Abstract
Casing corrosion during CO2 injection or storage results in significant economic loss and increased production risks. Therefore, in this paper, a corroded casing risk assessment model based on analytic hierarchy process and fuzzy comprehensive evaluation is established to identify potential risks in time. First, the corrosion rate and residual strength characteristics are analyzed through corrosion tests and numerical simulations, respectively, to determine the risk factors that may lead to an accident. Then, an index system for corroded casing risk evaluation is established based on six important factors: temperature, CO2 partial pressure, flow velocity, corrosion radius, corrosion depth and wellhead pressure. Subsequently, the index weights are calculated via the analytic hierarchy process. Finally, the risk level of corroded casing is obtained via the fuzzy comprehensive evaluation. The corroded casing risk assessment model has been verified by a case well, which shows that the model is valuable and feasible. It provides an effective decision-making method for the risk evaluation of corroded casing in CO2 injection well, which is conductive to improve the wellbore operation efficiency.
Highlights
Injecting CO2 into the depleted oil reservoirs for storage or to enhance oil and gas production is considered as one of the effective measures to reduce the content of CO2 in the atmosphere (Ajayi et al 2019; Kalra et al 2018; Khather et al 2019)
The corrosion specimens are exposed to C O2 mixtures with different conditions as the set scheme
It can be seen from the scanning electron microscope (SEM) images that
Summary
Injecting CO2 into the depleted oil reservoirs for storage or to enhance oil and gas production is considered as one of the effective measures to reduce the content of CO2 in the atmosphere (Ajayi et al 2019; Kalra et al 2018; Khather et al 2019). As an acid gas, CO2 is highly corrosive in water-containing environment (Zhu and Liu 2018). After operating under highly corrosive conditions for a certain period, the casing of CO2 injection wells in Shengli Oilfield exhibited serious corrosion behavior, posing a threat to well safety and severely limiting the promotion of CO2-enhanced oil recovery technology. Sui et al (2018) investigated the corrosion behavior of X65 carbon steel in water-saturated supercritical CO2 containing H2S and proposed that the highest corrosion rate was 0.19 mm/year at 35 °C and 8 MPa. Lin et al (2016) established two theoretical models for casing strength degradation due to corrosion and proposed that stress concentration factor increased exponentially, while residual burst strength and collapse strength decreased linearly with the increase in corrosion depth. Lin et al (2016) established two theoretical models for casing strength degradation due to corrosion and proposed that stress concentration factor increased exponentially, while residual burst strength and collapse strength decreased linearly with the increase in corrosion depth. Elgaddafi et al (2016) investigated the effects of C O2 partial pressure ratio and total pressure on corrosion behavior of C110 carbon
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
