Fluid properties measurements

Accuracy. All fluids properties measured were within 1%. The volumes injected and produced were in agreement within 0.1%. The reproducibility of the core floods was between 0.002-8%. 

Viscosity Expressed in centipoises it is a fluid property measuring how much a fluid in a pip>e drags along the walls. 

Using UNIQUAQ for fluid property measurement, the Aspen Plus process flow sheet and stream table compositions is shown in Figure 8.39. 

The fluid properties of formation water may be looked up on correlation charts, as may most of the properties of oil and gas so far discussed. Many of these correlations are also available as computer programmes. It is always worth checking the range of applicability of the correlations, which are often based on empirical measurements and are grouped into fluid types (e.g. California light gases). 

Keywords d rec methods, indirect methods, rock properties, coring, core barrel, standard core analysis, special core analysis, slabbed core, sidewall samples, direct indications, microfossils, sonde, logging unit, invasion, mudcake, formation pressure measurement, fluid sampling, measurement while drilling, formation evaluation while drilling. 

Reservoir engineers describe the relationship between the volume of fluids produced, the compressibility of the fluids and the reservoir pressure using material balance techniques. This approach treats the reservoir system like a tank, filled with oil, water, gas, and reservoir rock in the appropriate volumes, but without regard to the distribution of the fluids (i.e. the detailed movement of fluids inside the system). Material balance uses the PVT properties of the fluids described in Section 5.2.6, and accounts for the variations of fluid properties with pressure. The technique is firstly useful in predicting how reservoir pressure will respond to production. Secondly, material balance can be used to reduce uncertainty in volumetries by measuring reservoir pressure and cumulative production during the producing phase of the field life. An example of the simplest material balance equation for an oil reservoir above the bubble point will be shown In the next section. 

A number of considerations should be evaluated before a flow measurement method can be selected for any appHcation. These considerations can be divided into four general classifications fluid properties ambient environment measurement requirements and economics. 

Vegetable and seed oils as well as some synthetic base stocks present a new class of biodegradable base stocks. These fluids (10) have excellent biodegradation properties as measured by criteria developed by the Environmental Protection Agency (EPA) or Organization of Economic Cooperation and Development (OECD). OECD 301 and EPA 560/6-82-003 measure the biodegradation of lubricants. These tests were developed to measure the degradation of oil, especially two-cycle ok, on waterways. Aquatic toxicity criteria toward fish is also found to be acceptable for this class of fluids as measured by EPA 560/6-82-002 and OECD 203 1-12. 

Mass-Transfer Coefficient Denoted by /c, K, and so on, the mass-transfer coefficient is the ratio of the flux to a concentration (or composition) difference. These coefficients generally represent rates of transfer that are much greater than those that occur by diffusion alone, as a result of convection or turbulence at the interface where mass transfer occurs. There exist several principles that relate that coefficient to the diffusivity and other fluid properties and to the intensity of motion and geometry. Examples that are outlined later are the film theoiy, the surface renewal theoiy, and the penetration the-oiy, all of which pertain to ideahzed cases. For many situations of practical interest like investigating the flow inside tubes and over flat surfaces as well as measuring external flowthrough banks of tubes, in fixed beds of particles, and the like, correlations have been developed that follow the same forms as the above theories. Examples of these are provided in the subsequent section on mass-transfer coefficient correlations. 

Note in Eq. (18-112) that Vg is the settling rate under Ig, and it is a function of the particle size and density and fluid properties. The ratio ( /2Vg is then related only to the operating speed and geometry of the centrifuge, as well as to the size recoveiy. It measures the required... 

Determine the heat transfer eoeffieient from a eoil immersed in an agitated vessel with a diameter of 10 ft (3.048 m). The agitator is a paddle measuring 3.5 ft (1.01 m) in diameter and revolving at 200 rev/min. The fluid properties are ... 

The hot-wire anemometer sensor is a very fine wire with a diameter of few micrometers and length of few millimeters. This wire is connected to a measurement bridge and an electrical current is fed through the wire. The wire is heated to a temperature above the air temperature and the air velocity is determined by the cooling effect of the wire. The voltage over the wire, U, is a function not only of the velocity but also of the excess temperature and the fluid properties in the following way ... 

In each case the physical properties of the fluid are measured at the mean film temperature T f, taken as the average of the surface temperature Tw and the mean fluid temperature... 

Historically, viscosity measurements have been the single most important method to characterize fluids in petroleum-producing applications. Whereas the ability to measure a fluid s resistance to flow has been available in the laboratory for a long time, a need to measure the fluid properties at the well site has prompted the development of more portable and less sophisticated viscosity-measuring devices [1395]. These instruments must be durable and simple enough to be used by persons with a wide range of technical skills. As a result, the Marsh funnel and the Fann concentric cylinder, both variable-speed viscometers, have found wide use. In some instances, the Brookfield viscometer has also been used. 

Accurate interpretation of the formation properties (porosity, permeability and irreducible water saturation) requires reliable estimates of NMR fluid properties or the relationship between diffusivity and relaxation time. Estimation of oil viscosity and solution-gas content require their correlation with NMR measurable fluid properties. These include the hydrogen index, bulk fluid relaxation time and bulk fluid diffusivity [8]. 

The fluid properties and porosity and permeability are determined independently. Boundary and initial conditions are specified for the particular experiment to be considered. With specified multiphase flow functions, the state equations, Eqs. (4.1.28, 4.1.5 and 4.1.6), can be solved for the transient pressure and saturation distributions, p (z,t) and s,(z,t), t= 1, 2. The values for F can then be calculated, which correspond to the measured data Y. 

For the local process especially the borehole resistance is important. The borehole resistance depends mainly on the loop type and material, loop dimensions, circulation fluid properties, temperature of the process, borehole engineering (Hellstrom, 1991). Furthermore the far field temperature in the ground and geothermal gradient needs to be measured. 

It is obvious from Equation 14.14 that the most important parameter determining the volumetric air flow rate <2W is the intrinsic permeability K of soil. At this point it is important to stress the difference between water permeability (or hydraulic conductivity) k , air permeability ka, and intrinsic permeability K. In most cases, when permeability data are provided for a type of soil or geological formation, these data are based on hydraulic conductivity measurements and describe how easily the water can flow through this formation. However, the flow characteristic of a fluid depends greatly on its properties, e.g., density p and viscosity p. Equation 14.16 describes the relationship between permeability coefficient k and fluid properties p and p ... 

The viscosity of a fluid is an important property in the analysis of liquid behavior and fluid motion near solid boundaries. Viscosity is the fluid resistance to shear or flow and is a measure of the adhesive/cohesive or frictional fluid property. The resistance is caused by intermolecular friction exerted when layers of fluids attempt to slide by one another. 

When the measured values of shear stress or viscosity are plotted versus shear rate, various types of behavior may be observed depending upon the fluid properties, as shown in Figs. 3-5 and 3-6. It should be noted that the shear stress and shear rate can both be either positive or negative, depending upon the direction of motion or the applied force, the reference frame, etc. (however, by our convention they are always the same sign). Because the viscosity must always be positive, the shear rate (or shear stress) argument in... 

Actually measures kc PlfLDp, thus including some fluid properties as well, t See Table XIV for details. 

It is important to note that the small-scale agitator operations may be described in terms of impeller diameter and agitator speed, while manufacturing process equipment is more conveniently specified by horsepower and fluid velocity. For most standard turbine configurations, power number correlations are available to convert impeller diameter and agitator speed into a horsepower value for given fluid properties. Most laboratory bench equipment is designed to provide a torque measurement that can be readily converted to horsepower directly from the conditions of the pilot batches. 

This second method does not lend itself to the development of quantitative correlations which are based solely on true physical properties of the fluids and which, therefore, can be measured in the laboratory. The prediction of heat transfer coefficients for a new suspension, for example, might require pilot-plant-scale turbulent-flow viscosity measurements, which could just as easily be extended to include experimental measurement of the desired heat transfer coefficient directly. These remarks may best be summarized by saying that both types of measurements would have been desirable in some of the research work, in order to compare the results. For a significant number of suspensions (four) this has been done by Miller (M13), who found no difference between laboratory viscosities measured with a rotational viscometer and those obtained from turbulent-flow pressure-drop measurements, assuming, for suspensions, the validity of the conventional friction-factor—Reynolds-number plot.11 It is accordingly concluded here that use of either type of measurement is satisfactory use of a viscometer such as that described by Orr (05) is recommended on the basis that fundamental fluid properties are more readily determined under laminar-flow conditions, and a means is provided whereby heat transfer characteristics of a new suspension may be predicted without pilot-plant-scale studies. 

The over-all problem of measurement of fluid properties can be subdivided into four categories ... 

The Prandtl number is a fluid property that provides a nondimensional measure of a fluid s ability to diffuse momentum compared to heat. By definition,... 

Htitz, U., Englezos, P., Measurement of Structure H Hydrate Phase Equilbrium and Effect of Electrolytes, in Proc. 7th International Conference on Fluid Properties and Phase Equilibria for Chemical Process Design (1995). 

The thickness of the liquid film on the rotor packing helps determine mass transfer rates. Film thickness can be shown to be inversely proportional to rotor speed to the 0.8 power (17). Visual measurements using a video camera attached to the rotor show a water film thickness of 20-80 microns on foam metal packing and 10 microns on wire gauze packing (15). Theoretical models estimate similar film thickness values (13,18,19). Film flow is expected to be laminar. In addition to rotor speed, liquid flow rate and fluid properties affect the film thickness (14). 

Since liquid does not completely wet the packing and since film thickness varies with radial position, classical film-flow theory does not explain liquid flow behavior, nor does it predict liquid holdup (30). Electrical resistance measurements have been used for liquid holdup, assuming liquid flows as rivulets in the radial direction with little or no axial and transverse movement. These data can then be empirically fit to film-flow, pore-flow, or droplet-flow models (14,19). The real flow behavior is likely a complex combination of these different flow models, that is, a function of the packing used, the operating parameters, and fluid properties. Incorporating calculations for wetted surface area with the film-flow model allows prediction of liquid holdup within 20% of experimental values (18). 

Once low temperatures have been attained and cryogens have been produced, property measurements must often be made at these temperatures. Such measurements as temperature and pressure are typically required for process optimization and control. In addition, as cryogenic fluids... 

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