|
| Corrosion Failure Reason and Protection Measure of Oil well Production String in Bohai L Oilfield |
| Received:May 18, 2020 Revised:October 10, 2020 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.01.011 |
| KeyWord:oil well production string corrosion dissolved oxygen chloridion sulfate reducing bacteria erosion |
| Author | Institution |
| CHEN Hua-xing |
CNOOC China CO., Ltd., Tianjin Branch, Tianjin , China |
| PANG Ming |
CNOOC China CO., Ltd., Tianjin Branch, Tianjin , China |
| ZHAO Shun-chao |
CNOOC China CO., Ltd., Tianjin Branch, Tianjin , China |
| WANG Yu-fei |
CNOOC China CO., Ltd., Tianjin Branch, Tianjin , China |
| FANG Tao |
CNOOC China CO., Ltd., Tianjin Branch, Tianjin , China |
|
| Hits: |
| Download times: |
| Abstract: |
| The frequent corrosion failure and perforation of some oil well production strings in Bohai L Oilfield has a strong impact on normal production of oilfield. In order to prolong attended time of downhole pipe string, this paper analyzes the corrosion failure reason and protection measure of downhole pipe string. The failed pipe strings and corrosion product are studied by macroscopic morphology observing, metallographic structure analyzing and scanning electron microscope. Meanwhile corrosion reason is analyzed from ion composition of oilfield water, corrosion gas, bacteria and erosion. The result indicates that oil well production string of L oilfield has partial perforation and breakage. The inner surface of production string appears ulcerous corrosion and its colour is tawny and black. Metallographic structure of the failure pipe strings is composed of pearlite and ferrite, which is similar to matrix, and shows faveolate characteristic caused by corrosion. The main corrosion products are Fe, O and C. In conclusion, the key reason for the corrosion of oil well string in L Oilfield is that the dissolved oxygen in oilfield water exceeds the standard by 9 times, the chloridion concentration is greater than 3,500 mg/L, and sulfate reducing bacteria exceed the standard by 4 times, aggravating the partial corrosion of production string. Moreover, the flow state of the fluid at the intake of the electric submersible pump separator is changed to rotational flow, and the flow rate is greatly increased, resulting in erosion and aggravating the corrosion failure of the separator. It is suggested that L Oilfield should strengthen the monitoring and control of dissolved oxygen and chloridion in oilfield water. The corroded oil well should adopt anti-corrosion pipe and pump. In addition, the erosion resistance of separator should be improved. |
| Close |
|
|
|