SPWLA SYMPOSIUM Ranking Oil Viscosity in Heavy Oil Reservoirs

摘要

The Milne Point field in Alaska produces from the Kuparuk, Schrader and Ugnu formations. The Kuparuk formation contains light oil, while the Schrader and Ugnu contain heavy oil. The range of viscosities is 200 to 10,000 cp in the Ugnu, 20 – 200 cp in the Schrader, and about 3 cp in the Kuparuk. Over 200 wells have been completed in the Kuparuk and Schrader formations at Milne Point. The Ugnu contains the largest OIP in the field; however, it has not been developed yet due to the high oil viscosities. To date, only one well has been completed in the Ugnu. BP is engaged in new studies to find a way to make the Ugnu commercial. This paper discusses an attempt to identify lower-viscosity "sweet spots" within the Ugnu using NMR (nuclear magnetic resonance) measurements. In 2004, full suites of LWD and wireline data were acquired in two newly drilled wells. The primary goal was to compare viscosity predictions from NMR log measurements to geochemical measurements made on fluids extracted from core plugs. Integration of geochemical data and the NMR results indicate a strong correlation between T1LM and viscosity. LWD NMR successfully identified lighter oil in the Schrader and heavier oil in the Ugnu. Intermediate viscosity oil was correctly identified in the Schrader but not the Ugnu.