China Sinopec Zhongyuan Oilfield Company oil Wuchang well control workshop as well control equipment maintenance unit, charged with the whole plant wellhead, Plug valve and BOP maintenance, pressure test work, the well control equipment to the required time need to be maintenance and tightness test, pressure test after passing the order to continue to put into production use.
1 well control equipment pressure test Problems
Well control workshop pressure test of the daily needs of a larger number of well control equipment, larger workload. A pressure test will be able to draw accurate conclusions (qualifier distribution and use, who failed to repair), is the workshop routine pressure test work in the best efficient state. However, since the workshop is newly established working inexperience, beginning well control equipment a pressure test successful ratio is only 66.4%. In order to avoid invalid pressure test, pressure test to reduce workload, improve well control equipment must be a pressure test pass rate.
2 Analysis
Wellhead, Plug valve and BOP well control equipment in three categories, Plug valve a pressure test unsuccessful unsuccessful accounted for 72.5% of the total, resulting in well control equipment has become a pressure test pass rate of major problems.
The analysis verification, validation affect Plug valve once pressure test successful ratio of the main factors are the following two aspects.
2.1 defective pressure test device terminals Connection
pressure test joint use fine thread snap connector M22mm × 1.5 and threaded a length of 30mm, a copper pad in the joint, using seal sealing method. Because the joint is small, when unloading the joint inspection staff wearing gloves attached sludge and sand and other impurities and easy access to the threaded joints and the end, and over time, but also easy to damage the copper pad end face, causing pressure test fittings Leakage at.
2.2 pressure test device smaller volume of actual pressure part
After measuring, the existing Plug valve from the pressure test line connections to the actual pressure valve Plug valve between the partial volume is only 485mL, the actual pressure test process often cause pressure test could not steady, the pressure drop is large. Plug valve to increase a 50cm long EUE tubing pup joints, so that part of the increase in the volume of actual pressure to about 1.7L, with the same Plug valve made several comparative test results showed that: before Capacity low pressure drop an average of 0.60 MPa / 10min, the high pressure drop averaging 3.05MPa / 10min; low pressure drop after compatibilization average 0.36MPa / 10min, the high pressure drop averaging 1.39MPa / 10min. Visible, the pressure drop was significantly smaller, indicating a greater impact on the volume of the pressure part Plug valve pressure test.
3 Remedy
3.1 Improved joint connection
For the original pressure test joint connection of the pressure test joints has been improved on the basis of the original to add a connector at one end is threaded M22mm × 1.5mm male screw buckle and pressure test the pipeline joints M22mm × 1.5mm of and the other end is processed into M48mm × 5mm internal thread buckle, buckle-type connector and well control equipment and then connected to an external thread all into M48mmx5mm buckle.
For the same Plug valve with two kinds of connections do 10 repetitions comparative test results showed that: improve before the low pressure drop an average of 0.61MPa / 10min, high pressure drop an average of 5.51 MPa / 10min, 3 times leakage phenomenon; The improved low pressure drop an average of 0.51 MPa / 10min, high pressure drop an average of 2.12MPa / 10min, despite little change in low pressure drop, but declined significantly high pressure drop, and there is no leakage phenomenon, indicating that achieved the expected effect.
3.2 increase in the volume of actual pressure part of Plug valve
In Plug valve pressure test on the basis of joint improvements, adding a device connected together and Plug valve, thereby increasing the pressure when the volume pressure test. The device with 1.5m long 139.7mm (5 1/2 ") casing is made of 12mm thick steel plate bottom with welded side from the top of the sleeve of a joint welded 0.3m for and pressure test the pipeline connected to the top of the sleeve welding a joint, the joint buckle type of 73.03mm (2 7/8 ") within UPTBG of threads, one above and then connect couplings for mounting Plug valve (before the device is put into use after special test a pressure test security agencies detection).
After Plug valve pressure test joint improvement using the same Plug valve, Plug valve and pressure test conducted direct pipeline connection to increase connection and Plug valve sealing pressure comparison test volume and pressure test the pipeline before the connection on the device, result show: Capacity low pressure drop before averaging 0.51MPa / 10min, high pressure drop an average of 2.11MPa / 10min; Capacity low pressure drop after averaging 0.06MPa / 10min, high pressure drop an average of 0.39MPa / 10min, fully meet a low pressure drop <0.07MPa / 10min, high pressure drop <requirements 0.7MPa / 10min of.
4 Application Effect
By improving the pressure test joint connection, Plug valve increase pressure partial volume, greatly reducing the well control equipment leakage in pressure test process, the phenomenon of excessive pressure drop, after four consecutive months of 281st pressure test detection statistics, well control equipment a pressure test successful ratio reached 89.3 percent, a 22.9 percent increase over the original.
The implementation of the project, since the material cost savings, could create an annual inspection fees and 87,300 yuan of direct economic benefits, but also greatly reduces the labor intensity of workers, economic and social benefits significantly.