Well Integrity in Heavy Oil Wells: Challenges and Solutions

Abstract

Abstract Unconventional resources such as Heavy oil are becoming a target of most operators. Wells subjected to steam stimulation for heavy oil recovery are exposed to extreme temperature changes that can vary from 21° C to 348°C. This temperature cycling can have a drastic effect on the set cement sheath causing it to fail with a consequent loss of the well integrity. Loss of hydraulic isolation in the cement sheath will decrease control of steam placement leading to reduced hydrocarbon recovery and potentially health, safety and environmental challenges. Oudeh Petroleum Company (OPC) has been producing heavy oil since 2006 using the Huff and Puff technique. Complete Well Integrity has been achieved using an Advanced Cement System in more than two hundred wells exposed to steam injection temperatures up to 348°C and consequent high induced thermal stresses (Fig. 1 & 2). This paper will discuss the methodology of the risk analysis of the cement sheath failure under steam stimulation and selection criteria for the Advanced Cement System to withstand temperature cycling. Two case histories will be presented as well as a 50 well database.