The oil and gas industry includes the processes of exploration, extraction, upgrading, refining, transporting and marketing oil products. The largest volume products of the industry are fuel oil, <gasoline> and feedstock for bulk and fine chemicals [1]. There are two types of crude oil: one is <conventional> and the other is <unconventional> to which oil sand resource belongs. There are an estimated 1.5 and 170.4 billion barrels of established conventional and bitumen crude oil remaining as of 2009 in Alberta [2]. A typical production flow of conventional oil is shown in Figure 1. The extraction of heavy oil (bitumen) from oil sands conserves is shown in Figure 2; the rest of the flow is the same as the conventional crude oil.
Mixing is involved in every step of the oil industry from exploration to marketing products. While drilling oil and gas wells, drilling fluid is applied. The fluid consists of a mixture of clay and a stabilized water-in-oil emulsion. The emulsion is prepared batchwise by dispersing water in oil in agitated tanks. The main functions of drilling mud include providing hydrostatic pressure to prevent formation fluids from entering into the well bore, keeping the drill bit cool and clean during drilling, carrying drill cuttings out of the well and suspending the drill cuttings while drilling is paused and the drilling assembly is brought in and out of the hole. Thus, mixing technology plays an important role in the exploration stage [3].
Meanwhile, mixing is important for product sampling in the pipeline transport. When crude oil is sampled to determine its water content before its custody is transferred to refineries, the water has to be uniformly dispersed across the cross-section of pipes. Thus, a mixer system has to be installed upstream of the sampler. Adequate mixing should create a good dispersion but still allow water to easily settle in downstream storage tanks. Optimum mixing can add a high value for refineries as even a sampling error of 0.1% can cost refineries about $250, 000 per medium-sized tanker [4].
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