Method for recognizing and positioning stabbing leakage of drilling tool through while-drilling microchip device

Abstract

The invention discloses a method for recognizing and positioning stabbing leakage of a drilling tool through a while-drilling microchip device. The method comprises the steps that underground pressure data are collected through a microchip capsule circulating while drilling, and time-depth conversion is carried out; establishing a shaft theoretical pressure model under a normal working condition as a reference; performing multi-dimensional comparison on actually measured depth-pressure data and the theoretical model to identify abnormal features of pressure, pressure consumption and pressure consumption gradient; and according to the abnormal feature fusion, determining the accurate position of the puncture leakage, and further performing inversion calculation on the puncture leakage rate to evaluate the severity of the puncture leakage rate. Compared with a traditional method which depends on experience judgment or ground indirect parameters, the method has the advantages that continuous, real-time and automatic monitoring and high-precision positioning of the drilling leakage of the drilling tool are realized through in-situ and continuous underground pressure actual measurement data in combination with analysis of a fluid mechanics model, the timeliness and reliability of detection are remarkably improved, and the method is suitable for popularization and application. And powerful technical support is provided for guaranteeing drilling safety and avoiding major accidents.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of drilling engineering, and in particular to a method for identifying and locating drill tool leakage by means of a drilling microchip device. BACKGROUND

[0002] Petroleum and natural gas drilling engineering is an important part of energy development. With the increasing demand for oil and gas resources, the scale and depth of drilling operations are also increasing. During drilling, the changes in downhole pressure are crucial to ensuring drilling safety and improving operational efficiency. Real-time monitoring of downhole pressure changes can help identify potential safety hazards, such as drill tool leakage, and prevent serious accidents and economic losses. Effective pressure monitoring technology can help optimize drilling parameters, improve drilling efficiency, and promote the sustainable development of the oil and natural gas industry.

[0003] Currently, in the field of petroleum and natural gas drilling engineering, the judgment of drill tool leakage is mainly dependent on experience and conventional ground monitoring indicators. The driller usually relies on his own experience to determine whether leakage has occurred by observing sudden drops in pump pressure, abnormal back pressure, or changes in mud tank liquid level. Common methods such as gas logging, high-viscosity mud, particle plugging, drill pipe displacement, and "brown rope knot" plugging are also used to deal with drill tool leakage. The tracer gas method improves positioning accuracy by monitoring circulation return time.

[0004] However, these existing techniques have many drawbacks. Relying on the driller's experience for judgment can lead to missed reports, misjudgments, and significant delays. Common treatment methods generally have low positioning accuracy, are time-consuming and labor-intensive, and have high operational risks. Although the tracer gas method can improve positioning accuracy, it requires additional gas injection and analysis equipment, which is expensive. Therefore, there is an urgent need for a new technology that can achieve continuous, real-time, and automated leakage detection to improve detection timeliness and reliability. SUMMARY

[0005] The present application aims to overcome the above technical deficiencies and provides a method for identifying and locating drill tool leakage by means of a drilling microchip device.

[0006] To achieve the above technical objectives, the present application adopts the following technical solutions:

[0007] The present application provides a method for identifying and locating drill tool leakage by means of a drilling microchip device, comprising:

[0008] S1, data acquisition and conversion: collecting downhole pressure data by putting microchip capsules in the process of drilling operation, the microchip capsule is a device with a built-in pressure sensor and an outer diameter smaller than the diameter of the drill bit water eye, which can circulate completely in the drill string and annulus with drilling fluid; the microchip capsule continuously collects time series of downhole pressure data, and converts the time series data into depth-pressure data by time-depth conversion method;

[0009] S2, normal pressure model construction: based on drilling operation parameters, a theoretical pressure distribution model of the wellbore under the condition of no leakage is established as a judgment criterion;

[0010] S3, abnormality comparison and analysis: comparing the depth-pressure data measured by the capsule with the theoretical pressure distribution model to identify the pressure abnormality characteristics;

[0011] S4, leakage positioning: determining the well depth position of the drilling tool leakage according to the pressure abnormality characteristics.

[0012] In some embodiments, the time-depth conversion method in step S1 includes:

[0013] The instantaneous velocity model of the microchip capsule in the drill string and the annulus segment is established respectively:

[0014] The instantaneous velocity in the drill string:

[0015] v pipe =v avg ·M turb +V slip

[0016] Wherein, v pipe is the instantaneous velocity in the drill string, v avg is the average flow rate of drilling fluid, M turb is the ratio of average flow rate to central flow rate in turbulent flow state of drill pipe, V slip is the slip velocity, which is the difference between the movement speed of solid particles in fluid and the flow rate of fluid;

[0017] The instantaneous velocity in the annulus segment:

[0018] v ann =v avg ·M lam -V slip

[0019] Wherein, v ann is the instantaneous velocity in the annulus segment, v avg is the average flow rate of drilling fluid, M lam is the correction factor obtained by field iteration correction;

[0020] And by comparing the predicted total running time with the actual recovery time determined by the pressure inflection point, iteratively adjusting the correction factor M lam The final output is the well depth sequence.

[0021] In some embodiments, the theoretical pressure distribution model in step S2 outputs at least the following indicators: pressure value function, pressure consumption function, and pressure consumption gradient distribution function, wherein:

[0022] The formula for calculating the pressure value function is:

[0023]

[0024] P surf = P0+ P back

[0025] Where P model (z) is the theoretical pressure value at well depth z, P surf is the total surface pressure at the wellhead, i.e.: P surf = P0+ P back , P0 is the static pressure at the wellhead (the initial pressure based on the atmospheric pressure or the equipment base pressure), P back is the surface back pressure (additional control pressure applied for well control balance, if not applied then P back = 0. ρ is the drilling fluid density, g is the acceleration of gravity, θ is the inclination angle (considering non-vertical well, the inclination cosθ correction), f(z') is the friction gradient, z' is the integral variable (dummy variable, unit: m), only used for each point on the traversal path (from 0 to the target depth z) in the integration process.

[0026] This formula is based on the assumption of steady-state flow and is applicable to the calculation of pressure in the drill string from the wellhead to the bottom and the calculation of annulus pressure from the bottom to the wellhead, forming a closed-loop wellbore pressure profile.

[0027] To simulate the entire circulation flow, the pressure calculation needs to be processed in segments:

[0028] ① Drill string (downward path):

[0029] Taking the wellhead as the reference point, the positive direction is taken downward along the well depth, with z being the depth downward from the wellhead, starting from the wellhead pump pressure, and accumulating the hydrostatic pressure term ρgΔh (Δh = zcosθ) and the pipe friction gradient term ∫fpipe(z')dz'.

[0030] ② Bit pressure drop (bottom transition):

[0031]

[0032] Where Q is the displacement (m 3 / s), Cd≈0.95 (dimensionless, approximately 0.95 can be used in engineering), A nozzle Total nozzle area (m²) 2 ), ρ density at the nozzle (kg / m³) 3 If there is a compression effect / temperature gradient, local values ​​are required.

[0033] The pressure relationship at this location (at a drilling depth L) is as follows.

[0034] The pressure at the bottom of the drill pipe (upstream of the nozzle) is: P pipe (L).

[0035] The downstream pressure of the nozzle (the starting point for entering the annulus, i.e., the initial annulus pressure) is:

[0036] P ann (L)=P pipe (L)-ΔP nozzle

[0037] ③ Circular path (uplink path):

[0038] The pressure in the annulus from the bottom of the drill string (z = L) upwards to any depth (z) can be determined from the initial value P. ann (L) Subtract the static water term along the way and add the annular friction loss (the static water term is subtracted when the upward direction moves upward).

[0039]

[0040] The annular wellhead pressure equals the bottom annular pressure minus the accumulated hydrostatic recovery and frictional losses along the upward path. This closed-loop relationship is used to verify the cyclic consistency of the downward and upward pressure profiles, and can be used for inverting displacement or rheological parameters and model verification under the steady-state single-phase assumption; after operating condition calibration, the error can be controlled to about 5%.

[0041] Pressure loss function and pressure loss gradient function:

[0042] Pressure loss functions are defined as either drill string pressure loss or annular pressure loss. These refer to the pressure loss generated during drilling, specifically the pressure loss of drilling fluid flowing within the drill string and the pressure loss generated during drilling fluid flowing in the annular space between the drill string and the wellbore, respectively. The pressure loss function ΔP(z) and the pressure loss gradient g(z) are related to geometry (D... pipe and D eq Differences in rheology (Newtonian and non-Newtonian) and flow regime lead to variations in friction calculations, necessitating segmented calculations (within the drill string and within the annulus). The calculation logic is as follows:

[0043] Drill string pressure loss (inside the pipe):

[0044]

[0045] Annulus pressure loss (uplink direction diagram) :

[0046] (Integrated in uplink direction)

[0047] The pressure loss gradient f(z') represents the pressure loss distribution per unit length, which is essentially the derivative of the pressure loss dΔP / dz, used for local anomaly diagnosis (such as gradient mutation point detection), and the gradient is the friction gradient (in the absence of local loss section), which can be verified by difference in numerical value. The calculation logic is as follows:

[0048] Pressure loss gradient definition (local rate) :

[0049] g(z)=f(z)

[0050] Drill string and annulus segment calculation:

[0051] Drill string pressure loss gradient: g pipe (z)=f pipe (z)

[0052] Annulus pressure loss gradient: g ann (z)=f ann (z)

[0053] In some embodiments, before step S3, a leak detection step is further included, which divides the pressure measurement cycle into three working conditions of normal complete cycle, existence of leak but capsule not escaped, or existence of leak and capsule escaped in advance, based on at least one of the following criterion combinations:

[0054] Maximum depth condition: judge the maximum well depth z max whether to meet:

[0055] z max ≥H design -ε

[0056] Where, z max =max{z k |k=1,2,…,N} is the maximum well depth recorded by the microchip capsule in the entire measurement sequence, N is the total length of the data sequence, H design is the design well depth, and ε is the preset depth deviation tolerance;

[0057] Return segment existence condition: judge whether there is a return data segment with decreasing depth after the microchip capsule reaches the maximum well depth, specifically:

[0058] So that z j <z i , and |z i -z max |<ε1

[0059] where i is the time step in the time series that satisfies |z i -z max | the index of ε1, indicating the time step when the microchip capsule is close to the maximum well depth, j>i is the time step after i, ensuring that z j reflects the change in the depth of the annulus, z j <z i indicates that the depth of the microchip capsule decreases, i.e., it begins to return from the bottom of the well, and ε1 is a preset depth proximity tolerance;

[0060] Pressure consistency condition: determine whether the deviation between the measured pressure P meas (z i ) and the theoretical model pressure P model (z i ) satisfies:

[0061]

[0062] where P meas (z i ) is the pressure measured by the microchip capsule at well depth z i , P model (z i ) is the predicted pressure of the theoretical model at well depth z i , and ε2 is a preset pressure deviation threshold;

[0063] Pressure gradient deviation condition: determine whether the pressure gradient deviation satisfies:

[0064]

[0065] where ε3 is a preset pressure gradient deviation threshold.

[0066] In some embodiments, the abnormality comparison analysis in step S3 includes calculating at least one of the following indicators and comparing it with a preset threshold:

[0067] Pressure difference:

[0068] ΔP(z i ) = P meas (z) - P model (z)

[0069] Drill pipe internal pressure loss:

[0070]

[0071] Annulus pressure loss:

[0072]

[0073] Drill pipe internal pressure loss gradient:

[0074] gpipe (z) = f pipe (z)

[0075] annulus pressure depletion gradient:

[0076] g ann (z) = f ann (z)

[0077] In some embodiments, the leak location in step S4 is achieved by fusing the positions of the pressure differential break point z ΔP , the pressure depletion break point z loss and the pressure depletion gradient inflection point z grad , when |z ΔP -z loss | < δ, and |z loss -z grad | < δ, the leak location depth is calculated by the following formula:

[0078]

[0079] where z leak is the leak location depth.

[0080] In some embodiments, after step S4, it further includes step S5: leak rate inversion calculation: based on the deviation of the measured pressure data and the theoretical model, the leak rate η is inversely solved.

[0081] In some embodiments, when the microchip capsule completes a complete cycle, the calculation method of the leak rate η is a nonlinear fitting inversion method, including:

[0082] S411, express the leak point z leak downstream pipe effective displacement Q eff (z) in the form of piecewise function:

[0083]

[0084] where Q in is the ground pump displacement, and η is the leak rate;

[0085] S412, reconstruct the pressure model with the corrected displacement Q eff (z) to obtain the theoretical pressure curve related to the leak rate η

[0086]

[0087] where P surfis the total surface pressure at the wellhead, p is the drilling fluid density, g is the gravitational acceleration, q is the deviation angle (considering non-vertical wells, the deviation cos q is corrected), f(z'; n) is the friction gradient, n is the leakage rate (dimensionless). This reconstruction is based on the closed-loop wellbore pressure profile, and is applicable to complete circulation inversion.

[0088] S413, construct the objective function J(n) in the form of the residual sum of squares between the leakage model pressure and the measured pressure:

[0089]

[0090] where P meas (z i ) is the measured pressure value of the microchip capsule, z i is the discrete depth point;

[0091] S414, solve the optimal leakage rate by minimizing the objective function J(n):

[0092]

[0093] where n opt is the optimal leakage rate.

[0094] In some embodiments, the method of identifying and locating the drilling tool leakage by the while-drilling microchip device further comprises the step of calculating the leakage volume flow Q opt and the equivalent leakage hole area A leak based on the optimal leakage rate n leak :

[0095] Q leak = Q in · n opt

[0096] Given the leakage point pressure difference AP leak = P pipe - P ann , the equivalent leakage hole area can be estimated:

[0097]

[0098] where C d is the outflow coefficient, p is the mud density.

[0099] In some embodiments, when the microchip capsule escapes in advance at the leakage point, the method for calculating the leakage rate n is the residual fitting method, comprising the following steps:

[0100] S421, record the maximum depth z max reached by the microchip capsule during the downward process and the corresponding maximum pressure P max ;

[0101] S422, construct a local puncture correction model for calculating the theoretical pressure related to the puncture rate variable η The formula is:

[0102]

[0103] Where, P surf is the total surface pressure at the wellhead, p is the drilling fluid density, g is the acceleration of gravity, theta is the inclination angle (considering non-straight downhole, inclination cos theta correction), f(z'; eta) is the friction gradient, considering the puncture effect in sections, eta is the puncture rate (dimensionless). The model is suitable for early escape emergency inversion based on the upper section data of the closed loop wellbore pressure profile.

[0104] S423, adjust the puncture rate variable η by iteration to find the minimum solution η that satisfies the condition est , and take it as the estimated puncture rate.

[0105] Compared with the prior art, the method for identifying and positioning the drilling tool puncture by the drilling microchip device provided by the present application has the beneficial effects that: through a series of steps, from data acquisition to the final puncture rate inversion calculation, a complete drilling tool puncture identification and positioning system is formed. Data acquisition and conversion provide accurate basic data for subsequent analysis, normal pressure model construction provides a judgment benchmark, puncture condition judgment can preliminarily judge whether there is puncture and the approximate situation of puncture, abnormal comparison and analysis and puncture positioning can accurately determine the position of puncture, and puncture rate inversion calculation can evaluate the severity of puncture. Compared with the prior art, the method realizes continuous, real-time and automatic puncture detection, improves the detection timeliness and reliability, can timely find the drilling tool puncture and position, provides a strong guarantee for the safety and efficiency of drilling operation, and reduces accidents and economic losses caused by puncture. BRIEF DESCRIPTION OF DRAWINGS

[0106] Figure 1 is a flowchart of the method for identifying and positioning the drilling tool puncture by the drilling microchip device provided by an embodiment of the present application;

[0107] Figure 2 is the overall flowchart of the method for identifying and positioning the drilling tool puncture by the drilling microchip device provided by an embodiment of the present application;

[0108] Figure 3 is a physical diagram of the microchip capsule used in the present application;

[0109] Figure 4 is a comparison diagram of the microchip measured pressure under the puncture condition and the normal condition model pressure;

[0110] Figure 5The comparison chart of the measured pressure loss and pressure loss gradient of the microchip under the piercing leakage working condition and the model under the normal working condition is shown in the figure;

[0111] Figure 6 The piercing leakage positioning result schematic diagram in a specific embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0112] The technical solutions in the embodiments of the present application will be further described in detail below with reference to the drawings. The described embodiments are only possible technical implementations of the present application, but are not limited thereto, and other embodiments obtained by those skilled in the art without creative efforts based on the embodiments of the present application are also within the protection scope of the present application.

[0113] The present application mainly adopts the data collection and analysis of the while-drilling microchip device to realize the piercing leakage identification and positioning of the drilling tool, and achieves the effect of real-time and accurate identification and positioning of the piercing leakage of the drilling tool. The present application will be further described in detail as follows.

[0114] Please refer to Figure 1 and Figure 2 The method for realizing the piercing leakage identification and positioning of the drilling tool through the while-drilling microchip device provided by the embodiments of the present application includes the steps of data collection and conversion, normal pressure model construction, abnormality comparison analysis, piercing leakage positioning, and piercing leakage rate inversion calculation. The data collection and conversion provides basic data for subsequent analysis, the normal pressure model construction provides a judgment benchmark, the abnormality comparison analysis identifies pressure abnormalities, the piercing leakage positioning determines the piercing leakage depth position, and the piercing leakage rate inversion calculation evaluates the piercing leakage severity. Through the synergistic effect of these steps, the real-time and accurate identification and positioning of the piercing leakage of the drilling tool can be realized, which provides protection for the safety and efficiency of the drilling operation. The following will be introduced as follows:

[0115] S1, data collection and conversion: collecting downhole pressure data in the process of drilling operation by means of putting microchip capsules, the microchip capsule is a device with a built-in pressure sensor and an outer diameter smaller than the diameter of the drill bit water eye (as shown in Figure 3 ), so that it can circulate completely in the drill string and the annulus with the drilling fluid; the microchip capsule continuously collects time series of downhole pressure data, and converts the time series data into depth-pressure data through the time-depth conversion method; the pressure sensor can be selected from a high-precision piezoresistive pressure sensor, which has the advantages of high measurement accuracy and good stability, or a piezoelectric pressure sensor, which has fast response speed;

[0116] Specifically, the deployment of the microchip capsule is an operation performed on the surface. Before deployment, the microchip capsule undergoes a functional check to ensure that its built-in pressure sensor and battery are functioning properly and that there is sufficient internal memory space. The prepared microchip capsule is placed directly into the drilling fluid at the top of the drill string using a dedicated wellhead deployment device. Once inside the drill string, it is immediately captured by the drilling fluid driven by the circulation pump and begins to flow downhole with the drilling fluid. After deployment, the capsule enters a completely passive and autonomous circulation measurement phase. The capsule flows down the inner wall of the drill string with the drilling fluid from the wellhead, through the drill string assembly, through the water inlet at the bottom of the drill bit, and into the annulus between the drill string and the well wall. Throughout the entire downward and upward (returning through the annulus) circulation process, the pressure sensor built into the microchip capsule automatically and continuously records the pressure data of its environment at a preset frequency (e.g., once every 3 seconds) and stores the "pressure-time" sequence data in its internal memory. When the drilling fluid carrying the capsule returns from the annulus to the surface, it undergoes solid-liquid separation through a vibrating screen. As solid particles, the microchip capsules are separated from the drilling fluid along with the rock cuttings by a vibrating screen. Workers manually locate and recover the microchip capsules from the rock cuttings at the solids outlet of the vibrating screen. After cleaning, the recovered capsules are connected to a dedicated wireless data reader. The entire pressure-time data stored within the capsules is wirelessly downloaded to a computer for subsequent leak analysis.

[0117] To convert the collected time-series data into depth-pressure data, a time-depth conversion is required.

[0118] To achieve accurate interpretation of the data and subsequent modeling, the time series data collected by the capsule needs to be reasonably mapped to the well depth dimension, thereby establishing a three-dimensional data structure of "time-depth-pressure" to support subsequent steps such as normal pressure model construction, leakage identification and quantitative analysis.

[0119] In specific operations, while the capsule is being deployed into the wellhead, the drilling fluid pump displacement Q(t) and pump pressure P are simultaneously recorded on the ground. pump A standard timeline reference frame is constructed using auxiliary information such as (t), wellhead temperature, and capsule deployment timestamp. The downhole capsule records the instantaneous pressure P(t) at its location at equal intervals. i ) and temperature T(t) i Since the capsule itself is a solid particle, its movement speed is not entirely equivalent to the mud flow velocity, and the time-depth conversion needs to be carried out by comprehensively considering factors such as slip velocity.

[0120] To achieve time-to-depth mapping, the motion of the capsule within the drill string and the annulus needs to be modeled. Considering that the fluid within the drill string is typically turbulent, the capsule in this region can be approximated by moving at the center velocity of the drilling fluid, with a slip velocity V superimposed. slipits instantaneous velocity is:

[0121] v pipe = v avg · M turb + V slip

[0122] where M turb ≈ 1.25 is the ratio of average flow velocity to central flow velocity in turbulent flow state. The annular section usually presents laminar flow state, and the capsule may move close to the well wall due to density deviation and particle interference, at which time its velocity expression is

[0123] v ann = v avg · M lam - V slip

[0124] where M lam ∈ [0.7, 1.1] is a correction factor obtained by field iteration. The entire process of capsule downlink and return is discretely divided by time step Δt, and the micro displacement is calculated for each time period and accumulated to obtain the well depth sequence z i .

[0125] In practical application, the recovery time consistency principle is used for iterative calculation. The obvious inflection point (such as the pressure drop after entering the ground vibrating screen) is extracted from the measured pressure-time data as the actual recovery time of the capsule, and the predicted total running time is compared with the time, and M lam is gradually adjusted until the fitting error is lower than the preset threshold, and the solution of the depth conversion parameter is completed. The complete triplet data (t i , z i , P i ) is finally output, and the linkage relationship with the pump pressure and displacement data recorded on the ground is established to form a basic data set which can be used for model fitting and anomaly identification.

[0126] This stage not only realizes the standardization conversion of the original measurement data, but also provides the necessary basis for subsequent construction of ideal wellbore pressure model, ensuring that the subsequent leak identification analysis has sufficient depth accuracy and pressure reliability.

[0127] S2, normal pressure model construction: based on drilling operation parameters, a theoretical pressure distribution model in the wellbore under the condition of no leakage is established as a judgment reference;

[0128] Specifically, in order to identify the downhole leakage behavior and realize high-precision positioning, the pressure distribution in the wellbore under normal working condition is established as a reference. This part uses the existing mature multi-section coupled fluid mechanics modeling method of wellbore to establish a set of "normal working condition pressure model" under ideal conditions, which is used to simulate the flow and pressure loss characteristics of mud in the wellbore system under the condition of no leakage.

[0129] This model takes pump displacement, pump pressure, drilling fluid rheological parameters, and wellbore geometry recorded on the ground as inputs. It comprehensively simulates the coupled physical processes between three flow zones: the drill string interior, the nozzle outlet, and the annular backflow. The model outputs a continuous depth-pressure function curve as a theoretical benchmark for determining pressure anomalies. The core calculation formulas of the model are all selected from industry-recognized classical flow resistance and local pressure loss theories (Poiseuille, Darcy-Weisbach correlations, etc.). Related implementation details and parameter tuning can directly follow the standard procedures of publicly available literature or mainstream commercial software, and will not be elaborated here.

[0130] The model operates in a time-step manner, dynamically updating key physical properties based on operational parameters such as drilling rate of position (ROP), rotational speed (RPM), and formation temperature distribution, ensuring the real-time accuracy of the baseline curve throughout the entire cycle. The wellbore is discretized into several finite-length elements. Each element calculates pressure loss per unit length using the corresponding resistance correlation formula based on its inner and outer diameters, inclination angle, and mud properties. Nozzle pressure loss is processed using an empirical orifice flow coefficient and used as the boundary condition for the inner and outer sections of the drill string. The results from each element are accumulated and superimposed to form a complete theoretical pressure profile. To adapt to changes in field conditions, the model reserves interfaces for real-time updates of pump displacement and mud properties, allowing for automatic updates according to the cycle step size, ensuring that the baseline curve is always synchronized with the operational parameters.

[0131] To facilitate subsequent anomaly detection and leak localization, the model synchronously outputs at least the following comparative indicators at each depth point: pressure value function, pressure loss function, and pressure loss gradient distribution function, wherein:

[0132] The formula for calculating the pressure value function is:

[0133]

[0134] P surf =P0+P back

[0135] Among them, P model (z) represents the theoretical pressure value at well depth z, P surf The total surface pressure at the wellhead is P. surf =P0+P back P0 is the wellhead static pressure (initial foundation pressure, usually taken as atmospheric pressure or equipment base pressure), P back Surface back pressure (an additional applied control pressure used for well control balancing; if not applied, P) back=0. ρ is the drilling fluid density, g is the gravitational acceleration, θ is the well inclination angle (considering non-vertical downholes, well inclination cosθ correction), f(z') is the friction gradient, and z' is the integration variable (dummy variable, no physical meaning, unit: m), which is only used to traverse each point on the path during the integration process (from 0 to the target depth z).

[0136] Based on the steady-state flow assumption, this formula is applicable to the calculation of drill string pressure from wellhead to bottom of well, as well as the calculation of annular pressure from bottom of well to wellhead, forming a closed-loop wellbore pressure profile.

[0137] To simulate the entire circulation flow, pressure calculations need to be performed in segments:

[0138] ①Inside the drill string (downward path):

[0139] Taking the wellhead as a reference point, take the positive direction downward along the well depth, and let z be the depth downward from the wellhead. Starting from the pump pressure at the wellhead, accumulate the hydrostatic pressure term ρgΔh (Δh=zco sθ) and the pipe friction gradient term ∫fpipe(z')dz'.

[0140] ② Drill bit pressure drop (bottom hole transition):

[0141]

[0142] Where Q is the displacement (m) 3 / s), Cd≈0.95 (dimensionless, approximately 0.95 can be used in engineering), A nozzle Total nozzle area (m²) 2 ), ρ density at the nozzle (kg / m³) 3 If there is a compression effect / temperature gradient, local values ​​are required.

[0143] The pressure relationship at this location (at a drilling depth L) is as follows.

[0144] The pressure at the bottom of the drill pipe (upstream of the nozzle) is: P pipe (L).

[0145] The downstream pressure of the nozzle (the starting point for entering the annulus, i.e., the initial annulus pressure) is:

[0146] P ann (L)=P pipe (L)-ΔP nozzle

[0147] ③ Circular path (uplink path):

[0148] The pressure in the annulus from the bottom of the drill string (z = L) upwards to any depth (z) can be determined from the initial value P. ann (L) Subtract the static water term along the way and add the annular friction loss (the static water term is subtracted when the upward direction moves upward).

[0149]

[0150] Annulus wellhead pressure is equal to the bottom hole annulus pressure minus the static water recovery and friction loss accumulated along the uplink path. The closed relationship is used to verify the consistency of the downlink and uplink pressure profile cycle, and can be used to invert the displacement or flow parameter and model calibration under the steady-state single-phase assumption; when the working condition is calibrated, the error can be controlled at about 5%.

[0151] Pressure consumption function and pressure consumption gradient function:

[0152] The pressure consumption function is defined as the pressure loss of the drilling fluid in the space flow in the drill string and the pressure loss of the drilling fluid in the annular space between the drill string and the well wall. The pressure consumption function ΔP(z) and the pressure consumption gradient g(z) are different due to the different geometry (D pipe and D eq ), rheology (Newtonian, non-Newtonian) and flow state, so it needs to be calculated in segments (in the drill string and in the annulus), and the calculation logic is as follows:

[0153] Drill string pressure consumption (in the pipe):

[0154]

[0155] Annulus pressure consumption (uplink direction schematic):

[0156] (Integrate in the uplink direction)

[0157] The pressure consumption gradient f(z') represents the pressure consumption distribution per unit length, which is essentially the derivative of the pressure consumption dΔP / dz, used for local anomaly diagnosis (such as gradient mutation point detection), and the gradient is the friction gradient (in the absence of local loss section), which can be verified by difference in value. The calculation logic is as follows:

[0158] Pressure consumption gradient definition (local rate):

[0159] g(z) = f(z)

[0160] Drill string and annulus segmented calculation:

[0161] Drill string pressure consumption gradient: g pipe (z) = f pipe (z)

[0162] Annulus pressure consumption gradient: g ann (zi) = f ann (z)

[0163] The pressure consumption gradient is particularly sensitive to the abnormal changes before and after the puncture leakage, and can be used to identify the "slope mutation" features before and after the puncture leakage point.

[0164] The above-mentioned various outputs can not only be used as direct comparison references for microchip capsule data, but also can be used to construct the basis of subsequent key identification algorithms such as "gradient mutation criterion" and "pressure difference mutation criterion". The model supports both static analysis and dynamic simulation modes, and can not only perform instantaneous pressure mapping for a single working condition, but also can perform real-time iterative calculation of pressure evolution trajectory during the whole cycle of the microchip capsule.

[0165] By comparing with the measured pressure data of the capsule, once local deviation, pressure consumption mutation or gradient anomaly is found, the subsequent puncture leakage identification and accurate positioning process can be triggered.

[0166] S3, abnormal comparison and analysis: comparing the depth-pressure data measured by the capsule with the theoretical pressure distribution model to identify pressure abnormal features;

[0167] Specifically, after completing the depth mapping of the microchip capsule pressure data and the standard model construction, it is necessary to first identify whether the current pressure measurement cycle is completed, whether there is a downhole puncture and other key working conditions. Based on the structural continuity features of the depth-pressure curve collected by the capsule, combined with the matching relationship between the actual measurement data and the theoretical model, the preliminary classification and determination of the drilling tool puncture state is realized without relying on time threshold.

[0168] The data recorded by the capsule can be expressed as a continuous sequence:

[0169]

[0170] Wherein, z i is the depth position of the capsule downlink path or return path, P meas (z i ) is the measured pressure at the corresponding depth. By analyzing the sequence, the following three key features can be determined:

[0171] i Maximum recorded depth z max The maximum depth that the capsule can reach can be used to determine whether it has reached the bottom of the well;

[0172] ii Whether there is return segment data: judging whether the pressure curve appears a structure of returning and rising from the maximum depth, indicating whether the capsule enters the annulus and returns to the ground;

[0173] iii Comparison deviation of P meas (z i ) measured by the capsule and the normal model P model (z): used to identify whether there are abnormal mutations, deviations or gradient changes in the pressure curve, indicating signs of puncture leakage.

[0174] According to the combination results of the above three criteria, the pressure measurement cycle is divided into the following three working conditions:

[0175] ① Normal complete cycle (no leakage occurs)

[0176] Under normal working conditions, the microchip capsule (hereinafter referred to as "capsule") should complete a complete closed-loop cycle from the wellhead down to the designed well depth and return to the ground, and the measured pressure data is highly consistent with the theoretical model under the condition of no leakage. To accurately determine this working condition, the following three conditions must be met:

[0177] i Maximum depth condition

[0178] The maximum well depth z recorded by the capsule during the cycle max Should reach or approach the designed well depth H design , Specifically:

[0179] z max ≥ H design - ε

[0180] Where z max = max{z k | k = 1, 2, …, N} is the maximum well depth recorded by the capsule in the entire measurement sequence, N is the total length of the data sequence, H design is the designed well depth, and ε is the preset depth deviation tolerance, usually taking a value of 5m to 10m to adapt to the measurement error on site.

[0181] This condition ensures that the capsule has descended to the bottom of the well or a position close to the bottom of the well.

[0182] ii Existence of return section

[0183] After reaching the maximum well depth, the capsule should have a clear return section, i.e. the process of returning to the ground from the maximum well depth. Mathematically, this is expressed as:

[0184] So that z j < z i , and |z i - z max | < ε1

[0185] Where:

[0186] i is the index in the time sequence that satisfies |z i - z max | < ε1, indicating the time step when the capsule approaches the maximum well depth.

[0187] j > i is the time step after i, ensuring that z j Reflects the depth change of the return section.

[0188] z j <z i Indicates the capsule depth reduction, i.e. starting to return from the well bottom.

[0189] ε1 is the preset depth proximity tolerance, usually 5m or set according to the well depth ratio, to ensure z i Real proximity z max .

[0190] This condition confirms that the capsule successfully returns after reaching the well bottom, completing a complete downhole circulation.

[0191] iii Pressure consistency

[0192] The pressure P meas (z i ) measured by the capsule during the entire circulation process should be highly consistent with the theoretical model pressure P model (z i ) under the condition of no leakage, specifically:

[0193]

[0194] Where P meas (z i ) is the pressure measured by the capsule at well depth z i , P model (z i ) is the predicted pressure of the theoretical model at well depth z i , ε2 is the preset pressure deviation threshold, usually 0.1-0.3MPa (according to actual application), to tolerate measurement noise and model error.

[0195] This condition ensures that there is no significant deviation between the measured pressure and the theoretical model throughout the circulation path, indicating that no leakage or other abnormal conditions have occurred.

[0196] When the above three conditions (i, ii, iii) are met at the same time, it can be determined that the capsule has completed a normal complete circulation and no leakage has occurred. At this time, the measured data is reliable and can be used for subsequent analysis. If any condition is not met, further analysis is needed to determine whether there is a leakage or other abnormal working conditions.

[0197] ② There is leakage but the capsule does not escape

[0198] When the capsule depth also reaches or approaches the designed well depth, and there is a return section, but during the pressure consistency analysis of condition iii, there is a systematic deviation or inflection point anomaly in the pressure curve of some sections, such as:

[0199] The depth section makes P meas (z) << P model (z)

[0200] or the pressure depletion gradient suddenly changes at a certain depth:

[0201]

[0202] ε3 is a preset pressure gradient deviation threshold (determined according to actual application), to tolerate measurement noise and model error.

[0203] At this time, the broken capsule is considered to have completed a complete downhole circulation and the drilling tool has a leak condition. The capsule passes through the drilling tool section with a leak during the downward or return process, and the above pressure deviation is caused by the partial leakage of the mud.

[0204] ③ There is a leak and the capsule escapes in advance

[0205] If the maximum depth recorded by the capsule is significantly lower than the designed well depth, i.e.:

[0206] z max <<H design -ε

[0207] wherein ε is a preset leak escape identification threshold, and its typical value range is 5-10 meters, and the specific value can be determined according to the well depth, drilling fluid properties and engineering requirements during implementation. At the same time, the depth-pressure curve recorded by the capsule presents the following characteristics:

[0208] i The depth does not reach the designed well depth: the capsule does not reach the end of the drill string during the downward process, and the maximum depth z max is less than H design , indicating that the capsule escapes from the drill string to the annulus at z max .

[0209] ii Pressure suddenly drops to annulus pressure: at z max , the pressure recorded by the capsule suddenly drops from the higher pressure in the drill string to the lower pressure in the annulus, which is manifested as a sudden point of the pressure curve.

[0210] iii There is an annulus return section but the depth is not continuous: after the capsule escapes at z max , it enters the annulus and returns to the ground. Therefore, the depth-pressure curve records the pressure data in the annulus after z max , and the depth gradually decreases from z max to the surface pressure, rather than rising from the current drill bit depth H design to the surface pressure.

[0211] Based on the above characteristics, it can be determined that the capsule escapes from the drill tool leakage hole into the annulus before reaching the end of the drill string, and returns to the ground in advance, resulting in its incomplete completion of the complete drill string- bottom hole- annulus circulation path. Due to the interruption of the capsule running path, the pressure data of the whole well section cannot be obtained under this working condition. However, by analyzing the pressure mutation of the capsule at z max and the subsequent annulus pressure data, the position of the leakage point can still be preliminarily inverted. The specific inversion method can combine the fluid pressure gradient model in the well, use z max and the corresponding pressure value to calculate the leakage point depth, and the subsequent steps will be described in detail.

[0212] The working condition determination process provides a reliable prior basis for the subsequent modules of the application, including pressure anomaly analysis, rule matching identification, leakage location inversion, and leakage rate estimation. By determining the characteristics and determination logic of the early escape of the capsule, the application can realize real-time identification and preliminary positioning of the leakage event in a single pressure measurement cycle.

[0213] S4, leakage positioning: determining the depth position of the drill tool leakage according to the pressure anomaly characteristics.

[0214] Specifically, on the basis of completing the determination of the leakage working condition, if the system confirms that there is a downhole leakage in this pressure measurement cycle, it is necessary to further analyze the depth-pressure data recorded by the capsule, compare it with the normal model under the condition of no leakage, identify abnormal characteristics, and determine the specific depth position of the leakage point. Based on the pressure anomaly analysis and rule identification mechanism, this part constructs a high-precision leakage positioning algorithm, which is divided into two steps: abnormal comparison and multi-dimensional feature positioning.

[0215] ① Pressure anomaly comparison and analysis

[0216] The application uses the depth-pressure curve recorded by the microchip capsule as the measured data set, denoted as:

[0217] N{(z i ,P meas (z i ))},i=1,…,N

[0218] At the same time, the normal circulation pressure model P model (z) established in the second part is called as the theoretical reference curve, and the above measured curve is compared synchronously in the unified depth coordinate system. The comparison analysis includes three technical dimensions:

[0219] i Pressure profile

[0220] Directly compare the measured pressure and the model pressure to observe whether their depth distribution trends are consistent. If there is a depth section where the measured pressure is significantly lower than the model prediction (such as Figure 4The microchip inversion data is compared with the normal model pressure curve. If the red and blue line segments diverge, it indicates that abnormal fluid behavior occurs at this segment, which may be caused by a leak.

[0221] The pressure difference is defined as:

[0222] ΔP(z i )=P meas (z)-P model (z)

[0223] If the pressure difference in a certain depth interval is greater than a set threshold value (which is determined by the actual well depth, drilling fluid properties and engineering requirements), it is considered to trigger an abnormal criterion.

[0224] ii Pressure loss comparison

[0225] The pressure loss is defined as the pressure consumption per unit depth. The pressure loss functions of the drill pipe and the annulus are calculated under the conditions of having a leak and not having a leak, respectively:

[0226] Drill pipe pressure loss:

[0227] Annulus pressure loss:

[0228] Under abnormal leak conditions, the microchip measurement curve below the leak point is compared with the normal working condition simulation curve. The drill string pressure loss will have a sudden drop or a sudden change in slope, and the annulus pressure loss curve will also have a sudden drop. As shown in Figure 5 The microchip inversion data is compared with the normal model pressure curve. If the red and blue line segments diverge, it indicates that abnormal fluid behavior occurs at this segment, which may be caused by a leak.

[0229] iii Loss gradient comparison

[0230] The loss gradient is the change rate of the pressure loss per unit length, which is used to analyze the "slope" of the pressure loss curve:

[0231] Drill pipe loss gradient: g pipe (z)=f pipe (z)

[0232] Annulus loss gradient: g ann (z)=f ann (z)

[0233] Under normal working conditions, if Figure 5The comparison of annulus pressure loss gradient and the comparison of pressure loss gradient in the drill string can be seen that, above the depth of the leak location (about 5000 meters), the curve under the leak condition (red dotted line) is completely coincided with the curve under the normal condition (blue solid line), while at the leak occurrence point, the leak leads to the loss of flow in the drill string and the reduction of friction; the annulus pressure loss gradient at the leak location suddenly drops and stabilizes at a value less than the pressure loss gradient under the normal condition, and the pressure loss gradient value at the bottom of the well is less than that under the normal condition; at the same depth, the pressure loss gradient in the drill string suddenly drops at the leak point, and the drop is significantly greater than that on the annulus side. The above rules can determine the leak and determine its depth within a single measurement.

[0234] Based on the comparison results of the above three-dimensional indicators, once the following conditions are observed simultaneously:

[0235] The pressure deviation exceeds the threshold value;

[0236] The pressure loss curve appears to deviate simultaneously at the same depth in the drill string and annulus;

[0237] The pressure loss gradient suddenly drops simultaneously in the drill string and annulus at the same depth;

[0238] The next step of leak depth positioning mechanism can be entered.

[0239] ② Rule fusion positioning leak location

[0240] After triggering the anomaly, the depth of the leak occurrence is accurately positioned by comparing and intersecting the key physical feature points. The system takes the following three feature points as positioning criteria:

[0241] i Pressure difference mutation point: z ΔP It refers to the mutation point of the pressure difference curve between the measured and the model, reflecting the systematic pressure loss change caused by the leak.

[0242] ii Pressure loss mutation point: z loss It refers to the turning point of the pressure loss curve from continuous decline to sudden jump, indicating that the structure of the downhole flow channel has changed.

[0243] iii Pressure loss gradient inflection point: z grad It refers to the inflection point of the gradient curve from normal state to abnormal form (such as sharp decrease or reverse growth).

[0244] The above three feature points are fused, if they are close to each other, that is, if:

[0245] |z ΔP -z loss |<δ,|z loss -z grad |<δ,(δ≈5~m)

[0246] The average value is taken as the leak positioning depth:

[0247]

[0248] If the three do not coincide, the lightest point is taken as the warning position, and secondary microchip measurement review is recommended to prevent missed recognition.

[0249] The law fusion positioning mechanism avoids misjudgment caused by single curve interference and data jitter through the mutation joint verification of the triple curves of internal and external pipe pressure, pressure consumption and gradient, realizes real-time identification of high reliability and high resolution of the leakage point, and is especially suitable for complex well conditions such as deep wells and low pressure consumption areas that cannot be positioned by traditional methods.

[0250] S5: Leakage rate inversion calculation, that is, based on the deviation of the measured pressure data and the theoretical model, the leakage rate η is inversely solved.

[0251] Specifically, after identifying the downhole leakage and its occurrence depth, in order to further evaluate the severity and possible risks of the leakage behavior, the present application proposes a set of leakage rate inversion method based on the measured pressure data of the microchip. This method is suitable for two typical working conditions: one is that the probe core completes a complete cycle and returns to the ground, at this time the complete depth-pressure curve can be obtained; the second is that the probe core escapes and returns to the ground at the leakage point, only the upper section pressure data is recorded. In order to meet the precision and practical needs in different scenes, the present application designs corresponding leakage rate calculation and inversion mechanism.

[0252] ①Nonlinear fitting inversion method under the condition that the probe core does not escape

[0253] If the probe core successfully completes the drill string-bottom hole-annulus closed loop cycle, the complete wellbore pressure profile can be obtained, which has sufficient depth coverage. At this time, a nonlinear inversion model with leakage rate as a fitting variable can be used to obtain the pressure correction curve below the leakage point, and the least residual fitting with the measured data is carried out to inversely deduce the true leakage rate.

[0254] The modeling and solving steps are as follows:

[0255] a, Model correction: set the leakage rate variable η ∈ [0, 1], which represents the loss proportion of mud flow at the leakage point. Define the effective displacement Q eff (z) as a function of depth, where Q in is the surface pump displacement, z leak is the identified leakage depth. The effective displacement Q eff (z) expression

[0256] The piecewise function is expressed as follows:

[0257]

[0258] At the leakage depth zleak Before (i.e. z < z leak ), the effective displacement in the pipe is kept as the surface pump-in displacement Q in At the leak depth z leak and below (i.e. z ≥ z leak ), the effective displacement in the pipe is corrected as Q in · (1 - η) due to the partial flow loss caused by the leak.

[0259] b. Reconstruct the pressure model: Recalculate the pressure depletion distribution of the leak section (i.e. z ≥ z eff ) with the corrected displacement Q leak (z) to obtain the updated theoretical pressure curve:

[0260]

[0261] where:

[0262] P surf is the total surface pressure at the wellhead;

[0263] p is the drilling fluid density;

[0264] g is the acceleration of gravity;

[0265] q is the well inclination angle (considering non-vertical wells, the well inclination cos q correction);

[0266] f(z'; η) is the friction gradient, which is related to the leak rate η;

[0267] η is the leak rate, (dimensionless);

[0268] This reconstruction is based on the closed-loop wellbore pressure profile and is applicable to complete circulation inversion.

[0269] c. Construct the fitting objective function: Define the objective function J(η) as the sum of the squared residuals between the leak model pressure and the measured pressure, as follows:

[0270]

[0271] where P meas (z i ) is the measured pressure value of the microchip, and z i is the discrete depth point.

[0272] d. Solve the optimal leak rate: Solve the optimal leak rate η opt by minimizing the objective function J(η).

[0273]

[0274] Local bisection method, quasi-Newton method or grid search method can be used for numerical solution.

[0275] e. Leakage flow rate vs. orifice area (optional output):

[0276] Leakage volumetric flow rate:

[0277] Q leak = Q in · η opt

[0278] Given leakage point differential pressure ΔP leak = P pipe - P ann , the equivalent leakage orifice area can be estimated:

[0279]

[0280] where: C d is the discharge coefficient (typically taken as 0.6 - 0.8), and p is the mud density.

[0281] The nonlinear fitting inversion method under the condition of no escape of the probe core eventually obtains the optimal leakage rate η and its corresponding leakage flow rate Q leak and the equivalent leakage orifice area A leak The three key engineering quantities are outputs, which are used to guide the design of the site plugging scheme, the calculation of mud supplementing amount, and the evaluation of structural integrity.

[0282] 2. Residual fitting method under the condition of escape of the leakage orifice of the probe core

[0283] If the probe core does not complete the full circulation and escapes into the annulus to return to the ground before reaching the leakage point, only the pressure curve of the upper section (i.e., z max ) can be obtained. Although the data is incomplete, the present application can still construct a fitting through the deviation of the maximum pressure point and the model pressure to roughly estimate the leakage rate range.

[0284] The estimation process is as follows:

[0285] a. Record the maximum depth z max reached by the capsule during the downward process and the corresponding maximum pressure P max .

[0286] b. Calculate the predicted pressure of the normal model at this depth:

[0287] P model (z max )

[0288] c. Construct the pressure residual:

[0289] δP = P model (z max ) - P max

[0290] d. Assuming the leakage rate as a variable η, a local leakage correction model is constructed:

[0291]

[0292] e. By iteratively adjusting η, find the minimum solution η that satisfies:

[0293]

[0294] η est is the estimated leakage rate.

[0295] This method is suitable for emergency analysis scenarios where the probe escapes early. The result is an approximate estimate, and it is recommended to combine the pressure calibration results or ground flow information for secondary verification.

[0296] The residual fitting method under the condition of early escape of the probe is suitable for emergency scenarios where only the upper section pressure data is obtained. It can quickly invert the leakage rate range without return section pressure information, and it is recommended to combine ground flow closure or multiple cycle pressure results for review.

[0297] Specific implementation case:

[0298] The following is an application case of the technical solution based on the present application in a well in Bohai.

[0299] 1. Background information

[0300] A well in Bohai is an ultra-deep horizontal well with a design depth of 6345 meters, and the horizontal section extends from 1400 meters to 6345 meters. The drilling fluid density is 1.20 g / cm 3 , the surface mud pump displacement is 30 L / s, and the drill string inner diameter is 0.10 m. Drilling tools are subjected to high tension, compression and bending loads for a long time in deep wells and complex environments, and are subjected to erosion and corrosion, with a high risk of leakage. To ensure drilling safety, the present application method is used to measure the downhole pressure continuously using a microchip capsule to detect the drilling tool leakage in real time. The microchip sensor measures pressure at a frequency of 3 seconds, with a temperature tolerance of 150°C and a pressure tolerance of 80MPa.

[0301] 2. Implementation steps

[0302] The following is the complete operation step of applying this method in a well in Bohai.

[0303] Step 1: Use a special detection device on the ground to check the function of the microchip capsule, confirm the normal operation of the built-in pressure sensor and temperature sensor, and set the pressure measurement frequency to 3 seconds through a calibration instrument to ensure adaptation to the high temperature and high pressure environment in the downhole.

[0304] Step 2: Adjust the mud pump system at the well site, calibrate the surface displacement to 30 L / s through the flowmeter and pressure gauge, and detect the drilling fluid density to ensure it is stable at 1.20 g / cm 3 to ensure the normal operation of the drilling fluid circulation system.

[0305] Step 3: Place the microchip capsule into the drill string through the wellhead delivery device, record the initial timestamp at the wellhead and the surface pump pressure value when delivering, and ensure that the capsule enters the drill string smoothly and flows with the drilling fluid.

[0306] Step 4: Start the mud pump and set the displacement to 30 L / s to drive the microchip carried by the drilling fluid to flow along the inner wall of the drill string downward, maintaining stable pump pressure during the downward process, and it is expected to reach the bottom (6345 meters) in about 27.7 minutes.

[0307] Step 5: Record the time and mud pump pressure changes of the microchip during the downward process in real time through the data acquisition system on the ground, check the pump pressure readings every 30 seconds to ensure that there is no abnormal fluctuation in the circulation state.

[0308] Step 6: Wait for the microchip to enter the annulus along with the drilling fluid through the drill bit water hole and return to the ground along the annulus, the entire circulation process lasts about 112 minutes, during which the ground personnel monitor the drilling fluid return.

[0309] Step 7: Use the shaker at the wellhead to separate and recover the microchip capsule from the returned drilling fluid, check the capsule for integrity to ensure it is not damaged by the downhole environment.

[0310] Step 8: Connect the recovered microchip capsule to the wireless data reading device, extract the pressure and temperature time series data stored inside through wireless transmission, and save it to the ground computer system.

[0311] Step 9: Use the drilling fluid flow rate (calculated to be about 3.82 m / s from the displacement of 30 L / s and the well depth structure and drill tool combination data of this well and the drilling fluid properties), well depth (6345 meters), and timestamp to convert the collected time-pressure data into depth-pressure curve, ensuring the accuracy of depth mapping.

[0312] Step 10: According to the well depth of 6345 meters, the drilling fluid density of 1.20 g / cm 3 and the displacement of 30 L / s, use the fluid mechanics model to calculate the pressure distribution in the drill string and the annulus under normal working conditions, and obtain the pressure in the drill string at the bottom (6345 meters) of about 63 MPa and the annulus pressure of about 61 MPa as the theoretical reference.

[0313] Step 11: Compare the measured depth-pressure curve with the normal working condition pressure model point by point in the computer software, calculate the pressure deviation value at each depth point, and generate the deviation sequence data.

[0314] Step 12: analyze the deviation sequence, as shown in Figure 4 At a depth of 5000 meters, the measured inner pressure of the drill string is 1.5 MPa lower than the normal model, and the annular pressure is 1.0 MPa lower than the normal model, both of which exceed the preset pressure drop threshold of 0.3 MPa, and it is determined that there is an anomaly.

[0315] Step 13: calculate the pressure loss and pressure loss gradient of the drill string and the annulus, as shown in Figure 5 At the section of 5000.5 meters to 6345 meters, the gradient is 15% lower than the normal value, exceeding the preset gradient deviation threshold of 10%, while the gradient above 5000.5 meters is consistent with the model, confirming the abnormal interval.

[0316] Step 14: check the pressure difference between the inner pressure and the annular pressure of the drill string at 5000.5 meters, and find that the pressure difference is 0.5 MPa lower than the normal model, showing a sudden change, further supporting the anomaly determination.

[0317] Step 15: integrate the pressure deviation (1.5 MPa and 1.0 MPa), gradient reduction (15%), and pressure difference mutation (0.5 MPa) three characteristics, and determine that the puncture point is located at a depth of 5000.5 meters (as shown in Figure 6 ).

[0318] Step 16: stop the mud pump operation, pull out the drill string to the ground, and check the drilling tool at a depth of 5002 meters, find that the heavy drill pipe has a crack, and the actual leakage rate is 0.2, which is verified based on the microchip inversion data positioning, and the deviation between the actual puncture position and the puncture point located by the microchip inversion data is 1.5 meters, which meets the accuracy requirement of positioning the underground puncture under actual working conditions.

[0319] The technical effect of the present application is: through a series of steps from data acquisition to the final puncture rate inversion calculation, a complete drill tool puncture identification and positioning system is formed. Data acquisition and conversion provide accurate basic data for subsequent analysis, normal pressure model construction provides a judgment benchmark, puncture condition judgment can preliminarily judge whether there is a puncture and the approximate situation of the puncture, abnormal comparison and puncture positioning can accurately determine the position of the puncture, and puncture rate inversion calculation can evaluate the severity of the puncture. Compared with the prior art, the present method realizes continuous, real-time and automatic puncture detection, improves the detection timeliness and reliability, can timely find the drill tool puncture and positioning, provides a strong guarantee for the safety and efficiency of drilling operation, and reduces accidents and economic losses caused by puncture.

[0320] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, therefore: any equivalent changes made on the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A method for identifying and locating a drill pipe puncture by a while-drilling microchip device, characterized in that, Comprise: S1, data acquisition and conversion: collecting downhole pressure data by putting microchip capsules in the process of drilling operation, the microchip capsule is a device with a built-in pressure sensor and an outer diameter smaller than the diameter of the drill bit water eye, which can circulate completely in the drill string and annulus with the drilling fluid; the microchip capsule continuously collects time series of downhole pressure data, and converts the time series data into depth-pressure data by time-depth conversion method; S2, normal pressure model construction: based on drilling operation parameters, a theoretical pressure distribution model of the wellbore under the condition of no leakage is established as the judgment basis; S3, abnormal contrast analysis: comparing the depth-pressure data measured by the capsule with the theoretical pressure distribution model to identify the pressure abnormal characteristics; S4, leakage positioning: determining the depth position of the drill string leakage according to the pressure abnormal characteristics.

2. The method for identifying and locating a drill pipe puncture by a while-drilling microchip device according to claim 1, wherein, The time-depth conversion method in step S1 comprises: Respectively establish the instantaneous velocity model of the microchip capsule in the drill string and the annulus: The instantaneous velocity in the drill string: v pipe = v avg · M turb + V slip wherein v pipe is the instantaneous velocity in the drill string, v avg is the average flow rate of the drilling fluid, M turb is the ratio of the average flow rate to the center flow rate in turbulent flow conditions, V slip is the slip velocity, which is the difference between the velocity of the solid particles in the fluid and the flow rate of the fluid; The instantaneous velocity in the annulus: v ann = v avg • M lam - V slip wherein v ann is the annulus instantaneous velocity, v avg is the average flow rate of the drilling fluid, M lam is the correction factor obtained by iterative correction on site; and iteratively adjusting the correction factor M by comparing the predicted total run time with the actual recovery time judged from the pressure knee lam and outputting a final well depth sequence.

3. The method for identifying and locating a drill string puncture by a while-drilling microchip device according to claim 1, wherein, The theoretical pressure distribution model in step S2 outputs at least the following comparison indicators: pressure value function, pressure consumption function and pressure consumption gradient distribution function, wherein: The calculation formula of the pressure value function is: P surf = P0+ P back Among them, P model (z) represents the theoretical pressure value at well depth z, P surf The total surface pressure at the wellhead is P. surf =P0+P back P0 is the wellhead static pressure, P back This is the surface back pressure, i.e., the additional applied control pressure used for well control balancing. If it is not applied, then P back =0, ρ is the drilling fluid density, g is the gravitational acceleration, θ is the well inclination angle, f(z') is the friction gradient, and z' is the integral variable; The formula is based on the assumption of steady flow, which is suitable for calculating the pressure in the drill string from the wellhead to the bottom and the pressure in the annulus from the bottom to the wellhead, forming a closed loop wellbore pressure profile; Wherein, the pressure calculation is processed in sections: ① In the drill string: Taking the wellhead as the reference point, taking the positive direction along the depth downward, let z be the depth downward from the wellhead, starting from the wellhead pump pressure, adding the static water pressure term ρgΔh(Δh=zcosθ) and the pipe friction gradient term ∫fpipe(z')dz'; ② Drill bit pressure drop: where Q is the displacement, Cd ~ 0.95, A nozzle is the total nozzle area, p is the density of the drilling fluid at the nozzle, and if there are compressibility effects / temperature gradients, the local values should be used; The pressure at this point is related as follows, The pressure at the bottom of the pipe is: P pipe (L); The pressure downstream of the nozzle is: P ann (L) = P pipe (L) - ΔP nozzle ③ Annulus: The annulus pressure from the bottom of the hole at z = L up to any depth z can be derived from the starting value P ann (L) subtract the hydrostatic term and add the annular friction loss along the way; The annulus wellhead pressure is equal to the annulus bottom pressure minus the static water recovery and friction loss accumulated along the upward path, this closed relationship is used to check the consistency of the downlink and uplink pressure profile, and can be used to invert the discharge or flow parameter and model verification under the assumption of steady single-phase; Pressure consumption function and pressure consumption gradient function: The pressure consumption function is defined as the pressure loss of the drilling fluid flowing in the drill string space and the pressure loss of the drilling fluid flowing in the annular space between the drill string and the well wall during drilling, the pressure consumption function ΔP(z) and the pressure consumption gradient g(z) are calculated in sections, the calculation logic is as follows: Drill string pressure consumption: Annulus pressure consumption: wherein, The pressure drop gradient f(z') represents the pressure drop distribution per unit length, which is essentially the derivative dAP / dz of the pressure drop, and is used for local anomaly diagnosis. The gradient, i.e. the friction gradient, can be verified by difference in value, and the calculation logic is as follows: Pressure consumption gradient definition: g(z)=f(z) Drill string and annulus section calculation: Pressure loss gradient in the drill string: g pipe (z) = f pipe (z) Annulus pressure depletion gradient: g ann (z) = f ann (z).

4. The method for identifying and locating a drill string puncture by a while-drilling microchip device according to claim 1, wherein, Before step S3, it also includes a leakage condition judgment step, which divides the pressure measurement cycle into three conditions based on at least one of the following criterion combinations: normal complete cycle, leakage exists but the capsule does not escape, or leakage exists and the capsule escapes early: Maximum depth condition: judging the maximum well depth z recorded by the microchip capsule max Whether it is satisfied: z max ≥H design -ε where z max = max{z k | k = 1, 2, …, N} is the maximum well depth recorded by the microchip capsule throughout the measurement sequence, N is the total length of the data sequence, H design is the designed well depth, and ε is the preset depth deviation tolerance. Return segment existence condition: judge whether there is a return data segment with decreasing depth after the microchip capsule reaches the maximum depth, specifically: such that z j <z i , and |z i -z max |<ε1 where i is the time step in the time series that satisfies |z i - z max | the index of ε1, indicating the time step when the microchip capsule is close to the maximum well depth, j > i is the time step after i, ensuring that z j reflects the change in the depth of the annulus, z j < z i indicates that the depth of the microchip capsule decreases, i.e., it begins to return from the bottom of the well, and ε1 is a preset depth proximity tolerance; Pressure uniformity condition: whether the deviation of the measured pressure P meas (z i ) from the theoretical model pressure P model (z i ) satisfies: Among them, P meas (z i ) for microchip capsules at well depth z i The pressure measured at the point, P model (z i () is the theoretical model at well depth z i The predicted pressure at the location, where ε2 is the preset pressure deviation threshold; Pressure gradient deviation condition: judge whether the pressure gradient deviation satisfies: Wherein, ε3 is a preset pressure gradient deviation threshold.

5. The method for identifying and locating a drill string puncture by a while-drilling microchip device according to claim 4, wherein, The abnormal contrast analysis in the step S3 includes calculating at least one of the following indexes and comparing with the preset threshold value: Pressure difference: ΔP(z i ) = P meas (z) - P model (z) Pressure loss in the drill pipe: Annular pressure loss: Pressure loss gradient in the drill pipe: g pipe (z) = f pipe (z) Annular pressure loss gradient: g ann (z) = f ann (z).

6. The method for identifying and locating a drill pipe puncture by a while-drilling microchip device according to claim 5, wherein, The leak location in step S4 is achieved by fusing the positions of the differential pressure mutation point z ΔP , the pressure consumption mutation point z loss , and the pressure consumption gradient inflection point z grad . When |z ΔP -z loss |<δ and |z loss -z grad |<δ are satisfied, the leak location depth is calculated by the following formula: wherein z leak is the depth of the puncture.

7. The method for identifying and locating a drill string puncture by a while-drilling microchip device according to claim 1, wherein, After the step S4, the step S5 of leakage rate inversion calculation is further included: based on the deviation of the measured pressure data and the theoretical model, the leakage rate η is inversely solved.

8. The method for identifying and locating a drill string puncture by a while-drilling microchip device according to claim 7, wherein, When the microchip capsule completes a complete cycle, the calculation method of the leakage rate η is a nonlinear fitting inversion method, including: S411、adopting a segmented function form to express the leakage point z leak Downstream pipe effective discharge Q eff (z): where Q in is the surface pump displacement and η is the leakage rate. S412、with the corrected displacement Q eff (z) reconstructing the pressure model to obtain a theoretical pressure curve related to the leakage rate η where P surf is the total surface pressure at the wellhead, p is the drilling fluid density, g is the acceleration due to gravity, Q is the inclination angle, f(z'; η) is the friction gradient, and η is the leak-off rate. S413, constructing a target function J(η) in the form of the residual sum of squares between the leakage model pressure and the measured pressure: where P meas (z i ) is the measured pressure value of the microchip capsule, z i is the discrete depth point; S414, solving the optimal leakage rate by minimizing the target function J(η): where η opt is the optimal leak rate.

9. The method for identifying and locating a drill string puncture by a while-drilling microchip device according to claim 8, wherein, Also included are steps of determining an optimal leak rate η opt calculating a leak volume flow Q leak and an equivalent leak hole area A leak based on the optimal leak rate η Q leak = Q in · η opt The differential pressure ΔP at the point of leakage is known leak = P pipe - P ann where ΔP leak is the differential pressure inside and outside the drill pipe at the point of leakage z leak P pipe and P ann are the pressures inside the drill pipe and annulus respectively at that depth point, then the equivalent leak area can be estimated: where C d is the flow coefficient and p is the mud density.

10. The method for identifying and locating a drill string puncture by a while-drilling microchip device according to claim 7, wherein, When the microchip capsule escapes in advance at the leakage point, the calculation method of the leakage rate η is a residual fitting method, including the following steps: S421. recording the maximum depth z reached by the microchip capsule during the downward movement max and the corresponding maximum pressure P max ; S422, construct a local puncture correction model for calculating the theoretical pressure related to the puncture rate variable η The formula is: where P surf is the total surface pressure at the wellhead, p is the drilling fluid density, g is the acceleration due to gravity, Q is the inclination angle, f(z'; η) is the friction gradient, and η is the leak-off rate. S423、 Through iterative adjustment of the leakage rate variable η, find the minimum solution η that satisfies the condition est and take it as the estimated leakage rate.

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