Asphaltene precipitation has long been a challenge for the oil and gas industry during crude oil production and processing. The problem forms a significant part of the larger overarching issue of flow assurance that affects the viability of any asset in the oil production scenario. Asphaltenes can be precipitated when the oil experience changes in pressure, temperature and composition. Of these the most common are pressure and temperature changes that are unavoidable when oil is brought up through wellbores and flowed in pipelines. Therefore, a proper understanding of asphaltene precipitation leading to deposition is crucial in completions planning and effective management of a production system. It ultimately governs the production life of the reservoir.
This understanding is traditionally achieved through the laboratory study of pressurized fluid samples that are collected during the formation testing phase. Significant developments over the years have greatly improved this process, along with the introduction of downhole fluid analysis. However, variations in different laboratory methods and surface challenges of restoration to reservoir conditions and maintenance of equilibrium have often deterred good quality results when determining an accurate and representative measurement of Asphaltene Onset Pressure (AOP). Since the post-acquisition handling of fluid samples often induces inadvertent changes to the fluid properties, the most optimum place to determine this critical parameter then becomes the sandface. In this regard, wireline formation testers can aid in providing a reliable downhole analysis. This paper serves to provide a premiere industry technique that would allow in-situ measurement of asphaltene onset pressure (AOP). Precipitation of asphaltenes or flow assurance is one of the significant challenges in the oil and gas industry that the production engineers are faced with.
This study presents a novel method to estimate AOP at reservoir conditions. The metrics obtained from this methodology have significant economic implications with regards to reservoir management. The analysis performed on the downhole data can serve to augment the PVT tests carried out in laboratory to facilitate a better understanding of the fluid. The knowledge also allows for effective production planning in order to avoid costly mitigation procedures.
