Shifting The Focus To An Optimal Oil Recovery Strategy

Dr. John D.M. Belgrave, Belgrave Oil and Gas Corp.
13th International Oil and Gas Conference & Exhibition,
Delhi, India

February 10-12, 1019.

While much of the recent discussion on where the marginal barrel of new oil will come from focuses on unconventional plays, it misses the large upside and potentially lower supply cost from already discovered fields, through application of Improved Oil Recovery processes. Old oilfields are major source of new supply.

Current ultimate average recovery factor for oilfields, on a worldwide basis, is about 35%. This means that about two-thirds of the oil that has been discovered will still be left in the ground. We have under our feet, in well-known locations, enormous prospects for producing additional quantities of oil. Increasing the average ultimate recovery factor from 35% to 45% would bring about 1 trillion barrels of oil. There are many examples of petroleum jurisdictions and operating companies working against their self interest from the onset, or during later efforts to improve oil recovery. From a stakeholder perspective, an optimal oil recovery strategy needs to consider the nature of the oil accumulation, the existing infrastructure, lease duration, and the prevailing economic, regulatory and environmental framework. Some useful case histories and relevant arguments for consideration…

A lack of existing infrastructure in a previously abandoned oilfield may dictate the choice of the IOR process if revisited. Larger well spacings are mandated because of depleted oil saturation. An example of economics is presented.

Two interesting examples are discussed that demonstrate why reservoirs with significant structural relief should consider an exploitation strategy that makes use of gravity. In these instances, attempting to accelerate recovery beyond that of gravity-stable displacement proved inadvisable.

While seemingly simple to implement, waterflooding deep light oil reservoirs may be economically challenged by the associated lifting costs of the large quantity of produced fluids, or by lack of injectivity. Carbon dioxide sequestration in an oil reservoir is meritorious from an environmental viewpoint, but the efficacy of such a strategy is questionable from a recovery perspective below reservoir pressures around 1200 psig.

Depending on the oil viscosity, thin pay heavy oil reservoirs may be effectively exploited using horizontal wells and polymer injection, co-injection of solvents with steam, and air injection. It is useful to remind ourselves that selection of appropriate oil recovery technology is critical!

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