Transient Flow Analysis for Well CO2 Injection: Challenges and Methodologies to Consider for Well Design & Operating Envelope

PTTEP has been producing from field X, an offshore gas field located in the Southern part of the Gulf of Thailand. As one of the company's strategies to become a low-carbon organization with sustainable growth and to achieve Net Zero emissions within 2050, PTTEP has initiated Thailand's first Carbon Capture and Storage (CCS) project at the X field with the expectation to reduce carbon dioxide emissions by approximately 700,000 -1,000,000 tones per annum. For this CCS project, the gas containing CO2 produced from natural gas reservoirs at wellhead platforms will be captured at the processing platform using a 2-stage membrane technology to achieve a CO2 concentration of ~95%. The CO2 will then be compressed for transportation from the facility to the injection wellhead platform and will be injected into the targeted layers of the saline aquifer and depleted reservoir for permanent storage. Engineering studies have been conducted to identify challenges and assess the optimum design and operating measures for the future development of a sustainable CCS value chain. This paper focuses on the approach taken to analyze the requirement for well design and operating envelope to address the challenges of injecting high impurity of CO2 injection stream around 5% (one of the highest of the CCS projects) into both aquifer and depleted reservoirs.