Temperature reservoir

While the long chain hydrocarbons (above 18 carbon atoms) may exist in solution at reservoir temperature and pressure, they can solidify at the lower temperatures and pressures experienced in surface facilities, or even in the tubing. The fraction of the longer chain hydrocarbons in the crude oil are therefore of particular interest to process engineers, who will typically require a detailed laboratory analysis of the crude oil oomposition, extending to the measurement of the fraction of molecules as long as C3Q. 

For both volatile oil and blaok oil the initial reservoir temperature is below the critical point, and the fluid is therefore a liquid in the reservoir. As the pressure drops the bubble point is eventually reached, and the first bubble of gas is released from the liquid. The composition of this gas will be made up of the more volatile components of the mixture. Both volatile oils and black oils will liberate gas in the separators, whose conditions of pressure and temperature are well inside the two-phase envelope. 

The above equation is valid at low pressures where the assumptions hold. However, at typical reservoir temperatures and pressures, the assumptions are no longer valid, and the behaviour of hydrocarbon reservoir gases deviate from the ideal gas law. In practice, it is convenient to represent the behaviour of these real gases by introducing a correction factor known as the gas deviation factor, (also called the dimensionless compressibility factor, or z-factor) into the ideal gas law ... 

The previous equation is only valid as long as there is no compositional change of the gas between the subsurface and the surface. The value of E is typically in the order of 200, in other words the gas expands by a factor of around 200 from subsurface to surface conditions. The actual value of course depends upon both the gas composition and the reservoir temperature and pressure. Standard conditions of temperature and pressure are commonly defined as 60°F (298K) and one atmosphere (14.7 psia or 101.3 kPa), but may vary from location to location, and between gas sales contracts. 

Formation water density is a function of its salinity (which ranges from 0 to 300,000 ppm), amount of dissolved gas, and the reservoir temperature and pressure. As pressure increases, so does water density, though the compressibility is small... 

Miscible fluid displacement is a process in which a fluid, which is miscible with oil at reservoir temperature and pressure conditions, is injected into a reservoir to displace oil. The miscible fluid (an oil-soluble gas or liquid) allows trapped oil to dissolve in it, and the oil is therefore mobilised. 

Natural gas Hquids (NGL) a Hquid hydrocarbon mixture which is gaseous at reservoir temperatures and pressures, but recoverable by condensation or absorption (qv). 

One method of assuring that hydrates do not form is to assure that the amount of water vapor in the gas is always less than the amount required to fully saturate the gas. Topically, but not always, the gas will be saturated with water in the reservoir. As the gas is cooled from reservoir temperature, the amount of water vapor contained in the gas will decrease. That is, water will condense. 

Associated gas is natural gas found in contact with oil accumulations in the same reservoir. This gas may be dissolved in the oil under reservoir temperatures and pressure (solution gas) or may form a cap of free gas above the oil in the reservoir (gas cap gas). 

Consider a process shown in Figure 2.14 in which a quantity of heat q2 flows from a high temperature reservoir T2 into a reversible cyclic engine. Part of the heat is converted into work ir while the remainder q flows into a low temperature reservoir. The efficiency of this process is defined asqq r) = -w/q2, and it is a function of the reservoir temperatures. The relationship can be derived as follows ... 

Subsequent studies and applications with ether carboxylates have been published [73]. Phase inversion temperature measurements, which can be used to select surfactants for enhanced oil recovery, showed good results when the phase inversion temperature of the system was just below the reservoir temperature [184]. 

Results described in the literature have resulted in several patents, such as one for the improvement of the transport of viscous crude oil by microemulsions based on ether carboxylates [195], or combination with ether sulfate and nonionics [196], or several anionics, amphoterics, and nonionics [197] increased oil recovery with ether carboxylates and ethersulfonates [198] increased inversion temperature of the emulsion above the reservoir temperature by ether carboxylates [199], or systems based on ether carboxylate and sulfonate [200] or polyglucosylsorbitol fatty acid ester [201] and eventually cosolvents which are not susceptible for temperature changes. Ether carboxylates also show an improvement when used in a C02 drive process [202] or at recovery by steam flooding [203]. 

During the development of these criteria the Semenov analysis was extended to systems with heat-exchanger reservoir temperatures different from feed temperatures (Tr < Tq) and with delayed runaway (larger value of e), which resulted In significant concentration drift prior to runaway. Since values of e for chain-addition polymerizations are not nearly as small as those for the gaseous explosions Investigated by Semenov, R-A Is not as sensitive nor Is It as early In terms of extent of reaction. 

T) OIL AND WATER ZONE NEAR ORIGINAL RESERVOIR TEMPERATURE HOT WATER ZONE... 

The flow is induced in the following way. External forces are applied on the particles of each reservoir In order to ke p the average y velocities of the reservoirs constant. The Imposed motion of the reservoirs shears the liquid slab. The work supplied In order to keep the reservoirs moving eventually Is dissipated and heats up the liquid. In order to remove this extra heat from the system the velocities of the reservoir molecules are scaled at each time step so as to keep the average reservoir temperatures constant. The Imposed shear rate Is obviously... 

Fig. 2.19. Reservoir temperature versus saturation indices (logQ/K) for calcite, anhydrite, K-feldspar and K-mica based on the estimated composition of reservoir fluid (Seki, 1991). Estimation based on gas results of Seki (1990), with saturation calculations carried out by PECS (Takeno, 1988). Gas concentrations were assumed to be 1 wt% of CO2 and 250 mg/kg for H2S for all wells (Seki, 1991).

Fig. 2.28. Plot of logarithm of activity product (log Q) versu.s reservoir temperature. Solid circles stand for activity products of Ca + and in geothermal fluids, and open circles for Ca + and CO. Small and...

Several surfactants were studied in ambient-pressure foam tests, including alcohol ethoxylates, alcohol ethoxysulfates, alcohol ethoxyethylsulfonates, and alcohol ethoxyglycerylsuUbnates [210]. Surfactants that performed well in the 1-atm foaming experiment were also good foaming agents in site cell and core flood experiments performed in the presence of CO2 and reservoir fluids under realistic reservoir temperature and pressure conditions. 

I. R. Collins. Scale inhibition at high reservoir temperatures. In Proceedings Volume. IBC Tech Serv Ltd Advances in Solving Oilfield Scaling Int Conf (Aberdeen, Scotland, 11/20-11/21), 1995. 

For this study flow (dynamic) and static (batch) tests were carried out on Wilmington oil field unconsolidated sands at reservoir temperatures and flow rates with polyacrylamide (Dow Pusher-500) polymers. Effluent concentration, viscosity, and pH were monitored as a function of time. Extensive characterization studies for the sand were also carried out. 

Static(batch) and dynamic(flow) tests were carried out on toluene - extracted and peroxide - treated Wilmington oil field unconsolidated sands with dilute solutions of polyacrylamide (Dow Pusher-500) polymer in 1 wt% NaCl at 50° C and 1.5 ft./day, simulating reservoir temperature and flow rates. In the static tests, Ottawa sand, with particle size distributions similar to the Wilmington sand, were also used for comparison purposes. 

Oils The n-alkane series Cg-C, toluene and cyclohexane were purchased from BDH, Poole, UK, each with a stated purity of 99% reagents were used as received. Crude oil samples were obtained from two North Sea fields one located in the Norwegian sector and the other from the UK sector. Stock tank oil from the Gullfaks field was supplied by Statoil, Norway and the other stock tank oil from an undisclosed source. Both crude oils are derived from sandstone formations with reservoir temperatures of 70° and 101°C respectively. 

By the addition of other liquid reservoirs, e.g. for water and crude oils, and replacement of the capillary test unit by a sand pack, the effectiveness of the same foams for enhanced oil recovery at reservoir temperatures and pressures will be investigated. 

Specified concentrations of TFSA were injected into sample bottles containing 0.1 dm3 of the untreated crude oil emulsion. The sample bottles were then capped, vigorously shaken and heated to the approx>riate reservoir temperature. The volume percentage of the total water phase which separates from the oil, the clarity of... 

McDaniel, B.W. "Realistic Fracture Conductivities of Proppants as a Function of Reservoir Temperature," SPE/DOE paper 16453, 1987 SPE/DOE Low Permeability Reservoirs Symposium, Denver, May 18-19. 

Air is fed from a reservoir through a converging nozzle into a 1 /2 in. ID drawn steel tube that is 15 ft long. The flow in the tube is adiabatic, and the reservoir temperature and pressure are 70°F and lOOpsia. 

Fig. 30.1. Volumes of minerals precipitated during a reaction model simulating the mixing at reservoir temperature of seawater into formation fluids from the Miller, Forties, and Amethyst oil fields in the North Sea. The reservoir temperatures and compositions of the formation fluids are given in Table 30.1. The initial extent of the system in each case is 1 kg of solvent water. Not shown for the Amethyst results are small volumes of strontianite, barite, and dolomite that form during mixing.

Fig. 30.2. Saturation states (Q/K) of supersaturated sulfate minerals over the courses of simulations in which seawater mixes at reservoir temperature with formation fluids from three North Sea oil fields. Reaction paths are the same as shown in Figure 30.1, except that minerals are not allowed to precipitate.

In contrast, wells with low predicted reservoir temperature declines like SK5D and SK6D yielded higher actual values in 8 years of utilization. The actual temperature decline observed for SK5D and SK6D are 12°C and 9°C, respectively, but the maximum predicted temperature decline is about 1°C in both wells. The faster decline rates observed for these two... 

Carnot efficiency is one of the cornerstones of thermodynamics. This concept was derived by Carnot from the impossibility of a perpetuum mobile of the second kind [ 1]. It was used by Clausius to define the most basic state function of thermodynamics, namely the entropy [2]. The Carnot cycle deals with the extraction, during one full cycle, of an amount of work W from an amount of heat Q, flowing from a hot reservoir (temperature Ti) into a cold reservoir (temperature T2 < T ). The efficiency r] for doing so obeys the following inequality ... 

One of the main applications of hydrogen and oxygen isotope thermometry in geochemistry is the estimation of the reservoir temperatures of active geothermal systems or the evaluation of the ruling T conditions during deposition or alter-... 

Assessment of membrane damage was based on performance testing before and after chemical exposure. Testing was conducted in a small flat plate reverse osmosis unit designed to accommodate membrane discs of 45 mm diameter. Feed solution reservoir temperature was maintained at 25 1°C and the brine was continuously recirculated through a filter at the rate of 600 mL/min. Concentration polarization is considered negligible in this cell under these conditions. 

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