Predicting Oil Acidity Based from Oil Composition and Basin Modeling

Maowen Li¹, Dingsheng Cheng², Xiaohua Wang², Lirong Dou², Dujie Hou³, Qian Shi⁴, Zhigang Wen⁵, Youjun Tang⁵, and Sneh Achal^1
1Geological Survey of Canada, Calgary, AB, Canada
²CNPC International, Beijing, China
³China University of Geosciences, Beijing, China
⁴China University of Petroleum, Beijing, China
⁵Yangtze University, Jingzhou, China

High acidity crude oils have accounted for a growing share of the global oil supply in recent years. As a result, these oils are receiving increasing attention, because they present a financial opportunity, as well as a technical challenge to the oil industry. Oil companies and industry consultants have models for predicting oil quality such as GOR and API gravity, but these models are not widely known or have not been adapted to account for increasingly important oil quality characteristics such as acidity. Using geological samples from China, North America and Africa, we describe an integrated approach for characterizing oil acidity and a new approach for incorporating acidity in oil quality prediction, which can have a big effect on the price differential and project viability. The total acid number values of the studied oils range from less than 0.1 to over 20 mgKOH/g oil, and the related petroleum source rocks were deposited from marine, deltaic to lacustrine settings ranging from Paleozoic to Cenozoic in age. Biodegradation and multiple phase oil charging appear to be the principal controls for oil acidity. A combination of chemical analysis and 1-D basin modeling proves effective oil acidity prediction.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas