A structured approach to the diagnosis of formation damage caused by organic scale deposits and surface active agents, Part I: Development of a Diagnostic Process

Abstract A structured approach has been proposed for diagnosing formation damage caused by organic scale deposits and surface active agents. The approach is based on a comprehensive set of heuristic rules governing the formation of emulsions, water blocks, and wettability reversal as well as the deposition of asphaltenes and wax in hydrocarbon reservoirs. The compiled rules, representing experts' knowledge, have been derived from standard industrial practices and integrated with empirical models to ensure a robust view of the diagnosed damage types. The knowledge has been arranged in decision trees that form the core structure of a diagnostic process to identify types of formation damage. The damage diagnostic process is performed by walking through the history of the reservoir from drilling to production, stimulation, EOR processes, and workover jobs. The complete history of the well is carefully scrutinized for evidence of any field practices that might cause formation damage. The developed approach and knowledge has been tested with 3 comprehensive hypothetical cases that simulate a wide range of damage problems. This approach has also been validated with two documented field cases that involve producing wells in the West Coalinga field in California and in the Ghawar field in Saudi Arabia. Both cases resulted in thorough diagnoses of damage types in agreement with field observations. This paper forms the first leg of a two-part series: (I) Development of a Diagnostic Process, and (II) Expert System Development. Part I proposes a structured approach for diagnosing formation damage. Part II automates the diagnosis process developed in Part I.