Example of non stop pressure plugging process in Sichuan Chongqing area

In 2007 5~11 month, Chinese oil oil gas field company in Sichuan and Chongqing area was 3 times diameter pipeline with 720mm large diameter pipeline and a Phi 323.5mm, Phi 406mm does not stop plugging in the application, not shutdown conditions, effectively protect production, increase efficiency, stable social multiple objective that has had a profound impact on the pipeline expansion and maintenance.

1. north line Qingbaijiang new station change line with pressure plugging head project

Operation time: May 23, 2007 ~6 3; change line distance: 11.3km.

Pipeline specification: Phi 720mm * 8mm; pipeline pressure: 1.6Mpa; conveying medium: purification of natural gas; using technology: single side double seal and unilateral single seal.

The purpose of engineering is the original Qingbaijiang City Development Zone Planning after the change to the 8.9km pipeline, development planning area, but the old line shutdown will affect the lower reaches of Qingbaijiang and Chengdu, the Mianyang area daily about 460 * 104m3 gas, the Chengdu area of 29 key industrial users and hundreds of thousands of residents of households stop gas more than 3D, and 10 * 104m3 natural gas vent loss and environmental pollution.

The use of pressure sealing technology of the head point maintenance bypass line temporarily set after the construction section and gas at the same time, for the first time the Sichuan Chongqing pipeline plugging operation, to avoid the direct economic loss of 67 million yuan. In order to reduce the amount of plugging work and avoid risks as far as possible, a plugging method with a single plugging device and a station union pipe is adopted in the vicinity of Qingbaijiang railway station, and good results have been achieved.

2. 、 pressure plugging and pipe changing project of Nanchong south Chongqing Expressway

Operation time: September 9, 2007 ~26; change pipe distance: 180m.

Pipeline specification: Phi 720mm * 8mm; pipeline pressure: 2.8Mpa; transmission medium: purification of natural gas; the use of Technology: single side double seal.

Due to the construction of the south Chongqing Expressway, a section of the main line of the north trunk line was under heavy pressure of the high fill area, which caused a potential safety hazard for the section, so it was necessary to change the line 180m. If the gas exchange pipe is changed, the downstream gas supply will be reduced by 600 * 104m3/d, and the gas emptying loss will be 15 * 104m3.

It is the focus of the discussion that the bilateral double seal or bilateral single seal is used at the distance of 180m in the development of the pressure plugging scheme. The construction cost of bilateral single letter can save 30% and 40% of the construction time, but the two bypass line with 400mm (each 35m) into a 180m bypass pipe, through 600 * 104m3/d natural gas, gas shutoff the pressure drop and the turbulent kinetic energy of temporary bypass safety and capacity through bad while the bypass affected by topography, the height is about 6m higher than the old line, how to maintain stability is difficult.

Through calculation and analysis, determine the scope of the bypass pressure drop and turbulent kinetic energy in the pipeline within the middle way and use the flat slope on both sides and intensive scaffolding will bypass a stable, finally adopted a unilateral double sealing mode, and achieved success.

3. Chengxiang station plugging operation project with pressure plugging

Operation time: September 28, 2007 ~10 15, change one distance: 350m.

Pipeline specification: Phi 720mm * 8mm; pipeline pressure: 1.5Mpa; transmission medium: purification of natural gas; the use of Technology: bilateral double seal.

Because the new southwest oil and gas field company Chengxiang station in the north line of operation, need to communicate between north trunk and Chengxiang station. If the shutdown after the head of construction, lower volume reduced 680 * 104m3/d, natural gas vent loss is 10 * 104m3.

Due to the change of the distance from the line to 350m, the craft can adopt a by-pass double side single seal construction. But because the Chengxiang station is in the straight line between the two connecting points, the bypass must be bypassed. Through the station outside the small highway, the crossing or the viaduct will bring about the hidden danger to the transportation and the pipeline security. By Liu, the output is 680 * 104m3/d, the length is 350m, the bypass pipeline diameter should be at least 500mm, to meet the supply pressure downstream of the three pipe must also be re ordering, time and material are unfavorable to the investment test. At the same time, the use of 350m long-distance bypass construction units for the first time, there is a greater risk. After comparing all the factors, the project team decided to adopt two sides double sealing process, and successfully completed the construction task.

4. Meishan Taihe non-stop transmission and pressure plugging project

Operation time: November 8, 2007 ~11 20; pipe specification phi 323.5mm, Phi 406mm.

Pipeline pressure 1.5Mpa; adopt technology: single side double seal, single side blocking.

The project is to ensure the Taihe station station rectification process, the new east station put into operation, the 3 major natural gas users from MeiShan Railway Station, Meizhou Dongpo station moved to the station, to ensure that Meishan and Leshan along a number of users to 180 * 104m3/d gas, especially unilateral double seal, single side single blocking operations in TaiHe Railway Station. The project was a complete success.