Driving Cost Reduction Through Standardization, Practical Guidelines for Asphaltene Management in Carbonate Oilfields
Authors: Grutters Mark , Abdallah Dalia , Mogensen Kristian , Nighswander John , Flannery Matthew , Jamaluddin Abul , Tavakkoli Mohammad 
Published: November 2024

The financial impact of asphaltene deposition on oil & gas operations can be very substantial and this impact can be expected to grow with future EOR plans using CO2 or hydrocarbon gas. In large organizations, with multiple operating companies active in different areas, experience to mitigate asphaltene-related problems is often scattered and not aligned. ADNOC raised a task force to develop a new Asphaltene Management guideline, with the purpose of standardizing procedures and sharing best practices. The task force consisted of SME's from all group companies, covering reservoir engineering, petroleum engineering, flow assurance and production chemistry. A group of external experts provided the industry best-practice on asphaltene management based on information available in the public domain. This approach allowed for a gap analysis, and provided insight on technologies and analytical methods required to bridge the gap with the industry best practices. The asphaltene management guidelines were divided in five key areas: (1) sample collection, (2) risk assessment by fluid analysis, (3) asphaltene modeling, (4) inhibition and remediation and (5) surveillance. In this paper best practice highlights are provided for each key area, together with identified areas for future improvement. Sampling: Bottomhole and surface samples have been collected in the past 20+ years, always in line with industry best practices. It is important to realize that large reservoirs might be subject to lateral property variation, which can result in localized asphaltene problems. In these cases it is critical to collect multiple samples covering the entire reservoir to identify fluid property trends and develop correlations that will distinguish problematic from non-problematic areas. Risk Assessment: Applied stability screens often provide contradicting assessments and multiple screens must be applied with careful interpretation. The screens will have to be re-calibrated with samples from our own existing problematic and non-problematic wells. More attention should be paid to asphaltene deposition tests, rather than just precipitation tests. Modeling: Both cubic EOS or PC-SAFT can be applied to define the asphaltene precipitation boundary – when used to assess precipitation for typical formation to surface pressure and temperatures. Deposition modeling should be implemented in the future, for this using PC-SAFT is recommended. Remediation and Inhibition: A high level estimate indicates that protection of a well by inhibition becomes economic with a plugging frequency of more than 2 per year. Asphaltene Inhibitor formation squeezes have been applied multiple times with mixed success. Monitoring the squeeze performance by tracking inhibitor residuals was not very accurate and highlights the challenge that the minimum effective inhibitor dosage from the lab might not be applicable to field conditions. Surveillance: Close monitoring of high risk areas is important, and multiple surveillance tools must be applied as experience shows that wells plug with asphaltenes and cease to flow without clear warning. Steady state wellbore modeling has been successfully applied to detect blockages onshore and is being replicated in other fields. In summary, the new guidelines and best practices combine knowledge from the public domain with vast company experience, tailored to ADNOC's specific operational challenges. The information in the guidelines will be a pivotal source of information in driving standardization, reducing costs, optimizing resources and enhancing operational efficiency.