OF A FLUID

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of priority to Canadian Patent Application No. 2,989,018 filed on December 15, 2017, and to Canadian Patent Application No. 3,018,398 filed on September 24, 2018, the contents of both applications being incorporated herein by reference.

TECHNICAL FIELD

[0002] The following relates to systems and methods for improving water cut measurement accuracy of a fluid, for example by adjusting the differential of properties of the water and oil phases of the fluid, and reducing the magnitude of the contribution of the electric double layer of the fluid to the total electrical permittivity of the fluid.

BACKGROUND

[0003] Heavy oil such as bitumen is recovered using what are considered non- conventional methods. For example, bitumen reservoirs are typically extracted from a geographical area using either surface mining techniques, where overburden is removed to access the underlying pay (e.g., oil sand ore-containing bitumen) and transported to an extraction facility; or using in situ techniques, wherein subsurface formations (containing the pay), e.g., oil sands, are heated such that the bitumen is caused to flow into one or more wells drilled into the pay while leaving formation rock in the reservoir in place. Both surface mining and in situ processes produce a bitumen product that can be subsequently sent to an upgrading and refining facility, to be refined into one or more petroleum products, such as diesel and gasoline.

[0004] Bitumen reservoirs that are too deep to feasibly permit bitumen recovery by mining techniques are typically accessed by drilling wellbores into the hydrocarbon bearing formation (i.e., the pay) and implementing an in situ technology. Certain in situ technologies such as Steam Assisted Gravity Drainage (SAGD) or Cyclic Steam Stimulation (CSS) are deployed to produce fluids that typically include gas, water, and bitumen.

[0005] Water cut meters are used to determine the ratio of water produced compared to the volume of total liquids produced. In bitumen reservoirs this includes determining the ratio of water compared to the total produced fluid comprising bitumen and water. Typically, the water and the bitumen are produced in an oil-in-water emulsion. However, a water-in-oil emulsion can also be produced. Water cut meters typically operate in part by distinguishing the water phase from the bitumen phase of the produced fluid on the basis of a property such as electrical resistivity or conductivity, gamma ray absorption, capacitance. However, the composition of the water phase has been known to affect these measurements, such that water cut measurements of the fluid produced from one location are sometimes found to be more accurate than compared to those of fluid produced from other locations.

SUMMARY

[0006] The ability to differentiate between the water and oil (e.g., bitumen) phases in a produced fluid or emulsion can affect the accuracy and reliability of water cut measurements. It has been found that increasing the measurable difference (i.e., the“differential”) between a property of the water and oil, and/or reducing a magnitude of a dielectric constant or real component of the electrical permittivity of an electric double layer of the fluid or emulsion, can facilitate the ability to differentiate between them. For example, the salinity of the water phase has been found to impact readings of the electrical resistivity/conductivity and/or gamma ray absorption or attenuation of the water and oil phases, as well as reducing the magnitude of the dielectric constant or real component of the electrical permittivity of the electric double layer of an emulsion (also referred to below as reducing the magnitude of the electrical permittivity for brevity). As such, in emulsions produced from reservoirs having low water salinity, the water and oil phases of the emulsion both have high (or at least similar) electrical resistivity. This can lead to less accurate and less reliable water cut

measurements that rely on measuring electrical resistivity compared to emulsions or produced fluid from reservoirs that have high water salinity, with the water phase having a lower electrical resistivity compared to the oil phase. A similar principle can apply to water cut meters that measure gamma ray absorption or attenuation, wherein the gamma ray absorption or attenuation can likewise increase with increased salinity, or other properties of the water.

[0007] To improve the accuracy of water cut measurements, a system and method is provided in which an element that increases the differential of one or more properties of the water and oil phases of a produced fluid or emulsion is added upstream of a water cut meter, to increase an ability to differentiate between the water phase and the oil phase in the produced fluid or emulsion when measuring that property.

[0008] In one aspect there is provided a method for measuring a ratio of water to oil in a fluid, comprising: adding an element to the fluid upstream of a water cut meter to increase a differential of a property of the water and oil; providing a sample of the fluid with the added element to the water cut meter; and measuring the ratio of water to oil in the fluid with the added element using the water cut meter. [0009] In another aspect, there is provided a system for improving water cut

measurement accuracy in measuring a ratio of water to oil in a fluid, comprising: a device for adding an element to the fluid upstream of a water cut meter to increase a differential of a property of the water and oil for samples of the fluid with the added element that are provided to the water cut meter.

[0010] In an implementation, the element that is added adjusts an electrical property of the water phase (e.g. , electrical resistivity/permittivity), and can comprise a salt such as sodium chloride, calcium chloride, zinc chloride, potassium phosphate, magnesium chloride, etc. The salt can be injected upstream of the water cut meter as a saline solution or by adding the salt or other element on its own to be dissolved in the water phase. The salt also causes a reduction in the magnitude of the electrical permittivity of an electric double layer exhibited by bitumen-water emulsions. Specifically, the real component or dielectric constant of the electric double layer is reduced such that the total dielectric constant for the emulsion is made up predominantly of the bitumen and water phases, allowing capacitance- based water cut meters to more accurately resolve the water cut of the emulsion. In another implementation, the element that is added adjusts the differential in gamma ray absorption or attenuation between the water and oil phases. In yet another implementation, the element that adjusts one of the above-mentioned properties of the water phase comprises a deliquescent material such as a base (e.g., sodium hydroxide or potassium hydroxide), , that is capable of readily mixing with the produced water. In yet another implementation, a hydrophobic element can be added to the oil to adjust the differential of one of the above- mentioned properties between the water and oil phases of the produced fluid or emulsion.

[0011] Advantages of the systems and methods described herein are that increasing the differential of a property of the water and oil phases of a produced emulsion or fluid, and reducing the magnitude of the electrical permittivity of the electric double layer, can enable more accurate determination of the water cut based on the increased ability to differentiate between the water and oil phases based on readings of that property. The system can be deployed upstream of the water cut meter in various configurations, including configurations that utilize a multi-phase flow meter capable of performing a water cut measurement, configurations in which a separator is used with a water cut meter positioned on one of the outlet branches of the separator, configurations that utilize either slipstream (real-time) or periodic sampling, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Embodiments will now be described with reference to the appended drawings wherein:

[0013] FIG. 1 is a chart showing a ternary diagram illustrating a range in operating liquid cuts for a multi-phase flow meter in a first reservoir;

[0014] FIG. 2 is a chart showing a ternary diagram for a multi-phase flow meter in a second reservoir;

[0015] FIGS. 3A and 3B are charts showing water-in-oil emulsions at different water contents, and identifying theoretical and actual measured results of the real and imaginary components of electrical permittivity;

[0016] FIG. 4 is a block diagram illustrating a system for adjusting the differential of a property of the water and oil phases in a produced fluid or emulsion for samples provided to a water cut meter;

[0017] FIG. 5 is a block diagram illustrating a system for adding an element upstream of a multi-phase flowmeter to adjust the property differential of the water and oil phases in a produced fluid or emulsion for samples provided to the multi-phase flowmeter;

[0018] FIG. 6A is a block diagram illustrating a system for adding an element upstream of a test separator to adjust the property differential of the water and oil phases in a produced fluid or emulsion for samples provided to a water cut meter downstream of the test separator;

[0019] FIG. 6B is a block diagram illustrating a system for adding an element upstream of a water cut meter and downstream of a test separator, to adjust the property differential of the water and oil phases in a produced fluid or emulsion for samples provided to the water cut meter;

[0020] FIG. 7 is a block diagram illustrating a system for adding salty wastewater upstream of a multi-phase flowmeter to adjust an electrical property of the water phase in a produced fluid or emulsion for samples provided to the multi-phase flowmeter;

[0021] FIG. 8 is a flow chart illustrating a method for measuring a water/hydrocarbon ratio in a produced fluid or emulsion in which a property differential of the water and oil phases has been adjusted upstream of a water cut meter;

[0022] FIG. 9 is a chart comparing water cut measurements by a first type of water cut meter to physical samples at the first reservoir; [0023] FIG. 10 is a chart comparing water cut measurements by a second type of water cut meter to physical samples at the first reservoir;

[0024] FIG. 1 1 is a chart comparing water cut measurements by the first type of water cut meter to physical samples at the second reservoir;

[0025] FIG. 12 is a chart comparing water cut measurements by the second type of water cut meter to physical samples at the second reservoir; and

[0026] FIG. 13 is a chart illustrating the electrical resistivity differences created by differences in total dissolved solids in the first and second reservoirs.

DETAILED DESCRIPTION

[0027] The ability to differentiate between the water and oil (e.g., bitumen) phases in a produced fluid or emulsion can affect the accuracy and reliability of water cut measurements. Increasing the measurable difference (i.e., the“differential”) between a property of the water and oil, and reducing the magnitude of the electrical permittivity of the electric double layer can facilitate the ability to differentiate between them. For example, the property being measured in an attempt to differentiate the water and oil phases of a produced fluid can be an electrical property, e.g., resistivity or permittivity or the gamma ray absorption of the water, and therefore can adversely impact its ability to be differentiated from the oil. The impact of a difference in gamma ray absorption on water cut meter accuracy for a particular type of measurement apparatus used in two different bitumen reservoirs, is illustrated in FIGS. 1 and 2. While the following examples may refer to bitumen, particularly in connection with examples and data taken from bitumen reservoirs, it can be appreciated that the following principles can equally be applied to other types of produced oil and water.

[0028] FIG. 1 shows a ternary diagram for one type of a multi-phase flowmeter at the first reservoir that measures linear attenuation of the gamma rays being measured by the flowmeter in two dimensions. There are three vertices on this diagram, one identifying the proportion of gas, one identifying the proportion of oil, and one identifying the proportion of water. The estimated flow split is identified in FIG. 1 as an“operating point” that is plotted on the ternary diagram relative to the other points. The ratios of water, oil, and gas and therefore the water cut can be estimated by the proximity of the operating point to the different vertices on the triangle defined by the ternary diagram.

[0029] In FIG. 1 , the length of the triangle between the oil and water vertices is very short when compared to that between gas and water or gas and oil. This is because the gamma ray absorption capacities of the bitumen and water are very similar. As a result, the flowmeter in this example has a difficult time differentiating between the bitumen and the water. This principle applies to both water cuts determined using a multi-phase flowmeter such as that producing the operating triangle in FIG. 1 , and to water cuts determined by water cut meters such as those used downstream of a test separator wherein the gas phase has been removed from the emulsion.

[0030] In contrast, as illustrated in FIG. 2, the ternary diagram of a multi-phase flowmeter used at a second reservoir has a relatively larger difference between the oil and water vertices in the triangle that is defined by the ternary diagram. This illustrates that the differential in the property of the water and oil being measured from that second reservoir is observably higher than that at the first reservoir shown in FIG. 1. Since a multi-phase flowmeter allows for“remote” measurements without the need to separate the phases, enabling the water and oil readings to be more distinguishable from each other contributes to the accuracy of the flowmeter’s results. This increased ability to differentiate between the water and oil phases allows for more accurate water cut measurements using the flowmeter at the second reservoir than the first reservoir (i.e. , per FIG. 1).

[0031] It has been recognized that the differences in water cut measurement accuracies relate, at least partially, to the contrast between one or more physical properties (e.g. , electrical resistivity/permittivity, and/or gamma ray absorption or other properties) of the water and bitumen being relatively higher at the second reservoir (FIG. 2) than at the first reservoir (FIG. 1). The contrast between the physical properties in the example shown in FIGS. 1 and 2 was found to be significantly caused by the difference in the salinity of the produced water. That is, since the salinity of the water at the second reservoir is much higher than the salinity of the water at the first reservoir, the physical contrast between the water and bitumen at the second reservoir is higher than at the first reservoir, leading to more accurate water cut measurements.

[0032] It has also been found that the higher salinity of the water at the second reservoir (that is, the higher the physical contrast between the water and bitumen at the second reservoir) also causes a reduction in the magnitude of the electrical permittivity of an electric double layer exhibited by bitumen-water emulsions, allowing capacitance-based water cut meters to more accurately resolve the water cut of the emulsion.

[0033] Bitumen reserves, such as in the Alberta oil sands, have been found to be composed of up to 40% polar compounds, namely resins in asphaltenes. Since these polar compound are charged, they tend to form strong bitumen-water emulsions, and an electric double layer forms at each bitumen-water interface. As a result, each bitumen bubble in the bitumen-water emulsion has a positive charge in the fluid layer surrounding the bubble. These positive charges cause the bitumen bubbles to repel each other, causing the emulsion to be stable. These electric double layers are also found to act like capacitors, and thus have a dielectric constant that could be potentially large and unknown because of the large area of the bitumen-water interface and the electrical properties of the interface. As a result, the total dielectric constant for the emulsion is made up of three phases, namely the water, the bitumen, and the unknown and potentially large dielectric impact from the electric double layer.

[0034] Because of this additional potentially large and unknown component to the dielectric constant that is contributed by the electric double layer, it can be difficult for water cut meters, particularly microwave-based meters measuring capacitance, to be able to differentiate between the bitumen and the water. The addition of salt as herein described, is found to begin destroying the electric double layer, which greatly reduces the magnitude of the capacitance of the electric double layer and thus eliminates some of the“noise” encountered by the water cut meters. In this way, the dielectric constant of the emulsion is more dictated by the proportions contributed by the bitumen and the water, rather than the noise caused by the electric double layer. This reduction can allow capacitance-based water cut meters to more accurately resolve the water cut of bitumen-water emulsions that it encounters. The dielectric constant of the electric double layer can be reduced by the electric double layer being compressed and by the emulsion becoming less stable, reducing the number of bubbles of bitumen in the water phase, which will reduce the surface area of the bitumen-water interface.

[0035] FIGS. 3A and 3B provide plots that show the difference between theoretical results 6a/6b and measured results 8a/8b. It is postulated that in this example, the interaction between polar compounds in the bitumen and water create an electric double layer as discussed above, which accounts for a significant portion of the difference between the theoretical results 6a/6b and measured results 8a/8b.

[0036] In the example shown in FIGS. 1 and 2, the higher the salinity of the water phase, the higher the gamma ray absorption, which contrasts with the relatively lower gamma ray absorption of the bitumen. For water cut meters that measure electrical

resistivity/permittivity, such a difference in salinity creates a variation in electrical resistivity, and as noted above, reduces the magnitude of the electrical permittivity of the electric double layer. At low salinities, water and bitumen are both very insulating, with a higher dielectric constant or real component of the electrical permittivity being contributed by the electric double layer, and hence it is more difficult to distinguish water and bitumen from each other, in turn making it more difficult to obtain accurate water cut measurements. As such, in fluids and emulsions produced from reservoirs having low water salinity, the water and bitumen phases of the fluid or emulsion both have high resistivity, which can lead to less accurate and less reliable water cut measurements compared to fluids or emulsions from reservoirs that have high water salinity with the water phase of the fluid or emulsion having a lower resistivity compared to the bitumen phase. Generally speaking, salinity levels can affect one or more properties of the water and bitumen such that adjusting the salinity level of the water can increase the differential of the one or more properties of the water and the bitumen, and reduce the magnitude of the capacitance or real component of the electrical permittivity of the electric double layer.

[0037] To improve the accuracy of water cut measurements, a system and method are proposed in which an element that adjusts the differential of one or more properties of the water and bitumen phases of a produced fluid or emulsion, and reduces the magnitude of the dielectric constant or real component of the electrical permittivity of the electric double layer, is added upstream of a water cut meter to increase the ability to differentiate between the water phase and the oil phase. In one implementation, the element that is added adjusts a property of the water phase (e.g., electrical resistivity/permittivity and/or gamma ray absorption), and can comprise a salt such as sodium chloride, calcium chloride, zinc chloride, potassium phosphate, magnesium chloride, etc. The salt can be added upstream of the water cut meter as a saline solution comprising salt or by adding the salt on its own to be dissolved in the water phase. The salt thus added can reduce the electrical resistivity of the water phase in the fluid or emulsion samples, and reduce the magnitude of the dielectric constant or real component of the electrical permittivity of the electric double layer, to enable better differentiation of the water and bitumen.

[0038] In another implementation, the element that adjusts an electrical property of the water phase includes a deliquescent material such as a base (e.g., sodium hydroxide or potassium hydroxide) that is capable of readily mixing with the water phase. It can be appreciated that such adjusting can also be done by adding or removing an element that increases the differential of a particular physical property of the water and the bitumen. For example, a hydrophobic element can be added to the bitumen to adjust the differential of the electrical property or gamma ray absorption property, between the water and oil phases of the produced fluid or emulsion. In general, the element that adjusts the property can include various oil soluble, water soluble or very short half-life radioactive compounds. [0039] FIG. 4 schematically illustrates a system in which samples of a produced fluid or emulsion provided to a water cut meter 10 are adjusted 16 upstream 12 of the water cut meter 10, such that the samples being tested (and if applicable anything output downstream 14 of the water cut meter 10) have been altered by that adjustment. As discussed above, the adjustment at 16 increases the differential in at least one property of the water and the bitumen that is provided to the water cut meter 10, and can reduce the magnitude of the dielectric constant or real component of the electrical permittivity of the electric double layer.

[0040] One example is shown in FIG. 5 for a system having a multi-phase flowmeter 20 that performs a water cut measurement in real-time via a“slipstream” configuration as is known in the art. In this example, an element 22 is added upstream 12 of the multi-phase flowmeter 20 such that in an emulsion or fluid containing a gas phase, a water phase and a bitumen phase, the water phase is altered (as indicated by Water+ in the figure) to increase the differential of at least one property of the Water+ and the bitumen. In the above example, this can include adding a salt to adjust an electrical property of the water phase (e.g. , to adjust the electrical resistivity/permittivity and/or gamma ray absorption properties). The salt can be added as a solid to be dissolved in the water phase of the emulsion. The salt can also be added by way of a saline solution, e.g., a solution with a dissolved salt such as sodium chloride to more easily increase the salinity of the water phase. Other sources of the salt can also be used, such as salty wastewater, which may contain other components.

It can be appreciated that other elements 22 could be added. For example, an element 22 that changes an electrical property of the water phase can include a deliquescent material such as a base (e.g., sodium hydroxide or potassium hydroxide), that is capable of readily mixing with the produced water.

[0041] FIGS. 6A and 6B illustrate the addition of an element 20 upstream of a water cut meter 10 that is not a multi-phase flowmeter 20. For example, where a multi-phase flowmeter 20 is not used, a test separator 30 can be used to separate the gas phase from the water and bitumen phases. The gas phase may then be measured by a gas meter 34 and the water and bitumen phases measured by the stand-alone water cut meter 10. In the example shown in FIG. 6A, the element 22 is added upstream 12 of the test separator 30 and in turn upstream 12 of the water cut meter 10. In the example shown in FIG. 6B, the element 22 is added downstream of the test separator 30 but upstream 12 of the water cut meter 10. As illustrated, in either configuration this provides that the adjusted Water+ is included in the samples measured by the water cut meter 10. [0042] FIG. 7 provides an example in which the electrical resistivity of the water phase is reduced by repurposing salty water 40 from a wastewater source 42 that would normally be disposed of in the field. In this way, the system can efficiently reuse an element or solution that already includes the properties desired, in this case a high salinity fluid in order to mix with the water phase in the fluid or emulsion.

[0043] An example of a method for adjusting the differential of a property of the water and bitumen in a produced fluid or emulsion is shown in FIG. 8. In this example, an element is being added upstream 12 of the water cut meter 10 and at step 50 the element to be added is obtained. At step 52 the differential of the property of the water and the bitumen is adjusted by adding the element upstream 12 of the water cut meter 10, e.g., to increase the salinity of the water phase and reduce its electrical resistivity relative to the bitumen. An emulsion or fluid sample is introduced to the water cut meter 10 at step 54 and the water/bitumen ratio, i.e. the water cut is measured at step 56. Because of the differential of the property has been adjusted at step 52, the measurements performed at step 56 should be more accurate and more reliable. It can be appreciated that prior to performing the method, the particular reservoir can be tested to determine whether or not such a differential needs to be adjusted and, if so, determine a suitable amount of adjustment that would be required. For example, the salinity of the water phase can be measured against reservoirs in which good differentiation between the water and bitumen phases has been observed at a particular reservoir.

[0044] To demonstrate the effect similarities in physical properties between the water and bitumen phases can have on water cut measurement accuracy, the charts in FIGS. 9 to 13 can be observed. FIG. 9 includes a solid line with a 1 : 1 slope to visualize a match between the meter water cut measurements and the Dean Stark water cut results measured in the lab using physical samples. The diamond-shaped points in FIG. 9 represent data from lab measurements of water cuts compared against water cuts estimated from a meter. The cloud of points in FIG. 9 illustrates that the correlation between water cuts measured by the one type of multi-phase flowmeter 20 used at the first reservoir (see also FIG. 1) and actual physical samples measured by the Dean Stark analysis is weak. A similar comparison of water cut measurements taken by another type of multi-phase flowmeter 20 at the same reservoir also shows a very low correlation as shown in FIG. 10. Namely, the cloud of diamond points in FIG. 10 do not correlate well with the solid line representing a perfect correlation. [0045] As discussed above, water cuts taken at the second reservoir (see also FIG. 2) were found to be more accurate for both of the types of multi-phase flowmeters 20 as shown in FIGS. 1 1 and 12. In FIG. 1 1 , the trace line represents metered data comparing the water cut percentage over time. The“X” markings represent lab measurements performed using a Dean Stark analysis. A comparison between the X markings and the trace lines

demonstrates the improved correlation between the multi-phase flowmeter measurements and the lab results. Similarly, in FIG. 12, the trace line and the dots show a good correlation between the multi-phase flowmeter measurements and the lab results. FIG. 12 is similar to FIG. 1 1 but from the second type of multi-phase flowmeter, thus demonstrating that the differential of the electrical or gamma ray absorption property can increase the accuracy of both types of multi-phase flow meters used in collecting this data. In FIG. 12, P1 and P2 represent different wells at the reservoir associated with the test data.

[0046] FIG. 13 illustrates how rapidly electrical resistivity can change with salinity when salinity becomes small. Here it can be observed that at low salinity levels, the water becomes very resistive, like oil. Also, consistent with the above discussion, FIG. 13 demonstrates that the salinity differences created by differences in total dissolved solids (TDS) in the produced water between the first and second reservoirs creates a difference of about ten (10) in electrical resistivity. It may be noted that salinity measures the amount of salts dissolved in water while TDS measures all material dissolved in water that is less than 2 microns in size. In clean water most particles are ions or salts, but can also include some organic molecules. In clean, non-contaminated water, salinity and TDS are typically found to be similar. To account for such differences, the presently described system and method that adjusts the differential of a property of the water and bitumen phases upstream 12 of a water cut meter 10 can be used. For example, by introducing a salt (e.g. in a saline solution) or by repurposing salty wastewater 40, water cut measurement accuracy can be improved using existing water cut apparatus and production equipment.

[0047] In general, determining the amount of the element that is sufficient to achieve water cut measurement reliability can be performed in comparison to a laboratory analysis of corresponding water samples. This can be achieved by calibrating an amount of the element to be added by comparing one or more preliminary water cut measurements to one or more laboratory water cut analyses of corresponding fluid or emulsion samples. The approach used can be implemented by first determining how much concentration of salt or other material was needed to make a property of the oil sufficiently different from that of the water, and can sufficiently reduce the magnitude of the dielectric constant or real component of the electrical permittivity of the electric double layer, so that a water cut meter could accurately differentiate between the water and oil. This could be done for example through laboratory tests or looking at fields where water cut metering is accurate. A laboratory analysis of the impact of salt in the electrical permittivity can be conducted to better understand the impact of salt on reducing the dielectric constant of the electric double layer. This type of analysis would be done without a water cut meter. Once this analysis is completed, to estimate the preferred or optimal substance and amount of that substance to reduce the impact of the electric double layer, another test can be done to see how the levels of salt affect errors in the actual water cut measurements. Once a concentration is determined, the concentration needed to be added at a producing well can be calculated by mass balance using the salinity of the produced water, the total fluid flow rate of the a producer, and the injection rate of the liquid injected upstream of the water cut meter that contains the salt or other element. The accuracy of the methodology can be tested periodically as is normally done with water cut meters, by taking physical samples and comparing the Dean Stark water saturation against that measured by the water cut meter.

[0048] In this way, the element can be added upstream of the water cut meter in an amount sufficient to achieve a water cut measurement that is consistent with the one or more laboratory water cut analyses.

[0049] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the examples described herein. However, it will be understood by those of ordinary skill in the art that the examples described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the examples described herein. Also, the description is not to be considered as limiting the scope of the examples described herein.

[0050] It will be appreciated that the examples and corresponding diagrams used herein are for illustrative purposes only. Different configurations and terminology can be used without departing from the principles expressed herein. For instance, components and modules can be added, deleted, modified, or arranged with differing connections without departing from these principles.

[0051] The steps or operations in the flow charts and diagrams described herein are just for example. There may be many variations to these steps or operations without departing from the principles discussed above. For instance, the steps may be performed in a differing order, or steps may be added, deleted, or modified. [0052] Although the above principles have been described with reference to certain specific examples, various modifications thereof will be apparent to those skilled in the art as outlined in the appended claims.