Method for measuring production profile of oil and gas well

Abstract

The invention discloses an oil and gas well production profile measurement method which comprises the following steps: S1, establishing a simulation experiment well according to an oil and gas production well, sampling borehole fluid and oil, gas and water produced in a block where the oil and gas production well is located, and enabling an optical fiber to penetrate into the simulation experiment well from a wellhead of the simulation experiment well to reach a perforation hole; a plurality of sampling points corresponding to different depths are arranged on the optical fiber; s2, performing an experiment and data acquisition by using the simulation experiment well; s3, establishing a function relation between the frequency and the flow velocity of the light scattering signal; and S4, obtaining actual oil and gas production well output profile data. Based on the optical fiber monitoring technology, the simulation experiment well is established, the function relation between various frequency spectrums of the multiphase fluid and the fluid speed is established through optical fibers, and the actual flow velocity and flow of oil, gas and water in the oil and gas production well production layer can be obtained according to the established function relation. And the expectation of all-weather monitoring on the dynamic state of the output profile of the oil and gas production well is met.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a method for measuring an oil and gas well output profile. Background Art

[0002] In the process of oil and gas field development, timely and accurate measurement of the production profile of oil and gas wells to obtain the flow rate and flow rate of oil, gas and water in each production layer is a key means to achieve efficient development of oil and gas fields. However, traditional methods for measuring the production profile of oil and gas wells, such as seven-parameter logging, have long failed to enable oil and gas companies to obtain real-time, rich and accurate production profile data due to the defects of the methods themselves, the complexity of the construction method and the high measurement environment requirements. If distributed optical fiber is introduced and used for dynamic monitoring of oil and gas well production, it will provide new ideas 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 of the invention

[0003] The technical problem to be solved by the present invention 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 solution adopted by the present invention to solve the technical problem is: to provide a method for measuring the output profile of an oil and gas well, comprising the following steps:

[0005] S1. Establish a simulated experimental well according to the oil and gas production well, sample the wellbore fluid and the oil, gas and water produced in the block where the oil and gas production well is located, and 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 provided with a plurality of sampling points corresponding to different depths;

[0006] S2. Conduct experiments and collect data using simulated experimental wells:

[0007] Injecting wellbore fluid to fill the simulated experimental well, injecting oil, gas, and water phase fluids into the simulated experimental well respectively within a set time according to a set flow rate and flow rate through a three-phase fluid injection device, collecting and processing the light scattering signal of the optical fiber, and obtaining the spectrum of the light scattering signal corresponding to different flow rates when the oil, gas, and water phase fluids flow in the simulated experimental well;

[0008] S3. Establish the functional relationship between the frequency of the light scattering signal and the flow velocity:

[0009] The frequency values ​​of the light scattering signals corresponding to the oil, gas and water phase fluids at each sampling point are fitted with the flow velocities of the oil, gas and water phase fluids at each sampling point recorded manually, and the functional relationship between the frequency and the flow velocity is obtained;

[0010] S4. Acquisition of actual oil and gas production well output profile data:

[0011] Collect and process light scattering signals from multiple different depth points in the oil and gas production well, extract the frequency values ​​of the oil, gas and water phase fluids at each depth point, and obtain the flow rate of the oil, gas and water phase fluids at each depth point according to the functional relationship of step S3.

[0012] Preferably, in step S4, an optical fiber is provided in the oil and gas production well, and the optical fiber is lowered along with the production string and is permanently placed in the oil and gas production well; sampling points are sequentially arranged on the optical fiber according to set intervals.

[0013] Preferably, step S4 further comprises: obtaining the time experienced by the oil, gas and water phase fluids in the unit depth interval according to the flow rate of the oil, gas and water phase fluids in the unit depth interval; and obtaining the total time for the oil, gas and water phase fluids 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; the unit depth interval corresponds to the set interval distance of the optical fiber;

[0014] The daily production of oil, gas and water phases is obtained based on the production layer flow rate of the oil and gas production wells 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 of fluid at the wellhead; then the optical fiber in the oil and gas production well is used to measure and monitor the later production profile data in real time.

[0015] Preferably, in step S4, the production layer flow rate of the oil and gas production well is first obtained by the number of perforation holes and the hole diameter of the oil and gas production well to obtain the cross-sectional area of ​​the production layer output fluid, and the cross-sectional area is multiplied by the flow rate of the oil, gas and water phase fluids in the production layer, that is, the production layer flow rate corresponding to the oil, gas and water phase fluids is obtained.

[0016] Preferably, in step S1, field data of the oil and gas production wells are obtained, and specific parameters of the simulation test wells are determined based on the basic characteristics of the oil and gas production wells; the field data include drilling and completion data, well logging interpretation results, and the specific parameters include well diameter, well 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 minutes.

[0018] Preferably, the simulation test well is constructed of transparent fiberglass reinforced plastic material.

[0019] Preferably, depth marking lines are arranged on the outer surface of the simulated experimental well at a preset distance;

[0020] Step S2 also includes: after the oil-gas-water mixed fluid flows through the production layer of the simulated experimental well, injecting colored fluid or colored foam particles into the simulated experimental well, and recording the time when the colored fluid or colored foam particles flows through each depth mark line.

[0021] Preferably, in step S1, at least two simulation test wells are established; in steps S2 and S3, one of the simulation test wells is used to conduct experiments and collect data to obtain a functional relationship between frequency and flow rate, and at least one other simulation test well is used to verify the functional relationship.

[0022] Preferably, the process of establishing the functional relationship in step S3 is:

[0023] A linear relationship y=kx+b is established between the velocity value and the frequency value of a simulated experimental well, and the coefficients k and b are obtained. 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 satisfies the linear relationship, it is determined that the velocity and frequency are in a linear relationship; otherwise, the relationship is determined in accordance with the logarithmic relationship y=klnx+b and the polynomial relationship y=k0+k1x+k2x 2 +k3x 3 +…+k n x n To verify, y represents frequency, x represents speed, and all other parameters are unknown coefficients.

[0024] The beneficial effects of the present invention are as follows: based on the optical fiber monitoring technology, a simulated experimental well is established, and the optical fiber's strong anti-interference, high transmission efficiency and speed characteristics are utilized to establish a functional relationship between the various frequency spectra of the multiphase fluid and the fluid velocity. The actual flow rate and flow rate of oil, gas and water in the production layer of the oil and gas production well can be obtained based on the established functional relationship, which meets the expectation of all-weather monitoring of the dynamics of the output profile of the oil and gas production well, provides more real-time, rich and more accurate data for single well and block capacity evaluation and production control, and lays a big data foundation for the digital management of oil and gas fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

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

[0027] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0028] A method for measuring an oil and gas well production profile according to an embodiment of the present invention comprises the following steps:

[0029] S1. Establish a simulated experimental well.

[0030] Among them, the field data of oil and gas production wells are collected and sorted, including drilling and completion data, logging interpretation results, and sampling of wellbore fluids and oil, gas and water produced in the block where the oil and gas production wells are located. As an option, 1,000 liters or more of wellbore fluids, oil, gas and water can be sampled separately.

[0031] According to the basic characteristics of the above oil and gas production wells, the specific parameters of the simulation test wells are determined, including well diameter, well deviation, number of perforation holes, hole diameter, and the simulation test wells are established according to the above specific parameters. Table 1 shows the parameters of an oil and gas production well.

[0032] Table 1

[0033]

[0034] In one embodiment, three simulation test wells are established, respectively called 1#, 2#, and 3#. Each simulation test well is L-shaped, including a vertical well section and a horizontal well section, and the horizontal well section includes a production layer part and a non-production layer part. The length of the vertical well section of each simulation test well is proportional to the length of the non-production layer part of the horizontal well section (the vertical well section represents the vertical part of a vertical well or a directional well, and the horizontal well section represents the horizontal part of a directional well).

[0035] Each simulation test well is built with transparent fiberglass materials to facilitate observation of the internal conditions. Depth marking lines are set on the outer surface of the simulation test well at preset distances, for example, a depth marking line is set every 1 meter. Perforations are opened in the production layer of the simulation test well.

[0036] Table 2. Parameters of three simulation test wells

[0037] Ibetsu Vertical well section length Non-producing layer length of horizontal well section Horizontal well section production layer length 1# 3 meters 3 meters 3 meters 2# 6 meters 6 meters 3 meters 3# 9 meters 9 meters 3 meters

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

[0039] refer to Figure 1 , connect the three pipes of the oil, gas and water three-phase fluid injection device to the perforation holes of the simulated experimental well 30 respectively. Connect one end of the optical fiber 20 to the data acquisition panel (such as Figure 1The other end is inserted into the simulation test well 30 from the wellhead of the simulation test well 30 until it reaches the perforation hole and is fixed. Then, the wellhead device of the simulation test well is improved according to the actual well conditions.

[0040] S2. Conduct experiments and collect data using simulated experimental wells.

[0041] Specifically, the sampled wellbore fluid is injected into three simulated experimental wells, and the wellbore fluid fills the entire simulated experimental wells. The oil, gas and water three-phase fluid injection device is used to inject the oil, gas and water three-phase fluid into the simulated experimental wells within a set time at a set flow rate and a set flow rate.

[0042] In one embodiment, the flow rate is set to 100 m / min, the flow rate is set to 0.1 m3 / min, and the time is set to 60 min.

[0043] First, the oil, gas and water three-phase fluid injection device injects oil, gas and water samples into the No. 1 simulation test well according to the set flow rate and set flow ratio within the set time, and collects the optical scattering signal of the optical fiber at the same time. After the oil, gas and water mixed fluid flows through the production layer of the No. 1 simulation test 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 lines of the No. 1 simulation test well is recorded. In combination with the simulation test well being constructed with transparent fiberglass materials, the staff can record the time when the colored fluid or colored foam particles flow through the depth mark lines of the No. 1 simulation test well from the outside of the simulation test well.

[0044] The colored fluid or colored foam particles is determined according to the gas-liquid properties of the fluid, specifically, colored gas or colored liquid. The injection of the colored fluid or colored foam particles can be achieved through an oil-gas-water three-phase fluid injection device.

[0045] Starting from the wellhead of the simulated experimental well, a sampling point is set at every 1 meter of the optical fiber, and one sampling point corresponds to one depth point, and the light scattering signals of all sampling points are collected. The collected light scattering signals are processed and analyzed to obtain the spectrum range of the light scattering signals corresponding to different flow rate conditions when the oil, gas and water phases flow in the simulated experimental well.

[0046] Table 3.1# Simulation experiment well data

[0047]

[0048] S3. Establish a functional relationship between the frequency of the light scattering signal and the flow velocity.

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

[0050] 1# The fitting formula of the simulation test well

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

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

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

[0054] Referring to the experimental process in step S2, experiments and data collection are carried out in the 2# simulation experimental well and the 3# simulation experimental well respectively to obtain corresponding frequency values ​​and flow velocity values.

[0055] Table 4.2# Simulation experiment well data

[0056]

[0057] Table 5.3# Simulation experiment well data

[0058]

[0059]

[0060] Substitute the experimental data of 2# simulation test well and 3# simulation test well into the functional relationship obtained from 1# simulation test well for verification. If the experimental data of 2# simulation test well and 3# simulation test well both conform to the functional relationship, the relationship between frequency and flow velocity is confirmed. Otherwise, reselect the relationship to fit the data of 1# simulation test well and verify it with the data of the other two wells until the requirements are met.

[0061] Verification of 2# simulation test well and 3# simulation test well:

[0062] Table 6.2 Relative error between measured values ​​and calculated values ​​of simulation test well #

[0063] Serial number 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 7.3 Relative error between measured values ​​and calculated values ​​of simulation test well #

[0065] Serial number 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 errors all met the requirements, confirming that the frequency and flow rate conform to the logarithmic relationship.

[0067] S4. Acquisition of actual production well output profile data

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

[0069] Table 8. Fiber parameters

[0070]

[0071] The situation of optical fiber being lowered into the well:

[0072] (1) Permanent type, partly attached to the outside of the production string (fixed by a clamp), and partly through the Christmas tree, CAN packaging system and downhole pressure gauge;

[0073] (2) The tool string sequence (wellhead-bottomhole) is: Christmas tree-tubing-electric submersible pump-CAN packaging system-tubing-heel pressure gauge-tubing-toe pressure gauge.

[0074] Start the fiber optic monitoring ground system installed near the wellhead to collect light scattering signals from various depth points in the oil and gas production wells; separate and process the light scattering signals according to the respective spectral characteristics of oil, gas and water, extract the frequency value of each phase fluid at each depth point at a sampling interval of 1 meter, and obtain the flow rate of each phase fluid at each depth point based on the established functional relationship.

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

[0076] Table 9

[0077]

[0078]

[0079] The results of the calculation of oil and gas production wells are shown in Table 10. Production system: 12mm oil nozzle; ESP power 28KW, depth 1829 meters.

[0080] Table 10

[0081]

[0082] According to the flow rate of each phase of fluid in the unit depth interval (here, 1 meter interval), the time experienced by each phase of fluid in the unit depth interval is obtained; then the total time for each phase of fluid to reach the wellhead from the production layer is obtained according to the well depth. Then, the daily production of each phase of fluid is obtained based on the production layer flow rate and the total time of each phase of fluid, and the obtained daily production is compared with the actual daily production of each phase of fluid at the wellhead. If the accuracy requirements are met, it indicates that the calculation method is accurate, otherwise adjust the parameters until the method is accurate. Then use the optical fiber in the well to measure and monitor the production profile data in real time.

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

[0084]

[0085]

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

[0087] In the field of on-site engineering, the above 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 output profile measurement method of the present invention is applied in optimizing production system:

[0089] (1) Continuously adjust the nozzle diameter with a step length of 0.5 mm. Repeat the above step S4 under each nozzle diameter (production system), calculate the production profile data of different production layers of a single well per unit time, and record the dynamic changes of pressure data;

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

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

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

[0094] The process of adjusting the production system:

[0095] Starting from a 4mm nozzle, with a step size of 0.5mm and a time period of 3 days, the production system was gradually increased to a 24mm nozzle. The daily oil production and the ratio of the maximum pressure drop to the production layer are shown in Table 12.

[0096] Table 12

[0097]

[0098]

[0099] It was initially determined that the 8.5mm nozzle was the best production system for the oil well.

[0100] Physical basis of output profile measurement method:

[0101] Brillouin scattering: Light is inelastically scattered by various elementary excitations in a medium. The macroscopic manifestation of elementary excitations is pressure fluctuations that propagate at the speed of sound. The scattered light therefore undergoes a frequency change compared to the incident light, and the frequency change represents the energy of the elementary excitations.

[0102] In the present invention, the incident light is emitted by a ground light source and propagates along the optical fiber to the far end. Light is scattered during the propagation process, and the frequency of the scattered light is affected by various elementary excitations and changes compared to the frequency of the incident light. The elementary excitation effect comes from both the optical fiber itself and the surrounding medium (oil, gas, water and other fluids). The magnitude of the fluid flow rate corresponds to the magnitude of the elementary excitation pressure fluctuation. By establishing a corresponding relationship between the scattered light signal and the fluid flow rate signal, after the scattered light signal is monitored on the ground, the flow rate information of the fluid around the optical fiber downhole can be obtained.

[0103] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for measuring an oil and gas well production profile, characterized in that: The following steps are involved: S1. Establish a simulated experimental well according to the oil and gas production well, sample the wellbore fluid and the oil, gas and water produced in the block where the oil and gas production well is located, and 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 provided with a plurality of sampling points corresponding to different depths; S2. Conduct experiments and collect data using simulated experimental wells: Injecting wellbore fluid to fill the simulated experimental well, injecting oil, gas, and water phase fluids into the simulated experimental well respectively within a set time according to a set flow rate and flow rate through a three-phase fluid injection device, collecting and processing the light scattering signal of the optical fiber, and obtaining the spectrum of the light scattering signal corresponding to different flow rates when the 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 the oil, gas and water phase fluids at each sampling point are fitted with the flow velocities of the oil, gas and water phase fluids at each sampling point recorded manually, and the functional relationship between the frequency and the flow velocity is obtained; S4. Acquisition of actual oil and gas production well output profile data: Collect and process light scattering signals from multiple different depth points in the oil and gas production well, extract the frequency values ​​of the oil, gas and water phase fluids at each depth point, and obtain the flow rate of the oil, gas and water phase fluids at each depth point according to the functional relationship of step S3.

2. The oil and gas well production profile measurement method according to claim 1, characterized in that: In step S4, an optical fiber is provided in the oil and gas production well. The optical fiber is lowered along with the production string and is permanently placed in the oil and gas production well. Sampling points are sequentially arranged on the optical fiber according to set intervals.

3. The oil and gas well production profile measurement method according to claim 2, characterized in that: Step S4 also includes: obtaining the time experienced by the oil, gas and water phases in the unit depth interval according to the flow rate of the oil, gas and water phases in the unit depth interval; and 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; the unit depth interval corresponds to the set interval distance of the optical fiber; The daily production of oil, gas and water phases is obtained based on the production layer flow rate of the oil and gas production wells 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 of fluid at the wellhead; then the optical fiber in the oil and gas production well is used to measure and monitor the later production profile data in real time.

4. The oil and gas well production profile measurement method according to claim 3, characterized in that: In step S4, the production layer flow rate of the oil and gas production well is first obtained by the number of perforation holes and the hole diameter of the oil and gas production well to obtain the cross-sectional area of ​​the production layer output fluid, and the cross-sectional area is multiplied by the flow rate of the oil, gas and water phase fluids in the production layer to obtain the production layer flow rate corresponding to the oil, gas and water phase fluids.

5. The oil and gas well production profile measurement method according to any one of claims 1 to 4, characterized in that: In step S1, the field data of the oil and gas production wells are obtained, and the specific parameters of the simulation test wells are determined according to the basic characteristics of the oil and gas production wells; the field data include drilling and completion data, well logging interpretation results, and the specific parameters include well diameter, well inclination, number of perforation holes, and hole diameter.

6. The oil and gas well production profile measurement method according to any one of claims 1 to 4, characterized in that: 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 minutes.

7. The method for measuring the production profile of an oil and gas well according to any one of claims 1 to 4, characterized in that: The simulation experiment well is constructed with transparent fiberglass reinforced plastic material.

8. The method for measuring the production profile of an oil and gas well according to any one of claims 1 to 4, characterized in that: On the outer surface of the simulated experimental well, depth marking lines are set at preset distances; Step S2 also includes: after the oil-gas-water mixed fluid flows through the production layer of the simulated experimental well, injecting colored fluid or colored foam particles into the simulated experimental well, and recording the time when the colored fluid or colored foam particles flows through each depth mark line.

9. The method for measuring the production profile of an oil and gas well according to any one of claims 1 to 4, characterized in that: In step S1, at least two simulation test wells are established; in steps S2 and S3, one of the simulation test wells is used to conduct experiments and collect data to obtain a functional relationship between frequency and flow rate, and at least one other simulation test well is used to verify the functional relationship.

10. The oil and gas well production profile measurement method according to claim 9, 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 velocity value and the frequency value of a simulated experimental well, and the coefficients k and b are obtained. 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 satisfies the linear relationship, it is determined that the velocity and frequency are in a linear relationship; otherwise, the relationship is determined in accordance with the logarithmic relationship y=klnx+b and the polynomial relationship y=k0+k1x+k2x 2 +k3x 3 +…+k n x n To verify, y represents frequency, x represents speed, and all other parameters are unknown coefficients.

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