Steam-assisted gravity drainage is the method of choice to extract bitumen from Athabasca oil-sand reservoirs in Western Canada. Under reservoir conditions, bitumen is immobile because of high viscosity, and its typically high level of saturation limits the injectivity of steam. In current industry practice, steam is circulated within injection and production wells. Operators keep the steam circulating until mobile bitumen breaks through the producer and communication is established between the injector and the producer. The “startup” phase is a time-consuming process taking three or more months with no oil production. A variety of processes could be used to minimize the length of the startup phase, such as electromagnetic (EM) heating in either the induction (medium frequency) or radio-frequency ranges. Knowledge of the size of the hot zone formed by steam circulation and of the benefits of simultaneous EM-heating techniques increases understanding of the startup process and helps to minimize startup duration. The aim of the present work is to introduce an analytical model to predict startup duration for steam circulation with and without EM heating. Results reveal that resistive (electrothermal) heating with/without brine injection cannot be a preferable method for mobilizing the bitumen in startup phase. Induction slightly decreases startup time at frequencies smaller than 10 kHz, and at 100 kHz it can reduce startup time to less than two months.
With the depletion of conventional oil resources, heavy oil and bitumen play an increasingly important role as the main resources for crude oil. This is particularly true in Alberta since it has in excess of 400 x 109m3 of heavy oil and bitumen. In Canada, most of heavy oil and bitumen resources are developed with thermal methods. Thermal methods for heavy oil and bitumen recovery include the injection of steam in the form of SAGD (steam assisted gravity drainage), CSS (cyclic steam stimulation), and steam flooding, whereby thermal energy is given to the oil, reduces its viscosity and allows it to flow towards a production spot. These methods have not been yet investigated for the large fraction (in excess of 50%) of oil sands that are thinner, less permeable, heterogeneous, or contacted by water. Electrothermal methods have attracted more and more attention as an alternative to conventional thermal methods for the difficult reservoirs where conventional thermal methods are not expected to work well.
In this study, a series of comparative studies are carried out using a simulation tool developed by CMG (Computer Modeling Group). In a series of marginal reservoirs such as thin reservoirs, low permeability reservoirs, and reservoirs with bottom water, both the SAGD process and the electrothermal process are applied. The resulting recoveries are compared and economics are evaluated for both methods for each case. The typical SAGD problem of the McMurray oil sands is used as the base case benchmark.
Our results to date indicate that under favorable conditions, electrothermal methods have the potential to recover thin bitumen reservoirs that cannot economically be produced by the SAGD process. Furthermore, electrothermal methods can achieve recovery factors superior to SAGD in terms of the production of thin bitumen reservoirs with bottom water and low permeability bitumen reservoirs. Controlled heating seems to be beneficial in electrothermal processes. Innovative well placement also appears to have favorable effects.
A process for converting coal to synthetic pipeline-quality gas is in the final stage of development. A large pilot plant with a daily capacity of 80 tons of coal feed and 1.5 MMcf of gas product is now in operation. Three methods of generating hydrogen from coal char are being developed and will be tested with the HYGAS process, with the goal of establishing commercial operation by 1980.
The development of the HYGAS process at the Institute of Gas Technology (IGT) has been a continuous effort since 1946. The need for pipeline-quality gas from coal to supplement pipeline-quality gas from coal to supplement a projected shortage of natural gas was long forecast by IGT and others as being inevitable in the face of a continuing 5 to 6 percent annual increase in demand for natural gas. Despite this, even recently researchers had to defend the need for coal gasification. However, in the last 2 years, the projected shortage etched an indelible mark on the consciousness of both the public and private sectors when the annual discovery rate of gas fell far short of our past additions to reserves. The "energy crunch" for natural gas is now being realized by all - so much so that the development of coal gasification processes no longer needs justification, but only processes no longer needs justification, but only immediate commercialization.
Unfortunately, an industry for converting pipeline gas from coal cannot be established at will. To comprehend the sheer magnitude of such an industry we must realize that just to supply by coal gasification the incremental annual demand of about 1 Tcf/year would require an investment of about $2 billion and the development of more than 1 billion tons of coal deposit for an annual production of 50 million tons of coal. With these factors in mind, we shall discuss the status of HYGAS process development.
Work on the HYGAS process began in 1946 and continued under the sole sponsorship of the American Gas Association (AGA) until 1964. During this period much work was done on the fundamentals of reaction kinetics, process yields, and the incorporation of several key process innovations. Experiments went from bench-scale batch studies to small continuous units at high temperatures and pressures that could handle throughputs of about 10 pressures that could handle throughputs of about 10 lb of coal feed per hour. In 1964 the U.S. Dept. of the Interior, of Office of Coal Research (OCR), joined AGA as co-sponsors in a 3-year program that ended with a preliminary design for a large HYGAS pilot plant. During this period, effort was pilot plant. During this period, effort was concentrated on the testing of different types of coal from the U.S. and on defining suitable operating conditions for each type of coal. Most of the work was done in units having, a throughput up to 100 lb of coal feed per hour. In 1967 the contract with OCR was amended to cover the engineering, construction, and operation of the HYGAS pilot plant. Out of this phase of the program will come the necessary scale-up phase of the program will come the necessary scale-up data for a demonstration plant. During, the construction phase, OCR provided the bulk of the funding. In 1971, phase, OCR provided the bulk of the funding. In 1971, the federal government and the gas industry started a joint program, administered by OCR and AGA, to accelerate the development of coal gasification through the demonstration plant stage. Funding is two-thirds by government and one-third by industry.
Process Features Process Features There are two key features in the HYGAS process that should be clearly understood.