A Novel Approach to Detect Tubing Leakage in Carbon Dioxide (CO2)Injection Wells via an Efficient Annular Pressure Monitoring

摘要

Due to the unique corrosion potential and safety hazards of carbon dioxide (CO2), tubing leakage of CO2 in aCO2 injection well may occur and lead to undesired consequences to environment, human being and facility. As a result,quick detection of any carbon dioxide leakage and accurate identification of leakage location are extremely beneficial toobtain critical information to fix the leakage in a prompt manner, prevent incidents / injury / casualty, and achieve highstandards of operational safety. Annular pressure monitoring has been identified as an effective and reliable approach fordetecting tubing and casing leakage of fluids (including hazardous gas like CO2) in a well. Accurate prediction of annularpressure change associated with the leakage will certainly help the operation. In an effort to assess annular pressure characteristicsand thus improve understanding of tubing leakage, a multiphase dynamic modeling approach has been appliedto simulate the carbon dioxide, completion brine and formation water’s flow and associated heat transfer processes alongwellbore, tubing and annulus in carbon dioxide injection wells designed for carbon capture and sequestration (CCS) [1]projects. Two operational scenarios – one for routine CO2 injection and another for well shut-in – have been considered inthe investigation. Key parameters that may have significant impacts on the process have been investigated. On the basis ofthe investigation, a novel approach has been proposed in the paper for quickly detecting the leakage of carbon dioxide in aCO2 injection well. Two simple equations have been developed to pinpoint the leakage location by means of real-timemeasurement and monitoring of the change in annular pressure. Recommendations based on a series of dynamic simulationresults have been provided and can be readily incorporated into detailed operating procedures to enhance carbon dioxideinjection wells’ operational safety.