Method for measuring the production profile of a hydrocarbon well

Abstract

The application discloses a kind of oil and gas well production profile measurement method, comprising the following steps: S1, according to oil and gas production well, the wellbore fluid and the oil and gas production well is sampled in the block output oil and gas water, fiber is penetrated into the simulated experimental well from the wellhead of the simulated experimental well to perforation hole;Several sampling points corresponding to different depths are provided on the optical fiber;S2, using simulated experimental well to carry out experiment and data acquisition;S3, the function relationship of the frequency of light scattering signal and flow rate is established;S4, actual oil and gas production well production profile data acquisition.The application is based on optical fiber monitoring technology, establishes simulated experimental well, establishes function relationship using optical fiber the various frequency spectrum of multiphase fluid and fluid velocity, according to the function relationship formula established, the flow rate and flow of actual oil and gas production well production layer oil, gas and water can be obtained, meet the expectation of all-weather monitoring to the dynamic of oil and gas production well production profile.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field development, and particularly relates to a method for measuring the production profile of an oil and gas well. BACKGROUND

[0002] In the process of oil and gas field development, timely and accurate measurement of the production profile of an oil and gas well, and obtaining the flow rate and flow of oil, gas and water of each production layer, are key means to realize efficient development of oil and gas fields. However, due to the defects of the method itself, the complexity of the construction method and the high requirement of the measurement environment, the traditional method for measuring the production profile of an oil and gas well, such as seven-parameter logging, has not been able to provide real-time, rich and accurate production profile data for oil and gas companies for a long time. If a distributed optical fiber is introduced and used for oil and gas well production dynamic monitoring, it will provide a new idea for solving the above problems. At present, there is no precedent for using optical fiber technology for oil and gas field development related work. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a method for measuring the production profile of an oil and gas well based on optical fiber monitoring technology.

[0004] The technical scheme adopted by the present application to solve the technical problem is to provide a method for measuring the production profile of an oil and gas well, comprising the following steps:

[0005] S1. According to an oil and gas production well, a simulated experimental well is established, and the wellbore fluid and the oil, gas and water produced by the block where the oil and gas production well is located are sampled. An optical fiber is inserted into the simulated experimental well from the wellhead of the simulated experimental well to the perforation hole. The optical fiber is provided with a plurality of sampling points corresponding to different depths;

[0006] S2. Experiment and data collection are performed using the simulated experimental well:

[0007] The wellbore fluid is perfused and filled into the simulated experimental well. The oil, gas and water fluids are respectively perfused into the simulated experimental well at a set flow rate and flow rate within a set time through a three-phase fluid injection device. The light scattering signals of the optical fiber are collected and processed to obtain the frequency spectrum of the light scattering signals corresponding to different flow rates when the oil, gas and water samples flow in the simulated experimental well;

[0008] S3. A function relationship between the frequency of the light scattering signal and the flow rate is established:

[0009] The frequency values of the light scattering signals of the oil, gas and water fluids of each sampling point are fitted with the manually recorded flow rates of the oil, gas and water fluids of each sampling point to obtain a function relationship between the frequency and the flow rate;

[0010] S4. Actual oil and gas production well production profile data acquisition:

[0011] The light scattering signals from the multiple different depth points in the oil and gas production well are collected and processed, the frequency values of the oil, gas and water phases at each depth point are extracted, and the flow rates of the oil, gas and water phases at each depth point are obtained according to the function relationship of step S3.

[0012] Preferably, in step S4, an optical fiber is arranged in the oil and gas production well, the optical fiber is lowered into the production string and permanently arranged in the oil and gas production well, and sampling points are sequentially arranged on the optical fiber at a set interval distance.

[0013] Preferably, step S4 further comprises: obtaining the time experienced by the oil, gas and water phases in a unit depth interval according to the flow rates of the oil, gas and water phases in the unit depth interval; obtaining the total time for the oil, gas and water phases to reach the wellhead from the production layer of the oil and gas production well according to the depth of the oil and gas production well; and the unit depth interval corresponds to the set interval distance of the optical fiber.

[0014] The daily production of the oil, gas and water phases is obtained according to the production layer flow rate of the oil and gas production well and the total time of the oil, gas and water phases, and the obtained daily production is compared with the actual daily production of each phase at the wellhead; and the optical fiber in the oil and gas production well is used to measure and monitor the late production profile data in real time.

[0015] Preferably, in step S4, the production layer flow rate of the oil and gas production well is obtained by first obtaining the cross-sectional area of the production layer production fluid through the number of perforation holes and the hole diameter of the oil and gas production well, and then multiplying the cross-sectional area by the flow rate of the oil, gas and water phases at the production layer to obtain the production layer flow rate corresponding to the oil, gas and water phases.

[0016] Preferably, in step S1, field data of the oil and gas production well is obtained, and specific parameters of the simulation experimental well are determined according to the basic characteristics of the oil and gas production well; the field data includes drilling and completion data and well logging interpretation results, and the specific parameters include hole diameter, hole inclination, number of perforation holes and hole diameter.

[0017] Preferably, in step S2, the set flow rate is 100 m / min, the set flow rate is 0.1 m3 / min, and the set time is 60 min.

[0018] Preferably, the simulation experimental well is made of transparent glass steel material.

[0019] Preferably, depth marker lines are arranged on the outer surface of the simulation experimental well at a preset distance.

[0020] The step S2 further comprises: after the oil-gas-water mixed fluid flows through the pay zone part of the simulated experimental well, injecting a colored fluid or colored foam particles into the simulated experimental well, and recording the time when the colored fluid or colored foam particles flow through each depth mark line.

[0021] Preferably, in the step S1, at least two simulated experimental wells are established; in the steps S2 and S3, one of the simulated experimental wells is used for experiment and data collection to obtain the function relationship between the frequency and the flow rate, and the function relationship is verified by using at least one other simulated experimental well.

[0022] Preferably, in the step S3, the function relationship is established by the following process:

[0023] A linear relationship y=kx+b is established between the flow rate value and the frequency value of one simulated experimental well, and the coefficients k and b are obtained, and then the experimental data of at least one other simulated experimental well are substituted into the linear relationship for verification; if the experimental data of at least one other simulated experimental well satisfy the linear relationship, it is determined that the velocity and the frequency are in a linear relationship; otherwise, the verification is sequentially performed according to a logarithmic relationship y=klnx+b and a polynomial relationship y=k0+k1x+k2x+k3x+…+kix, where y represents the frequency, x represents the velocity, and the other parameters are all undetermined coefficients. 2 3 n n

[0024] The beneficial effects of the present application are as follows: based on the optical fiber monitoring technology, a simulated experimental well is established, the characteristics of the optical fiber such as strong anti-interference, high transmission efficiency and speed are used, the function relationship between the frequency spectrum of the multiphase fluid and the fluid velocity is established, the actual flow rate and flow of the oil, gas and water in the pay zone of the actual oil-gas production well can be obtained according to the established function relationship, the expectation of all-weather monitoring of the dynamic of the production profile of the oil-gas production well is met, more real-time, rich and more accurate data are provided for the single well and block productivity evaluation and production control, and a big data foundation is laid for the digital management of the oil-gas field. BRIEF DESCRIPTION OF DRAWINGS

[0025] The present application will be further described below in conjunction with the drawings and embodiments, wherein:

[0026] Figure 1 is a structural schematic diagram of an oil-gas-water three-phase fluid injection device established in the present application. DETAILED DESCRIPTION

[0027] In order to have a clearer understanding of the technical features, objects and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the drawings.

[0028] The oil-gas well production profile measurement method of one embodiment of the present application comprises the following steps:​​​​

[0029] S1. Establish a simulated experimental well.

[0030] This includes collecting and organizing field data from oil and gas production wells, including drilling and completion data, well logging interpretation results, and sampling wellbore fluids and oil, gas, and water produced in the block where the oil and gas production wells are located. Optionally, 1000 liters or more of each of the wellbore fluids, oil, gas, and water can be sampled.

[0031] Based on the basic characteristics of oil and gas production wells described above, specific parameters for the simulation test well were determined, including well diameter, well inclination, number of perforations, and perforation diameter. A simulation test well was then established based on these parameters. Table 1 shows the parameters for one type of oil and gas production well.

[0032] Table 1

[0033]

[0034] In one embodiment, three simulated experimental wells are established, designated as 1#, 2#, and 3#. Each simulated experimental well is L-shaped, comprising a vertical section and a horizontal section. The horizontal section further includes a producing layer portion and a non-producing layer portion. The lengths of the vertical sections and the non-producing layer portions of the horizontal sections of each simulated experimental well are proportional (the vertical section represents the vertical portion of a vertical or directional well, and the horizontal section represents the horizontal portion of a directional well).

[0035] Each simulated experimental well is constructed using transparent fiberglass material, facilitating observation of its internal structure. Depth markers are placed on the outer surface of the simulated experimental wells at predetermined intervals, for example, one marker every 1 meter. Perforations are drilled in the producing formation portion of the simulated experimental wells.

[0036] Table 2. Parameters of three simulated experimental wells

[0037] Well No. Vertical well section length Horizontal well section non-producing zone length Horizontal well section producing zone length 1# 3 meters 3 meters 3 meters 2# 6 meters 6 meters 3 meters 3# 9 meters 9 meters 3 meters

[0038] Establish a three-phase fluid injection device for oil, gas, and water. For example... Figure 1 As shown, the oil-gas-water three-phase fluid injection device includes an oil tank 1 for holding oil samples, a water tank 2 for holding water samples, a gas tank 3 for holding gas samples, and pipelines connecting the oil tank 1, gas tank 3, and water tank 2 respectively. Each pipeline is equipped with a flow rate control unit 4 and a flow rate control unit 5. All flow rate control units 4 and flow rate control units 5 are connected to the main control system (such as a main control computer) 10.

[0039] refer to Figure 1 The three pipes of the oil-gas-water three-phase fluid injection device are respectively connected to the perforation holes of the simulated experimental well 30. One end of the optical fiber 20 is connected to the data acquisition panel (e.g., Figure 1The other end of the signal generator and collector is connected to the wellhead of the simulation well 30 and fixed in the simulation well 30 until the perforation hole.

[0040] S2, experiment and data collection using the simulation well.

[0041] Specifically, the wellbore fluid samples are injected into the three simulation wells, and the wellbore fluid fills the entire simulation well. The oil-gas-water three-phase fluid injection device injects oil-gas-water three-phase fluid into the simulation well at a set flow rate and set flow rate for a set time.

[0042] In an embodiment, the set flow rate is 100 meters per minute, the set flow rate is 0.1 cubic meters per minute, and the set time is 60 minutes.

[0043] First, the oil-gas-water three-phase fluid injection device injects oil, gas, and water samples into the 1# simulation well at a set flow rate and set flow rate ratio for a set time, while collecting the optical scattering signal of the optical fiber. After the oil-gas-water mixed fluid flows through the pay zone of the 1# simulation well, the colored fluid or colored foam particles are injected, and the time when the colored fluid or colored foam particles flow through the depth mark line of the 1# simulation well is recorded. Since the simulation well is made of transparent glass steel, the staff can record the time when the colored fluid or colored foam particles flow through the depth mark line of the 1# simulation well outside the simulation well.

[0044] The colored fluid or colored foam particles are colored gas or colored liquid according to the gas-liquid properties of the fluid. The injection of colored fluid or colored foam particles can be realized by the oil-gas-water three-phase fluid injection device.

[0045] Starting from the wellhead of the simulation well, an optical fiber is provided every 1 meter, one sampling point corresponds to one depth point, and the optical scattering signals of all sampling points are collected. The collected optical scattering signals are processed and analyzed to obtain the frequency spectrum range of the corresponding optical scattering signals under different flow rates when the oil, gas, and water phases flow in the simulation well.

[0046] Table 3.1# simulation well data

[0047]

[0048] S3, establish the function relationship between the frequency of the optical scattering signal and the flow rate.

[0049] The frequency values of the light scattering signals corresponding to each phase of oil, gas and water of each depth point recorded (different sampling points on the optical fiber correspond to the depth) are fitted with the manually recorded velocity values of each phase of oil, gas and water of each depth point to obtain a functional relationship between the frequency and the flow rate:

[0050] 1#simulated well fitting formula

[0051] (1) Oil phase: y = 9433 + 1218lnx; in the formula, y is the change amount of scattered light frequency (Hz), and x is the flow rate of oil phase (m / min);

[0052] (2) Gas phase: y = 85397 + 9821lnx; in the formula, y is the change amount of scattered light frequency (Hz), and x is the flow rate of gas phase (m / min);

[0053] (3) Water phase: y = 15153 + 1477lnx; in the formula, y is the change amount of scattered light frequency (Hz), and x is the flow rate of water phase (m / min);

[0054] Referring to the experimental process in step S2, experiments and data collection are respectively performed in 2# simulated experimental well and 3# simulated experimental well to obtain corresponding frequency values and flow rate values.

[0055] Table 4. 2# simulated experimental well data

[0056]

[0057] Table 5. 3# simulated experimental well data

[0058]

[0059]

[0060] The experimental data of 2# simulated experimental well and 3# simulated experimental well are respectively substituted into the functional relationship formula obtained from 1# simulated experimental well for verification. If the experimental data of 2# simulated experimental well and 3# simulated experimental well both meet the functional relationship formula, the relationship between frequency and flow rate is confirmed, otherwise, a new relationship formula is selected to fit the data of 1# simulated experimental well, and the data of the other two wells are verified until the requirements are met.

[0061] Verification of 2# simulated experimental well and 3# simulated experimental well:

[0062] Table 6. Relative error between measured value and calculated value of 2# simulated experimental well

[0063] No. Fluid type Relative error range Relative error mean 1 Oil phase 0.43％～0.96％ 0.77％ 2 Gas phase 0.16％～0.29％ 0.22％ 3 Water phase 0.93％～1.14％ 1.04％

[0064] Table 7. Relative error between measured value and calculated value of 3# simulated experimental well

[0065] No. Fluid type Relative error range Relative error mean 1 Oil phase 0.65％～1.01％ 0.83％ 2 Gas phase 0.23％～0.43％ 0.30％ 3 Water phase 0.51％～1.47％ 1.08％

[0066] After the above verification, the error meets the requirements, and it is confirmed that the frequency and flow rate meet the logarithmic relationship.

[0067] S4, actual production well production profile data acquisition

[0068] In the actual production site, during the process of lowering the production string into the oil and gas production well, the optical fiber is lowered with the production string, and the optical fiber is attached to the outer surface of the oil pipe. The optical fiber passes through the completion tool in the well from bottom to top in turn, until it passes through the wellhead device, and is connected with the ground collection panel.

[0069] Table 8. Fiber parameters

[0070]

[0071] The situation of the optical fiber lowered into the well is as follows:

[0072] (1) Permanent, part of which is attached to the outside of the production string (fixed by fixed clamp), and part of which penetrates the Christmas tree, CAN packaging system and downhole pressure gauge;

[0073] (2) The tool string sequence (wellhead-bottom) is: Christmas tree-oil pipe-electric submersible pump-CAN packaging system-oil pipe-following end pressure gauge-oil pipe-toe end pressure gauge.

[0074] Start the optical fiber monitoring ground system set near the wellhead, collect light scattering signals from each depth point in the oil and gas production well; according to the spectral characteristics of oil, gas and water, separate and process the light scattering signals, extract the frequency value of each phase fluid at each depth point with a sampling interval of 1 meter, and obtain the flow rate of each phase fluid at each depth point according to the established function relationship.

[0075] The data measured by the optical fiber in the oil and gas production well are shown in Table 9. The production system is: 12mm nozzle; electric submersible pump power 28KW, down to 1829 meters.

[0076] Table 9

[0077]

[0078]

[0079] The results of the calculation of the oil and gas production well are shown in Table 10. The production system is: 12mm nozzle; electric submersible pump power 28KW, down to 1829 meters.

[0080] Table 10

[0081]

[0082] Based on the flow velocity of each fluid phase within a unit depth interval (here, a 1-meter interval), the time experienced by each fluid phase within that unit depth interval is obtained. Then, based on the well depth, the total time for each fluid phase to reach the wellhead from the production zone is calculated. Next, based on the production zone flow rate and the total time for each fluid phase, the daily production of each fluid phase is calculated. This calculated daily production is then compared with the actual daily production of each fluid phase at the wellhead. If the accuracy requirements are met, the calculation method is considered accurate; otherwise, the parameters are adjusted until the method is accurate. Afterward, fiber optic cables within the well are used to measure and monitor the production profile data in real time.

[0083] Table 11. Comparison of calculated output and measured output

[0084]

[0085]

[0086] Production system: 12mm nozzle; 28KW electric submersible pump; depth 1829 meters.

[0087] In the field of field engineering, the maximum error of 5.08% is within the acceptable error range, indicating the accuracy of the measurement method of the present invention.

[0088] The oil and gas well production profile measurement method of the present invention is applied to the optimization of production systems:

[0089] (1) Adjust the nozzle diameter continuously in increments of 0.5 mm. Repeat step S4 above under each nozzle diameter (production regime) to calculate the production profile data of different production layers in a single well per unit time and record the dynamic changes in pressure data.

[0090] (2) Based on all the recorded data, the rate of change of output profile data and pressure data of different production layers over time under different production systems was obtained;

[0091] (3) Calculate the daily production of oil, gas and water from a single well under different production systems;

[0092] (4) Calculate the ratio of the maximum rate of change of daily production of a single well and the maximum rate of change of pressure of different production layers under different production systems, and the ratio of the average rate of change of daily production of a single well and pressure of different production layers.

[0093] (5) Calculate the sum of the two flow rate ratios in step (4); find the production system with the smallest sum of ratios and determine it as the optimal production system for this well.

[0094] The process of adjusting the production system:

[0095] Starting with a 4mm nozzle, the production system was gradually increased to a 24mm nozzle in increments of 0.5mm, with a 3-day cycle. The daily oil production and the ratio to the maximum pressure drop of the production layer are shown in Table 12 below.

[0096] Table 12

[0097]

[0098]

[0099] Preliminary findings indicate that an 8.5mm nozzle is the optimal production system for oil wells.

[0100] Physical basis of the production profile measurement method:

[0101] Brillouin scattering: Light is inelasticly scattered by various elementary excitations in a medium. The macroscopic manifestation of these elementary excitations is pressure fluctuations propagating at the speed of sound. The scattered light therefore exhibits a frequency change relative to the incident light, and this frequency change characterizes the energy of the elementary excitation.

[0102] In this invention, incident light is emitted from a ground-based light source and propagates along an optical fiber to a distant location. During propagation, the light is scattered, and the frequency of the scattered light is affected by various elementary excitations, changing compared to the frequency of the incident light. These elementary excitations originate both from the optical fiber itself and from the surrounding medium (fluids such as oil, gas, and water). The magnitude of the fluid velocity corresponds to the magnitude of the pressure fluctuations caused by the elementary excitations. By establishing a correspondence between the scattered light signal and the fluid velocity signal, the flow velocity information of the fluid surrounding the downhole optical fiber can be obtained after the scattered light signal is detected on the ground.

[0103] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for measuring the production profile of an oil and gas well, characterized in that, Includes the following steps: S1. Establish a simulated experimental well based on the oil and gas production well, and sample the wellbore fluid and the oil, gas and water produced in the block where the oil and gas production well is located. Insert an optical fiber from the wellhead of the simulated experimental well into the simulated experimental well to the perforation hole. The optical fiber is equipped with several sampling points corresponding to different depths. S2. Conduct experiments and collect data using simulated experimental wells: The wellbore fluid is injected and filled into the simulated experimental well. Oil, gas and water phase fluids are injected into the simulated experimental well at set flow rates and flow rates within a set time using a three-phase fluid injection device. The light scattering signal of the optical fiber is collected and processed to obtain the spectrum of light scattering signal corresponding to different flow rates when oil, gas and water phase fluids flow in the simulated experimental well. S3. Establish the functional relationship between the frequency of the light scattering signal and the flow velocity: The frequency values ​​of the light scattering signals corresponding to each phase of oil, gas, and water at each sampling point are fitted with the flow velocities of each phase of oil, gas, and water at each sampling point recorded manually, and the functional relationship between frequency and flow velocity is obtained. S4. Acquisition of actual oil and gas production well production profile data: Light scattering signals from multiple sampling points at different depths in oil and gas production wells are collected and processed. The frequency values ​​of oil, gas and water phases at each sampling point at each depth are extracted. The flow velocities of oil, gas and water phases at each sampling point at each depth are obtained according to the functional relationship in step S3. An optical fiber is installed inside the oil and gas production well. The optical fiber is lowered into the production tubing and permanently placed inside the oil and gas production well. Sampling points are sequentially set on the optical fiber at set intervals. Step S4 also includes: obtaining the time experienced by each phase of oil, gas, and water within a unit depth range based on the flow rates of each phase of oil, gas, and water within the unit depth range; Then, based on the well depth of the oil and gas production well, the total time for each phase of fluid (oil, gas, and water) to reach the wellhead from the producing layer of the oil and gas production well is obtained; the unit depth interval corresponds to the set interval distance of the optical fiber. The daily production of each phase of the oil, gas, and water fluids is obtained based on the production flow rate of the oil and gas production well and the total time of each phase. The obtained daily production is then compared with the actual daily production of each phase at the wellhead. Subsequently, fiber optic cables inside the oil and gas production well are used to measure and monitor the production profile data in real time.

2. The method for measuring the production profile of an oil and gas well according to claim 1, characterized in that, In step S4, the production flow rate of the oil and gas production well is obtained by first obtaining the cross-sectional area of ​​the fluid produced in the production layer through the number and diameter of the perforations of the oil and gas production well, and then multiplying the cross-sectional area by the flow velocity of each phase of oil, gas and water at the production layer to obtain the production flow rate of each phase of oil, gas and water.

3. The method for measuring the production profile of oil and gas wells according to any one of claims 1-2, characterized in that, In step S1, field data of oil and gas production wells are acquired, and specific parameters of the simulation test well are determined based on the basic characteristics of oil and gas production wells. The field data includes drilling and completion data and logging interpretation results, and the specific parameters include well diameter, well inclination, number of perforations, and perforation diameter.

4. The method for measuring the production profile of oil and gas wells according to any one of claims 1-2, characterized in that, The simulated experimental well was constructed using transparent fiberglass material.

5. The method for measuring the production profile of an oil and gas well according to any one of claims 1-2, characterized in that, Depth marker lines are set at preset distances on the outer surface of the simulated experimental well; Step S2 further includes: after the oil-gas-water mixed fluid flows through the producing layer of the simulated experimental well, injecting colored fluid or colored foam particles into the simulated experimental well, and recording the time it takes for the colored fluid or colored foam particles to flow through each depth marker line.

6. The method for measuring the production profile of an oil and gas well according to any one of claims 1-2, characterized in that, In step S1, at least two simulated experimental wells are established; in steps S2 and S3, one of the simulated experimental wells is used to conduct experiments and collect data to obtain the functional relationship between frequency and flow velocity, and the functional relationship is verified using at least one other simulated experimental well.

7. The method for measuring the production profile of an oil and gas well according to claim 6, characterized in that, The process of establishing the functional relationship in step S3 is as follows: A linear relationship y=kx+b is established between the flow velocity and frequency values ​​of a simulated well, and the coefficients k and b are obtained. Then, experimental data from at least one other simulated well are substituted into this linear relationship for verification. If the experimental data from at least one other simulated well satisfies this linear relationship, then the velocity and frequency are determined to be linearly related; otherwise, the relationship is verified sequentially using the logarithmic relationship y=klnx+b and the polynomial relationship y=k0+k1x+k2x. 2 +k3x 3 +…+k n x n Verification is performed; where y represents frequency, x represents velocity, and all other parameters are undetermined coefficients.

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