| LIU Yang,WANG Xiao,XU Jie,FAN Bai-tao,ZHAO Shao-wei,HUANG Huan-ge.Anti-corrosion Techniques for Transition from Exploration Well to Development Well in Condensate Reservoirs in Bohai Sea[J],47(10):249-255 |
| Anti-corrosion Techniques for Transition from Exploration Well to Development Well in Condensate Reservoirs in Bohai Sea |
| Received:June 05, 2018 Revised:October 20, 2018 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2018.10.033 |
| KeyWord:offshore oilfield tube and casing CO2 corrosion H2S corrosion transition from exploration well to development well materials optimization |
| Author | Institution |
| LIU Yang |
Tianjin Branch, CNOOC China Co., Ltd, Tianjin , China |
| WANG Xiao |
Tianjin Branch, CNOOC China Co., Ltd, Tianjin , China |
| XU Jie |
Tianjin Branch, CNOOC China Co., Ltd, Tianjin , China |
| FAN Bai-tao |
Tianjin Branch, CNOOC China Co., Ltd, Tianjin , China |
| ZHAO Shao-wei |
Tianjin Branch, CNOOC China Co., Ltd, Tianjin , China |
| HUANG Huan-ge |
Tianjin Branch, CNOOC China Co., Ltd, Tianjin , China |
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| Abstract: |
| After the process of turning exploration well into production well, CO2 and H2S in reservoir may lead to corrosion and perforation of production casing and seriously affect safety. The work aims to explore the corrosion behavior of casing in the post-production process of deep exploration wells under the co-existence of CO2 and H2S in offshore condensate oil and gas reservoirs, control the corrosion risk of wellbore, and guide anti-corrosion design of deep exploration wells and material selection of oil casing in offshore oil field transferable development wells. The samples taken from the field reservoir were analyzed for components to determine the composition and physical and chemical properties of the reservoir fluid. Then, the indoor dynamic high temperature and high pressure corrosion evaluation kettle was used to test the corrosion of the casing materials with different corrosion prevention grades. Based on eruption velocity and micromorphology of corrosion (SEM), the best anti-corrosion material was selected for the production casing used in the process of turning exploration well into production well. The co-existence of CO2 and H2S was confirmed in the oil and gas samples taken from syntectonic adjacent wells. CO2 concentration was 6.57mol%, H2S concentration was 46.31 mg/m3, and reservoir temperature was 171.9 ℃. The reservoir test was free from water, but in later stage of transition from exploration well to development well, there still might be water. Casing out of water could be possibly corroded. 3 groups of corrosion tests were carried out by 3Cr stainless steel, 13Cr stainless steel and super 13Cr stainless steel at field conditions and the corrosion rate of these three types of cannulas was respectively 2.8844 mm/a, 0.0749 mm/a and 0.0182 mm/a. The corrosion rate of the conventional 3Cr stainless steel exceeds the corrosion control line. In consideration of the water leakage risk at the later development of the oil and gas wells, anticorrosion material above 13Cr was recommended. The above materials can effectively reduce the corrosion risk of the production of the casing in the later recovery production of the exploration well and has been applied to 7 inch tail pipe in the transferring of 4 exploration wells to development wells in Bohai oil and gas field with good effect of anticorrosion. |
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