Sunday, September 14, 2014

Oil casing and practical performance tests

Tubing and casing used in the oil and gas wells rely threaded steel pipe connected to the hundreds column, in the underground to the combined effects of various forces and subject to corrosive media, poor conditions of service as long as there is a steel pipe is a fault, it abandoned wells could cause huge economic losses. Therefore, the quality of oil casing pipe and threaded means quality, especially threaded quality is critical, requires inspection by the root, foolproof. Quality oil casing, in addition to the chemical composition, microstructure, mechanical properties, geometric dimensions and appearance quality assurance needs, the practical performance of the oil casing is of great importance. Because it is a concentrated expression of the above-mentioned quality of content, users are most worried about is performance factors, as well as oil and gas wells string design essential parameters and basis. With the development of oil and gas drilling industry, deep and ultra-deep growing number of bottom hole pressure and temperature rising, the coexistence of various corrosive media, making the oil casing of service environment is deteriorating. User according to API 5CT and oil, gas drilling actual needs, and constantly on the functional performance test oil casing made more and more urgent requirements.

Thousands of meters deep oil and gas wells in the drilling for oil, gas, oil must be hundreds of root screwed into the casing string to thousands of meters under the oil, gas wells. Oil casing in oil and gas wells to be affected by the combined effects of different variable load, different temperatures and corrosive media. The service is very complex conditions, bad. Correctness of the oil casing pipe and threaded connection string quality and is very critical, they are not only directly affect the sealing performance of the threaded connection string, but also directly affect the strength of the connection string in the thread and the oil, gas use lifetime. Is cementing casing pipe, one-time use. After cementing a permanent place on the ground is not made out. It points catheter surface casing, casing and production casing. The forces which are summarized as follows:

By axial tension caused by the weight of the role of the column itself, its size with the string tension diameter, wall thickness, and the total length of the size of the change. It can make a connection string in the thread slipping, can also make a column in the tube to take off. At the same time will reduce casing collapse resistance, especially in concentrated or ultra-deep well on the small size of the casing greater impact. To withstand the well bore instability in the underground rock formations such as easy to collapse, creeping rock salt formation and expansion, as well as water and mud endures pressure. Especially to withstand rock or rock crawling body to move a huge squeeze pressure. This external pressure can lead to casing collapse, especially caused by oil casing fall. Casing to resist the internal pressure inside the pipe mud, water, oil or gas column. Especially in the well or well kick off. The inner casing pressure is even greater, often burst failure occurs at this time. However, under the pressure of the inner casing, tubing string threaded connection strength will be raised.

No comments:

Post a Comment