Oil well yield monitoring method and system based on tracer injection concentration

Abstract

The invention relates to the technical field of oil well fluid channeling monitoring based on a tracer agent, in particular to an oil well yield monitoring method and system based on the injection concentration of the tracer agent. The method comprises the following steps: recording a pulse concentration total response sequence; the injection historical record and the output concentration of the background tracer agent are further compared, and a dynamic hydraulics baseline parameter set is constructed; further performing singular value decomposition on the current pulse concentration total response sequence to reconstruct a single-path concentration response sequence; further constructing a hydraulics feature set according to each single-path concentration response sequence in combination with a dynamic hydraulics baseline parameter set; further carrying out pairwise paired Granger causality test on all single-path concentration response sequences, and constructing a concurrent fluid channeling path system feature set in combination with a hydraulics feature set; and finally, a produced water source composition report is generated, the produced water source is quantitatively revealed, the transient channel structure of the oil reservoir is accurately reflected, and a reliable basis is provided for water plugging treatment and injection-production optimization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of monitoring oil well channeling based on tracers, and particularly relates to an oil well production monitoring method and system based on tracer injection concentration. BACKGROUND

[0002] The inherent heterogeneity of reservoir media, especially the existence of natural or artificial fractures, high-permeability channels and other advantage channels, can make the injected polymer solution flow along these advantage channels easily, causing channeling, and the polymer solution can quickly and inefficiently circulate to the production well without sufficient oil displacement, which not only causes waste of chemical agents, but also seriously reduces the economic benefits of the overall oil displacement project.

[0003] The existing method generally indirectly evaluates the development effect by periodically sampling the polymer concentration and other macroscopic indicators in the produced liquid at the production well at a low frequency. This method is essentially a lag observation of the average response of the reservoir at a long time scale, and cannot distinguish the concurrent channeling system activated by a single injection event, which is composed of multiple paths with different properties, nor can it determine the topological relationship between these paths, resulting in that the diagnosis of channeling and the evaluation of production always remain at a general and vague level, leading to high cost and low efficiency of the treatment scheme. SUMMARY

[0004] In order to solve the technical problem that the existing monitoring and analysis of channeling events are not deep enough, resulting in high cost and low efficiency of the treatment scheme, the purpose of the present application is to provide an oil well production monitoring method and system based on tracer injection concentration, and the technical solution adopted is as follows: An oil well production monitoring method based on tracer injection concentration, the method comprising: continuously and constantly injecting a background tracer and injecting a pulse tracer according to the pressure fluctuation of the injection pipeline; monitoring the output concentration of the background tracer and the pulse tracer; comparing the output concentration of the pulse tracer based on a preset noise threshold, recording a total pulse concentration response sequence; comparing the injection history record of the background tracer with the output concentration in the current preset historical neighborhood, constructing a dynamic hydrodynamic baseline parameter set; singular value decomposition is performed on the current total pulse concentration response sequence to reconstruct a single-path concentration response sequence; constructing a hydrodynamic feature set according to each single-path concentration response sequence combined with the dynamic hydrodynamic baseline parameter set; performing pairwise Granger causality test on all single-path concentration response sequences, and constructing a concurrent channeling path system feature set combined with the hydrodynamic feature set; In the current preset monitoring period, the total liquid production and the total water production are monitored, and all the total response sequences of the pulse concentration and the corresponding concurrent channeling path system characteristics set are combined to analyze the invalid circulation amount of the pore type and the fracture type in the total invalid circulation water amount, and a report on the composition of the produced water source is generated.

[0005] Further, the method for obtaining the dynamic hydrodynamic baseline parameter set comprises: The injection history of the background tracer and the two sequences of the produced concentration are deconvoluted to obtain the average transit time of the background tracer mass center and the time variance of the response curve in the preset historical neighborhood, and are input into an exponential moving average filter to output the dynamic baseline transit time and the dynamic baseline dispersion, thereby constituting the dynamic hydrodynamic baseline parameter set.

[0006] Further, the method for obtaining the single-path concentration response sequence comprises: The total response sequence of the pulse concentration is converted into a hydrodynamic trajectory matrix through a time delay embedding technique; The hydrodynamic trajectory matrix is singular value decomposed, the singular values in the diagonal matrix obtained by the decomposition are arranged in descending order, the singular values are accumulated in descending order until a preset energy ratio is first reached, the singular values participating in the accumulation are reserved and the number of concurrent paths is determined; Each reserved singular value, the corresponding left singular vector and the right singular vector are combined and reconstructed to obtain a single-path concentration response sequence corresponding to each reserved singular value.

[0007] Further, the method for obtaining the hydrodynamic characteristic set comprises: For each single-path concentration response sequence: a relative velocity index is obtained according to the difference between the time from injection to the occurrence of the concentration peak and the average transit time; a relative dispersion index is obtained according to the difference between the time variance of the single-path concentration response sequence and the dynamic baseline dispersion; and the proportion of the square of the singular value in the total sum of the squares of all the singular values of the single-path concentration response sequence is taken as the path dominance rate; The relative velocity index, the relative dispersion index and the path dominance rate constitute the hydrodynamic characteristic set of the single-path concentration response sequence.

[0008] Further, the method for obtaining the concurrent channeling path system characteristic set comprises: A Granger causality test is performed on all the single-path concentration response sequences in pairs to obtain a causality matrix; the sum of all element values of the corresponding prediction relationship of each single-path concentration response sequence in the causality matrix is taken as the convergence center score; and the sum of all non-diagonal elements in the causality matrix is normalized, and the normalized result is taken as the system convergence index. The merging center score, the system merging index, the total number of the single-path concentration response sequences, and the set of hydrodynamic characteristics of each of the single-path concentration response sequences are constructed into a concurrent channeling path system characteristic set.

[0009] Further, the method for generating the produced water source composition report comprises: In the current preset monitoring period, each pulse injection event is taken as a target event; For the target event, the pulse concentration total response sequence and the total produced fluid volume synchronously collected are fused to obtain the pulse tracer total mass of the target event; the product of the proportion value of the total mass of the pulse tracer recovered to the total mass of the pulse tracer at the time of injection and the total mass of all tracers injected in the process of injecting the pulse tracer is taken as the total ineffective circulation volume; the total ineffective circulation volume is divided into each of the single-path concentration response sequences according to the path dominance rate to obtain a single-path leakage volume; When the system merging index is less than or equal to a preset merging index threshold value, the single-path leakage volume is respectively added into a pore-type ineffective circulation amount and a fracture-type ineffective circulation amount based on the relative dispersion index; When the system merging index is greater than the preset merging index threshold value, the single-path leakage volume corresponding to the maximum relative dispersion index is taken as a main channel ineffective circulation amount, and the single-path leakage volumes corresponding to the remaining relative dispersion indexes are added into an upstream tributary ineffective circulation amount; Based on the total produced water volume in the preset monitoring period and various ineffective circulation amounts of all the target events, a produced water source composition report is generated.

[0010] Further, the method for respectively adding the single-path leakage volume into the pore-type ineffective circulation amount and the fracture-type ineffective circulation amount based on the relative dispersion index comprises: The relative dispersion indexes are classified based on a preset dispersion threshold value, the sum of the single-path leakage volumes corresponding to the relative dispersion indexes greater than or equal to the preset dispersion threshold value is taken as a pore-type ineffective circulation amount, and the sum of the single-path leakage volumes corresponding to the relative dispersion indexes less than the preset dispersion threshold value is taken as a fracture-type ineffective circulation amount.

[0011] Further, the method for recording the pulse concentration total response sequence comprises: When the produced concentration of the pulse tracer first exceeds a preset noise threshold value, the produced concentration sequence of the pulse tracer is started to be recorded, and the recording is stopped until the produced concentration is lower than the preset noise threshold value and lasts for a preset stable duration, so as to obtain a pulse concentration total response sequence.

[0012] Further, the method of injecting a pulse tracer according to the injection pipeline pressure fluctuation comprises: When the injection pipeline pressure reaches a preset pressure ratio of the average pressure of the preset first neighborhood, the pulse tracer is injected, and the injection is stopped after a preset single injection duration.

[0013] The present application also provides an oil well production monitoring system based on tracer injection concentration, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of any one of the oil well production monitoring methods based on tracer injection concentration.

[0014] The present application has the following advantages: The present application first adopts a double tracer strategy to separate at the data source, which is convenient for more accurate determination of abnormal events; further records the total response sequence of the pulse concentration based on a preset noise threshold to avoid false small fluctuations caused by measurement jitter or instrument drift from being misjudged as channel response, thereby narrowing the analysis range; further constructs a dynamic hydrodynamic baseline parameter set to provide a reference standard for subsequent analysis; further performs singular value decomposition on the current total response sequence of the pulse concentration to reconstruct a single-path concentration response sequence to capture more detailed channel structures; further constructs a hydrodynamic feature set according to each single-path concentration response sequence in combination with the dynamic hydrodynamic baseline parameter set to automatically eliminate systematic drift caused by overall reservoir evolution and improve the resolution and interpretation of channeling diagnosis; further performs pairwise Granger causality test on all single-path concentration response sequences in combination with the hydrodynamic feature set to construct a concurrent channeling path system feature set, which provides complete and quantitative input basis for subsequent analysis of the source composition of produced water; finally, integrates the concurrent channeling path system feature set and the monitoring data to generate a report on the source composition of produced water. The present application realizes concurrent channeling path identification and feature extraction by combining injection and high-frequency monitoring, using noise threshold screening, dynamic baseline, singular value decomposition, and Granger causality test, quantitatively reveals the source of produced water, accurately reflects the transient channel structure of the reservoir, and provides reliable basis for water plugging management and injection-production optimization. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, and the advantages thereof, a brief introduction will be given to the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on these drawings.

[0016] Figure 1 A flowchart of an oil well production monitoring method based on tracer injection concentration provided by an embodiment of the present application; Figure 2 A flow chart of a single-path concentration response sequence acquisition method provided by an embodiment of the present application; Figure 3 A flow chart of a method for generating a produced water source composition report provided by an embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to further clarify the technical means and effects taken by the present application to achieve the predetermined inventive purpose, the following describes in detail the specific embodiments, structure, features and effects of the oil well production monitoring method and system based on tracer injection concentration according to the present application, with reference to the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0019] The specific scheme of the oil well production monitoring method and system based on tracer injection concentration provided by the present application is described in detail below with reference to the accompanying drawings.

[0020] Please refer to Figure 1 which shows a flow chart of an oil well production monitoring method based on tracer injection concentration provided by an embodiment of the present application, specifically including: Step S1: continuously injecting background tracer and injecting pulse tracer according to injection pipeline pressure fluctuation; monitoring the produced concentration of background tracer and pulse tracer.

[0021] Because the overall pressure field and saturation field of the oil reservoir will slowly evolve in the long-term water injection development process, the main migration characteristics of interwell fluid are not a fixed constant, and if an early, static parameter is used as a judgment standard, it will inevitably lead to misjudgment of later events. At the same time, the opening or penetration of the dominant channel caused by injection pressure fluctuation is also instantaneous. Therefore, in an embodiment of the present application, a double-tracer injection strategy is adopted to separate "background" and "events" at the data source.

[0022] On the ground injection pipeline of the injection well, a double-tracer injection unit controlled by the central system is deployed. The injection unit is responsible for executing two independent injection logics, continuously injecting background tracer and injecting pulse tracer according to injection pipeline pressure fluctuation.

[0023] At the wellhead of the production well corresponding to the injection well, an online monitoring unit is installed to record and time-stamp synchronously at a high acquisition frequency of minute level. Since the dominant channels opened in the formation due to pressure fluctuation can be transient, their response at the production well can be very short, and the key modality information of such events can be completely missed or distorted by conventional low-frequency sampling, and the subsequent signal separation algorithm requires high-resolution data to construct an effective analysis matrix. The monitoring unit needs to acquire the following three time series data: the background tracer A production concentration C_A,prod(t), the pulse tracer B production concentration C_B,prod(t) and the total production liquid volume Q_total(t) of the production well.

[0024] Preferably, in an embodiment of the present application, in order to continuously track the changes of macroscopic percolation characteristics of the reservoir body, the system continuously injects an inert background tracer A into the injection fluid at a known, long-term constant mass flow rate, so as to maintain a traceable, slowly changing concentration background field of the tracer in the entire interwell swept region.

[0025] In order to specifically mark the fluid in the dominant channels that can be activated due to abnormally high pressure conditions, the system links the injection logic of the pulse tracer B to the injection line pressure P_inj(t). When the system detects that P_inj(t) is high within a set time window, it automatically triggers an injection of the pulse tracer B.

[0026] Specifically: when the injection line pressure reaches a preset pressure ratio of the average pressure of the preset first neighborhood, the injection of the pulse tracer is started, and the injection is stopped after a preset single injection duration.

[0027] As an example, the preset first neighborhood is the last 24 hours, the preset pressure ratio is 110%, and the preset single injection duration is 10 minutes. When the injection line pressure reaches 110% of the average pressure of the last 24 hours, there can be a high pressure condition of opening of micro-fractures in the formation or flushing of dominant channels, and the injection is stopped after the preset single injection duration, and the system records the injection start time t_inj,i and the total mass of the injected pulse tracer M_B_inj,i for each pulse injection event i. When the injection reaches the preset single injection duration, the pulse tracer injection condition is still met, and the injection is continued for the preset single injection duration.

[0028] It should be noted that in an embodiment of the present application, the acquisition frequency of the monitoring unit is set to 1 time per 10 seconds, the background tracer A is NaBr, which is injected at a constant rate of 1 mg / L, and the pulse tracer B is fluorobenzoate (3-FBA), which is continuously injected at a rate of 30 mg / L for 10 minutes.

[0029] In other embodiments of the present application, the implementer can adjust the preset first neighborhood, the preset pressure ratio, the preset single injection duration, the types of the tracers A and B, the injection scheme, and the acquisition frequency, which will not be described herein.

[0030] Step S2: record the total response sequence of the pulse concentration based on the preset noise threshold compared with the output concentration of the pulse tracer; compare the injection history record of the background tracer with the output concentration within the current preset historical neighborhood to construct a set of dynamic hydrodynamic baseline parameters; perform singular value decomposition on the current total response sequence of the pulse concentration to reconstruct a single-path concentration response sequence; construct a set of hydrodynamic characteristics based on each single-path concentration response sequence in combination with the set of dynamic hydrodynamic baseline parameters; perform pairwise Granger causality test on all single-path concentration response sequences in combination with the set of hydrodynamic characteristics to construct a set of concurrent channeling path system characteristics.

[0031] The overall purpose of Step S2 is to perform a progressive analysis from decomposition, qualitative analysis, quantitative analysis to structural diagnosis on the complex response signal marked by the pulse tracer B in S1, which may be caused by multiple concurrent dominant channels, to reveal the complete systematic characteristics behind the transient channeling event.

[0032] Therefore, first, record the total response sequence of the pulse concentration based on the preset noise threshold compared with the output concentration of the pulse tracer to avoid false small fluctuations caused by measurement jitter or instrument drift from being misjudged as channel responses, thereby narrowing the analysis range and providing an analysis basis for the subsequent analysis.

[0033] Preferably, in one embodiment of the present application, during the stable production of the pulse tracer B, the output concentration of B is collected for a period of time (such as 24 hours), and based on the 3σ principle, the sum of the mean value and three times the standard deviation of this data is taken as the preset noise threshold. When the output concentration of the pulse tracer first exceeds the preset noise threshold, start recording the output concentration sequence of the pulse tracer, and stop recording when the output concentration is lower than the preset noise threshold and continues for a preset stable duration to obtain the total response sequence of the pulse concentration.

[0034] In other embodiments of the present application, the preset noise threshold can also be set according to the empirical value, and the preset stable duration can be adjusted, which will not be described herein.

[0035] When the total response sequence of the pulse concentration starts to be recorded, it indicates that there is an abnormally high pressure working condition event, and in-depth analysis is needed. Since the macroscopic percolation characteristics of the oil reservoir will slowly drift with the development process, a reference benchmark that can be updated adaptively over time must be established to accurately peel off the "abnormal" properties of transient events, so within the current preset historical neighborhood, the injection history of the background tracer is compared with the output concentration to construct a dynamic hydrodynamic baseline parameter set for subsequent reference, wherein the current corresponds to the occurrence time of the current event (recorded pulse concentration total response sequence).

[0036] Preferably, in an embodiment of the present application, the preset historical neighborhood is 24 hours of historical neighborhood; the deconvolution calculation of the two sequences of the injection history record and the output concentration of the background tracer can restore the "impulse response function (response curve)" of the oil reservoir to the injected signal, and the centroid position (weighted average position on the time axis) of the impulse response function can obtain the average transit time, which represents the average migration time of the fluid through the main pore network of the oil reservoir; the time variance of the impulse response function can obtain the dispersivity, which represents the degree of response broadening (degree of dispersion and diffusion) caused by convection and dispersion when the fluid passes through the main pore network of the oil reservoir; In addition, considering that the single deconvolution result is easily affected by noise, short-term abnormalities or local disturbances, the exponential moving average filter can perform weighted smoothing on the transit time and the dispersivity, so that the parameters are slowly updated over time, retaining the long-term trend and weakening the occasional fluctuations, ensuring the continuity and stability of the dynamic baseline; Therefore, by means of the deconvolution calculation result, the average transit time of the centroid of the background tracer in the preset historical neighborhood and the time variance of the response curve are obtained and input into the exponential moving average filter, and the dynamic baseline transit time and the dynamic baseline dispersivity are output to form the dynamic hydrodynamic baseline parameter set, providing a reference basis for subsequent analysis, making the peeling, decomposition and diagnosis of abnormal events more accurate and reliable.

[0037] It should be noted that the time variance is the variance of the elements in the time series, and deconvolution and exponential moving average filtering are prior art and will not be described again.

[0038] It should be noted that the analysis process for constructing the dynamic hydrodynamic baseline parameter set is consistent for each time, and only one example is described here. The update frequency can be consistent with the data acquisition frequency; or a fixed periodical update can be set, and a supplementary update can be performed when recording the pulse concentration total response sequence, which will not be described again.

[0039] Due to single high-pressure injection pulse in heterogeneous formation, a main fracture and several secondary high-permeability zones can be simultaneously penetrated or activated, and the transport characteristics of these different channels are different, so the tracer responses of these different channels are superimposed at the end of the production well, forming a complex pulse concentration total response sequence, which cannot be directly analyzed. Therefore, the singular value decomposition method is used to separate the main transport components from the mixed signal, reconstruct the single-path concentration response sequence, and capture the more detailed channel structure.

[0040] Preferably, in one embodiment of the present application, please refer to Figure 2 , which shows a flow chart of a method for obtaining a single-path concentration response sequence according to an embodiment of the present application, which specifically includes: Step S201: converting the pulse concentration total response sequence into a hydrodynamic trajectory matrix by using time delay embedding technology.

[0041] In order to apply singular value decomposition, a one-dimensional time series needs to be converted into a two-dimensional matrix. In this embodiment, the time delay embedding technology is used to convert the pulse concentration total response sequence into a hydrodynamic trajectory matrix; Specifically, by intercepting d consecutive data points in the pulse concentration total response sequence to form a row vector, and sliding with a time step τ to generate subsequent rows until the end of the sequence. Wherein, τ takes the value of the first time the autocorrelation function of the pulse concentration total response sequence drops to zero, and d is determined by the pseudo-neighbor point method to ensure that the dynamic structure can be fully unfolded in the embedding space.

[0042] Step S202: singular value decomposition is performed on the hydrodynamic trajectory matrix, and the singular values in the diagonal matrix obtained by the decomposition are arranged in descending order. The singular values are accumulated from large to small, and the singular values participating in the accumulation are retained and the number of concurrent paths is determined until the preset energy ratio is first reached.

[0043] The preset energy ratio is set to 99%, and the numerical value of the singular value reflects the energy proportion of each transport component in the total response signal. By analyzing the energy distribution of the singular value spectrum, the singular values whose cumulative energy contribution reaches 99% of the total energy are retained, and the number k is defined as the number of concurrent paths of this event; Specifically, the singular values are accumulated from large to small until the preset energy ratio is first reached, the singular values participating in the accumulation are retained, and the number of concurrent paths is determined, which quantitatively represents the number of concurrent dominant channels activated by the (pulse) injection event.

[0044] Step S203: combination reconstruction based on each retained singular value, corresponding left singular vector and right singular vector to obtain a single-path concentration response sequence corresponding to each retained singular value.

[0045] After determining the number of concurrent paths, it is also necessary to restore these abstract mathematical components to the response sequence with clear hydraulic significance and to perform feature calculation; Specifically, for each single-path concentration response sequence, the outer product matrix of singular value, left singular vector and transposed right singular vector is obtained, and then the diagonal average is performed to obtain the corresponding single-path concentration response sequence. Wherein, when performing diagonal average, for each time point t of the single-path concentration response sequence, the arithmetic average of all elements X(p, q) in the outer product matrix satisfying p+q-1=t is taken, and p and q are the horizontal and vertical coordinates in the matrix respectively.

[0046] Obtaining the single-path concentration response sequence corresponding to each preserved singular value can be regarded as assuming that the tracer B only passes through a single path, and the expected concentration change curve (sequence) of the production well is obtained. At this point, the number of potential independent fluid paths is obtained, and the relative importance of the single path is quantified by means of singular value.

[0047] It should be noted that the time delay embedding technique and singular value decomposition are well-known techniques and will not be described again.

[0048] Each single-path concentration response sequence provides a potential independent fluid migration path, corresponding to a single path, which contains the specific response form of the path in the time domain, and the dynamic hydraulic baseline parameter set provides a reference system. According to each single-path concentration response sequence combined with the dynamic hydraulic baseline parameter set, a set of hydraulic characteristics is constructed, which automatically eliminates the systematic drift caused by the overall reservoir evolution, and improves the resolution and interpretation of channeling diagnosis.

[0049] Preferably, in an embodiment of the present application, for each single-path concentration response sequence: according to the difference between the time from injection to the appearance of the concentration peak and the average transit time, the multiple of the flow rate of the corresponding path relative to the main background (indicator A) is reflected, so as to obtain the relative velocity index; According to the difference between the time variance of the single-path concentration response sequence and the dynamic baseline dispersion, whether the dispersion / mixing degree of the material in the channel is abnormal is reflected, and the relative dispersion index is obtained; Considering that the singular value represents the energy proportion (contribution rate) of the path, in order to distinguish the dominant degree of different single paths, the proportion of the square of the singular value in the total sum of the squares of the singular values of all single-path concentration response sequences is taken as the path dominance rate; The relative velocity index, the relative dispersion index and the path dominance rate constitute the hydraulic characteristic set of the single-path concentration response sequence.

[0050] As an example, to express the difference between data in the form of a ratio, for each single-path concentration response sequence: take the average transit time as the numerator, take the time from injection to the appearance of the concentration peak as the denominator, and take the fractional ratio as the relative velocity index; Take the time variance of the single-path concentration response sequence as the numerator, take the dynamic baseline dispersion as the denominator, and take the fractional ratio as the relative dispersion index; the relative dispersion index is used to distinguish between fracture-type flow and pore-type flow, and the relative dispersion index of the fracture-type flow is much smaller than 1, and the relative dispersion index of the pore-type flow is approximately equal to 1.

[0051] To explore whether there is a structural association between these concurrent paths, for example, in a complex fracture network underground, multiple upstream secondary channels may eventually converge into a downstream main channel, and this “converging” structure is quite different from multiple “parallel” channels that are not related to each other in subsequent engineering management strategies.

[0052] Therefore, the single-path concentration response sequences are further paired, the Granger causality test of all pairs of single-path concentration response sequences is performed, and a concurrent channeling path system feature set is constructed in combination with the set of hydraulic characteristics, thereby providing complete and quantitative input basis for subsequent analysis of the source composition of produced water.

[0053] Preferably, in an embodiment of the present application, the Granger causality test of all pairs of single-path concentration response sequences is performed, that is, the single-path concentration response sequences are combined in pairs for testing to obtain a causality matrix; the element M(m, n) in the matrix reflects the degree of contribution of the past value of path m to the future value of path n, and path n corresponds to the prediction relationship. Based on the causality matrix, topological structure features are further extracted: The sum of all element values of each single-path concentration response sequence in the causality matrix corresponding to the prediction relationship is taken as the hub score; as an example: S_hub,i,s represents the hub score of the s th path in the i th event, S_hub,i,s = ΣM(m, s), where Σ is the summation symbol, and the summation is performed on all m≠s. This score quantifies the possibility of the s th path as a downstream “main road” or “hub”.

[0054] After normalizing the sum of all non-diagonal elements in the causality matrix, the normalized result is taken as the system convergence index; the diagonal element refers to the element in the causality matrix where the horizontal coordinate and the vertical coordinate are the same, representing the causality relationship of a path to itself, and the non-diagonal element refers to the element where the horizontal coordinate and the vertical coordinate are different, representing the causality value between the path and other different paths.

[0055] Wherein the normalization is linear normalization, and it is a prior art to construct the sum of all non-diagonal elements in the causality matrix of all historical events as a data dimension, and to normalize in the data dimension, which will not be described here.

[0056] Finally, the merging center score of each single-path concentration response sequence, the system merging index, the total number of single-path concentration response sequences, and the set of hydrodynamic characteristics are constructed into the concurrent channeling path system characteristic set. The concurrent channeling path system characteristic set includes the number of concurrent paths (the total number of single-path concentration response sequences), the relative velocity index of each single path, the relative dispersion index and the path dominance, the merging center score of each path, and the system merging index.

[0057] It should be noted that Granger causality test is a known technology and will not be described here.

[0058] Step S3: In the current preset monitoring period, monitor the total liquid production and total water production, and combine all pulse concentration total response sequences and the corresponding concurrent channeling path system characteristic set to analyze the pore type and fracture type ineffective circulation amount in the total ineffective circulating water amount, and generate a produced water source composition report.

[0059] In step S2, the pulse concentration total response sequence is divided into several single-path concentration response sequences by singular value decomposition combined with baseline reference, and they are labeled with hydrodynamic characteristic tags in the hydrodynamic characteristic set, and further structural constraints are provided in the concurrent channeling path system characteristic set. Finally, in the current preset monitoring period, the total liquid production and total water production are monitored, and all pulse concentration total response sequences and the corresponding concurrent channeling path system characteristic set are combined to analyze the pore type and fracture type ineffective circulation amount in the total ineffective circulating water amount, and generate a produced water source composition report, which provides a path-level quantitative basis for engineering guidance and provides a deeper decision basis, so as to develop a more suitable treatment scheme, reduce the cost of the scheme, and improve the efficiency of the scheme.

[0060] Preferably, in an embodiment of the present application, please refer to Figure 3 which shows a method flowchart for generating a produced water source composition report provided by an embodiment of the present application, specifically comprising: Step S301: In the current preset monitoring period, each pulse injection event is taken as a target event.

[0061] Each pulse injection event is analyzed, and in this case, each pulse injection event is taken as a target event, and the current (latest) pulse injection event is taken as a target event, which will not be described repeatedly.

[0062] Step S302: For the target event, fuse the pulse concentration total response sequence and the synchronously collected total liquid production to obtain the total recovery mass of the pulse tracer of the target event; multiply the proportion of the total recovery mass of the pulse tracer to the total mass of the pulse tracer at the time of injection by the total mass of all tracers injected in the process of injecting the pulse tracer to obtain the total ineffective circulation volume; and divide the total ineffective circulation volume according to the path dominance rate to each single-path concentration response sequence to obtain the single-path leakage volume.

[0063] In order to associate the concurrent channeling path system feature set obtained in step S2 with the actual liquid production, path-specific ineffective circulation water volume calculation is required. Based on the principle of material balance, the total ineffective circulation water volume caused by a single complex channeling event (pulse injection event) is allocated according to the contribution proportion of each path. Specifically: First, the pulse concentration total response sequence C_B,i(t) is fused with the synchronously collected total liquid production Q_total(t) to obtain the total recovery mass M_B,rec_total,i of the pulse tracer of the target event (the serial number corresponds to i), and the calculation formula is: The integral interval is from the start time to the end time of the pulse concentration total response sequence of the event.

[0064] Further, the proportion of the total recovery mass M_B,rec_total,i of the pulse tracer to the total mass M_B,inj,i of the pulse tracer at the time of injection is multiplied by the total mass V_inj_pulse,i of all tracers injected in the process of injecting the pulse tracer to obtain the total ineffective circulation volume V_leak_total,i.

[0065] It should be noted that the pulse concentration total response sequence is matched with the most recent pulse injection event; in another embodiment of the present application, the implementer can also obtain the time interval between the start time of the pulse concentration total response sequence and the start time of the historical pulse injection event based on the dynamic baseline transit time, and match the pulse concentration total response sequence corresponding to the time interval closest to the dynamic baseline transit time with the most recent pulse injection event; in other embodiments of the present application, the implementer can use multiple pulse tracers alternately to reduce the possibility of event matching errors.

[0066] Finally, the total ineffective circulation volume is divided according to the path dominance rate to each single-path concentration response sequence to obtain the single-path leakage volume.

[0067] As an example, the product of the path dominance of each single path and the total volume of invalid circulation is taken as the single path leakage volume of each single path.

[0068] Step S303: When the system convergence index is less than or equal to the preset convergence index threshold, the single path leakage volume is respectively added to the pore type invalid circulation amount and the fracture type invalid circulation amount based on the relative dispersion index; when the system convergence index is greater than the preset convergence index threshold, the single path leakage volume corresponding to the maximum relative dispersion index is taken as the trunk invalid circulation amount, and the single path leakage volumes corresponding to the remaining relative dispersion indexes are added to the upstream tributary invalid circulation amount.

[0069] Since the engineering treatment countermeasures for the "parallel" channel system and the "convergent" channel system are completely different, it is necessary to distinguish them at the production monitoring level.

[0070] When the system convergence index is less than or equal to the preset convergence index threshold, it indicates that there is no significant convergence relationship between the paths of the target event, which is dominated by a parallel channel channeling system, and the single path leakage volume is respectively added to the pore type invalid circulation amount and the fracture type invalid circulation amount based on the relative dispersion index. Considering that the relative dispersion index of the fracture type flow state is much smaller than 1, and the relative dispersion index of the pore type flow state is approximately equal to 1, the relative dispersion index is classified based on the preset dispersion threshold, and the sum of the single path leakage volumes corresponding to the relative dispersion indexes greater than or equal to the preset dispersion threshold is taken as the pore type invalid circulation amount; the sum of the single path leakage volumes corresponding to the relative dispersion indexes less than the preset dispersion threshold is taken as the fracture type invalid circulation amount.

[0071] When the system convergence index is greater than the preset convergence index threshold, it indicates that there is a downstream trunk (such as a plurality of fractures converging into a main channel) in the target event, the single path leakage volume corresponding to the maximum relative dispersion index is taken as the trunk invalid circulation amount, and the single path leakage volumes corresponding to the remaining relative dispersion indexes are added to the upstream tributary invalid circulation amount.

[0072] It should be noted that in an embodiment of the present application, the system convergence index of historical events can be collected, a distribution histogram is drawn, and in theory, the distribution presents a bimodal peak, so the system convergence index value corresponding to the valley between the bimodal peaks is taken as the preset convergence index threshold; the relative dispersion indexes of historical events are collected, and the maximum inter-class variance method is used to obtain the preset dispersion threshold; In other embodiments of the present application, the implementer can set an empirical value as the preset convergence index threshold, and can also establish a numerical model of a typical channeling system (such as parallel fractures or tree-shaped fracture network), simulate the system convergence index theoretical value of each model, and take the point with the largest discrimination as the threshold.

[0073] Step S304: generating a produced water source composition report based on the total produced water volume and the various invalid circulation volumes of all target events within the preset monitoring period.

[0074] Finally, the various invalid circulation volumes are integrated, combined with the total produced water volume, to obtain the effective displacement water volume, and a produced water source composition report is generated.

[0075] Specifically, the preset monitoring period is set to 24 hours, and a produced water source composition report is generated every 24 hours, or a report is generated using the data of the last 24 hours at the end of each pulse injection event. The sum of the various invalid circulation volumes of all events within the preset monitoring period currently being analyzed is taken as the total invalid circulation water volume, and the difference between the total produced water volume and the total invalid circulation water volume is taken as the effective displacement water volume.

[0076] The report is subdivided into: · Effective displacement water: [percentage %] · Invalid circulation water: [percentage %] Pore type invalid circulation contribution: [percentage %] Fracture type invalid circulation contribution: [percentage %] Contribution from upstream tributaries: [percentage %] Contribution from the main channel: [percentage %] Among them, the invalid circulation water corresponds to the total invalid circulation water volume. In other embodiments of the present application, the implementer can set other report styles, which will not be described again.

[0077] The report realizes deep and dynamic monitoring of the "quality" of oil well production, provides direct and quantitative data support for managers to optimize injection and production parameters, and provides an evaluation benchmark for the effectiveness evaluation of subsequent profile control and water plugging engineering measures, forming a complete "monitoring-diagnosis-decision-evaluation" closed loop.

[0078] One embodiment of the present application also provides an oil well production monitoring system based on tracer injection concentration, which comprises a memory, a processor and a computer program, wherein the memory is used to store the corresponding computer program, the processor is used to run the corresponding computer program, and the computer program can realize the oil well production monitoring method based on tracer injection concentration described in steps S1-S3 when running in the processor.

[0079] In summary, in view of the technical problems that the monitoring and analysis depth of the existing cross-flow events is insufficient, resulting in high cost and low efficiency of the treatment scheme, the present application provides an oil well production monitoring method and system based on tracer injection concentration, which first compares the output concentration of the contrast pulse tracer based on a preset noise threshold, records the total response sequence of the pulse concentration, further compares the injection history record of the background tracer with the output concentration, constructs a dynamic hydrodynamic baseline parameter set, further singular value decomposes the current total response sequence of the pulse concentration, reconstructs the single-path concentration response sequence, further constructs a hydrodynamic feature set according to each single-path concentration response sequence combined with the dynamic hydrodynamic baseline parameter set, further performs pairwise Granger causality test on all single-path concentration response sequences, combines the hydrodynamic feature set to construct a concurrent cross-flow path system feature set, and finally integrates the concurrent cross-flow path system feature set and the monitoring data to generate a production water source composition report. The present application realizes concurrent cross-flow path identification and feature extraction by combining injection and high-frequency monitoring, using noise threshold screening, dynamic baseline, singular value decomposition and Granger causality test, quantitatively reveals the production water source, accurately reflects the transient channel structure of the oil reservoir, and provides a reliable basis for water plugging treatment and injection-production optimization.

[0080] It should be noted that the above-mentioned sequence of the embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are possible or can be advantageous.

[0081] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment mainly describes the differences from other embodiments.

Claims

1. A method of monitoring the production of an oil well based on the concentration of a tracer injected into the well, characterized in that, The method comprises: continuously injecting a background tracer and injecting a pulse tracer according to injection pipeline pressure fluctuations; monitoring the output concentration of the background tracer and the pulse tracer; comparing the output concentration of the pulse tracer with a preset noise threshold, recording a pulse concentration total response sequence; comparing the injection history of the background tracer with the output concentration within a current preset historical neighborhood, constructing a dynamic hydrodynamic baseline parameter set; singular value decomposition of the current pulse concentration total response sequence to reconstruct a single-path concentration response sequence; constructing a hydrodynamic feature set according to each single-path concentration response sequence combined with the dynamic hydrodynamic baseline parameter set; performing pairwise Granger causality test on all single-path concentration response sequences, and constructing a concurrent channeling path system feature set combined with the hydrodynamic feature set; monitoring the total liquid production and the total water production within a current preset monitoring period, and analyzing the invalid circulation amount of the pore type and the fracture type in the total invalid circulation water amount combined with all pulse concentration total response sequences and the corresponding concurrent channeling path system feature set, and generating an output water source composition report.

2. A method of monitoring the production of an oil well based on the concentration of a tracer injected into the well as claimed in claim 1, wherein, The method for obtaining the dynamic hydrodynamic baseline parameter set comprises: deconvolution calculation on the two sequences of the injection history of the background tracer and the output concentration to obtain the average transit time of the background tracer centroid and the time variance of the response curve within a preset historical neighborhood, and input into an exponential moving average filter to output a dynamic baseline transit time and a dynamic baseline dispersion, which constitute the dynamic hydrodynamic baseline parameter set.

3. The method of claim 1, wherein, The method for obtaining the single-path concentration response sequence comprises: converting the pulse concentration total response sequence into a hydrodynamic trajectory matrix through time delay embedding technology; singular value decomposition is performed on the hydrodynamic trajectory matrix, the singular values in the diagonal matrix obtained by decomposition are arranged from large to small, and the singular values are accumulated from large to small until the first preset energy ratio is reached, the singular values participating in accumulation are reserved and the number of concurrent paths is determined; each reserved singular value, the corresponding left singular vector and the right singular vector are combined and reconstructed to obtain the single-path concentration response sequence corresponding to each reserved singular value.

4. The method of claim 2, wherein, The method for obtaining the hydrodynamic feature set comprises: for each single-path concentration response sequence: obtaining a relative velocity index according to the difference between the time from injection to the appearance of the concentration peak and the average transit time; obtaining a relative dispersion index according to the difference between the time variance of the single-path concentration response sequence and the dynamic baseline dispersion; taking the proportion of the square of the singular value in the total sum of the squares of all singular values of the single-path concentration response sequence as the path dominance rate; the relative velocity index, the relative dispersion index and the path dominance rate constitute the hydrodynamic feature set of the single-path concentration response sequence.

5. A method of monitoring the production of an oil well based on the concentration of tracer injected into the well as claimed in claim 4, wherein, The method for obtaining the concurrent channeling path system feature set comprises: performing Granger causality test on each pair of the single-path concentration response sequences to obtain a causality matrix; summing all element values corresponding to a prediction relationship in the causality matrix for each single-path concentration response sequence as a convergence center score; normalizing a sum of all non-diagonal elements in the causality matrix, and taking the normalization result as a system convergence index; constructing the convergence center score, the system convergence index, the total number of the single-path concentration response sequences, and the set of hydrodynamic characteristics of each single-path concentration response sequence into a concurrent channeling path system characteristic set.

6. A method of monitoring the production of an oil well based on the concentration of tracer injected into the well as claimed in claim 5, wherein, The method for generating the produced water source composition report comprises: taking each pulse injection event as a target event in a preset monitoring period; for the target event, fusing the total pulse concentration response sequence and the total produced fluid volume synchronously collected to obtain a total mass of pulse tracer of the target event; multiplying a proportion value of a total mass of the pulse tracer recovered to a total mass of the pulse tracer injected at the time of injection by a total mass of all tracers injected in the process of injecting the pulse tracer to obtain a total ineffective circulation volume; and dividing the total ineffective circulation volume to each single-path concentration response sequence according to the path dominance rate to obtain a single-path leakage volume; when the system convergence index is less than or equal to a preset convergence index threshold value, adding the single-path leakage volume to a pore-type ineffective circulation amount and a fracture-type ineffective circulation amount respectively based on the relative dispersivity index; when the system convergence index is greater than the preset convergence index threshold value, taking the single-path leakage volume corresponding to the maximum relative dispersivity index as a main channel ineffective circulation amount, and adding the single-path leakage volumes corresponding to the remaining relative dispersivity indexes to an upstream tributary ineffective circulation amount; generating a produced water source composition report based on a total produced water volume in a preset monitoring period and various ineffective circulation amounts of all target events.

7. A method of monitoring the production of an oil well based on the concentration of tracer injected into the well as claimed in claim 6, characterised in that, The method for adding the single-path leakage volume to the pore-type ineffective circulation amount and the fracture-type ineffective circulation amount respectively based on the relative dispersivity index comprises: classifying the relative dispersivity index based on a preset dispersivity threshold value, adding the single-path leakage volumes corresponding to the relative dispersivity indexes greater than or equal to the preset dispersivity threshold value to obtain a pore-type ineffective circulation amount, and adding the single-path leakage volumes corresponding to the relative dispersivity indexes less than the preset dispersivity threshold value to obtain a fracture-type ineffective circulation amount.

8. The method of claim 1, wherein, The method for recording the total pulse concentration response sequence comprises: when the produced concentration of the pulse tracer exceeds a preset noise threshold value for the first time, starting to record the produced concentration sequence of the pulse tracer until the produced concentration is lower than the preset noise threshold value and lasts for a preset stable duration, stopping recording, and obtaining a total pulse concentration response sequence.

9. The method of claim 1, wherein, The method for injecting the pulse tracer based on injection pipeline pressure fluctuation comprises: when the injection pipeline pressure reaches a preset pressure proportion of an average pressure of a preset first neighborhood, starting to inject the pulse tracer, and stopping injection after a preset single injection duration.

10. A tracer injection concentration based oil well production monitoring system, the system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor implements the steps of the oil well production monitoring method based on tracer injection concentration according to any one of claims 1-9 when executing the computer program.

Images