Carbon Dioxide Corrosion on Casing Under High-Temperature and High-Pressure Conditions in Deep Wells

Abstract

In order to explore the corrosion and protection methods of casing used in CO₂-riching block deep oil and gas wells, CO₂ development wells, CO₂ storage wells, we used high-temperature and high-pressure corrosion instrument and SEM to detect the form of corrosion product film and corrosion rate. We analyzed the basic principle of CO₂ corrosion on casing steel and the influence of temperature and CO₂ partial pressure on corrosion rate. We also established mathematical model for calculation and analysis of corrosion rate. The result shows that the corrosion product layer consists of three layers of films with different microstructures; the temperature and CO₂ partial pressure affect the casing corrosion rate by affecting the chemical reaction process and the corrosion product film formation mechanism; the composition of the casing material, temperature, CO₂ partial pressure conditions are different, the degree of change in the corrosion rate of the steel is different; when the temperature increases, the corrosion rate of N80 and J55 casings decreases, while the corrosion rate of P110 casing increases; the partial pressure of CO₂ increases, and the corrosion rate of steels generally increases; the corrosion resistance of J55 steel in three casing grades is relatively strong, increasing the Cr content in the steel can effectively improve the corrosion resistance of the steel. The above research system reveals the law and mechanism of CO₂ corrosion in down-hole casing under high-temperature and high-pressure conditions and establishes a corrosion rate calculation model suitable for higher temperature and pressure conditions, which provides a basis for reasonable determination of corrosion protection measures.

Copyright 2018, Shanxi Petroleum Society.

This paper was prepared for presentation at the 2018 International Field Exploration and Development Conference in Xi’an, China, 18–20 September, 2018.

This paper was selected for presentation by the IFEDC Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the IFEDC Committee and are subject to correction by the author(s). The material does not necessarily reflect any position of the IFEDC Committee, its members. Papers presented at the Conference are subject to publication review by Professional Committee of Petroleum Engineering of Shanxi Petroleum Society. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of Shanxi Petroleum Society is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of IFEDC. Contact email: paper@ifedc.org.