Deposition of the high-molecular-weight components of petroleum fluids as solid precipitates in surface facilities, pipelines, downhole tubulars, and within the reservoir are well-recognized production problems. The deposits also can contain resins, crude oil, fines, scales, and water. Asphaltenes and waxes are a general category of solids and, thus, cover a wide range of materials. Understanding the fundamental characteristics that define the nature of asphaltenes and waxes is valuable in reducing or avoiding the production impacts of their deposition. This page examines the general chemical classifications and types of asphaltenes and waxes, in addition to their solidification behaviors.
Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. That quantity of petroleum which is estimated, on a given date, to be contained in known accumulations, plus those quantities already produced therefrom. Discovered Petroleum-initially-in-place may be subdivided into Commercial and Sub-commercial categories, with the estimated potentially recoverable portion being classified as Reserves and Contingent Resources respectively (SPE).
Once oil and gas are located and the well is successfully drilled and completed, the product must be transported to a facility where it can be produced/treated, stored, processed, refined, or transferred for eventual sale. Figure 1 is a simplified diagram that illustrates the typical, basic "wellhead to sales" concept. The typical system begins at the well flow-control device on the producing "wing(s)" of the wellhead tree and includes: A brief description of the associated piping/pipeline systems is given next. The well flowline, or simply flowline, is the first "pipeline" system connected to the wellhead. The flowline carries total produced fluids (e.g., oil, gas, and production water) from the well to the first piece of production equipment--typically a production separator.
When product vapor pressure is greater than 0.5 psia (more in some states) but less than 11.1 psia, the U.S. Environmental Protection Agency permits the use of a floating-roof as the primary means of vapor control from the storage tank. Floating-roof tanks are not intended for all products. In general, they are not suitable for applications in which the products have not been stabilized (vapors removed). The goal with all floating-roof tanks is to provide safe, efficient storage of volatile products with minimum vapor loss to the environment. Design requirements for external floating roofs are provided in Appendix C of the API Standard 650.
Fixed roof tanks are common in production facilities to store hydrocarbons with vapor pressures close to atmospheric pressure. In this use, they should be equipped with pressure-vacuum valves and purged with natural gas to eliminate air intake into the vapor space. In crude oil terminals and pumping stations, internal floating roofs may be added to the fixed-roof tank to reduce product vapor losses if the crude oil has been stabilized to vapor pressures less than 11 psia. Examples of fixed-roof tanks are shown in Figure 1. The most common fixed-roof design contains a shallow cone roof utilizing a single center column plus internal (or external) framing to support the roof plates.
Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. A theory of petroleum formation in which the petroleum is thought to have originated from plant and animal material that has undergone transformation from deep burial.
Production, refining, and distribution of petroleum products require many different types and sizes of storage tanks. Small bolted or welded tanks might be ideal for production fields while larger, welded storage tanks are used in distribution terminals and refineries throughout the world. Product operating conditions, storage capacities, and specific design issues can affect the tank selection process. Storage tanks come in all sizes and shapes. Special applications might require tanks to be rectangular, in the form of horizontal cylinders, or even spherical in shape.
Recently, global climate change and air quality have become increasingly important environmental concerns. Consequently, there has been a rise in collaborative international efforts to reduce the concentration of greenhouse gases and criteria pollutants. Greenhouse gases include carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), occurring naturally and as the result of human activity. In addition, criteria pollutants (1970 amendments to the Clean Air Act required EPA to set National Ambient Air Quality Standards for certain pollutants known to be hazardous to human health) include emissions of nitrogen oxide, sulfur dioxide, carbon monoxide, and total unburned hydrocarbons. International and national governments are implementing more regulations on air emissions.
CO2 sequestration, also known as CO2 capture and storage (CCS), uses a range of technologies and approaches that isolate, extract, and store carbon dioxide emissions from industrial and energy-related sources in order to prevent the release of it into the atmosphere. Carbon capture and storage technology involves the process of trapping and separating the CO2, transporting it to a storage location, and then storing it long-term so that it does not enter into the atmosphere. It is not a new technology and has been used by petroleum, chemical, and power industries for decades. In fact, carbon capture was first used in Texas in 1972 as a method to enhance oil recovery. CO2 emissions from the burning of fossil fuels has been on the incline since the industrial era; and with more than 85% of the world's energy coming from fossil fuels, it will remain an important energy source well into the future. As the demand for fossil fuels is growing, so is the volume of CO2 emitted each year.