The liquefaction, solubilization and/or extraction of fossil fuels, also called hydrocarbon-containing organic matter, in solid, semi-solid, highly viscous or viscous form (individually and jointly referred to as fossil fuels hereafter) have proven to be extremely challenging and difficult. As used herein, such fossils fuels include, but are not limited to, hydrocarbon-containing organic matter within coal, oil shale, tar sands and oil sands (hereinafter jointly called tar sands), as well as crude oil, heavy or extra heavy crude oil, natural gas and petroleum gas, crude bitumen, kerogen, natural asphalt and/or asphaltene. The difficulty can in part be attributed to the fact that these fossil fuels include complex organic polymers linked by oxygen and sulfur bonds, which are often imbedded in the matrices of inorganic compounds. A need exists to produce additional liquid hydrocarbon feed stock for the manufacture of liquid and gaseous fuels as well as for the production of various chemicals, pharmaceuticals and engineered materials as the demand and consumption for hydrocarbon based materials increases.
Various technologies or processes have been developed to liquefy, solubilize and/or extract the fossil fuels. None of the prior art liquefaction, solubilization and extraction technologies or processes, however, has proven to be commercially viable on a large scale for all types of fossil fuels. This is due to the fact that all of the prior art technologies and processes for the liquefaction, solubilization or extraction of hydrocarbons developed to date are expensive to deploy and operate. Additionally, the prior art processes and technologies for the liquefaction, solubilization and/or extraction of hydrocarbons may be difficult to scale up, operate and/or control because of one or more of the following reasons: (1) operating at an inordinately elevated pressure; (2) operating at a very high temperature; (3) the need for expensive processing vessels and equipment that require the external supply of hydrogen under extreme conditions; (4) being subjected to a mixture, or composition, of two or more reagents, catalysts and/or promoters, which are frequently highly toxic and are neither renewable nor recyclable; (5) requiring to supply a special form of energy, e.g., microwave radiation; (6) long process times for partial liquefaction, solubilization or extraction; (7) requiring extraordinarily fine particles with a size of about 200 mesh (0.074 mm), which is profoundly difficult and costly to manufacture and handle; and (8) being incapable of recovering and recycling the necessary reagents, catalysts and/or promoters. Thus, there exists a need to provide additional techniques and processes for the increased recovery of hydrocarbon materials.
In the past, small-scale experiments have shown that d-limonene solutions can act as solvents for hydrocarbon-containing materials. However, d-limonene is only partially successful in solubilizing hydrocarbon-containing materials. Further, because d-limonene is extracted from citrus rinds, it is available only in limited quantities and at high cost compared with other solvents.
Other solvents used in the past include alkaline solutions and alcohol-water mixtures. These compositions are only marginally useful for solubilizing hydrocarbon-containing materials due to the low solubility of hydrocarbons in aqueous solutions.
Other prior art methods utilize toluene and/or xylene to re-liquefy paraffin and thick oil to a less viscous material. Such methods re-liquefy the paraffins using one or more volatile, very dangerous, cancer causing chemicals. These products potentially pollute the ground water and must be handled with extreme caution as indicated on each chemical's Material Safety Data Sheet. The paraffin and thick oil revert to their original state once these products have revolatilized causing deposits in flow lines or storage tank “dropout”.
“Sour” hydrocarbon-containing materials contain greater than about 0.5% sulfur by weight. “Sour” gas contains greater than 4 ppm H2S and other sulfonated gaseous matter. This sulfur can exist in the form of free elemental sulfur, hydrogen sulfide gas, and various other sulfur compounds, including but not limited to, sulfide, disulfides, mercaptans, thiophenes, benzothiophenes, and the like. Each crude material or gas may have different amounts or different types of sulfur compounds, but typically the proportion, complexity and stability of the sulfur compounds are greatest in heavier crude oil fractions. Hydrogen sulfide gas is a health hazard because it is poisonous. Further, hydrogen sulfide can react with water to form sulfuric acid, which can corrode equipment, pipelines, storage tanks, and the like. Thus, it is important that those sulfur-containing hydrocarbon-containing materials that are reactive be modified to reduce the corrosive effects and to avoid the health risks associated with untreated sulfur-containing hydrocarbon-containing materials.
For primary drilling operations, it would be advantageous to employ a process that would enhance solubilization and encourage movement of additional or trapped hydrocarbon-containing organic matter that could then be recovered allowing existing pressure gradients to force the hydrocarbon-containing organic matter through the borehole. In particular, it would be useful to solubilize heavier hydrocarbons that usually remain in the reservoir through primary drilling operations.
For secondary and tertiary or enhanced oil recovery operations, it would be advantageous to employ a process that would enhance solubilization of oil to recover hydrocarbon-containing organic matter in the reservoir in a manner that is cost effective and that does not damage the reservoir. While effective methods and compositions exist for tertiary operations, current methods suffer due to expense of operations in comparison to the value of the produced hydrocarbon-containing organic matter.
USPTO Backgrounds
USPTO Backgrounds