Petroleum

D

Product Percentages

In 1920 a U.S. barrel of crude oil, containing 42 gallons, yielded 11 gallons of gasoline, 5.3 gallons of kerosene, 20.4 gallons of gas oil and distillates, and 5.3 gallons of heavier distillates. In recent years, by contrast, the yield of a barrel of crude oil has increased to almost 21 gallons of gasoline, 3 gallons of jet fuel, 9 gallons of gas oil and distillates, and somewhat less than 4 gallons of lubricants and 3 gallons of heavier residues.

X

Petroleum Engineering

The disciplines employed by exploration and petroleum engineers are drawn from virtually every field of science and engineering. Thus the exploration staffs include geologists who specialize in surface mapping in order to try to reconstruct the subsurface configuration of the various sedimentary strata that will afford clues to the presence of petroleum traps. Subsurface specialists then study drill cuttings and interpret data on the subsurface formations that is relayed to surface recorders from electrical, sonic, and nuclear logging devices lowered into the bore hole on a wire line. Seismologists interpret sophisticated signals returning to the surface from sound waves that are propagated through Earth’s crust. Geochemists study the transformation of organic matter and the means for detecting and predicting the occurrence of such matter in subsurface strata. In addition, physicists, chemists, biologists, and mathematicians all support the basic research and development of sophisticated exploration techniques.

Petroleum engineers are responsible for the development of discovered oil accumulations. They usually specialize in one of the important categories of production operation: drilling and surface facilities, petrophysical and geological analysis of the reservoir, reserve estimation and specification of optimal development practices, or production control and surveillance. Although many of these specialists have formal training as petroleum engineers, many others are drawn from the ranks of chemical, mechanical, electrical, and civil engineers; physicists, chemists, and mathematicians; and geologists.

The drilling engineer specifies and supervises the actual program by which a well will be bored into the Earth, the kind of drilling mud to be used, the way in which the steel casing that isolates the productive strata from all other subsurface strata will be cemented, and how the productive strata will be exposed to the well bore. The facilities-engineering specialists specify and design the surface equipment that must be installed to support the production operation, the well-head pumps, the field measurement and collection of produced fluids and gas separation systems, the storage tankage, the dehydration system for removing water from the produced oil, and the facilities for enhanced recovery programs.

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The petrophysical and geological engineer, after interpreting the data supplied by analysis of cores and by various logging devices, develops a description of the reservoir rock and its permeability, porosity, and continuity. The reservoir engineer then develops the plan for the number and location of the wells to be drilled into the reservoir, the rates of production that can be sustained for optimum recovery, and the need for supplementary recovery technology. The reservoir engineer also estimates the productivity and ultimate recovery (reserves) that can be achieved from the reservoir, in terms of time, operating costs, and value of the crude oil produced.

Finally, the production engineer monitors the performance of the wells. The engineer recommends and implements remedial tasks such as fracturing, acidizing, deepening, adjusting gas to oil and water to oil ratios, and any other measures that will improve the economic performance of the reservoir.

XI

Production Volumes and Reserves

Crude oil is perhaps the most useful and versatile raw material that has become available for exploitation. By 2003, the United States was using 7 billion barrels of petroleum per year, and worldwide consumption of petroleum was 29.3 billion barrels per year.

A

Reserves

The world’s technically recoverable reserves of conventional crude oil totaled about 1.3 trillion barrels in 2004, of which some 216 billion barrels were in North America. Of the known oil reserves that can be profitably extracted at current prices, about 57 percent (730 billion barrels) were in the Middle East.

However, beginning in the 21st century oil companies became more focused on exploiting unconventional crude oil reserves. Improved techniques for the extraction of unconventional crude oil, especially of bitumen in the tar sand deposits of western Canada, combined with higher conventional crude oil prices, made exploitation of unconventional reserves more cost-efficient. The reserves of bitumen in the province of Alberta were believed sufficient to yield 1.7 trillion barrels of synthetic crude oil. Only ten percent of this amount, however, was thought to be technically recoverable. Nevertheless, by 2007 Canada had become the principal foreign supplier of oil to the United States.

B

Projections

It is likely that some additional discoveries will be made of new reserves in coming years, and new technologies will be developed that permit the recovery efficiency from already known resources to be increased. The supply of crude oil will at any rate extend into the early decades of the 21st century. Virtually no expectation exists among experts, however, that discoveries and inventions will extend the availability of cheap crude oil much beyond that period. For example, the Prudhoe Bay field on the North Slope of Alaska is the largest field ever discovered in the Western Hemisphere. The ultimate recovery of crude oil from this field is anticipated to be about 10 billion barrels, which is sufficient to supply the current needs of the United States for less than two years, but only one such field was discovered in the West in more than a century of exploration. Furthermore, drilling activity has not halted the steady decline of North American crude oil reserves that began during the 1970s.

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