and logging lithology interpretation tables; rock drill resistance parameters are derived from core and cuttings test reports; drilling condition parameters are derived from the surface engineering parameter acquisition system; PDC drill bit structure parameters are derived from the drill bit structure parameter table; and drill bit usage performance data is derived from drill bit pull-out inspection records and downhole complex condition records. The main extracted fields are shown in the table below:

[0094] To illustrate the scenario segmentation method for historical drill bit usage records, the usage record of drill bit PDC-J1-03 in well J1 is used as an example. This drill bit entered the well at a depth of 2200.0 m and withdrew at a depth of 2800.0 m, corresponding to a nominal well section length of 600.0 m. Geological stratigraphic data, lithological interpretation data, and the drill bit usage record are unified to the well depth baseline, and the usage record is segmented based on formation and lithological interfaces. Geological stratigraphic data shows that 2500.0 m is the boundary between Q4 and Q3 sections. Lithological interpretation data shows that the well section from 2200.0 to 2500.0 m is mainly sandstone, while the well section from 2500.0 to 2800.0 m is mainly mudstone. Therefore, using 2500.0 m as the stratigraphic-lithological dividing line, the PDC-J1-03 drill bit usage record is divided into the following two sub-usage scenarios: [2200.0, 2500.0) corresponds to the Q4 sandstone sub-scenario; [2500.0, 2800.0) corresponds to the Q3 mudstone sub-scenario. Each sub-scenario is associated with its geological engineering parameters, drilling condition parameters, drill bit structural parameters, and drill bit usage effect parameters.

[0095] Data cleaning was performed on historical drill bit usage scenarios. In Well J1, two consecutive records at 2265.2 m showed zero depth increments, and the operation was in a cyclic state; therefore, these records were marked as abnormal drilling records. The 2378.4–2381.1 m section was recorded as pressure buildup in the daily drilling report, and was therefore marked as an abnormal operating condition record with an abnormal feed rate of 2.7 m. The 2440.0–2443.5 m section was recorded as severely mud-packed with an abnormal feed rate of 3.5 m. The 2228.6–2233.4 m section showed persistently excessive drilling pressure exceeding the normal drilling range and exhibiting significant fluctuations; this section was marked as an abnormal drilling pressure section, with a corresponding abnormal feed rate of 4.8 m. The 2412.0–2416.5 m section showed a persistently abnormally high torque, accompanied by significant stick-slip vibration; this section was marked as a torque-stick-slip abnormal section, with a corresponding abnormal feed rate of 4.5 m. The 2471.2–2475.7 m section... The drill string vibration amplitude in section m continuously exceeded the preset threshold under normal drilling conditions, and this section was marked as an abnormal vibration section, corresponding to an abnormal drilling footage of 4.5 m. This was recorded as an abnormal operating condition. The drill bit usage scenario was a total new drilling footage Li = 300 m. After removing the abnormal drilling records and 20 m of abnormal operating condition records, the remaining effective drilling footage L... eff,i = 280 m, normal drilling time is 25 h, its effective sample weight q i = 0.93, average mechanical drilling speed v1 = 11.2 m / h; the drill bit wear determination in this embodiment is shown in the table below:

[0096] Inspection after the drill bit was retrieved revealed that most cutting teeth remained intact, some cutting teeth showed moderate wear, and the outer teeth showed localized wear. There was no large-scale tooth loss or severe damage to the drill bit body, and the drill bit still had a certain degree of continued usability. That is, A1=3; a total of 30 cutting teeth of this PDC drill bit were inspected, of which 1 tooth was chipped, 1 tooth was severely worn, and 1 tooth was partially broken. Therefore, the number of damaged cutting teeth was 3, and the cutting tooth damage ratio was C1=0.1.

[0097] Six valid historical drill bit usage scenarios were selected from historical wells such as J1, J2, and J3, all of which involve the Q4 section of the formation and sandstone lithology. The drill bit diameter used in each scenario was 215.9 mm, corresponding to a wellbore size of 216 mm. During normal drilling, the drill pressure was 80–125 kN, the rotation speed was 90–145 r / min, the torque was 8–16 kN·m, the displacement was 29–34 L / s, and the riser pressure was 15–19 MPa. The six scenarios are derived from different wells or different drill bit runs, and are grouped into structural combinations A, B, and C according to the drill bit structural parameters. Each structural combination corresponds to two historical usage scenarios. The historical usage scenarios of the drill bits are shown in the table below:

[0098] Among them, combination A consists of 16 mm cutting teeth, compound teeth, 6 blades, a middle crown, and reinforced diameter maintenance; combination B consists of 19 mm cutting teeth, flat teeth, 5 blades, a short crown, and ordinary diameter maintenance; combination C consists of 13 mm cutting teeth, compound teeth, 7 blades, a middle crown, and super-strong diameter maintenance.

[0099] The effective drilling footage and average mechanical drilling rate were forward normalized, while the drill bit wear, cutting tooth damage ratio, and frequency of abnormal events per unit footage were inversely normalized, as shown in the table below:

[0100] The weights of the five basic indicators were calculated using the entropy weight method: When p ij When =0, p is defined ij ln p ij =0. The calculation results are shown in the table below:

[0101] Therefore, the weights of the five basic evaluation indicators are: ω1 = 0.2454, ω2 = 0.3147, ω3 = 0.1446, ω4 = 0.1610, ω5 = 0.1342 If q i Let be the effective sample weights for the i-th historical scene, then the final evaluation value is:

[0102] When scenarios 1 and 2 belong to structural combination A, scenarios 3 and 4 belong to structural combination B, and scenarios 5 and 6 belong to structural combination C, the average evaluation values ​​of each structural combination are 0.5936, 0.6097, and 0.0962, respectively. Since structural combination B has the highest average evaluation value, combination B is determined to be the optimal PDC drill bit structural combination for historical drill bit usage scenarios where all strata are Q4 and the lithology is sandstone, namely 19 mm cutting teeth, flat teeth, 5 blades, short crown, and ordinary gauge protection.

[0103] The optimal structure of 12 stratigraphic-lithological units in the Songliao Basin block was determined, and the resulting modeling samples are shown in the table below:

[0104] Among them, the cutting tooth type codes 1, 2, and 3 correspond to planar teeth, composite teeth, and irregular teeth, respectively; the crown feature codes 1, 2, 3, and 4 correspond to shallow crowns, short crowns, medium crowns, and long crowns, respectively; and the diameter preservation level codes 1, 2, and 3 correspond to ordinary diameter preservation, reinforced diameter preservation, and super-strong diameter preservation, respectively.

[0105] The rock drillability parameters in the table are derived from laboratory test reports of core samples or cuttings from historical wells corresponding to the strata and lithology. Specifically, the rock drillability grade value Kd is obtained through laboratory micro-drilling tests using a rock drillability tester. Drilling time is measured under specified drilling pressure, rotation speed, and drilling depth conditions, and the value is converted to a drillability grade value according to a unified drillability grading method. Uniaxial compressive strength σc is obtained through uniaxial compression tests, measured in MPa. The internal friction angle φ is obtained through triaxial compression tests under different confining pressures, determined by fitting the Mohr-Coulomb strength envelope to the failure strength under each confining pressure level, measured in degrees. The rock hardness parameter H and plasticity coefficient Kp are obtained through joint rock hardness and plasticity coefficient determination tests. A cylindrical indenter is used to press into the rock sample, and the load-indentation depth curve is recorded to calculate the rock hardness and plasticity coefficient. H is the rock hardness grade value recorded in the historical rock test reports according to a unified standard (in this embodiment, H ranges from 2.4 to 4.8, corresponding to an original rock indentation hardness Hs of 240 to 480 MPa). The value is dimensionless; Kp is the plasticity coefficient, which is also dimensionless. Rock hardness and plasticity coefficient can be obtained from the same cylindrical indenter indentation test.

[0106] Based on 12 historical best samples, Z-score standardization was performed on rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient. Ordinary least squares method was then used to fit the multiple linear regression relationship between the rock drillability parameters and the PDC drill bit structural parameters. The intercepts, regression coefficients, and coefficients of determination for each model are shown in the table below.

[0107]

[0108] The fitting results using multiple linear regression are shown below:

[0109] When target well X1 reached 3100 m, based on drilling logging, formation correlation, cuttings analysis, and experimental results from adjacent wells, the 3100–3220 m interval was predicted to be Q1 sandstone, with parameters Kd = 5.6, σc = 102 MPa, φ = 32°, H = 3.5, and Kp = 2.2. After standardization: ZKd = 0.1726, Zσc = 0.2106, Zφ = 0.3164, ZH = 0.2305, ZKp = Substituting 0.3533 into the fitting formula yields... c = 14.4136 c = 2.2148, Ñb = 6.7528 c=3.0207 = 2.3842 Based on the mapping relationship, we finally obtain Dc=13mm, Tc=2, Nb=7, Pc=3, G=2. The determined result is 13mm cutting teeth, compound teeth, 7 blades, middle crown, and reinforced diameter maintenance.

[0110] Example 2 like Figure 6 As shown in the diagram, this embodiment provides a functional block diagram of a PDC drill bit structure parameter determination system based on rock drill resistance characteristics. The PDC drill bit structure parameter determination system 300 is installed in an electronic device, which includes at least a processor, a memory, a data input interface, and a result output interface. The memory stores a computer program, which, when executed by the processor, performs tasks such as filtering historical drill bit usage scenarios, establishing a mapping relationship between rock drill resistance characteristics and PDC drill bit structure parameters, and determining the PDC drill bit structure parameters for the target well section.

[0111] Based on its implemented functions, the PDC drill bit structure parameter determination system 300 includes a historical preferred database analysis and screening module 301, a rock drill resistance characteristic parameter and PDC drill bit structure parameter mapping relationship establishment module 302, and a target well section PDC drill bit structure parameter determination module 303. A module, also referred to as a unit, is a series of computer program segments that can be executed by the processor of an electronic device to complete corresponding data processing functions, and these computer program segments are stored in the memory.

[0112] The historical preferred database analysis and filtering module 301 includes a data acquisition and scenario segmentation unit 3011, a data cleaning and weight calculation unit 3012, and a historical preferred structure filtering unit 3013.

[0113] The data acquisition and scene segmentation unit 3011 is used to acquire historical well geological stratification data, lithological interpretation data, rock drill resistance parameters, drilling condition data, PDC drill bit structural parameters, drill bit usage records, and drill bit pull-out inspection data, and associate the multi-source data according to well number, drill bit number, and well depth.

[0114] The data acquisition and scenario segmentation unit 3011 determines the nominal usage well section of the drill bit based on the drill bit's entry and exit depths, and segments a single drill bit usage record into multiple historical drill bit usage scenarios based on the formation and lithological interfaces within the nominal usage well section. A continuous well depth interval defined by the same formation and lithology constitutes a historical drill bit usage scenario. Each historical drill bit usage scenario is associated with its formation, lithology, wellbore size, rock drill resistance parameters, drilling condition parameters, drill bit structural parameters, and drill bit usage effect parameters.

[0115] The data cleaning and weight calculation unit 3012 is used to identify one or more abnormal drilling records or abnormal working condition records in historical drill bit usage scenarios, including tripping in and out of the drill bit, stopping the drill bit, circulating the drill bit, reaming the drill bit, enlarging the drill bit, repeated drilling, well depth increment less than or equal to zero, pressure buildup, stuck drill bit, abnormal drilling pressure, abnormal torque, severe mud bagging, and missing data.

[0116] The historical preferred structure screening unit 3013 is used to group effective historical drill bit usage scenarios according to stratigraphy and lithology, and compare different PDC drill bit structure combinations in the same group of historical drill bit usage scenarios with the same or similar wellbore size and normal drilling conditions within a preset comparable range, based on the drill bit usage effect evaluation value and effective sample weight.

[0117] The historical preferred structure screening unit 3013 determines the PDC drill bit structure combination that meets the preset screening conditions as the historical preferred PDC drill bit structure combination of the corresponding stratigraphic-lithological unit, and establishes a stratigraphic-lithological historical preferred PDC drill bit structure database.

[0118] The preferred stratigraphic-lithological history PDC drill bit structure database stores at least the stratigraphic position, lithology, rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, plasticity coefficient, cutting tooth size, cutting tooth type, number of blades, crown features, and gauge protection grade.

[0119] The module 302 for establishing the mapping relationship between rock anti-drilling characteristic parameters and PDC drill bit structural parameters includes a standardization processing unit 3021, an input parameter determination unit 3022, a regression modeling unit 3023, and a mapping threshold determination unit 3024.

[0120] The standardization processing unit 3021 is used to receive the historical preferred sample set output by the historical preferred database analysis and screening module 301.

[0121] The input parameter determination unit 3022 is used to determine the set of regression input parameters corresponding to the cutting tooth size, cutting tooth type, number of blades, crown features and diameter preservation grade according to the correlation between the structural parameters of each PDC drill bit and the rock anti-drilling characteristic parameters, the historical sample fitting results and the engineering mechanism.

[0122] The regression modeling unit 3023 is used to take the standardized rock drill resistance parameters as input variables, and the continuous predicted values ​​of cutting tooth size, cutting tooth type, number of blades, crown features and gauge grade as output variables. The corresponding regression intercept and regression coefficient are fitted by the multiple linear regression method to establish the regression relationship between the rock drill resistance parameters and various PDC drill bit structural parameters.

[0123] The mapping threshold determination unit 3024 is used to obtain a preset set of standard structural parameters of PDC drill bit, and determine the mapping threshold between the continuous predicted value and the standard structural parameter based on the arithmetic midpoint of adjacent standard structural parameters.

[0124] The target well section PDC drill bit structure parameter determination module 303 includes a parameter acquisition unit 3031, a standardization processing unit 3032, a prediction calculation unit 3033, a discrete mapping unit 3034, and a result output unit 3035.

[0125] The parameter acquisition unit 3031 is used to acquire the well number, well depth range, stratigraphy, lithology, wellbore size of the target well section, as well as rock drillability grade, uniaxial compressive strength, internal friction angle, hardness and plasticity coefficient.

[0126] The rock drill resistance characteristics parameters of the target well section can be derived from the rock test results of the target well, well logging interpretation results, well logging interpretation results, formation comparison results of adjacent wells, or parameters obtained as the target well data is updated.

[0127] The standardization processing unit 3032 is used to call the historical preferred sample mean and sample standard deviation stored in the mapping relationship establishment module 302 to perform Z-score standardization processing on the rock drill resistance characteristic parameters of the target well section. The sample mean and sample standard deviation are not recalculated for the target well section.

[0128] The prediction calculation unit 3033 is used to substitute the standardized rock anti-drilling characteristic parameters of the target well section into the regression formula to calculate the continuous predicted values ​​of the cutting tooth size, cutting tooth type code, number of blades, crown code, and diameter preservation code corresponding to the target well section.

[0129] The discrete mapping unit 3034 is used to call the mapping threshold determined by the mapping relationship establishment module 302 to convert each continuous predicted value into the corresponding standard cutting tooth size, cutting tooth type, integer number of blades, crown feature, and diameter preservation level. When a continuous predicted value is between two adjacent standard structural parameters, it is converted into the standard structural parameter that is closer in distance; when a continuous predicted value exceeds the allowable range of the preset standard structural parameter set, it is restricted to the upper or lower limit of the corresponding standard structural parameter set, and an out-of-range mark is generated.

[0130] The result output unit 3035 is used to output the determination results of the PDC drill bit structure parameters corresponding to the target well section. The determination results include at least the cutting tooth size, cutting tooth type, number of blades, crown characteristics and diameter protection level, and may also include the corresponding continuous prediction values, the stratigraphy and lithology of the target well section, the applicable range of the model, and out-of-range verification prompts.

[0131] In this embodiment, historical well geological engineering data, rock drill resistance parameters, drilling condition parameters, PDC drill bit structure parameters, and drill bit usage effect parameters are input into the historical preferred database analysis and filtering module 301. The historical preferred database analysis and filtering module 301 sequentially completes scene segmentation, data cleaning, effective sample weight calculation, usage effect evaluation, and historical preferred structure filtering, and outputs the historical preferred sample set.

[0132] The historical preferred sample set inputs the rock drill resistance characteristic parameters and the PDC drill bit structure parameter mapping relationship establishment module 302; the mapping relationship establishment module 302 sequentially completes parameter standardization, input parameter determination, multiple linear regression modeling and mapping threshold determination, and outputs the model parameter set.

[0133] The rock anti-drilling characteristic parameters of the target well section and the model parameter set are input into the target well section PDC drill bit structure parameter determination module 303; the target well section PDC drill bit structure parameter determination module 303 sequentially completes the standardization, continuous prediction, discrete mapping and result output of the target well section parameters to obtain the PDC drill bit structure parameter determination result corresponding to the target well section.

[0134] When the parameters of the formation, lithology, or rock drill resistance of the target well section are updated, the parameter acquisition unit 3031 acquires the updated parameters of the target well section, the standardization processing unit 3032, the prediction calculation unit 3033, and the discrete mapping unit 3034 re-execute the calculation according to the updated parameters, and the result output unit 3035 outputs the updated PDC drill bit structure parameter determination result.

Claims

1. A method for determining the structural parameters of a PDC drill bit based on the rock's anti-drilling properties, characterized in that, include: Obtain geological interpretation data, rock test data, drilling condition data, PDC drill bit structure data, and drill bit performance data of existing wells in the same or adjacent blocks; Based on the PDC drill bit number, entry time, pull-out time, entry depth and pull-out depth, determine the drill bit usage scenario corresponding to a single PDC drill bit, and assign the drill bit usage scenario according to the formation and lithology; By associating the rock drillability grade, uniaxial compressive strength, internal friction angle, hardness and plasticity coefficient corresponding to each drill bit usage scenario with the cutting tooth size, cutting tooth type, number of blades, crown features, gauge protection grade and drill bit usage effect data of the corresponding PDC drill bit, a historical drill bit usage scenario database is established. Abnormal drilling records, abnormal working condition records, and invalid usage scenarios are removed from the historical drill bit usage scenario database to determine the valid historical drill bit usage scenarios. Based on the remaining normal drilling footage after removing the abnormal drilling records and abnormal working condition records, the effective sample weight of each valid historical drill bit usage scenario is determined. The drill bit usage scenarios are assigned and segmented according to stratigraphic and lithological interfaces to obtain one or more stratigraphic-lithological sub-usage scenarios. Based on the drill bit performance evaluation values ​​and effective sample weights corresponding to each PDC drill bit structure combination under the same stratigraphic and lithological conditions, the optimal PDC drill bit structure combination for each stratigraphic and lithological condition is determined. The stratigraphic, lithological, and rock drill resistance parameters, along with the corresponding optimal PDC drill bit structure combination, are associated and stored to establish a stratigraphic-lithological optimal PDC drill bit structure database. The drill bit performance evaluation value is determined by weighting the rock breaking efficiency evaluation value, wear resistance evaluation value, and drilling stability evaluation value using the entropy weight method. Each stratum-lithology unit in the optimal PDC drill bit structure database is used as a modeling sample. Rock drill resistance parameters are standardized, and the input parameter set corresponding to each PDC drill bit structure parameter is selected. A regression relationship is established between standardized rock drill resistance parameters and cutting tooth size, cutting tooth type, number of blades, crown features and gauge protection level. A mapping relationship between continuous predicted values ​​and preset standard structure parameter set is also established. During the drilling of the target well, the rock drill resistance parameters of the subsequent drilling sections of the target well are acquired or updated. The rock drill resistance parameters of the subsequent drilling sections of the target well are standardized using the standardized parameters saved by the modeling sample. The regression relationship is input to obtain the continuous predicted values ​​of the structural parameters. After mapping by the mapping relationship, the PDC drill bit structural parameter determination results are output. When the updated layer, lithology or rock drill resistance parameters are acquired, the standardization process is repeated and the determination results are updated.

2. The method according to claim 1, characterized in that, The acquisition of geological interpretation data, rock test data, drilling condition data, PDC drill bit structure data, and drill bit performance data from existing wells in the same or adjacent blocks includes: Obtain the drill bit number, drill bit type, depth of entry, depth of exit, and drilling process records from the drill bit log sheet and drilling daily report; Obtain stratigraphic boundaries, stratigraphic names, lithological boundaries, and lithological names from well logging interpretation results, well logging lithological profiles, or geological stratification data; Obtain rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient from laboratory rock mechanics tests of cores, cuttings, or rock samples from existing wells in the same or adjacent blocks. Obtain the drill bit diameter, cutting tooth size, cutting tooth type, number of blades, crown features, and gauge protection rating from the drill bit usage record, drill bit instruction manual, or drill bit structural parameter table. Obtain information on individual drill bit footage, average mechanical drilling speed, drill bit wear, cutting tooth damage, and downhole complexities from drill bit retrieval inspection records, daily drilling reports, logging records, or downhole complexity records. When existing wells lack rock drill resistance parameters of the same well, same stratigraphy, and same lithology, rock experimental parameters of adjacent wells of the same stratigraphy and lithology are selected as the rock drill resistance parameters of the corresponding stratigraphy-lithology unit, according to the order of priority for the same block over adjacent blocks.

3. The method according to claim 1, characterized in that, The process of removing abnormal drilling records, abnormal working condition records, and invalid usage scenarios from the historical drill bit usage scenario database and determining the weight of valid samples includes: When the well depth increment between adjacent sampling records is less than or equal to 0, or when the operation status record shows that the corresponding period is in the operation status of stopping drilling, tripping in and out of the hole, circulating, connecting a single joint, changing the drill bit, or other operation statuses that have not resulted in new wellbore footage, the corresponding record will be marked as an abnormal drilling record; When unplanned reaming, pressure buildup, stuck pipe, or severe mud bagging are recorded in the daily drilling report or logging event log, the records for the corresponding event duration will be marked as abnormal operating condition records; If any of the necessary data in the drill bit usage scenario is missing, such as stratigraphy, lithology, PDC drill bit structural parameters, rock drill resistance parameters, or drill bit usage performance data, the drill bit usage scenario will be determined as an invalid usage scenario. Abnormal drilling records and abnormal operating condition records are removed from the calculated data of average mechanical drilling speed, average drilling pressure, average rotational speed, average torque, average displacement, and average standpipe pressure. The number of unplanned reaming, pressure buildup, stuck pipe, and severe mud packing occurrences are retained as the basic data for drilling stability evaluation. Calculate the effective sample weights for the i-th drill bit usage scenario, where L i Let Mi be the total footage corresponding to the i-th drill bit usage scenario, and let Mi be the effective drilling footage of the i-th historical drill bit usage scenario. The effective drilling footage is obtained by accumulating the positive well depth increments in the remaining normal drilling records after further removing abnormal operating condition records such as pressure buildup, stuck pipe, abnormal drilling pressure, abnormal torque, severe mud bag, and missing data from the records that form Li. When, the i-th drill bit usage scenario is retained as a valid historical drill bit usage scenario; when When the i-th drill bit usage scenario is removed from the calculation of the drill bit usage effect evaluation value, the i-th drill bit usage scenario will be removed.

4. The method according to claim 1, characterized in that, The drill bit performance evaluation value is determined by weighting the rock breaking efficiency evaluation value, wear resistance evaluation value, and drilling stability evaluation value using the entropy weight method, including: The effective drilling footage and average mechanical drilling rate are forward normalized to obtain normalized effective drilling footage and normalized average mechanical drilling rate, which together constitute the rock breaking efficiency evaluation index; The wear degree of the drill bit and the proportion of damaged cutting teeth are reverse normalized to obtain normalized drill bit wear evaluation value and normalized cutting tooth integrity evaluation value, which together constitute the wear resistance performance evaluation index; The drilling stability evaluation value is obtained by inverse normalization based on the frequency of abnormal events per unit footage; the frequency of abnormal events per unit footage is the total number of abnormal events such as unplanned reaming, pressure buildup, stuck drill, and severe mud packing corresponding to every 100 meters of effective drilling footage. The entropy weight method is adopted to determine the weight coefficients based on the dispersion of each normalized evaluation index within the corresponding stratigraphic-lithological unit. The rock breaking efficiency evaluation value, wear resistance evaluation value, and drilling stability evaluation value are calculated separately, and then weighted and summed to obtain the drill bit performance evaluation value.

5. The method as described in claim 1, characterized in that, The construction of the historical drill bit usage scenario database includes: Each database record is defined as a single PDC drill bit usage scenario or a sub-use scenario after being divided by stratum and lithology, and a usage scenario identifier is set for each database record. When a database record is a sub-use scenario, its corresponding original single PDC drill bit usage scenario identifier is also saved. Each database record must include at least: Scene attribute fields include well number, drill bit number, drill bit type, entry time, pull-out time, entry depth, pull-out depth, usage scene identifier, and original usage scene identifier; Geological attribute fields include stratigraphic name, stratigraphic top boundary depth, stratigraphic bottom boundary depth, lithology name, lithology interface depth, and wellbore size; Rock drillability characteristics include rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient; Drilling condition fields include drilling pressure, rotational speed, torque, displacement, riser pressure, mechanical drilling speed, drilling fluid density, and drilling time; PDC drill bit structure fields include drill bit diameter, cutting tooth size, cutting tooth type, number of blades, crown features, and gauge protection rating; The drill bit performance field includes records of single drill bit footage, normal drilling time, average mechanical drilling speed, drill bit wear, cutting tooth damage, and occurrences of unplanned reaming, pressure buildup, stuck drill bit, and severe mud packing.

6. The method according to claim 1, characterized in that, The establishment of regression and mapping relationships between standardized rock drill resistance parameters and PDC drill bit structural parameters includes: The rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient in each modeling sample were Z-score normalized to obtain dimensionless normalized values. The correlations between various standardized rock drill resistance parameters and cutting tooth size, cutting tooth type coding value, number of blades, crown feature coding value, and gauge protection grade coding value were analyzed. Based on the model prediction error, the input parameter set corresponding to each PDC drill bit structural parameter was selected from the rock drill resistance parameters. For each PDC drill bit structural parameter, a multiple linear regression relationship is established between the standardized rock drill resistance parameter and the continuously predicted value of that structural parameter using all modeling samples: Establish a mapping relationship between continuous predicted values ​​and a preset set of standard structural parameters. Specifically, the continuous predicted values ​​of cutting tooth size are mapped to a set of standard sizes, the predicted values ​​of cutting tooth type coding are mapped to a set of cutting tooth type categories, the continuous predicted values ​​of blade number are rounded and limited to a preset blade number range, the predicted values ​​of crown feature coding are mapped to a set of crown feature categories, and the predicted values ​​of diameter preservation grade coding are mapped to a set of diameter preservation grades.

7. The method according to claim 1, characterized in that, The acquisition or updating of rock resistance parameters for subsequent sections of the target well during drilling includes: Based on logging-while-drilling data, well logging data, geological stratification data, and rock test data from adjacent wells in the same or adjacent blocks, obtain or update the stratigraphy, lithology, rock drillability grade, uniaxial compressive strength, internal friction angle, hardness, and plasticity coefficient of the subsequent drilling section of the target well; When the target well has the rock test parameters for the subsequent drilling section, the rock test parameters for this well shall be used; when the rock test parameters for this well are missing, the corresponding rock anti-drilling characteristic parameters shall be selected from the historical drill bit usage scenario database in the order of same stratum and same lithology, similar lithology in the same stratum, and same lithology in adjacent stratum. The standardized rock anti-drilling characteristic parameters of the subsequent drilling section of the target well are input into the regression formula to obtain continuous predicted values ​​of cutting tooth size, cutting tooth type code prediction value, cutting wing number, crown feature code prediction value, and gauge preservation level code prediction value. After mapping by the mapping relationship, the results of determining the cutting tooth size, cutting tooth type, cutting wing number, crown feature, and gauge preservation level corresponding to the subsequent drilling section or the next drilling run of the target well are output.

8. A PDC drill bit structural parameter determination system based on rock drill resistance characteristics, characterized in that, include: The historical best database analysis and filtering module is used to perform scenario segmentation, data cleaning, usage effect evaluation and historical best structure filtering on historical drill bit usage records, and output the historical best PDC drill bit structure combination corresponding to each stratum-lithological unit. A module for establishing the mapping relationship between rock drill resistance parameters and PDC drill bit structural parameters is used to execute the method described in claims 1 and 6, and to establish and store the regression expression and mapping relationship. The target well section PDC drill bit structure parameter determination module is used to execute the method as described in claims 1 and 7, output the PDC drill bit structure parameter determination result based on the rock anti-drilling characteristic parameters obtained or updated from the target well, and recalculate when the parameters are updated.

9. The system according to claim 8, characterized in that, The historical best database analysis and filtering module includes: The data acquisition and scenario segmentation unit is used to acquire multi-source data and classify and segment the drill bit usage scenarios according to stratigraphy and lithology. The data cleaning and weight calculation unit is used to identify and remove abnormal drilling records, abnormal working condition records, and invalid usage scenarios, and to calculate the weight of valid samples; The optimal structure screening unit is used to group by stratum and lithology, determine the optimal PDC drill bit structure combination based on the drill bit performance evaluation value and effective sample weight, and establish a stratum-lithology optimal PDC drill bit structure database.

10. The system according to claim 8, characterized in that, The module for establishing the mapping relationship between rock drill resistance parameters and PDC drill bit structural parameters includes: The historical sample standardization unit is used to calculate the sample mean and sample standard deviation of rock drillability grade, uniaxial compressive strength, internal friction angle, hardness and plasticity coefficient in the historical best sample, and to perform Z-score standardization on each rock drillability parameter based on the sample mean and sample standard deviation. The input variable determination unit is used to determine the input set of rock drill resistance characteristic parameters corresponding to the cutting tooth size, cutting tooth type, number of blades, crown characteristics, and diameter protection grade, respectively. The regression modeling unit is used to take the standardized rock drill resistance parameters as input variables and the continuous predicted values ​​corresponding to the cutting tooth size, cutting tooth type, number of blades, crown features and gauge grade as output variables. The regression intercept and regression coefficient are determined by the multiple linear regression method, and the regression relationship between the rock drill resistance parameters and the continuous predicted values ​​of various PDC drill bit structural parameters is established. The mapping threshold determination unit is used to obtain a set of preset PDC drill bit standard structural parameters, and to establish a discrete mapping relationship between each continuous predicted value and the standard cutting tooth size, standard cutting tooth type, integer number of blades, standard crown features and standard diameter protection level, using the arithmetic midpoint of adjacent standard structural parameters as the mapping threshold. The target well section PDC drill bit structure parameter determination module includes: The parameter acquisition unit is used to acquire the rock drillability grade, uniaxial compressive strength, internal friction angle, hardness and plasticity coefficient of the target well section. The target parameter standardization unit is used to call the sample mean and sample standard deviation determined by the historical sample standardization unit to perform Z-score standardization on the rock drill resistance characteristics parameters of the target well section. The continuous prediction unit is used to input the standardized rock anti-drilling characteristic parameters of the target well section into the regression formula to obtain continuous prediction values ​​corresponding to the cutting tooth size, cutting tooth type, number of blades, crown characteristics and diameter protection level; The discrete mapping unit is used to call the mapping threshold to convert each continuous predicted value into the corresponding standard cutting tooth size, standard cutting tooth type, integer number of blades, standard crown feature and standard diameter preservation level; The result output unit is used to output the determination results of the PDC drill bit structure parameters of the target well section. When the rock anti-drilling characteristic parameters of the target well section are updated, the target parameter standardization unit, the continuous prediction unit and the discrete mapping unit recalculate according to the updated rock anti-drilling characteristic parameters, and the result output unit outputs the updated PDC drill bit structure parameter determination results.

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