CN110344816A - A kind of sand production of oil-gas wells monitoring method based on the monitoring of distribution type fiber-optic sound - Google Patents

Abstract

A method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring, comprising: a method for installing a distributed optical fiber sound monitoring device in an oil and gas well to be monitored for sand production, a method for monitoring sand production in the oil and gas wells, and a DAS oil and gas well sand production monitoring and interpretation method . The invention adopts distributed optical fiber sound monitoring to realize distributed and real-time monitoring of sand production in all production intervals; it can qualitatively judge the sand production degree of each interval; it can realize temporary monitoring of downhole sand production; and it can realize sand control in sand production intervals. The effect evaluation is of great significance to practice and research.

Description

A method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring

technical field

The invention relates to a method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring, and belongs to the technical field of oil and gas exploitation.

Background technique

In the process of oil and gas field exploitation, a large number of sand production or continuous sand production in the reservoir will cause sand burial in oil and gas layers, sand plugging in oil pipes, sand accumulation in ground manifolds, formation deficit and collapse, etc., which seriously affect the normal production of oil and gas wells. Therefore, being able to know the sand production horizon and sand production volume of oil and gas wells in real time is very important to ensure the safe, efficient and continuous production of oil and gas wells. At present, the sand production monitoring methods used in the field mainly include ultrasonic method, piezoelectric method, acceleration sensor method, etc. These methods are mainly based on wellhead monitoring, which obtains the sand production situation of the whole well, and cannot reveal the production interval of each downhole production interval in real time. Sand conditions and the flow of sand particles in the wellbore.

In recent years, with the development of distributed optical fiber sound monitoring technology, hereinafter referred to as DAS technology, it has provided an important means for distributed and real-time monitoring of reservoir sand production and wellbore sand flow. Applied to the process of detecting sand production in oil and gas wells.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention discloses a method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring.

SUMMARY OF THE INVENTION

The main principle of DAS technology is to use the principle of coherent optical time domain reflectometry to inject coherent short pulse laser into the fiber. As a result, the back-rayleigh scattering signal changes, so that the received reflected light intensity changes. By detecting the intensity change of the Rayleigh scattering light signal before and after the downhole event, the ongoing downhole event can be detected and accurately located. When sand is produced from the reservoir, the sand particles impact the downhole optical fiber and generate vibration events. According to the vibration events and vibration intensity at different positions of the optical fiber, the sand production layer and the degree of sand production can be determined. At the same time, by monitoring the movement of sand grains entering the wellbore, it can be determined whether sand grain subsidence will occur at the current production rate, which in turn can provide guidance for oil and gas wells to carry sand. Because the optical fiber has the characteristics of anti-electromagnetic interference, corrosion resistance and good real-time performance, it has greater advantages in real-time monitoring of downhole sand production.

The detailed technical scheme of the present invention is as follows:

A method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring, characterized by comprising: a method for installing a distributed optical fiber sound monitoring device in an oil and gas well to be monitored for sand production;

Wherein, the distributed optical fiber sound monitoring device includes a DAS sand production monitor and an armored optical cable, and the DAS sand production monitor includes a laser light source, a sound signal receiver and a computer control and display system;

The DAS sand production monitor is used for real-time monitoring and feedback sound data to the monitoring personnel; the armored optical cable is used to be vertically arranged in the oil and gas well, and the monitored sound data of the downhole sand production is transmitted to the DAS sand production monitor;

The method for installing a distributed optical fiber sound monitoring device in a sand-producing oil and gas well to be monitored includes:

The armored optical cable is installed in the oil and gas well vertically and along the axial direction of the oil and gas well; the installation depth of the armored optical cable covers all the sand producing layers of the oil and gas well to be detected;

The end of the armored optical cable is provided with a part that keeps its natural hanging; the DAS sand production monitor collects the sound signal of the oil and gas well in real time through the armored optical cable, and transmits the sound signal to the computer control and display system.

Preferably according to the present invention, the armored optical cable is installed on the outer wall of the oil pipe in the oil and gas well, or installed in the annular space between the oil pipe and the casing.

Preferably according to the present invention, the method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring further includes a method for monitoring sand production in oil and gas wells, and the steps are as follows:

The laser light source sends pulsed laser light to the single-mode sound-sensing fiber in the armored optical cable; the sound signal receiver receives the sound signal reflected from the single-mode sound-sensing fiber in the armored fiber optic cable;

The computer control and display system controls the signal transmission and reception of the laser light source and the sound signal receiver.

According to the preferred embodiment of the present invention, the computer control and display system is used to feed back the sand production conditions of each production interval of the oil and gas well.

According to the preferred embodiment of the present invention, the spatial resolution of the DAS sand production monitor is 1 meter, and the maximum sampling frequency is 15 kHz.

Preferably according to the present invention, the method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring further includes a DAS oil and gas well sand production monitoring interpretation method, and the computer control and display system for realizing the interpretation method includes a data preprocessing module and a sand production system. Monitoring data interpretation module:

The data preprocessing module is used to obtain the denoised sound data related to the entry of the reservoir sand into the wellbore, including steps 1-1)-1-3):

1-1) The frequency-space deconvolution filter is used to process the sound data collected in the sand production monitoring process to obtain sound data with random spike noise removed;

1-2) Using a band-pass filter to limit the frequency range of the sound data to the impact energy range of the sand entering the wellbore, thereby eliminating irrelevant noise signals in the data;

1-3) Obtain the sound data after denoising related to the entry of reservoir sand into the wellbore;

The sand production monitoring and interpretation module includes: establishing a sound intensity coordinate system and generating a sound intensity "waterfall diagram", including:

2-1) Establish a sound intensity coordinate system, the depth of oil and gas wells is the abscissa, and the time of sound monitoring of oil and gas wells is the ordinate;

2-2) Use the sound data related to the entry of the reservoir sand into the wellbore to draw the sound intensity "waterfall diagram" in the above sound intensity coordinate system:

2-3) Define the sand producing interval:

Since the positions of all production intervals in the oil and gas well are known, that is, the depth range covered by the production intervals of the oil and gas well is known, the sound intensity "waterfall map" is extracted from the sound intensity "waterfall diagram" within the depth range covered by the production intervals at any time. The curve of sound intensity changing with oil and gas well depth is shown in Figure 2; based on the minimum sound intensity value of the sound intensity changing curve with oil and gas well depth extracted at any time in the depth range covered by the production interval, a horizontal line, as shown by the dotted line in Figure 2;

According to the depth range covered by each production interval, the area method is used to calculate the graph enclosed by the horizontal line based on the minimum sound intensity value and the curve of sound intensity changing with the depth of oil and gas wells within the depth range covered by each production interval area;

Then, calculate the area variance: the production interval whose area corresponding to the production interval is greater than 1 times the area variance is judged as the sand producing interval;

2-4) Definition of severe sand production, moderate sand production and slight sand production:

Divide the area corresponding to each production section by the thickness of the production section to obtain the area per unit thickness of the production section;

The area per unit thickness of each production section is added up to obtain the total area per unit thickness, and the area percentage of the unit thickness corresponding to each production section is calculated;

The area percentage per unit thickness greater than or equal to 50% is defined as severe sand production, the area percentage per unit thickness between 20% and 50% is defined as medium sand production, and the area percentage per unit thickness is less than or equal to 20% as slight sand production.

The beneficial effects of the present invention are:

1. The present invention adopts distributed optical fiber sound monitoring to realize distributed and real-time monitoring of sand production in all production sections;

2. The distributed optical fiber sound monitoring method of the present invention can qualitatively judge the sand production degree of each interval;

3. The distributed optical fiber sound monitoring method of the present invention can realize long-term monitoring of downhole sand production, and can also realize temporary monitoring of downhole sand production.

4. The distributed optical fiber sound monitoring method of the present invention can realize the evaluation of the sand control effect of the sand producing interval, which is of great significance to practice and research.

Description of drawings

FIG. 1 is a schematic diagram of a working condition of a method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring according to the present invention.

Fig. 2 is a schematic diagram showing the monitoring results of sand production of oil and gas wells monitored at a certain time by the method of the present invention.

In Figure 1-2: 1. Production interval I; 2. Production interval II; 3. Production interval III; 4. Casing; 5. Tubing; 6. Wellhead; 7. DAS sand production monitor; 8. Armored optical cable; 9. The heavy object that keeps the armored optical cable hanging naturally; 10. The bottom of the artificial well.

Detailed ways

The present invention will be described in detail below with reference to the embodiments and the accompanying drawings, but is not limited thereto.

As shown in Figures 1 and 2.

Embodiment 1,

A method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring, comprising:

A method for installing a distributed optical fiber sound monitoring device in an oil and gas well to be monitored for sand production;

Wherein, the distributed optical fiber sound monitoring device includes a DAS sand production monitor 7 and an armored optical cable 8, and the DAS sand production monitor 7 includes a laser light source, a sound signal receiver and a computer control and display system;

The DAS sand production monitor 7 is used for real-time monitoring and feedback sound data to the monitoring personnel; the armored optical cable 8 is used to be vertically arranged in the oil and gas well, and the monitored downhole sand production sound data is transmitted to the DAS sand production monitoring device Instrument 7;

The method for installing a distributed optical fiber sound monitoring device in a sand-producing oil and gas well to be monitored includes:

The armored optical cable 8 is installed in the oil and gas well vertically and along the axial direction of the oil and gas well; the installation depth of the armored optical cable 8 covers all the sand producing layers of the oil and gas well to be detected;

The end of the armored optical cable 8 is provided with a part 9 that keeps its natural overhang; the DAS sand production monitor 7 collects the sound signal of the oil and gas well in real time through the armored optical cable 8, and transmits the sound signal to the computer control system. display system.

The armored optical cable 8 is installed on the outer wall of the oil pipe in the oil and gas well, or installed in the annular space between the oil pipe 4 and the casing 5 .

Embodiment 2,

The method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring as described in Embodiment 1 also includes a method for monitoring sand production in the oil and gas wells, and the steps are as follows:

The laser light source sends pulsed laser light to the single-mode sound-sensing fiber in the armored optical cable 8; the sound signal receiver receives the sound signal reflected from the single-mode sound-sensing fiber in the armored fiber optic cable 8;

The computer control and display system controls the signal transmission and reception of the laser light source and the sound signal receiver.

The computer control and display system is used to feed back the sand production situation of each production interval of the oil and gas well.

The spatial resolution of the DAS sand production monitor is 1 meter, and the maximum sampling frequency is 15 kHz.

The method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring also includes a DAS oil and gas well sand production monitoring and interpretation method, and the computer control and display system for realizing the interpretation method includes a data preprocessing module and a sand production monitoring data interpretation module:

The data preprocessing module is used to obtain the denoised sound data related to the entry of the reservoir sand into the wellbore, including steps 1-1)-1-3):

1-1) The frequency-space deconvolution filter is used to process the sound data collected in the sand production monitoring process to obtain sound data with random spike noise removed;

1-2) Using a band-pass filter to limit the frequency range of the sound data to the impact energy range of the sand entering the wellbore, thereby eliminating irrelevant noise signals in the data;

1-3) Obtain the sound data after denoising related to the entry of reservoir sand into the wellbore;

The sand production monitoring and interpretation module includes: establishing a sound intensity coordinate system and generating a sound intensity "waterfall diagram", including:

2-1) Establish a sound intensity coordinate system, the depth of oil and gas wells is the abscissa, and the time of sound monitoring of oil and gas wells is the ordinate;

2-2) Use the sound data related to the entry of the reservoir sand into the wellbore to draw the sound intensity "waterfall diagram" in the above sound intensity coordinate system:

2-3) Define the sand producing interval:

Since the positions of all production intervals in the oil and gas well are known, that is, the depth range covered by the production intervals of the oil and gas well is known, the sound intensity "waterfall map" is extracted from the sound intensity "waterfall diagram" within the depth range covered by the production intervals at any time. The curve of sound intensity changing with oil and gas well depth is shown in Figure 2; based on the minimum sound intensity value of the sound intensity changing curve with oil and gas well depth extracted at any time in the depth range covered by the production interval, a horizontal line, as shown by the dotted line in Figure 2;

According to the depth range covered by each production interval, the area method is used to calculate the graph enclosed by the horizontal line based on the minimum sound intensity value and the curve of sound intensity changing with the depth of oil and gas wells within the depth range covered by each production interval area;

Then, calculate the area variance: the production interval whose area corresponding to the production interval is greater than 1 times the area variance is judged as the sand producing interval;

2-4) Definition of severe sand production, moderate sand production and slight sand production:

Divide the area corresponding to each production section by the thickness of the production section to obtain the area per unit thickness of the production section;

The area per unit thickness of each production section is added up to obtain the total area per unit thickness, and the area percentage of the unit thickness corresponding to each production section is calculated;

The area percentage per unit thickness greater than or equal to 50% is defined as severe sand production, the area percentage per unit thickness between 20% and 50% is defined as medium sand production, and the area percentage per unit thickness is less than or equal to 20% as slight sand production.

Application example 1,

Using the method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring according to the present invention, the specific steps to obtain the sand production conditions of each production interval of the wellbore under different working regimes are as follows:

Step 1: Determine the oil and gas well production string according to the oil and gas well production process, determine the length of the armored optical cable 8 armored by the seamless stainless steel pipe, and ensure that the length of the armored optical cable 8 exceeds the length of the oil pipe 5 and can be extended to artificial Bottom 10; connect the weight 9 to the lower end of the armored optical cable 8; fix the part of the armored optical cable 8 less than the length of the oil pipe 5 in the groove of the outer wall of the oil pipe 5; attach the armored optical cable 8 to the lower end of the oil and gas well production string into production wells;

Step 2: Connect the armored optical cable 8 to the DAS sand production monitor 7 placed on the ground after passing through the wellhead 6;

Step 3: Start the DAS sand production monitor 7, and open the well for production;

Step 4: observe the sound data displayed on the computer control and display system in the DAS sand production monitor 7, and after the sound data is stable, record the sound data, and obtain the schematic diagram as shown in Figure 2;

Step 5: Use the built-in DAS oil and gas well sand production monitoring and interpretation method in the computer control and display system of the DAS sand production monitor 7 to interpret the sound data collected in step 4 in real time, and obtain the sand production conditions of each production interval of the wellbore;

Step 6: Change the working system of the oil and gas well, repeat steps 4 and 5, and obtain the sand production conditions of each production interval of the wellbore under different working systems.

Application example 2,

Using the method for monitoring sand production in oil and gas wells based on distributed optical fiber sound monitoring according to the present invention, the steps of temporarily monitoring sand production in oil and gas wells are completed:

Step 1: According to the depth of the artificial bottom 10 of the oil and gas well, determine the length of the armored optical cable 8 armored by seamless stainless steel pipe or armored by decomposable aluminum alloy, and ensure that the length of the armored optical cable 8 exceeds The length of the oil pipe 5 can be extended to the bottom of the artificial well 10; the weight 9 is connected to the lower end of the armored optical cable 8; the armored optical cable 8 is lowered into the oil and gas well from the annular space between the oil pipe 5 and the casing 4;

Step 2: Connect the armored optical cable 8 to the DAS sand production monitor 7 placed on the ground after passing through the wellhead 6;

Step 3: Start the DAS sand production monitor 7, and open the well for production;

Step 4: observe the sound data displayed on the computer control and display system in the DAS sand production monitor 7, and after the sound data is stable, record the sound data, and obtain the schematic diagram as shown in Figure 2;

Step 5: Use the built-in DAS oil and gas well sand production monitoring and interpretation method in the computer control and display system of the DAS sand production monitor 7 to interpret the sound data collected in step 4 in real time, and obtain the sand production conditions of each production interval of the wellbore;

Step 6: Change the working system of the oil and gas well, repeat steps 4 and 5, and obtain the sand production conditions of each production interval of the wellbore under different working systems;

Step 7: After the test is completed, turn off the DAS sand production monitor 7; if the armored optical cable 8 made of seamless stainless steel pipe armor is used, take out the armored optical cable 8 from the annular space between the oil pipe 5 and the casing 4. The weight 9 is used to complete the temporary monitoring of sand production in oil and gas wells; if the armored optical cable 8 made of decomposable aluminum alloy armor is used, the armored optical cable 8 is cut at the wellhead to complete the temporary monitoring of sand production in oil and gas wells. .

Application example 3,

Using the sand production situation of each production interval of the wellbore after sand control obtained by the method for monitoring sand production of oil and gas wells based on distributed optical fiber sound monitoring according to the present invention, the steps of evaluating the sand control effect of oil and gas wells are carried out:

Step 1: According to the depth of the artificial bottom 10 of the oil and gas well, determine the length of the armored optical cable 8 armored by seamless stainless steel pipe or armored by decomposable aluminum alloy, and ensure that the length of the armored optical cable 8 exceeds The length of the oil pipe 5 can be extended to the bottom of the artificial well 10; the weight 9 is connected to the lower end of the armored optical cable 8; the armored optical cable 8 is inserted into the production well from the annular space between the oil pipe 5 and the casing 4;

Step 2: Connect the armored optical cable 8 to the DAS sand production monitor 7 placed on the ground after passing through the wellhead 6;

Step 3: Start the DAS sand production monitor 7, and open the well for production;

Step 4: observe the sound data displayed on the computer control and display system in the DAS sand production monitor 7, and after the sound data is stable, record the sound data, and obtain the schematic diagram as shown in Figure 2;

Step 5: Use the built-in DAS oil and gas well sand production monitoring and interpretation method in the computer control and display system of the DAS sand production monitor 7 to interpret the sound data collected in step 4 in real time, and obtain the sand production conditions of each production interval of the wellbore before sand control;

Step 6: After the test is completed, turn off the DAS sand production monitor 7; if the armored optical cable 8 made of seamless stainless steel pipe armor is used, take out the armored optical cable 8 and The weight 9 is used to complete the temporary monitoring of sand production in oil and gas wells; if the armored optical cable 8 made of decomposable aluminum alloy armor is used, the armored optical cable 8 is cut at the wellhead to complete the temporary monitoring of sand production in oil and gas wells. ;

Step 7: Implement the gravel packing sand control process;

Step 8: After the gravel packing sand control process is completed, take out the gravel packing sand control string;

Step 9: Repeat steps 1 to 6 to obtain the sand production of each production interval of the wellbore after sand control;

Step 10: Compare the sand production of each production interval of the wellbore before sand control obtained in step 5 with the sand production of each production interval of the wellbore after sand control obtained in step 9, to provide a basis for evaluating the sand control effect of oil and gas wells.

Claims (5)

1. a kind of sand production of oil-gas wells monitoring method based on the monitoring of distribution type fiber-optic sound characterized by comprising to be monitored The method of the oil/gas well that shakes out installation distribution type fiber-optic sound monitoring device；

It is described to include: in the method to be monitored for shaking out oil/gas well installation distribution type fiber-optic sound monitoring device

It is armored optical cable is vertical and be mounted in oil/gas well along oil/gas well axial direction；The fitting depth of the armored optical cable covers All sanding formation positions of oil/gas well to be detected；

The end of the armored optical cable is provided with the part for keeping it to dangle naturally；DAS sand production monitoring instrument passes through the armouring light Cable acquires the voice signal of oil/gas well in real time, and the transmission of sound signals to computer is controlled and display system.

2. a kind of sand production of oil-gas wells monitoring method based on the monitoring of distribution type fiber-optic sound according to claim 1, special Sign is that the armored optical cable is mounted on the outer wall of oil/gas well inner oil tube, or the annular being mounted between oil pipe and casing In space.

3. a kind of sand production of oil-gas wells monitoring method based on the monitoring of distribution type fiber-optic sound according to claim 1, special Sign is that the monitoring further includes the method for monitoring the sand production of oil-gas wells, and steps are as follows:

Single mode sense acousto-optic fibre of the laser light source into armored optical cable sends pulse laser；The sound signal receiver Receive the fine reflected voice signal of single mode sense acousto-optic from armored optical cable；

The signal of the computer control and display system control laser light source and sound signal receiver emits and receives work Make.

4. a kind of sand production of oil-gas wells monitoring method based on the monitoring of distribution type fiber-optic sound according to claim 1, special Sign is that the computer control is used to feed back the situation of shaking out of each pay interval of oil/gas well with display system；The DAS goes out The spatial resolution of sand monitor is 1 meter, and highest sample frequency is 15kHz.

5. a kind of sand production of oil-gas wells monitoring method based on the monitoring of distribution type fiber-optic sound according to claim 1, special Sign is that the sand production of oil-gas wells monitoring method based on the monitoring of distribution type fiber-optic sound further includes the monitoring of DAS sand production of oil-gas wells Means of interpretation realizes that the computer control of the means of interpretation and display system are interior including data preprocessing module and sand production monitoring Data interpretation module:

The data preprocessing module is used to obtain to enter the later voice data of the relevant denoising of pit shaft to reservoir sand grains, including Step 1-1) -1-3):

1-1) voice data acquired during sand production monitoring is handled using frequency-space deconvolution filter, is obtained Remove the voice data of random peaks noise；

The frequency range of voice data 1-2) is limited in by the impact energy model that sand grains enters Wellbore Flow using bandpass filter In enclosing, to eliminate noise signal unrelated in data；

It 1-3) obtains entering the later voice data of the relevant denoising of pit shaft to reservoir sand grains；

The sand production monitoring explanation module includes: to establish sound intensity coordinate system and generate the sound intensity " Waterfall plot ", comprising:

The sound intensity coordinate system 2-1) is established, oil gas well depth is abscissa, is ordinate to the time of oil/gas well sound monitoring；

The sound intensity " waterfall 2-2) is drawn in above-mentioned sound intensity coordinate system using entering the relevant voice data of pit shaft to reservoir sand grains Figure ":

2-3) define sand producing interval:

The sound intensity of any time is extracted in the depth bounds that pay interval is covered from the sound intensity " Waterfall plot " with oil gas well depth The curve for spending variation, with the sound intensity of any time extracted in the depth bounds that pay interval is covered with oil gas well depth Make a horizontal line based on the minimum sound intensity value of change curve；

According to the depth bounds that each pay interval is covered, the depth model that each pay interval is covered is calculated using area-method The interior horizontal line by making based on minimum sound intensity value and the sound intensity are enclosed with the figure of the surrounded formation of curve of oil/gas well change in depth Area；

Then, reference area variance: the pay interval that area corresponding to pay interval is greater than 1 times of area variance is judged as out Sand section；

2-4) definition seriously shakes out, medium shake out and slightly shake out:

By area corresponding to each pay interval divided by the thickness of the pay interval, the unit thickness of the pay interval is obtained Area；

The area of the unit thickness of each pay interval is added to the area for acquiring total unit thickness, calculates each pay interval The area percentage of corresponding unit thickness；

The area percentage of unit thickness is more than or equal to 50% be defined as seriously shaking out, the area percentage of unit thickness exists Be defined as between 20%-50% it is medium shake out, the area percentage of unit thickness is less than or equal to 20% be defined as slightly shaking out.