Steam Chambers and Oil Leaks

A major issue for producers of Alberta heavy oil relates to one of the foundational technologies for producing the viscous fluid, which is using steam to extract the oil. This is a multidimensional problem. First the production of steam requires a source of water and access to subsurface and surface waters is being carefully monitored and throttled by the Provincial Government of Alberta. Another consideration is that using steam to produce heavy oil is energy intensive, and that contributes to the premise that heavy oil is dirty oil. More pressing recently are the mechanics of how steam is used to produce heavy oil.

Steam has a dual role. The most obvious is that the heat substantially lowers the viscosity of heavy and ultra-heavy oil. For example, the viscosity of McMurray Formation “oil” can be similar to that of smooth peanut butter. Think about that: oil producers need to move a fluid similar to peanut butter through the very small pore throats in the reservoir sandstone. When heated by steam, however, the viscosity becomes so low that it is similar to that of water. This brings us to the second role of steam, which is that a steam chamber must be allowed to develop. A steam chamber is a heated zone of the reservoir that is in part occupied by steam. The chamber not only heats the rock and oil, but it also expands the reservoir, due to steam pressure. This is important, as the dilation of the reservoir expands pore throats and fractures, improving the overall permeability within the steam chamber: this allows oil to flow even better. And therein is the problem. The expansion of the rock and fractures in some cases leads to steam and oil leaving the reservoir and migrating into rock formations above the resource. In extreme cases, the steam can arrive at the surface. This happened near the Ells River in the Athabasca area and the steam release was explosive, producing a large crater in the process.

A current example of resource escaping the oil reservoir due to steam drive is the CNRL Primrose leak. See:

In this case, it is still a little unclear how the oil made it to surface. But, there are only two feasible explanations. One is that the oil escaped upwards through fractures that were dilated by the steam pressure. Another is that the steam chamber intersected an older and forgotten well bore drilled by another oil company in decades past. The difference is not trivial, because the presence of fractures suggests that the whole play area cannot be developed with the steam pressures used prior to the leak. Lower steam pressures can be used but oil recovery is reduced. It is also fair to say that if one does not know where all of the previous boreholes are, you are left with a similar problem.

Objectively speaking, Alberta literally has a trillion of barrels of oil that, under the present technology absolutely require steam to be removed from the Earth. That is a century’s worth of oil production. So, you can see the problem, the steam is heavily linked to Alberta’s economic well being.

What would you do?