A method for monitoring a SAGD channeling path

Abstract

The application discloses a kind of SAGD channeling monitoring method belongs to oilfield well area monitoring identification technical field, the present application can quickly and accurately find out the distribution state of SAGD channeling to surface by carrying out high-density electrical method monitoring in oilfield well area ground, in the monitoring process, it does not inject any chemical agent into oil well, will not cause damage to oil well, and does not affect normal production of oilfield;After obtaining resistivity data, with the original stratum electrical characteristic data, the resistivity response characteristic of SAGD channeling is calibrated to improve the reliability of interpretation;After finding out the distribution state of SAGD channeling, the root cause of SAGD channeling can be found out, which provides accurate and efficient guidance for subsequent development of targeted measures to control SAGD surface channeling, and eliminates the blindness of SAGD surface channeling control.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oilfield well area monitoring and identification, and particularly relates to a monitoring method for SAGD channeling and leakage. BACKGROUND

[0002] Steam assisted gravity drainage (SAGD) technology is an effective thermal recovery technology for heavy oil development. High-temperature and high-dryness steam is continuously injected into the oil layer through a vertical well or a horizontal well. The latent heat of the steam is released, and the heated crude oil and steam condensate seep under the action of gravity to the horizontal production well and is recovered. The injected steam forms a steam chamber with a certain pressure and temperature at the upper part of the horizontal well. As production proceeds, the steam chamber gradually develops upward to the top of the oil layer. Once there is a fracture at the top, the high-temperature and high-pressure steam enters the fracture and forms an upward channeling and leakage channel, which then channels to the ground, affecting the normal development of SAGD, and causing environmental pollution and safety hazards. Therefore, it is necessary to identify the channeling and leakage channel to provide guidance for managing the channeling and leakage problem.

[0003] The existing technology for identifying the channeling and leakage channel is mainly the interwell potential method. This technology is based on the change in resistivity caused by the change in fluid in the steam channeling channel, so that the potential anomaly is tested. First, measurement points are deployed around the well to be tested. A current return well is set up 4-6 km away from the well to be tested. The channeling conductor connects the two wells to the signal output device. Then, the potential difference is measured when the artificial electric field signal is transmitted. Generally, two tests are needed: one to measure the potential background value when the steam injection is stopped, and the other to test the potential anomaly value after the steam is injected into the relevant well. The difference between the two observation results is analyzed to understand the steam diffusion channel, so as to characterize the distribution characteristics of the steam channeling channel.

[0004] The interwell potential method for monitoring the channeling and leakage channel is currently mainly used for identifying the channeling and leakage in the production area of the vertical well. The potential anomaly obtained by the test mainly reflects the change characteristics of the ground potential after the change of the fluid in the target layer channel, so as to analyze the channel distribution characteristics in the plane, but there is a deficiency in the vertical channel characterization. With the development of potential method processing technology, the distribution of the formation resistivity can be calculated by inverting the potential data, but the vertical processing accuracy is greater than 10 meters, which cannot meet the characterization of the vertical channel. SUMMARY

[0005] The purpose of the present application is to: SAGD channeling and leakage mainly occurs after the steam chamber top communicates with the overlying stratum fracture. The high-temperature and high-pressure steam enters the fracture channel and breaks through to the ground upward, affecting the normal development of SAGD, and causing environmental pollution and safety hazards. Therefore, the purpose of the present application is to monitor and identify the channel above the oil layer, identify the channeling and leakage path, and provide a basis for formulating measures to manage the channeling and leakage channel.

[0006] The monitoring method for the SAGD channeling and leakage channel of the present application comprises the following steps:

[0007] 1.1 Prepare the instrument equipment for monitoring the oilfield drilling target area, specifically including:

[0008] The transmitting power system 6 with pulse signal width of 0.125s, 0.25s, 0.5s, 1s, 2s, 4s, 8s, 16s, 32s, 64s as the signal transmitting part;

[0009] The high-density electrical method host 1, 10-20 high-density cables of the high-density cable group 2, each high-density cable containing 12 taps of the tap group 4, 10-20 intelligent bidirectional cable heads of the intelligent bidirectional cable head group 3, and 120-300 electrodes of the electrode group 5 as the signal receiving part;

[0010] 1.2 On-site deployment of the instrument equipment for monitoring the oilfield drilling target area of step 1.1, data monitoring includes the following steps:

[0011] 1.2.1 At the monitoring points of the oilfield drilling target area, 10-20 high-density cables of the high-density cable group 2 of step 1.1 are laid in parallel along the horizontal direction of x, the interval between every two taps of each high-density cable, i.e. the interval L1 between every two monitoring points is 1-10m, and the interval L2 between every two parallel high-density cables is 1-10m, forming a rectangular grid arrangement state of four monitoring points in adjacent two rows;

[0012] 1.2.2 At each tap of the high-density cable laid in step 1.2.1, 1 electrode connected by a wire clamp is disposed to the ground, and the head and tail ends of the adjacent two high-density cables are connected by an intelligent bidirectional cable head until all the high-density cables are connected in series;

[0013] 1.2.3 Connect one end of the high-density cable connected in series in step 1.2.2 to the measurement port of the high-density electrical method host 1 to complete the connection of the signal receiving part;

[0014] 1.2.4 Along the y direction perpendicular to the high-density cable, at a position with a distance D of 30-300m from the upper end and the lower end of the high-density cable, deploy initial power supply electrodes A and B respectively, and connect them to the transmitting power system 6 by wires to complete the layout of the signal transmitting part;

[0015] 1.2.5 Supply power to the ground by the initial power supply electrodes A and B of step 1.2.4 through the transmitting power system 6 according to the selected pulse signal, and automatically collect and store data by the high-density electrical method host 1 to complete the data receiving work under the current layout mode;

[0016] 1.2.6 After the completion of step 1.2.5, disconnect the power supply electrodes, keep the signal receiving part in the same layout, and move the initial power supply electrodes A and B by a distance d of 10m-50m in the positive and negative y directions, respectively, wherein the initial power supply electrode A is moved upward to A1 and the initial power supply electrode B is moved downward to B1, and then connect the power supply electrodes A1 and B1 to the transmitting power supply system 6 by wires, respectively, and complete the data collection and storage after the replacement of the electrodes according to step 1.2.5; each movement of the power supply electrodes completes one data measurement, and the maximum distance of the power supply electrodes is 500m-1500m, which completes the data collection of one electrode arrangement;

[0017] 1.2.7 According to the electrode arrangement of step 1.2.6, move the interval L1 of the two monitoring points described in step 1.2.1 forward, repeat the operations of steps 1.2.1 to 1.2.6, and measure the next electrode arrangement until the data measurement of the entire oil field drilling target area is completed;

[0018] 1.3 Process the data measured in steps 1.2.6 and 1.2.7 to obtain the resistivity results, including the following steps:

[0019] 1.3.1 Output the collected and measured data of steps 1.2.6 and 1.2.7, perform format conversion and data evaluation, and eliminate individual abnormal points;

[0020] 1.3.2 Use high-density electrical method three-dimensional inversion software to perform inversion fitting on the data processed in step 1.3.1 to obtain resistivity data reflecting the geological body;

[0021] 1.3.3 Draw the resistivity data obtained in step 1.3.2 into geoelectric section and slice maps;

[0022] 1.4 According to the geoelectric section and slice maps drawn in step 1.3.3, determine the SAGD channeling leakage channel, including the following steps:

[0023] 1.4.1 Collect the well logging data of the existing wells in the oil field, and extract the resistivity data of the upper formation of the SAGD oil layer;

[0024] 1.4.2 Compare and calibrate the resistivity data extracted in step 1.4.1 with the measured resistivity by high-density electrical method: when there is no channeling leakage channel in the upper formation of the oil layer, the electrical property of the formation is relatively stable due to no development or fluid invasion, and the two are equivalent; when there is a channeling leakage channel in the upper formation of the oil layer, the oil and water channeling in the channel change the fluid characteristics of the local area of the upper formation, resulting in abnormal resistivity; then, according to the calibration result, determine the resistivity response characteristics and resistivity anomaly threshold of the channeling leakage channel;

[0025] 1.4.3 According to the resistivity anomaly threshold of the channeling leakage channel determined in step 1.4.2, the resistivity anomaly response characteristics of different depth level slices and different position vertical slices are divided, and finally the SAGD channeling leakage channel is monitored.

[0026] The present application can quickly and accurately find out the distribution state of the SAGD channeling leakage channel to the ground by carrying out high-density electrical method monitoring on the ground of the oilfield well area, does not inject any chemical agent into the oil well in the monitoring process, does not cause damage to the oil well, and does not affect the normal production of the oil area; after obtaining the resistivity results, the resistivity response characteristics of the SAGD channeling leakage channel are calibrated by means of the existing original stratum electrical property characteristic data, the reliability of the interpretation is improved; after finding out the distribution state of the SAGD channeling leakage channel, the root cause of the SAGD channeling leakage can be found out, efficient guidance for subsequent development of targeted measures to control the SAGD ground channeling leakage is provided, and the blindness of controlling the SAGD ground channeling leakage problem is eliminated. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a schematic diagram of a high-density electrical method three-dimensional measurement device;

[0028] Among them: 1. High-density electrical method host 2. High-density cable group 3. Intelligent two-way cable head group 4. Tap group 5. Electrode group 6. Transmission power supply system;

[0029] Figure 2 It is a high-density electrical method three-dimensional measurement area deployment diagram;

[0030] Among them: numbers ① to ⑤ represent five arrangement areas collected in the implementation process of the present application;

[0031] Figure 3 It is a high-density electrical method inversion resistivity data result map;

[0032] Among them: HW3, HW6, and HW7 represent three SAGD wells; X1, X2, X3, and F10 represent four straight wells;

[0033] Figure 4 It is a high-density electrical method inversion resistivity and logging resistivity comparison calibration map;

[0034] Figure 5 It is a high-density electrical method inversion interpretation result map of each depth section. DETAILED DESCRIPTION

[0035] The core content of the present application is to monitor the stratum resistivity by using a high-density electrical method three-dimensional layout method, and then to determine the channeling leakage channel interpretation threshold by comparison and calibration with the stratum resistivity revealed by the known drilling, so as to depict the SAGD area channeling leakage channel.

[0036] The present application will be described below in conjunction with the drawings.

[0037] As Figure 1 shown, 1. A method for monitoring SAGD channeling, comprising the following steps:

[0038] 1.1 Prepare the instrument equipment for monitoring the target area of oil field drilling, specifically including:

[0039] The transmitting power system 6 with pulse signal width of 0.125s, 0.25s, 0.5s, 1s, 2s, 4s, 8s, 16s, 32s, 64s as the signal transmitting part;

[0040] The high-density electrical method host 1, the 10-20 high-density cables of the high-density cable group 2, each high-density cable containing 12 taps of the tap group 4, 10-20 intelligent bidirectional cable heads of the intelligent bidirectional cable head group 3, and 120-300 electrodes of the electrode group 5 as the signal receiving part;

[0041] 1.2 On-site deployment of the instrument equipment for monitoring the target area of oil field drilling in step 1.1, data monitoring, comprising the following steps:

[0042] 1.2.1 At the monitoring points of the target area of oil field drilling, the 10-20 high-density cables of the high-density cable group 2 in step 1.1 are arranged in parallel along the horizontal direction of x, the interval between every two taps of each high-density cable, i.e. the interval L1 between every two monitoring points is 1-10m, and the interval L2 between every two parallel high-density cables is 1-10m, forming a rectangular grid arrangement state of four monitoring points in adjacent two rows;

[0043] 1.2.2 At each tap of the high-density cable arranged in step 1.2.1, 1 electrode connected by a wire clamp is disposed to the ground, and the head and tail ends of the adjacent two high-density cables are connected by an intelligent bidirectional cable head until all the high-density cables are connected in series;

[0044] 1.2.3 Connect one end of the high-density cable connected in series in step 1.2.2 to the measurement port of the high-density electrical method host 1 to complete the connection of the signal receiving part;

[0045] 1.2.4 Along the y direction perpendicular to the high-density cable arrangement, at the positions with a distance D of 30-300m from the upper end and the lower end of the high-density cable, respectively deploy the initial power supply electrodes A and B, and connect them to the transmitting power system 6 by wires to complete the arrangement of the signal transmitting part;

[0046] 1.2.5 The transmitting power system 6 supplies power to the ground through the initial power supply electrodes A and B in step 1.2.4 according to the selected pulse signal, and the high-density electrical method host 1 automatically collects and stores data to complete the data receiving work under the current arrangement mode;

[0047] 1.2.6 After completing step 1.2.5, disconnect the power supply electrodes, keep the signal receiving part in the same layout, and move the initial power supply electrodes A and B by a distance d of 10-50 m in the positive and negative y directions, respectively, where the initial power supply electrode A is moved up to A1 and the initial power supply electrode B is moved down to B1. Then, connect the power supply electrodes A1 and B1 to the transmitting power supply system 6, respectively, and complete the data collection and storage after electrode replacement according to step 1.2.5. Each movement of the power supply electrodes completes one data measurement, and the maximum distance of the power supply electrodes is 500-1500 m, which completes the data collection of one electrode arrangement;

[0048] 1.2.7 According to the electrode arrangement of step 1.2.6, move the distance L1 between the two monitoring points described in step 1.2.1, and repeat the operations of steps 1.2.1-1.2.6 to measure the next electrode arrangement until the data measurement of the entire oil field drilling target area is completed.

[0049] 1.3 Process the data measured in steps 1.2.6 and 1.2.7 to obtain the resistivity results, including the following steps:

[0050] 1.3.1 Output the collected and measured data of steps 1.2.6 and 1.2.7, perform format conversion and data evaluation, and eliminate individual abnormal points;

[0051] 1.3.2 Use high-density electrical method three-dimensional inversion software to invert and fit the data processed in step 1.3.1 to obtain resistivity data reflecting geological bodies;

[0052] 1.3.3 Draw the geoelectric section and slice map of the resistivity data obtained in step 1.3.2;

[0053] 1.4 According to the geoelectric section and slice map drawn in step 1.3.3, determine the SAGD channeling leakage channel, including the following steps:

[0054] 1.4.1 Collect the well logging data of the existing wells in the oil field, and extract the resistivity data of the upper formation of the SAGD oil layer;

[0055] 1.4.2 Compare and calibrate the resistivity data extracted in step 1.4.1 with the measured resistivity by high-density electrical method: when there is no channeling leakage channel in the upper formation of the oil layer, the electrical characteristics of the formation are relatively stable due to no development or fluid intrusion, and the two are equivalent; when there is a channeling leakage channel in the upper formation of the oil layer, the oil and water channeling in the channel change the fluid characteristics of the local area of the upper formation, resulting in abnormal resistivity; then, according to the calibration results, determine the resistivity response characteristics and resistivity anomaly threshold of the channeling leakage channel;

[0056] 1.4.3 The resistivity anomaly threshold of the channeling leakage channel determined according to step 1.4.2 is used to divide the resistivity anomaly response characteristics of different depth level slices and different position vertical slices, and finally the SAGD channeling leakage channel is monitored.

[0057] As shown in Figure 2 Fig. 1 shows that in a certain SAGD production area in the northwest margin of the Junggar Basin, there is a surface channeling leakage problem, and a high-density electrical method monitoring area is deployed to study the SAGD channeling leakage channel. The acquisition method of steps 1.2.1 to 1.2.4 in the present application is adopted, and the area is divided into five acquisition arrangement areas, each of which is numbered ① to ⑤. Taking the deployment parameters of the ① arrangement area as an example, the A and B electrode distance arrangement top and bottom end distance is 100 meters, the moving interval is 50 meters, and the maximum A and B electrode distance is 1200 meters. According to steps 1.2.5 to 1.2.6, the data acquisition of the ① arrangement area is completed, and then according to step 1.2.7, the data acquisition of the whole measurement area is completed.

[0058] Figure 3 As shown in Fig. 3, according to step 1.3, the data collected by the high-density electrical method is processed to obtain the three-dimensional space resistivity data body in the monitoring area. The resistivity result map is drawn by the voxler software, and the geoelectric section map and slice map can be extracted.

[0059] Figure 4 Fig. 4 shows the curve comparison of the well logging resistivity of four known wells in the area and the measured resistivity obtained by the high-density electrical method. According to the method described in step 1.4.2, the measured resistivity value of the high-density electrical method is generally consistent with the well logging resistivity, and the curve shape is similar. There is a significant low-resistivity anomaly (resistivity value < 3 Ω·m) in the local part. The low-resistivity anomaly is caused by the increase of water saturation due to the occurrence of fluid in the channel, so the SAGD channeling leakage channel interpretation threshold is determined to be less than 3 Ω·m.

[0060] Figure 5 As shown in Fig. 5, different depth resistivity slice interpretation results are obtained from the SAGD channeling leakage channel interpretation threshold. The low-resistivity anomaly area is interpreted as the SAGD channeling leakage channel anomaly. The range of the channel anomaly area changes obviously at different depths, gradually expanding from the deep to the shallow, and gradually connecting. The channel area at a depth of 138 m is small (a); the channel area at a depth of 108 m expands sporadically to the north (b); the channel area at a depth of 92 m gradually forms a connected piece (c); and the channel area at a depth of 65 m forms a connected piece with the largest area (d). The channeling leakage channel as a whole presents a north-south distribution and a "narrow at the bottom and wide at the top" feature, mainly distributed near the front end of the horizontal section of the HW7 well. According to the monitoring data interpretation, it is determined that the root cause of the surface channeling leakage in the block comes from the HW7 well. The key well and channeling leakage channel distribution data provided by the implementation of the treatment can effectively guide the subsequent measures, improve the success rate of the treatment, and quickly restore the block productivity.

Claims

1. A method for monitoring SAGD channeling, characterized in that it comprises the following steps: 1.1 Preparing the equipment for monitoring the target area of oil drilling, specifically comprising: a transmitting power system (6) with pulse signal width of 0.125s, 0.25s, 0.5s, 1s, 2s, 4s, 8s, 16s, 32s, 64s as the signal transmitting part; a high-density electrical method host (1), a high-density cable group (2) of 10-20 high-density cables, each high-density cable containing 12 taps of tap group (4), 10-20 intelligent bidirectional cable heads of intelligent bidirectional cable head group (3), and 120-300 electrodes of electrode group (5) as the signal receiving part; 1.2 On-site deployment of the equipment for monitoring the target area of oil drilling in step 1.1, data monitoring, comprising the following steps: 1.2.1 At the monitoring points of the target area of oil drilling, the 10-20 high-density cables of step 1.1 are arranged in parallel along the horizontal direction of x, the interval between every two taps of each high-density cable, i.e. the interval L1 between every two monitoring points is 1-10m, and the interval L2 between every two parallel high-density cables is 1-10m, forming a rectangular grid arrangement state of four monitoring points in adjacent two rows; 1.2.2 At each tap of the high-density cable line laid in step 1.2.1, an electrode connected by a wire clamp is arranged to the ground, and the head and tail ends of two adjacent high-density cable lines are connected by a smart bidirectional cable head until all the high-density cable lines are connected in series; 1.2.3 One end of the high-density cable line connected in series in step 1.2.2 is connected to the measurement port of the high-density electrical method host (1) to complete the connection of the signal receiving part; 1.2.4 Along the y direction perpendicular to the high-density cable line, initial power supply electrodes A and B are respectively arranged at positions 30m-300m away from the upper and lower ends of the high-density cable line, and are connected by wires to the transmission power supply system (6) to complete the layout of the signal transmitting part; 1.2.5 The transmission power supply system (6) supplies power to the ground through the initial power supply electrodes A and B according to the selected pulse signal, and the high-density electrical method host (1) automatically collects and stores data to complete the data reception work under the current layout; 1.2.6 After completing step 1.2.5, disconnect the power supply electrodes, keep the layout of the signal receiving part, and move the initial power supply electrodes A and B along the positive and negative y directions with a spacing d of 10m-50m, respectively, wherein the initial power supply electrode A is moved up to A1, and the initial power supply electrode B is moved down to B1. Then, the power supply electrodes A1 and B1 are respectively connected by wires to the transmission power supply system (6), and the data collection and storage work after electrode replacement is completed according to step 1.2.

5. Each movement of the power supply electrode completes one data measurement, and the maximum power supply electrode distance is 500m-1500m, which completes the data collection of one electrode arrangement; 1.2.7 According to the electrode arrangement of step 1.2.6, move the interval L1 of the two monitoring points described in step 1.2.1, repeat the operations of steps 1.2.1-1.2.6, and measure the next electrode arrangement until the data measurement of the entire oilfield drilling target area is completed; 1.3 Process the data measured in steps 1.2.6 and 1.2.7 to obtain resistivity results, including the following steps: 1.3.1 Output the collected and measured data of steps 1.2.6 and 1.2.7, perform format conversion and data evaluation, and eliminate individual abnormal points; 1.3.2 Use high-density electrical method three-dimensional inversion software to invert and fit the data processed in step 1.3.1 to obtain resistivity data reflecting geological bodies; 1.3.3 Draw the geoelectric section and slice map from the resistivity data obtained in step 1.3.2; 1.4 According to the geoelectric section and slice map drawn in step 1.3.3, determine the SAGD channeling leakage path, including the following steps: 1.4.1 Collect the well logging data of existing wells in the oilfield, and extract the resistivity data of the upper formation of the SAGD oil layer; 1.4.2 Compare the resistivity data extracted in step 1.4.1 with the measured resistivity of the high-density electrical method: when the upper formation of the oil layer does not appear to have a channeling and leaking channel, the electrical characteristics of the formation are relatively stable due to the lack of development or fluid invasion, and the two are equivalent; when the upper formation of the oil layer appears to have a channeling and leaking channel, the oil and water that channel and leak in the channel change the fluid characteristics of the local area of the upper formation, resulting in an abnormal resistivity; then, according to the calibration results, the resistivity response characteristics and the resistivity anomaly threshold of the channeling and leaking channel are determined; 1.4.3 According to the resistivity anomaly threshold of the channeling and leaking channel determined in step 1.4.2, the resistivity anomaly response characteristics of different depth horizontal slices and different position vertical slices are divided, and finally the SAGD channeling and leaking channel is monitored.

Images