Downhole fluid fiber optic monitoring system and method based on composite material continuous tubing

Abstract

The present invention discloses a downhole fluid optical fiber monitoring system and a monitoring method based on a composite material continuous pipe, and relates to the field of in-hole geophysics and well logging technology. The present invention can at least partially solve the problem in the prior art that a safe, low-cost optical fiber measurement and monitoring system that does not interfere with downhole operations and oil and gas production is urgently needed to be deployed downhole. The downhole fluid optical fiber monitoring system based on a composite material continuous pipe in Embodiment 1 of the present invention comprises a composite modem and a continuous pipe body, wherein a straight optical fiber and a spiral optical fiber connected to the composite modem are embedded in the continuous pipe body; the straight optical fiber is used for real-time monitoring and measurement of fluid noise data, temperature data and fluid pressure data inside and outside the downhole continuous pipe body; the spiral optical fiber is used for real-time monitoring and measurement of temperature data inside and outside the downhole continuous pipe body, three-component stress data on the outside of the continuous pipe body and three-component microseismic data.

Description

Technical Field

[0001] The invention belongs to the technical field of well geophysics and well logging, and in particular relates to a downhole fluid optical fiber monitoring system and a monitoring method based on a composite material continuous pipe. Background Art

[0002] At present, armored optical cables are laid inside and outside the casing, bundled on the outside of the coiled tubing or gas pipe, or laid inside the coiled tubing for full-well distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) measurements. This has been widely used in oil and gas resource development. However, it is currently mainly used for DAS-VSP data acquisition, microseismic monitoring, passive seismic data acquisition, and well temperature measurement.

[0003] However, laying permanent armored optical cables outside metal casings faces problems such as difficult construction operations, high costs, difficulty in detecting the position of optical cables, and immature underground avoidance technology, which leads to the armored optical cables being cut during perforation operations. The armored optical cables laid in the casing can only be used for temporary data collection. Because the armored optical cables laid in the casing will affect or interfere with other operations in the well, it is impossible to lay the armored optical cables in the casing for a long time for monitoring operations. Although laying armored optical cables in continuous oil pipes can be used for microseismic monitoring and production profile measurement of horizontal well sections, it can only be temporary. It is impossible to lay continuous oil pipes with built-in armored optical cables in horizontal wells for a long time without affecting the production of oil and gas in the well. Therefore, we urgently need to lay a safe, low-cost, long-term, stable, reliable, and non-destructive optical fiber measurement and monitoring system in the well that does not interfere with underground operations and oil and gas production. Summary of the invention

[0004] The present invention proposes a downhole fluid optical fiber monitoring system and monitoring method based on a composite material coiled tube, the purpose of which is to solve the problem of urgently needing to deploy a safe, low-cost optical fiber measurement and monitoring system downhole that does not interfere with downhole operations and oil and gas production;

[0005] By using a continuous tube body embedded with straight optical fibers and spiral optical fibers and lowering the continuous tube body into the well, a downhole optical fiber sensing unit of a long-term dynamic monitoring system is constructed. By connecting different optical fibers with a composite modem, a long-term comprehensive monitoring system for the dynamic distribution of downhole and underground fluids based on composite continuous tubes and distributed optical fiber sensing technology can be constructed, providing indispensable means, systems and methods for scientific management of oil and gas reservoirs and improving recovery rates.

[0006] Distributed fiber optic sensing technology is the best choice for permanent downhole monitoring and is the basis for realizing the true informatization and intelligence of oil and gas field production. The advantages of distributed downhole fiber optic sensing are:

[0007] It can provide real-time, high-density, multi-parameter parameters for the entire life cycle of oil and gas field development, and improve the scientific level and efficiency of decision-making for fine oil and gas reservoir description; there is no need to interrupt production for downhole operations, no production loss, no operating costs, no personnel risks, and no environmental pollution risks; it can replace and surpass conventional logging, not only providing more real-time and high-quality data, but also with high cost-effectiveness, one-time investment and lifelong benefits; no special equipment is required, it can be easily applied to high-angle and horizontal wells, etc., and does not affect operations in casing.

[0008] In order to achieve the above object, the present invention adopts the following scheme:

[0009] A downhole fluid optical fiber monitoring system based on a composite material continuous tube includes a composite modem and a continuous tube body, wherein a straight optical fiber and a spiral optical fiber connected to the composite modem are embedded in the continuous tube body;

[0010] Straight optical fiber is used to monitor and measure the fluid noise data, temperature data and fluid pressure data inside and outside the downhole coiled tubing in real time;

[0011] The spiral optical fiber is used for real-time monitoring and measurement of temperature data inside and outside the downhole coiled tubing body, three-component stress data outside the coiled tubing body, and three-component seismic data.

[0012] Optionally, the composite modem includes a DAS signal input terminal, a DTS signal input terminal, a DSS signal input terminal and a DPS signal input terminal;

[0013] The straight optical fiber includes a straight single-mode optical fiber and a straight multi-mode optical fiber. The straight single-mode optical fiber is connected to the DAS signal input end, and the straight multi-mode optical fiber is connected to the DTS signal input end. The straight optical fiber also includes a straight continuous grating optical fiber or / and a straight microstructure optical fiber connected to the DPS signal input end.

[0014] Optionally, the spiral optical fiber includes a spiral single-mode optical fiber and a spiral multi-mode optical fiber, the spiral single-mode optical fiber is connected to the DAS and DSS signal input ends, and the spiral multi-mode optical fiber is connected to the DTS signal input end;

[0015] The spiral single-mode optical fiber is used to monitor and measure in real time the three-component stress data outside the coiled pipe body, the three-component microseismic data in the formation around the coiled pipe body, and the time-shifted three-component in-well seismic data;

[0016] The spiral multimode optical fiber is used to monitor and measure the temperature data inside and outside the continuous tube body in real time.

[0017] Optionally, the spiral single-mode optical fiber includes three groups of spiral single-mode optical fibers with different spiral angles, and the spiral multimode optical fiber includes three groups of spiral multimode optical fibers with different spiral angles, and the three spiral angles of the spiral single-mode optical fiber and the spiral multimode optical fiber are 30 degrees, 45 degrees and 60 degrees.

[0018] Optionally, it also includes a regularly excited artificial seismic source, which is located on the ground and monitors and collects time-shifted three-component wellbore seismic data regularly excited by the artificial seismic source through a spiral single-mode optical fiber and a composite modem.

[0019] Optionally, it also includes a detector for collecting ground seismic data. The detector is arranged on the ground in a two-dimensional or three-dimensional manner. When the detector is used to collect conventional ground seismic data or time-shifted ground seismic data, conventional three-component wellbore seismic data or time-shifted three-component wellbore seismic data is collected through spiral single-mode optical fiber at the same time, thereby realizing joint well-ground three-dimensional exploration.

[0020] Optionally, the continuous tube body includes a core material and a protective layer, the straight optical fiber and the spiral optical fiber are both embedded between the core material and the protective layer, the straight optical fiber is arranged parallel to the axis of the continuous tube body, and the spiral optical fiber is wound on the core material.

[0021] Optionally, the continuous pipe body is formed by, but not limited to, any of the following methods:

[0022] The first type is horizontal dry winding;

[0023] The second type is horizontal wet longitudinal yarn dipping and winding;

[0024] The third type is horizontal wet method of circumferential yarn dipping and winding;

[0025] The fourth type is vertical winding with a mandrel that moves upward vertically;

[0026] The fifth type is vertical low-melting-point metal core mode winding molding.

[0027] The optical fiber monitoring method for downhole fluid based on composite material coiled tube is applicable to any of the above-mentioned monitoring systems for downhole fluid optical fiber monitoring based on composite material coiled tube, and specifically comprises the following steps:

[0028] Step S1: lowering a continuous pipe body embedded with straight optical fibers and spiral optical fibers into a wellbore;

[0029] Step S2: Connecting the straight optical fiber and the spiral optical fiber to the composite modem, specifically comprising:

[0030] Connect the straight single-mode optical fiber to the DAS signal input terminal.

[0031] Connect the straight multimode optical fiber to the DTS signal input terminal.

[0032] Connect the straight continuous grating fiber or straight microstructure fiber to the DPS signal input end.

[0033] Connect the spiral single-mode optical fiber to the DAS and DSS signal input terminals.

[0034] Connect the spiral multimode optical fiber to the DTS signal input terminal;

[0035] Step S1: During oil and gas production, the DSS signal on the outside of the coiled tubing body is monitored and measured in real time by the composite modem, and the DAS signal, DTS signal and DPS signal on both sides of the inside and outside of the coiled tubing body are monitored and measured in real time by the composite modem;

[0036] Step S2: modulate and demodulate the DTS signal and DSS signal measured in step S1 to obtain temperature data and three-component stress data at different depths and different orientations outside the coiled tubing body, and correct the three-component stress data by temperature data to obtain the real three-component stress data at different depths and different orientations underground; and simultaneously monitor the three-component microseismic data underground;

[0037] In step S2, the strain e or temperature t The response spectrum drift is similar to the drift of the resonant wave Dl or spectral drift of the Bragg grating Two , use the formula to correct the data:

[0038] Δλ / λ=−Δυ / υ=K T Δt+K ε e

[0039] in, l and u are the average light wavelength and frequency, respectively; K T and K ε are the standard constants for temperature and strain, respectively;

[0040] Step S3: based on the stress data at different depths and azimuths obtained in step S2, a three-dimensional distribution map of the underground stress field at each depth and each orientation is drawn to obtain the distribution change characteristics of the underground stress field along the well trajectory, and a three-dimensional underground stress field model is established based on the three-dimensional distribution map of the underground stress field;

[0041] Step S4: Projecting the well trajectory into the underground three-dimensional stress field model in step S3, and designing the optimized perforation position and fracturing section of the downhole coiled tubing body according to the distribution variation characteristics of the underground stress field along the well trajectory;

[0042] Step S5: Based on the distribution of the microseismic data monitored and measured in step S2 in the three-dimensional space around the well trajectory, the occurrence time, the energy size and the rupture mechanism of the source point, the reservoir transformation effect is evaluated in real time, the fracturing parameters in step S4 are adjusted and optimized in time, and the well spacing and segment spacing of the multi-branch horizontal wells are optimized.

[0043] Optionally, the following specific steps are also included:

[0044] Step Sa: modulating and demodulating the DAS signal, DTS signal and DPS signal in step S3 to obtain noise data, temperature data and pressure data distributed downhole;

[0045] Step Sb: Calculate each liquid production or gas production profile and its change and each water absorption or gas absorption profile and its change in the well through a multi-parameter comprehensive inversion method according to the noise data, temperature data and pressure data distributed in the well in step Sa;

[0046] Step Sc: regularly exciting an artificial seismic source located on the ground, and collecting time-shift variable offset vertical seismic profile (Walkaway DAS-VSP) data or time-shift three-dimensional vertical seismic profile (3D DAS-VSP) data through a spiral single-mode optical fiber;

[0047] Step Sd: performing surface consistent amplitude compensation processing, surface consistent deconvolution processing and relatively amplitude-preserving wavefield separation processing on the Walkaway DAS-VSP data or 3D DAS-VSP data collected at different times in step Sc;

[0048] Step Se: the Walkaway DAS-VSP data or the 3D DAS-VSP data processed in step Sd are subjected to amplitude-preserving prestack depth migration processing by the same process in stages, and the fluid sensitive attribute parameters in the seismic data volume after the migration processing are extracted. The distribution and temporal changes of the oil-water two-phase fluid boundary or the oil-gas-water three-phase fluid boundary around the well are calculated and monitored in combination with the highlight volume data obtained by S transformation;

[0049] Step Sf: Based on each downhole liquid production or gas production profile and its changes and each water absorption or gas absorption profile and its changes obtained in step Sb, as well as the changes in the oil-water two-phase or oil-gas-water three-phase fluid boundary around the well obtained in step Se, real-time measurement and monitoring of the changes in the oil-water two-phase or oil-gas-water three-phase fluid boundary in and around the well are achieved, and the development plan and production system are optimized and adjusted in a timely manner.

[0050] The present invention has the beneficial effects:

[0051] The downhole fluid optical fiber monitoring system based on composite material continuous tube in the present invention comprises a composite modem and a continuous tube body, wherein a straight optical fiber and a spiral optical fiber connected to the composite modem are embedded in the continuous tube body;

[0052] Straight optical fiber is used to monitor and measure the fluid noise data, temperature data and fluid pressure data inside and outside the downhole coiled tubing in real time;

[0053] The spiral optical fiber is used for real-time monitoring and measurement of temperature data inside and outside the downhole coiled tubing body, three-component stress data outside the coiled tubing body, and three-component seismic data.

[0054] Its function is: by embedding the straight optical fiber and the spiral optical fiber in the continuous tube body and connecting the straight optical fiber and the spiral optical fiber with the composite modem, a low-cost, high-precision, high-reliability downhole and underground fluid distribution dynamic integrated optical fiber monitoring system can be constructed.

[0055] Through real-time monitoring and measurement of the fluid noise data, temperature data and fluid pressure data inside and outside the coiled tubing body, the liquid production or gas production profile or water absorption or gas absorption profile and its changes of the oil and gas production wells can be calculated and monitored, so as to realize long-term real-time dynamic monitoring of the oil and gas production wells, and provide indispensable means, systems and methods for scientific management of oil and gas reservoirs and improving recovery rates.

[0056] The spiral optical fiber and composite modem can be used to continuously record the three-component stress data in the formation around the coiled tubing in real time for a long time. A three-dimensional stress field model can be established based on the obtained three-component stress data to optimize the design of the perforation position and fracturing section of the downhole coiled tubing body; microseismic data can be recorded to optimize the design of the well spacing and segment spacing of multi-branch horizontal wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic diagram of the structure of a straight optical fiber and a spiral optical fiber in a continuous tube body according to a first embodiment of the present invention;

[0058] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0059] Figure 3This is a schematic diagram of collecting microseismic data in the formation around the coiled tubing body according to the first embodiment of the present invention;

[0060] Figure 4 This is a schematic diagram of collecting seismic data in a well when an artificial seismic source is excited in the second embodiment of the present invention;

[0061] Figure 5 This is a schematic diagram of well-ground combined stereoscopic exploration according to the second embodiment of the present invention;

[0062] Figure 6 This is a schematic diagram of a monitoring method according to Embodiment 3 of the present invention.

[0063] Reference numerals:

[0064] 1-protective layer, 2-core material, 3-continuous tube body, 4-straight single-mode optical fiber, 5-straight multi-mode optical fiber, 6-straight continuous grating optical fiber, 7-straight microstructure optical fiber, 8-straight optical fiber, 9-spiral optical fiber, 10-composite modem, 11-microseismic, 12-artificial seismic source, 13-detector. DETAILED DESCRIPTION

[0065] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0066] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inside", "outside", "front", "back", "top", "bottom" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0067] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed", "opened", "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments:

[0069] Embodiment 1:

[0070] like Figure 1 , Figure 2 and Figure 3 A downhole fluid optical fiber monitoring system based on a composite material continuous pipe includes a composite modem 10 and a continuous pipe body 3, wherein the continuous pipe body 3 is embedded with a straight optical fiber 8 and a spiral optical fiber 9 both connected to the composite modem 10;

[0071] The straight optical fiber 8 is used to monitor and measure the fluid noise data, temperature data and fluid pressure data inside and outside the downhole coiled tubing body 3 in real time;

[0072] The spiral optical fiber 9 is used for real-time monitoring and measurement of temperature data inside and outside the downhole coiled tubing body 3 , three-component stress data outside the coiled tubing body 3 , and three-component seismic data.

[0073] The composite modem 10 in this embodiment is a composite modem 10 having distributed acoustic sensing (DAS), distributed temperature sensing (DTS), distributed stress sensing (DSS), quasi-distributed or array pressure sensing (DPS). The composite modem 10 is placed near the wellhead to facilitate connection with various optical fibers in the coiled tubing body 3.

[0074] The straight optical fiber 8 and the spiral optical fiber 9 in this embodiment are both bare optical fibers that are resistant to high temperatures and hydrogen damage.

[0075] In this embodiment, by real-time monitoring and measurement of the fluid noise data, temperature data and fluid pressure data inside and outside the downhole continuous pipe body 3 by the straight optical fiber 8, the liquid production or gas production profile or water absorption or gas absorption profile and its changes of the oil and gas production wells can be calculated and monitored, so as to realize long-term real-time dynamic monitoring of the oil and gas production wells, and provide indispensable means, systems and methods for scientific management of oil and gas reservoirs and improving recovery rates.

[0076] By real-time monitoring and measurement of temperature data and three-component stress data inside and outside the coiled pipe body 3 by the spiral optical fiber 9, the real three-component stress data distribution after eliminating the temperature influence can be obtained, and then a three-dimensional stress field model is established based on the real three-component stress data distribution diagram, so as to optimize the design of the perforation position and fracturing section of the downhole coiled pipe body 3. By real-time monitoring and measurement of three-component microseismic 11 data by the spiral optical fiber 9, the three-component microseismic 11 data in the formation around the coiled pipe can be recorded, so as to timely adjust and optimize the fracturing parameters according to the distribution characteristics of the three-component microseismic data in the underground three-dimensional space, and optimize the design of the well spacing and segment spacing of the multi-branch horizontal well.

[0077] Specifically, the composite modem 10 includes a DAS signal input terminal, a DTS signal input terminal, a DSS signal input terminal and a DPS signal input terminal;

[0078] The straight optical fiber 8 includes a straight single-mode optical fiber 4 and a straight multimode optical fiber 5. The straight single-mode optical fiber 4 is connected to the DAS signal input end, and the straight multimode optical fiber 5 is connected to the DTS signal input end. The straight optical fiber 8 also includes a straight continuous grating optical fiber 6 and / or a straight microstructure optical fiber 7 connected to the DPS signal input end.

[0079] Specifically, the spiral optical fiber 9 includes a spiral single-mode optical fiber and a spiral multi-mode optical fiber, the spiral single-mode optical fiber is connected to the DAS and DSS signal input ends, and the spiral multi-mode optical fiber is connected to the DTS signal input end;

[0080] The spiral single-mode optical fiber is used for real-time monitoring and measurement of three-component stress data outside the continuous pipe body 3, three-component microseismic 11 data in the formation around the continuous pipe body 3, and time-shifted three-component in-well seismic data;

[0081] The spiral multimode optical fiber is used to monitor and measure the temperature data inside and outside the continuous tube body 3 in real time.

[0082] Specifically, the spiral single-mode optical fiber includes three groups of spiral single-mode optical fibers with different spiral angles, and the spiral multimode optical fiber includes three groups of spiral multimode optical fibers with different spiral angles. The three spiral angles of the spiral single-mode optical fiber and the spiral multimode optical fiber are 30 degrees, 45 degrees and 60 degrees.

[0083] In this embodiment, three groups of spiral single-mode optical fibers and spiral multimode optical fibers with different spiral angles are selected. When real-time monitoring and measurement of three-component stress signals, three-component microseismic events, and three-component wellbore seismic signals are performed, the spiral angle optical fiber with the best real-time monitoring and measurement effect can be selected for recording and calculation, so that the spiral optical fiber 9 in this system can achieve better monitoring and measurement effects for three-component stress signals, three-component microseismic events, and three-component wellbore seismic signals.

[0084] Embodiment 2:

[0085] Based on the above embodiments, specifically, Figure 4 and Figure 5 , and also includes a regularly excited artificial seismic source 12, which is set on the ground. The time-shifted three-component wellbore seismic data regularly excited by the artificial seismic source 12 are collected through a spiral single-mode optical fiber and a composite modem 10.

[0086] Specifically, Figure 5, and also includes a detector 13 for collecting ground seismic data. The detector 13 is arranged on the ground in a two-dimensional or three-dimensional manner. When the detector 13 is used to collect conventional ground seismic data or time-shifted ground seismic data, conventional three-component wellbore seismic data or time-shifted three-component wellbore seismic data is collected through a spiral single-mode optical fiber at the same time, thereby realizing well-ground joint three-dimensional exploration.

[0087] Specifically, Figure 1 The continuous tube body 3 includes a core material 2 and a protective layer 1, and the straight optical fiber 8 and the spiral optical fiber 9 are both embedded between the core material 2 and the protective layer 1. The straight optical fiber 8 is arranged parallel to the axis of the continuous tube body 3, and the spiral optical fiber 9 is wound on the core material 2 according to different spiral angles.

[0088] Specifically, the continuous pipe body 3 is formed by, but not limited to, any of the following methods:

[0089] The first type is horizontal dry winding;

[0090] The second type is horizontal wet longitudinal yarn dipping and winding;

[0091] The third type is horizontal wet method of circumferential yarn dipping and winding;

[0092] The fourth type is vertical winding with a mandrel that moves upward vertically;

[0093] The fifth type is vertical low-melting-point metal core mode winding molding.

[0094] In this embodiment, the above five processing and forming processes are all existing processes for producing the continuous pipe body 3.

[0095] In this embodiment, the processing technology of the continuous pipe body 3 can also use the continuous production process of thermoplastic and thermosetting composite structure pipes (EPF process), which is a continuous pipe making method combining extrusion, pultrusion and winding, and uses ultraviolet radiation to initiate curing. This method uses an extruded plastic pipe as the core material 2 (lining), lays a pultruded thermosetting glass fiber reinforced plastic layer along the axial direction, and then lays a thermosetting glass fiber reinforced plastic layer in the circumferential direction by a fiber winding method, and finally coats a thermosetting or thermoplastic resin-rich layer on the surface of the pipe to form a smooth and flat surface appearance. The whole process is carried out continuously.

[0096] In the production process of the continuous pipe body 3, the extruded plastic pipe is first used as the core material 2 (inner lining), and a pultruded thermosetting fiberglass layer is laid axially as the bottom layer of the inner lining layer. Subsequently, straight optical fibers 8 and wound spiral optical fibers 9, power cables, auxiliary heating cables, signal lines, etc. are continuously laid axially, and then a thermosetting fiberglass layer is laid in the circumferential direction as a fiber reinforcement layer by a fiber winding method. Finally, a thermosetting or thermoplastic resin-rich layer is coated on the surface of the pipe as an outer protective layer to form a smooth and flat surface appearance.

[0097] In this embodiment, by setting up an artificial seismic source 12 and a detector 13 on the ground, conventional ground seismic data can be collected separately, and conventional three-component well seismic data can be collected simultaneously (conventional well-ground joint production); when the artificial seismic source 12 is stimulated, conventional three-component well seismic data or time-shifted three-component well seismic data can be collected separately, and time-shifted three-component well seismic data can be collected simultaneously with time-shifted ground seismic data (time-shifted well-ground joint production), thereby realizing well-ground time-shifted combined stereoscopic exploration and monitoring of the dynamic changes of underground oil-water two-phase or oil-gas-water three-phase fluid interfaces.

[0098] Embodiment three:

[0099] Based on the above embodiments, Figure 6 As shown, the optical fiber monitoring method for downhole fluid based on a composite material coiled tube is applicable to any of the above-mentioned optical fiber monitoring systems for downhole fluid based on a composite material coiled tube, and specifically comprises the following steps:

[0100] Step S1: During oil and gas production, the composite modem 10 is used to monitor and measure the DSS signal on the outside of the coiled tubing body 3 in real time, and the composite modem 10 is used to monitor and measure the DAS signal, DTS signal and DPS signal on both sides of the inside and outside of the coiled tubing body 3 in real time;

[0101] Before step S1, Figure 6 , you also need:

[0102] The continuous pipe body 3 embedded with the straight optical fiber 8 and the spiral optical fiber 9 is lowered into the wellbore;

[0103] After the coiled tubing body 3 is lowered into the wellbore, cement slurry needs to be pumped in from the bottom of the well using a high-pressure pump truck, so that the cement slurry returns from the bottom of the well along the annulus area between the outer wall of the coiled tubing body 3 and the wellbore to the wellhead. After the cement slurry solidifies, the coiled tubing body 3 is permanently fixed to the formation rock.

[0104] Connecting the straight optical fiber 8 and the spiral optical fiber 9 to the composite modem 10 specifically includes:

[0105] Connect the straight single-mode optical fiber 4 to the DAS signal input terminal.

[0106] Connect the straight multimode optical fiber 5 to the DTS signal input terminal.

[0107] Connect the straight continuous grating fiber 6 or the straight microstructure fiber 7 to the DPS signal input end.

[0108] Connect the spiral single-mode optical fiber to the DAS and DSS signal input terminals.

[0109] Connect the spiral multimode optical fiber to the DTS signal input terminal;

[0110] Step S2: modulate and demodulate the DTS signal and the DSS signal measured in step S1 to obtain temperature data and three-component stress data at different depths and different orientations outside the coiled tubing body 3, and correct the three-component stress data by the temperature data to obtain the real three-component stress data at different depths and different orientations underground; and simultaneously monitor and measure the three-component microseismic data underground;

[0111] In step S2, the strain ε or temperature t response obtains a spectral drift similar to the drift of the resonance wave Dl or spectral drift of the Bragg grating Two , use the following formula to correct the data:

[0112] Δλ / λ=−Δυ / υ=K T Δt+K ε e

[0113] in, l and u are the average light wavelength and frequency, respectively; K T and K ε are the standard constants for temperature and strain, respectively;

[0114] The temperature value at a specific measurement position is used to correct the DSS signal measurement data affected by the spectral drift of scattered light in the spiral single-mode optical fiber, thereby obtaining the true three-component stress data and three-dimensional stress field changes on the outside of the coiled tubing body 3 in the measurement well section with the temperature effect eliminated.

[0115] Step S3: based on the three-component stress data at different depths and azimuths obtained in step S2, a three-dimensional distribution map of the underground stress field at each depth and each orientation is drawn to obtain the distribution change characteristics of the underground three-dimensional stress field along the well trajectory, and an underground three-dimensional stress field model is established based on the three-dimensional distribution map of the underground stress field;

[0116] Step S4: Projecting the well trajectory into the underground three-dimensional stress field model in step S3, optimizing and designing the perforation positions and fracturing sections of the downhole coiled tubing body 3 according to the distribution variation characteristics of the underground three-dimensional stress field along the well trajectory;

[0117] Step S5: According to the distribution range, occurrence time, energy size and rupture mechanism of the earthquake source point in the three-dimensional space around the well trajectory monitored and measured in step S1, the reservoir transformation effect is evaluated in real time, the fracturing parameters in step S4 are adjusted and optimized in time, and the well spacing and segment spacing of the multi-branch horizontal wells are optimized. Through long-term real-time monitoring of the three-dimensional spatial distribution changes of underground fluids around the liquid production or gas production profile and the water absorption or gas absorption profile, the residual oil and gas and remaining oil and gas resources around the well can be discovered and identified, and the mining plan and production system can be adjusted and optimized in time to improve the oil and gas recovery rate.

[0118] Specifically, the following steps are also included:

[0119] Step Sa: modulating and demodulating the DAS signal, DTS signal and DPS signal in step S1 to obtain noise data, temperature data and pressure data distributed downhole;

[0120] The composite modem 10 can be used to demodulate the noise data of the DAS signal, the temperature data in the DTS signal, and the pressure data at each grating or microstructure position on the continuous grating optical fiber or microstructure optical fiber in the DPS signal, thereby obtaining the distribution of downhole noise data, temperature data, and pressure data.

[0121] Step Sb: Calculate each liquid production or gas production profile and its change and each water absorption or gas absorption profile and its change in the well through a multi-parameter comprehensive inversion method according to the noise data, temperature data and pressure data distributed in the well in step Sa;

[0122] Step Sc: regularly exciting an artificial seismic source 12 disposed on the ground, and collecting time-shift variable offset vertical seismic profile (Walkaway DAS-VSP) data or time-shift three-dimensional vertical seismic profile (3D DAS-VSP) data through a spiral single-mode optical fiber;

[0123] Step Sd: performing surface consistent amplitude compensation processing, surface consistent deconvolution processing and relatively amplitude-preserving wavefield separation processing on the Walkaway DAS-VSP data or 3D DAS-VSP data collected at different times in step Sc;

[0124] Step Se: The Walkaway DAS-VSP data or the 3D DAS-VSP data processed in step Sd are subjected to amplitude-preserving prestack depth migration processing by the same process in stages, and the fluid sensitive attribute parameters in the seismic data volume after the migration processing are extracted. Combined with the highlight volume data obtained by S transformation, the distribution range of the oil-water two-phase or oil-gas-water three-phase fluid boundary around the well in three-dimensional space and its change over time are calculated and monitored;

[0125] In this embodiment, the fluid sensitive property parameters include but are not limited to longitudinal and transverse wave velocities, longitudinal and transverse wave velocity ratios, Poisson's ratio, longitudinal wave impedance, transverse wave impedance, longitudinal and transverse wave impedance ratios, Young's elastic modulus, shear elastic modulus, and fluid density in pores.

[0126] Step Sf: Based on each liquid production or long-term profile (oil, gas and water flow profile) and water absorption or gas absorption profile (injection flow profile of water, water vapor, carbon dioxide or polymer injection section) of the downhole oil and gas producing section obtained in step Sb and its changes, as well as the changes in the three-dimensional space of the oil-water two-phase fluid or oil-gas-water three-phase fluid boundary around the well obtained in step Se, real-time measurement and monitoring of the changes of the oil-water two-phase fluid or oil-gas-water three-phase fluid in and around the well are achieved, and the development plan and production system are optimized and adjusted in time, so as to achieve the purpose of improving the oil and gas recovery rate.

[0127] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A downhole fluid optical fiber monitoring method based on a composite material coiled tube, which is applicable to a downhole fluid optical fiber monitoring system based on a composite material coiled tube, and is characterized in that: The specific steps include: Step S1: During oil and gas production, the composite modem (10) is used to monitor and measure in real time the DSS signal on the outside of the coiled tubing body (3), and the composite modem (10) is used to monitor and measure in real time the DAS signal, DTS signal and DPS signal on both sides of the inside and outside of the coiled tubing body (3); Step S2: modulating and demodulating the DTS signal and the DSS signal measured in step S1 to obtain temperature data and three-component stress data at different depths and different orientations outside the coiled tubing body (3), and correcting the stress data using the temperature data to obtain true three-component stress data at different depths and different orientations underground; and simultaneously monitoring and measuring the three-component microseismic data underground; Step S3: based on the stress data at different depths and orientations obtained in step S2, a three-dimensional distribution map of the underground stress field at each depth and orientation is drawn to obtain the distribution variation characteristics of the underground stress field along the well trajectory, and a three-dimensional underground stress field model is established based on the three-dimensional distribution map of the underground stress field; Step S4: projecting the well trajectory into the underground three-dimensional stress field model in step S3, and designing the perforation positions and fracturing sections of the downhole coiled tubing body (3) according to the distribution variation characteristics of the underground stress field along the well trajectory; Step S5: adjusting the segment spacing of the fracturing segments and the well spacing of the multi-branch horizontal wells in step S4 according to the distribution of the three-component microseismic data monitored and measured in step S2 in the three-dimensional space around the well trajectory and the fracture mechanism of the earthquake source point; The following specific steps are also included: Step Sa: modulating and demodulating the DAS signal, DTS signal and DPS signal in step S1 to obtain noise data, temperature data and pressure data distributed downhole; Step Sb: Calculate each liquid production or gas production profile and each water absorption or gas absorption profile in the well by a multi-parameter comprehensive inversion method according to the noise data, temperature data and pressure data distributed in the well in step Sa; Step Sc: regularly exciting an artificial seismic source (12) disposed on the ground, and collecting time-shift variable offset vertical seismic profile (Walkaway DAS-VSP) data or time-shift three-dimensional vertical seismic profile (3D DAS-VSP) data through a spiral single-mode optical fiber; Step Sd: performing surface consistent amplitude compensation processing, surface consistent deconvolution processing and relatively amplitude-preserving wavefield separation processing on the Walkaway DAS-VSP data or 3D DAS-VSP data acquired at different times in step Sc; Step Se: The Walkaway DAS-VSP data or the 3D DAS-VSP data processed in step Sd are subjected to amplitude-preserving prestack depth migration processing by using the same process in stages, and the fluid sensitive attribute parameters in the seismic data volume after the migration processing are extracted. Combined with the highlight volume data obtained by S transformation, the three-dimensional spatial distribution range and the change over time of the oil-water two-phase or oil-gas-water three-phase fluid boundary around the well are calculated and monitored; Step Sf: Based on each downhole liquid production or gas production profile and water absorption or gas absorption profile obtained in step Sb, and the oil-water two-phase or oil-gas-water three-phase fluid interface changes around the well obtained in step Se, the real-time measurement and monitoring of the oil-water two-phase or oil-gas-water three-phase fluid interface changes in the well and around the well are achieved simultaneously; The downhole fluid optical fiber monitoring system comprises a composite modem (10), and also comprises a continuous tube body (3), wherein the continuous tube body (3) is embedded with a straight optical fiber (8) and a spiral optical fiber (9) both connected to the composite modem (10); The straight optical fiber (8) is used to monitor and measure in real time the fluid noise data, temperature data and fluid pressure data inside and outside the downhole continuous pipe body (3); The spiral optical fiber (9) is used for real-time monitoring and measurement of temperature data inside and outside the downhole continuous pipe body (3), three-component stress data outside the continuous pipe body (3), and three-component seismic data.

2. The optical fiber monitoring method for downhole fluid based on composite material coiled tubing according to claim 1 is characterized in that: The composite modem (10) comprises a DAS signal input terminal, a DTS signal input terminal, a DSS signal input terminal and a DPS signal input terminal; The straight optical fiber (8) comprises a straight single-mode optical fiber (4) and a straight multi-mode optical fiber (5); the straight single-mode optical fiber (4) is connected to a DAS signal input end, and the straight multi-mode optical fiber (5) is connected to a DTS signal input end; the straight optical fiber (8) further comprises a straight continuous grating optical fiber (6) or / and a straight microstructure optical fiber (7) connected to a DPS signal input end.

3. The optical fiber monitoring method for downhole fluid based on composite material coiled tubing according to claim 2 is characterized in that: The spiral optical fiber (9) comprises a spiral single-mode optical fiber and a spiral multi-mode optical fiber, the spiral single-mode optical fiber is connected to the DAS and DSS signal input ends, and the spiral multi-mode optical fiber is connected to the DTS signal input end; The spiral single-mode optical fiber is used for real-time monitoring and measurement of three-component stress data outside the continuous pipe body (3), three-component microseismic (11) data in the formation around the continuous pipe body (3), and time-shifted three-component in-well seismic data; The spiral multimode optical fiber is used to monitor and measure the temperature data inside and outside the continuous tube body (3) in real time.

4. The optical fiber monitoring method for downhole fluid based on composite material coiled tubing according to claim 3, characterized in that: The spiral single-mode optical fiber includes three groups of spiral single-mode optical fibers with different spiral angles, and the spiral multimode optical fiber includes three groups of spiral multimode optical fibers with different spiral angles. The three spiral angles of the spiral single-mode optical fiber and the spiral multimode optical fiber are 30 degrees, 45 degrees and 60 degrees.

5. The optical fiber monitoring method for downhole fluid based on composite material coiled tubing according to claim 3 is characterized in that: It also includes a regularly excited artificial seismic source (12), which is arranged on the ground. The time-shifted three-component wellbore seismic data regularly excited by the artificial seismic source (12) is collected through a spiral single-mode optical fiber and a composite modem (10).

6. The optical fiber monitoring method for downhole fluid based on composite material coiled tubing according to claim 5, characterized in that: It also includes a geophone (13) for collecting ground seismic data. The geophone (13) is arranged on the ground in a two-dimensional or three-dimensional manner. When the geophone (13) is used to collect conventional ground seismic data or time-shifted ground seismic data, corresponding conventional three-component wellbore seismic data or time-shifted three-component wellbore seismic data are collected simultaneously through a spiral single-mode optical fiber, thereby realizing well-ground combined three-dimensional exploration.

7. The optical fiber monitoring method for downhole fluid based on composite material coiled tubing according to claim 1, characterized in that: The continuous tube body (3) comprises a core material (2) and a protective layer (1), the straight optical fiber (8) and the spiral optical fiber (9) are both embedded between the core material (2) and the protective layer (1), the straight optical fiber (8) is arranged parallel to the axis of the continuous tube body (3), and the spiral optical fiber (9) is wound on the core material (2).

8. The optical fiber monitoring method for downhole fluid based on composite material coiled tubing according to claim 1, characterized in that: The continuous tube body (3) is processed and formed by, but not limited to, any of the following methods: The first type is horizontal dry winding; The second type is horizontal wet longitudinal yarn dipping and winding; The third type is horizontal wet method of circumferential yarn dipping and winding; The fourth type is vertical winding with a mandrel that moves upward vertically; The fifth type is vertical low-melting-point metal core mode winding molding.

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