Method for monitoring well temperature of horizontal well after perforation-bridge plug fracturing and evaluating fracturing effect

Abstract

The invention relates to the technical field of oil and gas well oil testing and production testing, in particular to a method for monitoring the well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect, and the method comprises the steps that before the horizontal well is fractured, well shaft temperature response data of well shut-in stability before fracturing are measured and collected through a strip-shaped temperature detector, and a well temperature response curve before fracturing is obtained; staged fracturing is carried out in the horizontal well, after staged fracturing of the horizontal well is completed, all bridge plugs in the well are drilled, after the well shut-in temperature is stable, well shaft temperature response data of well shut-in stability after fracturing are measured and collected through a strip-shaped temperature detector, a well shaft temperature response curve after fracturing is obtained, the shapes of the well shaft temperature response curve before fracturing and the well shaft temperature response curve after fracturing are compared, and the well temperature response curve before fracturing and the well shaft temperature response curve after fracturing are obtained. And the fracturing effect is evaluated according to the well section distribution position and amplitude change of the negative temperature anomaly. According to the invention, the ground direct reading of temperature data can be realized, the temperatures of different positions in the whole shaft space can be continuously measured in real time, the temperature monitoring is accurate, and the accurate evaluation of the fracturing effect is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas well testing and production, and is a method for monitoring the well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect. Background Art

[0002] With the continuous deepening of oil and gas exploration and development, the development of low permeability oil and gas reservoirs mainly adopts the large-scale segmented multi-cluster fracturing technology of horizontal wells. However, due to the complex reservoir conditions, long horizontal well sections, uneven reservoir utilization in each section, and large differences in production capacity after fracturing. Therefore, accurate evaluation of the fracturing effect of each section of the horizontal well is of great significance to the increase of single well production and efficiency and the efficient and economic development of oil and gas reservoirs in the later stage.

[0003] Conducting well temperature tests before and after fracturing can help understand the distribution of fracturing fluid and fracture height, and effectively evaluate the fracturing effect. Due to the special wellbore structure of horizontal wells, the well temperature test methods conventionally used in vertical wells cannot be directly implemented on horizontal wells. For well temperature monitoring after fracturing in horizontal wells, there are currently mainly coiled tubing-carried storage well temperature meters.

[0004] When the coiled tubing is tested with a storage-type well temperature meter, the coiled tubing needs to be dragged. The slower the dragging speed, the more accurate the well temperature test result. However, if the dragging speed is too slow and the coiled tubing speed is uneven, the depth meter will record inaccurate results, resulting in errors in the correspondence between the well depth and the test temperature, causing the test results to fail to truly reflect the temperature anomaly of the test well section. At the same time, this method is only applicable to fracturing processes with no bridge plugs in the wellbore after fracturing and unobstructed wellbore, such as wellbore flow limiting fracturing, double-seal single-card fracturing dragged by coiled tubing, and hydraulic sandblasting annulus sanding fracturing wells.

[0005] In vertical well fracturing, due to the small scale of fracturing, the temperature around the well recovers quickly, and the well temperature needs to be measured quickly after fracturing. For fracturing horizontal wells, the perforation-bridge plug integrated fracturing process is mostly used. After all the fracturing is completed, the bridge plug is drilled. The construction period is long, and everyone thinks that the best time for post-fracturing well temperature testing has been missed. Therefore, there is no pre- and post-fracturing well temperature test for perforation-bridge plug staged fracturing horizontal wells.

[0006] Due to the large scale of horizontal well staged fracturing and the large amount of low-temperature fracturing fluid injected, the temperature data analysis of continuous optical fiber monitoring of multiple large-scale fracturing horizontal wells for 1 to 2 years found that the formation temperature recovered slowly. This makes it possible to drill the bridge plug after the perforation-bridge plug staged fracturing and then conduct post-fracturing well temperature testing to evaluate the fracturing effect.

[0007] Therefore, it is necessary to study a safe, accurate, convenient and economical horizontal well fracturing well temperature testing method, which will facilitate the accurate evaluation of the fracturing effect. Summary of the invention

[0008] The present invention provides a method for monitoring the well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problems of large temperature error of the existing storage well temperature meter carried by the continuous oil pipe in the well temperature monitoring after fracturing and the method being only applicable to the wellbore after fracturing without a bridge plug.

[0009] The technical scheme of the present invention is achieved through the following measures: a method for monitoring the well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect, which is carried out according to the following method: the first step is that before the fracturing of the horizontal well, a strip temperature probe with a plurality of temperature monitoring units spaced apart is inserted into a continuous oil pipe and then lowered into the well. After the shut-in temperature is stable, the wellbore temperature response data of the wellbore before fracturing is measured and collected by the strip temperature probe to obtain a wellbore temperature response curve before fracturing; the second step is to perform staged fracturing in the horizontal well. After the staged fracturing of the horizontal well is completed, all bridge plugs in the well are drilled out; the third step is that after the fracturing of the horizontal well, after the shut-in temperature is stable, the wellbore temperature response data of the wellbore after fracturing is measured and collected by the strip temperature probe to obtain a wellbore temperature response curve after fracturing; the fourth step is to compare the shapes of the wellbore temperature response curves before and after fracturing, and evaluate the fracturing effect according to the distribution position and amplitude change of the well section with negative temperature anomalies.

[0010] The following are further optimizations and / or improvements to the above technical solutions: In the first step above, the strip temperature sensor is a distributed optical fiber having a plurality of temperature monitoring units distributed at intervals.

[0011] In the first step, when the strip temperature sensor is inserted into the coiled tubing and lowered into the well, the coiled tubing is lowered to the maximum well depth.

[0012] In the fourth step above, the criterion for determining negative temperature anomaly is that the wellbore temperature after horizontal well fracturing is 0.3°C lower than the wellbore temperature before fracturing.

[0013] In the fourth step above, the specific method for evaluating the fracturing effect is: according to the distribution position and amplitude change of the temperature negative anomaly section, determine the well section where the fracturing fluid mainly enters the fluid, and use numerical simulation technology to quantitatively interpret the horizontal well fracture morphology based on the well temperature data.

[0014] The present invention can realize direct reading of temperature data on the ground and real-time continuous measurement of the temperature at different positions in the entire wellbore space. The temperature monitoring is accurate, which is conducive to the accurate evaluation of the fracturing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Attached Figure 1 This is a comparison diagram of the wellbore temperature response curves before and after fracturing of the XHW6005 well in Example 6 of the present invention. DETAILED DESCRIPTION

[0016] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0017] The present invention will be further described below in conjunction with embodiments: Embodiment 1: The method for monitoring the well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect is carried out according to the following method: the first step is that before fracturing the horizontal well, a strip temperature probe having a plurality of temperature monitoring units spaced apart is inserted into a continuous tubing and then lowered into the well. After the shut-in temperature is stabilized, the wellbore temperature response data of the wellbore before fracturing is measured and collected by the strip temperature probe to obtain a wellbore temperature response curve before fracturing; the second step is to carry out staged fracturing in the horizontal well. After the staged fracturing of the horizontal well is completed, all bridge plugs in the well are drilled out; the third step is that after fracturing the horizontal well, after the shut-in temperature is stabilized, the wellbore temperature response data of the wellbore after fracturing is measured and collected by the strip temperature probe to obtain a wellbore temperature response curve after fracturing; the fourth step is to compare the shapes of the wellbore temperature response curves before and after fracturing, and evaluate the fracturing effect according to the distribution position and amplitude change of the well sections with negative temperature anomalies.

[0018] The present invention drills a bridge plug to clear the wellbore after perforating-bridge plug staged fracturing, and monitors the well temperature after fracturing by passing through an optical fiber continuous oil pipe. The continuous oil pipe has strong permeability and can cover the entire perforating and fracturing well section. The distributed optical fiber passed through the continuous oil pipe can realize direct reading of temperature data on the ground and real-time continuous measurement of the temperature at different positions in the entire wellbore space. The temperature monitoring is accurate, which is conducive to the accurate evaluation of the fracturing effect. The problems of large temperature error of the storage well temperature meter carried by the continuous oil pipe, difficulty in avoiding shooting of optical fiber monitoring outside the casing, complex construction and high cost are solved. The well temperature of the horizontal well after perforating-bridge plug fracturing is tested, and the fracturing effect is quickly evaluated through the temperature abnormality characteristics. It plays an important role in optimizing the design of the fracturing scheme and improving the fracturing effect.

[0019] Embodiment 2: As an optimization of the above embodiment, in the first step, the strip temperature detector is a distributed optical fiber with a plurality of temperature monitoring units distributed at intervals.

[0020] The distributed optical fiber in the present invention is an optical fiber produced and sold by Beijing Feibo Optoelectronics Technology Co., Ltd.

[0021] Embodiment 3: As an optimization of the above embodiment, in the first step, when the strip temperature detector is inserted into the coiled tubing and lowered into the well, the coiled tubing is lowered to the maximum well depth.

[0022] Example 4: As an optimization of the above example, in the fourth step, the judgment standard of negative temperature anomaly is that the wellbore temperature after the horizontal well is fracturing is 0.3°C lower than the wellbore temperature before the fracturing.

[0023] Example 5: As an optimization of the above example, in the fourth step, the specific method for evaluating the fracturing effect is: according to the distribution position and amplitude change of the temperature negative anomaly section, determine the well section where the fracturing fluid is mainly inflowing, and use numerical simulation technology to quantitatively interpret the horizontal well fracture morphology based on the well temperature data.

[0024] The numerical simulation technology is a publicly known and commonly used numerical simulation technology in the art.

[0025] Example 6: Well temperature monitoring and evaluation of fracturing effect in XHW6005 well: In the first step, before fracturing the XHW6005 well, the coiled tubing with distributed optical fiber was lowered slowly to the maximum well depth, and the ground data acquisition equipment was connected to the downhole distributed optical fiber to measure the well temperature before fracturing. The temperature was stable at 90.9℃ to 91.3℃ (such as Figure 1 As shown, the right side shows three temperature response curves); In the second step, the XHW6005 well was subjected to perforation-bridge plug staged fracturing, with a total of 12954.5 cubic meters of liquid and 820 cubic meters of sand used for large-scale fracturing in 13 stages. After the fracturing was completed, all 12 bridge plugs in the well were drilled (as shown in Table 1, which is a table of fracturing construction parameters); The third step is to run the coiled tubing through the distributed optical fiber into the well. After the shut-in temperature stabilizes, the wellbore temperature response data is collected to measure the well temperature that is stable after shut-in. Figure 1 As shown, there is a temperature response curve on the left); The fourth step is to compare the wellbore temperature response curves before and after fracturing, and evaluate the fracturing effect according to the distribution position and amplitude change of negative temperature anomalies: well sections 4150m to 4210m, 4220m to 4300m, 4320m to 4450m, 4600m to 4700m and 4750m to 4800m are negative temperature anomaly well sections, which are the main fracturing fluid inflow areas, and the fracturing transformation is sufficient. At the same time, numerical simulation technology is used to quantitatively interpret the horizontal well fracture morphology based on well temperature data.

[0026] The present invention has been applied and verified in many blocks such as Mahu and Jimusar shale oil in Xinjiang Oilfield, and is of great significance for the evaluation of fracturing effect of large-scale staged fracturing horizontal wells with perforation bridge plugs.

[0027] In summary, the present invention can realize direct reading of temperature data on the ground and real-time continuous measurement of the temperature at different positions in the entire wellbore space. The temperature monitoring is accurate, which is conducive to the accurate evaluation of the fracturing effect.

[0028] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A method for monitoring the well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect, characterized in that The method is as follows: the first step is to insert a strip temperature probe with several temperature monitoring units at intervals into the continuous tubing and then lower it into the well before fracturing before fracturing. After the shut-in temperature is stable, the wellbore temperature response data of the well before fracturing is measured and collected by the strip temperature probe to obtain the wellbore temperature response curve before fracturing. The second step is to perform staged fracturing in the horizontal well. After the staged fracturing of the horizontal well is completed, all bridge plugs in the well are drilled. The third step is to perform horizontal well fracturing after the shut-in temperature is stable. After the well is shut-in temperature is stable, the wellbore temperature response data of the well after fracturing is measured and collected by the strip temperature probe to obtain the wellbore temperature response curve after fracturing. The fourth step is to compare the shapes of the wellbore temperature response curves before and after fracturing, and evaluate the fracturing effect according to the distribution position and amplitude change of the well section with negative temperature anomaly.

2. The method for monitoring well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect according to claim 1, characterized in that In the first step, the strip temperature sensor is a distributed optical fiber with a number of temperature monitoring units spaced apart.

3. The method for monitoring well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect according to claim 1 or 2, characterized in that In the first step, when the strip temperature probe is inserted into the coiled tubing and lowered into the well, the coiled tubing is lowered to the maximum well depth.

4. The method for monitoring well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect according to claim 1, 2 or 3, characterized in that In the fourth step, the judgment standard for negative temperature anomaly is that the wellbore temperature after horizontal well fracturing is 0.3°C lower than the wellbore temperature before fracturing.

5. The method for monitoring well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect according to claim 1, 2 or 3, characterized in that In the fourth step, the specific method for evaluating the fracturing effect is: according to the distribution position and amplitude change of the temperature negative anomaly section, determine the well section where the fracturing fluid mainly enters the fluid, and use numerical simulation technology to quantitatively interpret the horizontal well fracture morphology based on the well temperature data.

6. The method for monitoring well temperature of a horizontal well after perforation-bridge plug fracturing and evaluating the fracturing effect according to claim 4, characterized in that In the fourth step, the specific method for evaluating the fracturing effect is: according to the distribution position and amplitude change of the temperature negative anomaly section, determine the well section where the fracturing fluid mainly enters the fluid, and use numerical simulation technology to quantitatively interpret the horizontal well fracture morphology based on the well temperature data.

Images