4D seismic monitoring of CO2 flood in a thin fractured carbonate reservoir

Abstract

The miscible CO2 flood in Weyburn Field is a massive process for enhanced tertiary oil recovery and greenhouse gas sequestration, the largest of this kind ever in western Canada. This field, a mature Paleozoic carbonate pool of 1.4 billion-barrel reserves, has had nearly 48 years of conventional production history, mostly through waterflooding. Since October 2000 and in an effort to arrest production decline and improve recovery, the field operator has pipelined 50∼95 MMcf of CO2 each day as by-products of a coal gasification operation in North Dakota, and pumped it into the 30-m fractured reservoir at a mean depth of 1450 m. Over a 25-year project life, an estimated 14 million tons of the greenhouse gas, which would otherwise be vented into the atmosphere, will be injected and stored in the field's producing formations.