Cyclic steam

The system was operated cyclically. Steam was supplied to a process reactor to start an exothermic chemical reaction. Once the reaction began, cooling water was supplied to maintain process temperature. Cooling water at 200°F (93°C) entered the retiurn header after exiting the process reactor. 

Enhanced oil-recovery processes include chemical and gas floods, steam, combustion, and electric heating. Gas floods, including immiscible and miscible processes, are usually defined by injected fluids (carbon dioxide, flue gas, nitrogen, or hydrocarbon). Steam projects involve cyclic steam (huff and puff) or steam drive. Combustion technologies can be subdivided into those that autoignite and those that require a heat source at injectors [521]. 

TFSA molecules have been extensively and successfully used as steam additives in cyclic steam operations(27-32). Recently, results of a TFSA-waterflood which was conducted in West Texas were reported(33). The purpose of the work described in this paper was to further evaluate the feasibility of recovering incremental oil in a mature waterflood by injection of surfactants which change the wettability of reservoir rock surfaces. In this paper, we present the results of laboratory studies with Thin Film Spreading Agents and the results of a carefully conducted TFSA-waterflood pilot in the Torrance Field located in the Los Angeles Basin of California. 

Oil-well cements, 5 493, 500t, 502 U.S. shipments, 5 498t Oil wells, cyclic steam stimulation of, 73 619... 

There are numerous in-situ recovery methods that include steam injection, the most common ones being cyclic steam... 

Ober AG, Santa Maria I, Carmi JD. 1987. Organochlorine pesticide residues in animal feed by cyclic steam distillation. Bull Environ Contam Toxicol 38 404-408. 

To date (ca 1997), steam methods have been applied almost exclusively in relatively thick reservoirs containing viscous crude oils. In the case of heavy oil fields and tar sand deposits, the cyclic steam injection technique has been employed with some success. The technique involves the injection of steam at greater than fracturing pressure, usually in the 10.3—11.0 MPa (1500—1600 psi) range, followed by a soak period, after which production is commenced (15). 

Cyclic steams injection the alternating injection of steam and production of oil with condensed steam from the same well or wells. 

Cooke, R.W. Eson, R.L. Field Results of Optimizing the Steam Foam Diversion Process in Cyclic Steam Applications in Proc., SPE International Thermal Operations Symposium, Society of Petroleum Engineers Richardson, TX, 1991, SPE paper 21531. 

UNMIXED REFORMING A NOVEL AUTOTHERMAL CYCLIC STEAM REFORMING PROCESS... 

To enhance the heating value of the gas product, a cyclic steam-air process was developed in 1873. This process produced water gas, composed chiefly of carbon monoxide and hydrogen, which had a higher heat value (12,000-13,000 kJ/m3) compared with the producer gas. Furthermore, by adding oil to the reactor, the heating value was enhanced (to 19,000-20,500kJ/m3). This type of fuel gas, carbureted water gas, became the standard for gas distributed to residences and industry in the U.S. until the 1940s. 

Catalysts CPS (Mettallated and Cyclic) steaming. Test Conditions Davison Circulating Riser, Reactor Temperature 521° C, Full Bum Regenerator, Countrymark feed. 

The two main thermal recovery processes are steam injection and in situ combustion. In the steam injection process, steam of 80% quality is injected into the reservoir to displace oil. The steam can be injected continuously (called steam drive ) or intermittently (called cyclic steam injection ). In the steam drive process, steam is injected in several injection wells and the oil is produced in several production well. In cyclic injection process, steam is injected in several (previously producing) wells for 2-6 weeks, soaked for 3-7 days, and produced back for a few weeks or months. This cycle can be repeated several times. Often, the steam flood is preceded by cyclic injection. Steam injection has been used commercially for several decades. In fire flooding or in situ combustion process, air is injected and ignited inside the reservoir. A combustion front... 

Steam-based processes in heavy oil reservoirs that are not stabilized by gravity have poor vertical and areal conformance, because gases are more mobile within the pore space than liquids, and steam tends to override or channel through oil in a formation. The steam-foam process, which consists of adding surfactant with or without noncondensible gas to the injected steam, was developed to improve the sweep efficiency of steam drive and cyclic steam processes. The foam-forming components that are injected with the steam stabilize the liquid lamellae and cause some of the steam to exist as a discontinuous phase. The steam mobility (gas relative permeability) is thereby reduced, and the result is in an increased pressure gradient in the steam-swept region, to divert steam to the unheated interval and displace the heated oil better. This chapter discusses the laboratory and field considerations that affect the efficient application of foam. 

Cyclic Steam. The idea of using foams in cyclic-steam operations to control injection profiles is well understood and has been demonstrated in the field (next section). However, the role of a foaming surfactant dur-... 

For cyclic steam-foam injection, it is important that the foam breaks down in the presence of oil or after prolonged exposure to high temperature. In this way, the resistance to the flow of production fluid will not be substantially increased. A concern with a cyclic foam injection process is that the low mobility foam will displace oil further (as compared to steam-only injection) from the well during the injection portion of the cycle. The oil will then have a greater distance to flow to the well during production. Thus, initial water cuts may actually increase in cyclic steam-foam tests (26). The oil recovery may also be low initially but then increase to a level higher than that obtained from a steam-only cycle. 

One of the concerns regarding solids production during primary production from heavy oil reservoirs is the impact it may have on subsequent secondary or tertiary recovery. Chalaturnyk et al. (103) commented that subsequent thermal operations on wells that have produced a lot of solids will benefit from easier injection of steam. They thus maintain that cyclic steam processes and steam drive will be more manageable under such circumstances. However, both Chalaturnyk et al. 

These stem from the early attempts of thermodynamicists to study the steam engine. For a steady-running or cyclical steam engine, Eq. 4.4a reduces to... 

Temperature studies were also conducted during the process of oil well steaming in the Zybza field. In order to obtain maximum effectiveness of cyclic steaming, it was necessary to raise the temperature of the petroliferous formation in the well-bottom zone to 120-130°C. The attainment of best results in the earlier identiffed range from 30 to 120°C of formation temperature was found to be a uniform rule. This behavior can be explained by sharp changes that occur in the properties of petroleum within the temperature range of 30-120°C. For example, the decrease in viscosity and changes in elastic properties of oil both take place at that time. 

Beginning in 1965, studies were undertaken at Zybza field on cyclic steaming of near bottomhole zones of old wells. In general, this steam treatment proved highly effective. However, in some of the wells, especially those strongly invaded by reservoir water, the results were disappointing. 

Fig. 14. Dependence of oil yield on the degree of water invasion of the reservoir during cyclic steaming.

Thus, experiments proved that even at water-saturation levels as high as 75%, cyclic steaming can still produce maximum oil yields from the bed model. In this case, however, the temperature of the bed must be raised substantially. Highest oil recoveries were observed at the temperature of 2(X)°C. 

In conducting stimulation treatment of near bottomhole zone by cyclic steaming, a number of parameters must be determined (a) the oil recovery factor obtained from that zone after a single cycle treatment (b) the ultimate oil recovery factor for the treated zone (c) optimal number of effective steam cycles for the particular oil well. 

The above-described laboratory studies of reservoir stimulation by cyclic steaming conducted at different temperatures of the bed model showed a strong dependence of oil recovery on the temperature of the steam-treated zone. Thus, at the formation temperature of 12S°C, after seven cycles of steaming the oil recovery was 60.3% of oil in place at 150°C, 68.5% and at 200°C, 77.0% (see Table 10). 

The distribution of the residual oil along the bed in the zone of steam penetration must be known in order to effectively cairy out cyclic steam treatment of the near bottomhole zone. For this purpose after the completion of the above experiments, and while the bed model was being dismantled, samples of porous medium were removed from the model and placed in a special instrument, the LP-4, used for extraction of liquids from porous media. The oil distribution data obtained during the extraction are shown in Table 11 and on Figure 17. 

Three principal variants of steam treatment are (a) cyclical steam injection (steam soak or "huff and puff ) (b) steam circulation technique and (c) area steam injection (steam flooding) (see Fig. 18). 

The basic steps followed in cyclic steaming by this technique are as follows ... 

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