Heavy oil is qualitatively defined as any oil that does not flow easily. Quantitively, it scores a low number on the American Petroleum Institute's inverted gravity scale for comparing the stickiness of crudes. For example, asphalt, used to tar roads, is typically scored at around 8 API; Brent crude from the North Sea, the European benchmark, rates 35-38 API; light crude from Saudi Arabia's biggest oilfield, Ghawar, is 40 API or higher.
Manifa's oil is about 28 API, which is not too bad compared with Venezuela's Orinoco heavy crude, for example, which rings in at 10 API.
It could still make quite a mess of the environment, however, in the event of a spill from a ruptured pipeline or a well blowout. It should be noted that the potential for environmental damage tends to be higher for heavy crude than light crude projects, in part because more wells are required to produce the intractable oil. Drilling the Manifa field will require "many" rigs based on artificial islands and offshore platforms, Mr al Abdulkarim said.
Yet there is little doubt that Aramco has gone to considerable lengths to minimise the huge project's environmental impact.
For a start, it has built a causeway to connect the 31 drilling islands it will use to access oil under the shallower parts of Manifa bay, keeping a lot of the project's infrastructure, such as pipelines "onshore", where oil spills have a better chance of being stopped and mopped up before they contaminate the coastal waters of the Gulf.
That is important in Saudi Arabia, which obtains most of its drinking water from the Gulf via desalination plants. As even schoolchildren know, it is a bad idea to pollute one's supply of clean water.
In another plus for the environment, Aramco will use "extended reach drilling", which employs long horizontal bores beneath the seabed to get at the Manifa oil reserves. That greatly reduces the number of wells that must be drilled and their above-ground footprint.
Rock cuttings, or pieces of loose or crumbly rock that fall into the bore hole and must be cleaned out during drilling, will not be thrown into the sea, but transported to an onshore site for disposal, Mr al Abdulkarim said. That is also important, as cuttings disposed of in the shallow waters of Manifa Bay could create enough turbidity to cut off the sunlight that sustains corals and seaweeds, while smothering other marine life. Such cuttings would also be contaminated with chemicals used in drilling.
Following an earlier presentation at the conference, Mr Abdulkarim admitted in response to a delegate's question that dredging waste had been tipped into the sea during construction of Manifa's infrastructure. He said Aramco was working to eliminate such practices.
Last but not least, before building the causeway, Aramco modeled the earthworks' potential effects on water flow and temperature in Manifa Bay. The company determined that bridges would been needed to allow proper mixing between the water in different parts of the bay. The L-shaped causeway now contains a long bridge in its short arm, running out from the shore, and several smaller bridges in the longer arm that connects the drilling islands.
Only time will tell if these measures will be sufficient to protect Manifa Bay's thick beds of sea grass, coral outcrops and mangrove swamps. The bay is home to such regionally important animal species as pearl oysters, the prized food-fish hamour, dolphins and sea turtles, including the endangered hawksbill turtle.
Many of Aramco's managers already have first-hand knowledge of what could happen if their environmental precautions fall short. Manifa Bay was heavily contaminated by the oil spills unleashed by the the Gulf War. Mr al Abdulkarim, for one, is keen to prevent a repetition of that kind of environmental disaster.
Pic courtesy of Saudi Aramco