Zhang W.,Puguang Branch |
Zhang X.,University Of Science And Technology Liaoning |
An B.,University Of Science And Technology Liaoning
Corrosion Science and Protection Technology | Year: 2017
The coating/metal system served in atmosphere inevitably suffers from local degradation of coating and thus results in exposure of the metal substrate locally. When there is an electrolyte film formed on such a coating/metal system, it makes metal substrate partly covered by the open electrolyte film, but the nearby metal substrate beneath the coating is covered by an occlusive electrolyte film. Therefore, an electrochemical cell to simulate such system was designed and built up. By using this cell, the corrosion behavior of epoxy coating/carbon steel system by wet-dry cyclic test beneath a thin electrolyte film of 3%NaCl solution was investigated by means of electrochemical impedance spectroscopy, scanning electronic microscopy and Fourier transformation infrared spectroscopy. The results show that the corrosion rate of the exposed steel reaches the largest value by the 4th wet-dry cycle and then gradually decreases, however, the corrosion rate of coated steel reaches maximum by the 6th cycle and then decreases slowly to a steady-state with cycles. Because the electrolyte film on the exposed steel is an open form, but that is an occlusive for the metal beneath the coating, thus a corrosion cell of oxygen difference was formed, in which the exposed steel plays as the anode and thus its corrosion rate is always higher than that beneath coating. Owning to the diffusion and migration of ions occurred between the two type electrolyte films, the corrosion products on the exposed steel present multi-layered ladder-like morphology from the centre to its periphery. However, the corrosion product formed on the steel beneath the coating exhibits ripple morphology. © 2017, Chinese Academy of Sciences. All rights reserved.
Wang H.,Puguang Branch |
Sun G.,Puguang Branch |
Li Y.,Puguang Branch |
Chen X.,Puguang Branch |
Zhang Y.,Downhole Testing Company
Well Testing | Year: 2011
Acidic gas field contains much of hydrogen sulfide and carbon dioxide. When completing the well testing operation, it is not only required that the down hole testing equipment, instruments and matching tools have a high-acid corrosion and tightness, but also requires the surface well testing flow has a reliable performance of anti-hydrogen sulfide and carbon dioxide. Through surface testing process optimization, dual processe that is compound, processes of EE and HH, coupled with imports QTI3000 type of blowout gas incinerator for burning, the amendment well testing has been completed successfully, a variety of formation parameters are gained and the geological tasks are completed.
Chen W.-G.,Puguang Branch |
Zhang Q.-S.,Puguang Branch |
Zhang Q.-S.,Petroleum Engineering Institute of Zhongyuan Oil Field |
Liu D.-X.,Puguang Branch |
And 4 more authors.
Corrosion and Protection | Year: 2014
Cyclic voitammetry' potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) were used to investigate the corrosion behavior of L360MCS pipeline steel in condensed water of Puguang gas- field. The results showed that the polarization resistance decreased with increasing corrosion time. At the same time' the corrosion current density increased and corrosion potential decreased. EIS indicated that there was no protective corrosion product film formed. The corrosion rate showed a significant difference between the base' HAZ and weld' which would lead to grooving corrosion.
Zhang C.,Henan Institute of Engineering |
Zhang Q.,Henan Institute of Engineering |
Chen W.,Puguang Branch |
Liu D.,Puguang Branch |
And 5 more authors.
Society of Petroleum Engineers - International Petroleum Technology Conference 2013, IPTC 2013: Challenging Technology and Economic Limits to Meet the Global Energy Demand | Year: 2013
In this work, the corrosion behavior and mechanical degradation of two types of pipe steel, Inconoy 825 and L360, after two years of high sour environments service in Puguang gas-field were studied. Results demonstrated that a fearful elemental sulfur layer deposited on the inner wall of pipeline, pitting corrosion and hydrogen-induced cracking was observed in L360 pipe. In comparison, no pitting corrosion and hydrogen-induced cracking was found in Inconoy 825 steel pipe due to its excellent resistance to corrosion. Furthermore, mechanical properties (yield strength, impact strength, elongation, hardness, fracture toughness) and stress corrosion cracking were investigated. Results showed that the yield strength decreased obviously and the percentage of elongation increased in Inconoy 825 steel but little change in L360. The analysis a change of the mentioned mechanical characteristics together with the results of the diffusion and tapping of hydrogen of them indicated that the properties degradation of Inconoy 825 pipeline steel after long term service was associated with essential role of hydrogen in these processes. The consequences of sudden failures and severe corrosion of metallic material in the high sour gas-field, which associated with their exposure to H2S/CO2 containing gas, led to the preparation of evaluation tests of pipeline. However, passing evaluation tests cannot guarantee the safety in actual work condition unless the field experience had been at least two years. As the first attempt to exploit high sour gas-field in China, it is anticipated that this work of Puguang provides valuable data and an essential insight into the corrosion and degradation of pipeline steel services in high-sour environmental. Copyright © 2013 International Petroleum Technology Conference.
Heqin W.,Puguang Branch |
Kailiang Z.,Puguang Branch |
Shunlin L.,Puguang Branch |
Yanli L.,Puguang Branch
Well Testing | Year: 2011
Traditional wireline perforation technology can't meet the need of well control and operation security in sour gas field with high content of hydrogen sulfide and carbon dioxide gas, deep buried layer, high thickness. Tubing conveyed perforation is difficult to make true at once time because of long perforated section. In response to these problems, a set of supporting perforation tech and its auxiliary technologies to meet the production safety of long perforated section in high sulfur gas field are developed, that has been applied in more than30 wells and the success rate is 100%.