A Fracturing Rehabilitation Technology of Oil and Gas Well Using Controlled Time Delay Opening of Sliding Sleeve at Toe End

Abstract

The invention provides an oil and gas well fracturing reformation process using a controllable delayed opening toe end sliding sleeve, the process includes: setting the delayed opening toe end sliding sleeve at a predetermined position in the wellbore; Start the whole wellbore pressure test, and gradually increase the pressure to the peak pressure test pressure value. When the sum of the pressure test pressure and the drilling fluid column pressure reaches the first predetermined pressure value, the toe sliding sleeve starts and delays, and the first predetermined pressure value It is less than the sum of the peak pressure test pressure and the drilling fluid column pressure, and is greater than the initial pressure value. If abnormal pressure test is found, release the test pressure to suspend the delay time. After the abnormality is resolved, restore the pressure test pressure to continue the delay time. , after the end of the whole wellbore pressure test, the toe end sliding sleeve completes the delay and realizes the fracturing. The invention can be used for fracturing of the first stage of oil and gas wells (for example, shale gas wells), and has simple structure and convenient operation, and can effectively solve the problem that the existing toe end sliding sleeve has a strict opening pressure error range, uncontrollable opening time and low opening success rate. , and technical problems such as abnormal pressure test.

Description

technical field [0001] The present invention relates to the technical field of downhole operations in the oil and gas industry, and specifically relates to a method of using a time-delayed opening of the toe-end sliding sleeve to realize the first-stage fracturing reconstruction of oil and gas wells (for example, shale gas wells) and effectively overcome abnormal pressure test conditions. method. Background technique [0002] At present, there are two methods of fracturing the first stage of shale gas wells: one is perforation through coiled tubing; the other is toe-end sliding sleeve. The coiled tubing transmission perforation method is mature and reliable, but the construction time is low, and the running in the ultra-long horizontal well is limited; the toe-end sliding sleeve method is directly opened with pressure, and the construction time is high, and it is not limited by the length of the horizontal section. Compared with coiled tubing transmission perforation, the t...

AI Technical Summary

Problems solved by technology

Coiled tubing transmission perforation technology is mature and reliable, but the construction time is low, and the running in the ultra-long horizontal well is limited; the toe-end sliding sleeve method is directly opened with pressure, the construction time is high, and it is not limited by the length of the horizontal section

Compared with coiled tubing transmission perforation, the toe-end sliding sleeve has the advantages of high operational efficiency, low cost, low risk, and unlimited operating depth. However, due to the immature technology of the toe-end sliding sleeve, the success rate of opening is low. The first fracturing channel is still dominated by coiled tubing perforation

[0003] Due to the extremely low permeability of shale gas reservoirs, shale gas production is closely related to the number of wells drilled and the scale of fracturing. With the continuous improvement of drilling technology, horizontal wells with ultra-long horizontal sections (over 2,500 meters) will be the most efficient way to develop shale gas. With the development trend of the development trend, the coiled tubing transmission perforation method can no longer meet the first-stage fracturing and perforation requirements of deep and ultra-long horizontal wells

The inventor believes through research and analysis that the low success rate of opening the existing toe end sliding sleeve technology is mainly due to the following technical defects:

[0004] 1. Before the domestic shale gas well fracturing operation, the whole well pressure test is required to check the tightness of the wellbore. For example, the pressure test pressure (equivalent to the pump pressure) is sometimes as high as 90MPa; The pressure rating is 15000psi, and the maximum pressure limit during construction is not allowed to exceed 100MPa; therefore, for such cases, the opening pump pressure of the existing toe-end sliding sleeve can only be within the range of 90-100MPa, and the corresponding opening pressure of the toe-end sliding sleeve It needs to be within the range of (90+P) ~ (100+P) MPa, and the allowable opening pressure error range is strict, where P is the pressure generated by the drilling fluid column;

[0005] 2. During the full wellbore pressure test, the pressure test pressure can be gradually increased from the pressure value of 60MPa to the peak value of the pressure test pressure (for example, 90MPa). The opening pressure of the existing toe end sliding sleeve usually needs to be higher than the pressure test pressure The sum of the pressure peak value and the drilling fluid column pressure (for example, 120MPa), which leads to excessive requirements on the toe end sliding sleeve;

[0006] 3. Most of the existing toe-end sliding sleeves are opened by rupture disc rupture, which is instantaneous opening. Since the cement slurry has a great influence on its opening pressure after solidification, the opening success rate of the toe-end sliding sleeves is low and the opening Uncontrollable time

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