Corrosion Mechanism Of Well Tubulars And Research Of Protective Coating Under Harsh Surroundings

At some regions, the conditions developing gas and oil become more and more harsh. Especially many oil and gas fields, which contain highly carbon dioxide, hydrogen sulfide and element sulfur, have been found. The problem of corrosion, wax and scaling of well tubulars become intensely. Well tubular contains drill pipe, oil tubing and casing mainly. The principal research object in this paper is downhole tubing and casing. As working condition is very harsh, well tubular's working life and performance will affect exploratory development and operating beneficial result importantly. In gas fields which contains sulfur, the bad working condition may lead serious safety accidents and environment problems. So, research of corrosion mechanism and preservation technologies of well tubular is very important.During the study period, I take part in the research of the third scientific research of the state "tenth five year" project-"Research of critical technology for development of the gas & oil field resource in China", I get deeper understanding of present situation of well tubular's corrosion. Scientific and reasonable sorting of well tubular corrosion is worked out. The surrounding factors, such as flow field induced corrosion, crevice corrosion and bimetallic corrosion and phase-change induced corrosion, control the corrosion of well tubulars. The thermodynamic model of galvanic corrosion of well tubulars under bad setting is deduced. Well tubular corrosion prediction software which has autonomous intellectual property is been programmed. Drawing support from some relevant theory of modern calculating fluid mechanics and electrochemical corrosion, mathematic model of computer simulation of flow field induced corrosion is been set up. Flow field distribution in a special flow channel is simulated; coordinated reaction of flow channel's structure and flow field induced corrosion is studied. On this foundation, the reason and mechanism of serious corrosion of API circular thread joint are analyzed. And resolved method to prevent flow field induced corrosion is posed.I attend the scientific research of tutor's scientific research, and also attend the development of MPS anti-corrosion coating which has highly overall performance. The coating used in industry at present is epoxy-phenol resin. It belongs to the common part of macromolecule and it is one kind of thermosetting resin. MPS coating is special macromolecule material, belonging to the range of thermoplastic resin. It may become the newly anti-corrosion coating. According to the research on nanometer material and technology, many kinds of nanometer materials are add into MPS coating. The dispersion of nanometer materials is solved technologically. So MPS coating has better capability of corrosionresistance, anti-wax depositing and anti-scaling. The modern analyzing way of performance testing and microstructure observing of MPS coating is explored by fully use of modern testing equipment in SKL of geology and development of oil and gas in SWPI. These methods contain the following: research on microstructure of MPS coating by using SEM and AFM, analyzing components of MPS coating by X'Pert Pro X-ray diffract meter. At the same time, we have done these evaluation testsxorrosion simulating evaluate test of MPS coating, anti-sulfide stress evaluate test of MPS, adhesion test of MPS coating, impact resistance test of MPS coating, erosion and abrasion resistance performance test of MPS.