A method and apparatus for estimating a property of a fluid downhole

(54) Title: METHOD AND APPARATUS TO ESTIMATE (57) Summary: PROPERTY OF A WELL BACKGROUND FLUID (30) Unionist Priority: 3/20/2007 us 11 / 725,620 (73) Owner (s): Baker Hughes Incorporated (72) Inventor (s): Rocco Difoggio (74) Attorney (s): Dannemann, Siemsen, Bigler & Ipanema Moreira (86) International Order: pct US2008057503 of 19/03/2008 (87) International Publication: wo 2008/115991 of 09/25/2008

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Invention Patent Descriptive Report for METHOD AND APPARATUS TO ESTIMATE THE PROPERTY OF A WELL BACKGROUND FLUID.

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to the field of the analysis of downhole fluid in hydrocarbon production wells to determine density, viscosity, and other fluid parameters for a downhole fluid in a downhole during production, monitoring during drilling or wire rope operations.

BACKGROUND

Oil and gas companies spend large sums of money to find hydrocarbon deposits. Oil companies drill exploration wells on their most promising prospects and use those exploration wells, not only to determine whether hydrocarbons are present, but also to determine the properties of these hydrocarbons, which are present.

To determine the properties of hydrocarbons, oil and gas companies often remove some hydrocarbon from the well. Wire rope forming testers can be lowered into the well for this purpose. Initially, the fluids that are removed can be highly contaminated by filtrates from the fluids (sludge) that were used during drilling. To obtain samples that are sufficiently clean (usually &lt;10% contamination) so that the sample will provide significant laboratory data regarding formation, the formation fluids are usually pumped from the well bore for 30 to 90 minutes, at the same time. that cleaning is monitored in real time. Then, these withdrawn fluids can be collected at the bottom of the well in tanks for further analysis in a laboratory on the surface.

Alternatively, for some properties, samples can be analyzed at the bottom of the well in real time. The present invention is related to the monitoring of sample cleanliness and to the execution of bottom-of-sample analysis of samples under the conditions of temperature and pressure of the reservoir. A rock bottom environment is difficult to operate a sensor. Measuring instruments in the downhole environment must operate under extreme conditions that include high temperatures, extreme vibration, and shocks and within the limited space of a pressure housing for tools.

SUMMARY

A method for estimating a property of a downhole fluid is disclosed, in which the method includes, but is not limited to, exposing the fluid to light at the bottom of the well, directing different wave sizes of light that interacted with the light of the fluid towards a first optical network, measure the light at different wavelengths reflected from the first optical network, and estimate a measured light fluid property. An apparatus for estimating a property of a downhole fluid is disclosed, wherein the apparatus includes, but is not limited to, a downhole tool for estimating a property of a downhole fluid, including, but not limited to a light source that illuminates the downhole fluid, a first optical network that has a plurality of elements that selectively illuminate the one that interacted with the fluid, and a sensor that measures the reflected light from the elements of the first optical network.

Examples of certain features of the invention have been summarized here preferably extensively so that its detailed description which follows can be better understood and so that the contributions it represents to the technique can be appreciated. There are, of course, additional features of the invention that will be described hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

For a detailed understanding of the present invention, reference can be made to the detailed description of the exemplary modality that follows, taken together with the attached figures, in which similar numbers were given for similar elements, in which:

Figure 1 is a schematic diagram of an illustrative embodiment of the present invention arranged on a steel cable in a rock bottom environment;

Figure 2 is a schematic diagram of an illustrative embodiment of the present invention arranged on a drilling column in an environment that monitors while drilling;

Figure 3 is a schematic diagram of an illustrative embodiment of the present invention arranged in a flexible pipe in a rock bottom environment;

Figure 4 is a schematic diagram of an illustrative embodiment of the present invention as arranged on a steel cable in a downhole environment showing a cross section of a forming test tool;

Figure 5 is a schematic diagram of an illustrative modality that shows a tunable optical network spectrometer (TOG) with an electromechanical micro system (MEMS).

Figure 6 is a schematic diagram of members mirrored in a TOG in an illustrative embodiment;

Figure 7 is a flow chart that illustrates the collection and analysis of spectrum for an unknown fluid in an illustrative modality;

Figure 8 is a flowchart that illustrates scanning a range of wavelengths to find spectral peaks in an illustrative modality;

Figure 9 is a representation of an apparatus for performing Hadamard spectroscopy in a particular illustrative embodiment; and

Figure 10 is a flow chart that illustrates fluids exposed to light in a downhole.

DETAILED DESCRIPTION OF THE INVENTION

Due to the uncertainties and huge expenses associated with the production of hydrocarbons for a formation, rock bottom sampling of the formations is critical to support the planning of oil companies before undertaking production. In this way, oil companies consider downhole indications about the properties of formation fluids indispensable because these downhole indications about the properties of formation fluid are extremely useful for accurately indicating the feasibility of oil production and gas from a formation's hydrocarbon production capacity. Thus, there is great public benefit provided by the illustrative modality since it helps efficient energy planning and production. For these reasons, oil companies are willing to pay significant amounts of money for estimates of downhole fluid properties, as provided by an illustrative modality.

In a particular illustrative embodiment, a method for estimating a property of a downhole fluid is disclosed, the method that includes, but is not limited to, exposing the fluid to light at the bottom of the well, reflecting different sizes of light waves who interacted with the fluid from a first optical network, measured the light at different wavelengths reflected from the first optical network, and estimated a fluid property from the measured light. In another particular illustrative embodiment of the method, the light that interacts with the fluid further comprises light selected from the group consisting of light that reflects from the fluid and light that passes through the fluid.

In another particular illustrative embodiment of the method the first optical network additionally includes, but is not limited to, a plurality of elements, the method additionally includes, but is not limited to, activating a part of a plurality of elements in the first optical network to select a range of light wavelengths reflected by the activated part.

In another particular illustrative embodiment of the method, the method additionally includes, but is not limited to, reflecting different wavelengths of light that interacted with the fluid from a second optical network that reflects a different wavelength of light for each of the elements of the first optical network. In another particular illustrative embodiment of the method includes, but is not limited to, exposing a secondary fluid to light, estimating a secondary fluid property, comparing the fluid property with the secondary fluid property and determining whether the fluid is derived from the same fluid compartment. formation than the secondary fluid.

In another particular illustrative embodiment of the method, the plurality of elements further comprises an upper line of the plurality of elements aligned over a lower line of the plurality of elements. In another particular modality illustrating the method, the lower line reflects light that is not measured by the optical sensor that measures the reflected light from the elements of the upper line.

In another particular illustrative embodiment of the method, the method additionally includes, but is not limited to, performing Hadamard spectroscopy on the light measured from the activated part of the first optical network. In another particular embodiment illustrating the method, the method additionally includes, but is not limited to, optically multiplexing the reflected light from each element of the first optical network. In another particular illustrative embodiment of the method, the first optical network additionally comprises a tunable optical filter and the elements additionally comprise mirrored members. In another particular illustrative embodiment of the method, the method additionally includes, but is not limited to, filtering the reflected light from the TOG before the reflected light is measured.

In another particular illustrative embodiment, a downhole tool is disclosed to estimate a property of a downhole fluid. In a particular illustrative embodiment, the downhole tool includes, but is not limited to, a light that illuminates the downhole fluid, a first optical network that has a plurality of elements that selectively reflect light that interacted with the fluid and a sensor that measures the reflected light from the elements of the first optical network. In another particular illustrative embodiment, the downhole tool additionally includes, but is not limited to, a network that reflects a different wavelength of light for each of the plurality of elements of the first optical network, in which when each of the plurality of elements is activated, each of the plurality of elements reflects the different wavelength of light that collides with the activated element.

In another particular illustrative embodiment of the downhole tool, the downhole tool additionally includes, but is not limited to, a circuit that selectively acts each of the plurality of elements of the first optical network to vary a light wave size reflected by the first optical network. In another particular embodiment, the downhole tool additionally includes, but is not limited to, an optical filter between the optical detector and the first optical network, in which the optical filter reduces a spectrum of light reflected from the first optical network . In another particular embodiment, the downhole tool additionally includes, but is not limited to, a filter positioned between the fluid and the first optical network that reduces the spectrum of light reflected from the fluid. In another particular embodiment, the downhole tool additionally includes, but is not limited to, a processor in data communication with the photodetector that estimates a downhole fluid property from the photodetector data, in which the processor it is configured to use the data from the photodetector and a software modeling technique to estimate the property of the fluid. In another particular embodiment, the downhole tool includes, but is not limited to, a reference fluid in optical communication with the light source and the first optical network, in which the processor is configured to estimate the property of the fluid based in a comparison with the reference fluid.

In another particular modality of the downhole tool, the elements can be, but are not limited to, a multiplicity of members or mirrored elements, in which the elements are individually selectable to reflect the light. In a particular embodiment, the elements of an upper line are selectable to reflect light to an optical sensor and the elements of a lower line do not reflect light to the optical sensor. In one aspect of the invention, a method is provided for estimating a property of a downhole fluid. The method provides exposure of the fluid to light, and reflects the light that interacted with the fluid coming out of an electromechanical micro system (MEMS) with a tunable optical network (TOG) that has a first mirrored member and a second mirrored member. In an illustrative way, for the purposes of this disclosure, reflection (or reflecting) means reflection, diffraction, and light interference. The method additionally comprises measuring the reflected light from the TOG and estimating a property of the forming fluid from the measured light. For greater overall resolution of wavelengths, the light that interacted with the fluid can first be filtered using an optical bandpass filter or other means to select only those wavelengths in a narrow range of wavelengths before projecting that pre-filtered light for the tunable network.

In another particular embodiment, the method provides variation of a distance between the first mirrored member and the second mirrored member to scan a wave size of light reflected by the TOG over a range of wave sizes. In another aspect of the invention the method provides for the exposure of a second system to light. The second system additionally provides a second TOG which has a third mirrored member and a fourth mirrored member, wherein the third mirrored member and the fourth mirrored member are substantially parallel to each other and not directly in contact with each other. The second system additionally provides a secondary formation fluid, estimates a property of the secondary formation fluid, compares the property of the formation fluid to the property of the secondary formation fluid, and determines whether the formation fluid derives from the same formation compartment as the secondary formation fluid.

In another aspect of the invention, the method provides for the modulation of the distance between the mirrored members by controlling a piezoelectric element. In another aspect of the invention, the distance between the mirrored members is controlled by the control of a micro-electromechanical device. In another aspect of the invention the wavelength range includes, but is not limited to, a wavelength hydrocarbon band. The method additionally provides for the location of at least one peak in the wavelength range and performs spectroscopic wave size modulation around a central wave size for at least one peak.

In another aspect of the invention, its method uses measured light and a software modeling technique to estimate the property of the forming fluid. In another aspect of the invention, the method provides for estimating at least one of the sets consisting of a distribution of carbon number and percentage of drilling mud contamination. In another aspect of the invention a downhole tool is provided to estimate a property of a downhole fluid that provides a light source that illuminates the downhole fluid, a TOG that has two separate mirrored members that reflect a light wave size based on a control input, a photodetector that measures light that interacted with the downhole fluid and was reflected by TOG, and a processor in data communication with the photodetector that estimates a property of the downhole fluid from the photodetector data.

In another aspect of the invention the rock bottom additionally provides a circuit that adjusts the TOG to a wave size and includes a modulator that modulates the wave size. In another aspect of the invention a control input varies a distance between the two parallel members. In another aspect of the invention the optical filter provides a piezoelectric element or a micro electromechanical device that adjusts the distance between the two parallel members. In another aspect of the invention the processor uses data from the photodetector and a piezoelectric modeling technique to estimate the property of the initial formation fluid.

In another aspect of the invention the bottom of the well additionally provides a secondary formation fluid in optical communication with the light source and the TOG, in which the processor estimates the property of the formation fluid and the comparison with the secondary formation fluid. Previously, downhole optical spectrometers can be described as photometers with near infrared filters. That is, commercial downhole optical spectrometers have positively used individual broadband optical filters that were centered on a small number of discrete wavelengths. The bandwidth for each of the optical filters was typically 20 to 30 nm although a few filters may have provided a narrower bandwidth of only 11 nm, which is close to the limit for interference filters that can be manufactured for rock bottom using current technology. Also, there was often a substantial gap in coverage wavelengths between the region of wavelengths covered by an optical filter and the region of wavelengths covered by the next optical filter so a continuous spectrum at nanometric resolution was not obtained.

An illustrative embodiment of the system, apparatus and method disclosed here provides a tunable optical network (TOG) to estimate a property of a downhole fluid. TOG can be selected from electronically tunable optical Electromechanical Micro System (MEMS) networks to collect the spectrum of downhole fluids with resolution of wavelengths in the order of one nanometer. The nanometer resolution spectrum can be used to, but not limited to, estimate or determine physical properties and composition (synthetic chromatogram), oil-based mud filtrate contamination, H concentrations₂S, and CO₂for downhole fluids. The TOG reflects light at a wave size selected by the spacing between the mirrored members in the TOG. In an illustrative embodiment, TOG's tunable wavelength range is continuous.

TOG provides high wavelength resolution on the order of 1 to 2 nm at the bottom of the well, thus providing spectroscopy with continuous nanometer resolution (NRS) of the bottom of the well. Most, if not all of the MEMS TOGs currently available are not qualified by their manufacturers for the high temperatures (up to 175 ° C or more) found at rock bottom. Thus, the present invention provides, when desired, absorption cooling or another type of cooling system to overcome temperature limitations to allow TOG operation at downhole temperatures of up to and exceeding 175 ° C.

There are numerous advantages to using continuously tunable TOGs. An advantage is that the present invention uses only a single photodetector to perform continuous downhole NRS. Using a single photodetector to collect data for all wavelengths significantly improves the quality of the spectral response and the sensitivity between members of a series of photodetectors. A single detector also offers many practical design advantages. With a non-tunable network the reflected light spectrum is spread over a defined angle. If the angle between the network and the detector is fixed, then a series of detectors such as a photodiode or CCD series can be used to collect the reflected light spectrum. An illustrative modality provides a multiplexer for low level signals that can operate at the high temperatures found at the bottom of the well.

The present invention provides continuous NRS to estimate the concentration of a gas in a mixture of gases such as a concentration of H₂S in a mixture of natural gas. The term continuous as used here means that there are no gaps in the coverage wavelengths of the reflected light spectrum. That is, the difference in central wavelengths between any two channels of neighboring wavelengths does not exceed twice the total size of half the maximum response wavelength for each channel. The present example of the invention provides a single photodetector, instead of trying to synchronize or calibrate the response of two photodetectors under rock bottom conditions. Furthermore, because the present invention can rapidly or continuously change the wavelength of the light reflected by the TOG, the present invention can also perform wavelength modulation spectroscopy (WMS) around a central wavelength (or frequency) of light. The WMS is discussed in a number of documents and texts. In one embodiment of the invention, a hydrocarbon band (1650 nm to 1850 nm) is continuously scanned and spectral peaks or other spectral characteristics located within the band. The WMS is then run for each peak located in the band.

In a particular illustrative embodiment, a tool and method provide the WMS, to obtain the first derivative of an absorption spectrum over one or more central wavelengths by modulating the TOGs' wavelengths around a central wavelength. To calculate the change in absorption for a fluid sample (instead of the absorption itself) using WMS, it is not necessary to determine how much transmitted light has entered a sample, but only how much transmitted light has changed from its average value after passing through the sample. The WMS can also be run to determine reflectance. Thus, when applying the WMS, an illustrative modality collects the spectrum with the use of a single beam instrument with as much, or better, precision than a dual beam instrument for which errors can be introduced due to differences between the two photodetectors (reference and sample) that are used commonly in dual beam instruments. The WMS is performed by modulating the distance between two mirrored members in the TOG.

By definition, the absorbance A at the wave size λ is Α (λ) = Ιο_Β,₀[Μλ) / Ι (λ)] (I) where Io is the intensity of light entering the sample and I is the intensity of light leaving the sample. If one modulates the wavelength of light from λι to some nearby wavelength, λ₂, then the change in absorbance, ΔΑ, is given by,

ΔΑ = Α &lt;λ₂&gt; -Α (λ₁) = Ιο₈₃ο [Ι₀(λ₂χϊ (λ₂)] - Ιο₈,₀Π₀(Μ / Ι (λ₁)] (2)

AA-IogíoPo ^ / loCXijHogjoPCÀ ^ / KX,)] (3)

One defines,

ΔΙ = 1 (λ₂) “Ι (λ &lt;) (4)

By modulating over a spectral region where the absorbance of the sample changes rapidly with the wave size (close to an absorbance peak), one can assume that the fractional change in incident intensity (source) with the wave size is small compared to fractional change in the intensity transmitted with the wave size. That is, we assume that Ιο (λ₂) / Ι_ο(λ₁) = 1 so that the first logarithmic term of (3) disappears. So, replacing (4) in the remaining term (3) to get,

ΔΑ - ^, ^ Κλ, ηΔΟνΚλΟ ^ -Ιοβ, οίΙ + ΔΙ / Κλ,)] (5)

Note that ΔΑ now has no dependence on the intensity of the source so it is not necessary to provide a second photodetector to obtain neither the intensity of the source nor an optical multiplexer to oscillate between source and transmitted light colliding in a single detector. This eliminates the need for a second detector (which can be difficult to accurately calibrate against the first detector, especially at extreme downhole temperatures) and reduces or eliminates the need for a multiplexer to switch between the two intensities.

Because Δλ = λ₂-λ₂, is very small, it can be assumed that Δΐ «Ι (λι). Then, defining ε, ε = ΔΙ / Ι (λ₁). (6)

Note that ΔΙ can be considered as an AC signal that is modulated by modular λ₂ around a fixed λι. Similarly, ϊ (λ-ι) can be considered with a DC signal to an λ_Ί fixed. The ratio, ε, from AC to DC is used to calculate ΔΑ. In this way, absorbance spectroscopy can be performed without having to determine reference light transmission through an empty sample cell.

Then, one can employ the expansion to the natural logarithm around the unit, ln (l + ε) ~ ε-ε²/ 2 ± ε V3-e⁴/ 4 + ... for -1 &lt;ε &lt;1 (7) and the identity, log_The(N) = log_B(N) / log_B(a) to write,

ΑΑ = - [ε-ε²/ 2 + ε³/ 3-ε⁴/ 4- + ... j / 2,303 (8)

Finally, one estimates the first derivative of the spectrum around λι, as

ΔΑ / Δλ— [ε-ε²/ + ε³/ -ε⁴/ 4-ι -...] / (2,303 Δλ) (9)

The present invention provides a nanometer resolution of a spectrometer using a TOG to allow spectral measurements of nanometric resolution to determine or estimate physical and chemical properties of a gas, which includes the percentage of oil-based mud filtrate contamination in samples of crude oil. The present invention also allows spectral measurements to determine or estimate the fraction or molar percentage of chemical groups (aromatics, olefins, saturated) in a fluid such as crude oil or gas sample. The present invention also allows the analysis of spectral measurements of nanometric resolution to determine or estimate or directly measure the oil ratio (GOP) for a fluid.

The illustrative modality provides a nanometer resolution spectrometer that incorporates a TOG to allow the spectral measurement of nanometer resolution to determine or estimate the composition of a fluid. The illustrative modality can determine or estimate other parameters of interest to a fluid, such as estimating which of the two the crude oil contains, wet gas (high methane) or dry gas (low methane), which is determined by the relative concentrations of Ci, C₂, C3, C₄. The illustrative modality provides a nanometer resolution spectrometer with the use of a TOG to allow spectral measurements of nanometer resolution to determine or estimate CO₂ in methane or CO₂ dissolved in a fluid, for example, crude oil.

The illustrative modality provides a nanometer resolution spectrometer with the use of a TOG to allow spectral measurements using the nanometer solution to provide improved correlation of spectral measurements for physical properties (API gravity, cloud point, bubble point, asphaltene precipitation pressure, etc.) or chemical properties (acid number, nickel, vanadium, sulfur, mercury, etc.) of crude oil. The illustrative modality provides a nanometer resolution spectrometer that uses a TOG to provide a nanometer resolution spectral measurement to determine or estimate fluid properties, for example, the phytane / pristane ratios of the crude oil.

The illustrative modalities provide a nanometer resolution spectrometer with the use of a TOB to allow for specific nanometer resolution measurements to determine or estimate fluid properties such as the amount of H₂S that is dissolved in the crude oil, which is commercially important because the value of a barrel of crude oil drops with increasing concentration of H₂S due to the extra costs to handle and remove the H₂S.

The illustrative modality provides a nanometric resolution TOG for spectral measurements from which a correlative equation derived from software modeling (chemometric such as multiple line regression, principal component regression, partial least square, or a neural network) can be used to infer the physical and chemical properties of sample-forming fluids or other fluids. The illustrative modality takes advantage of TOG's fast, continuous wavelength switching ability to perform derivative spectroscopy or WMS to find spectral peaks on one shoulder from another larger spectral peak or to significantly improve the signal / noise ratio and make it possible to observe subtle changes.

The illustrative modality allows the quantification of aromatics, olefins (unlikely in crude oil, but common in OBM filtrate so it can be used to quantify the percentage of filtrate), saturated, methane, ethane, propane, and butane. The illustrative modality determines or estimates the percentage of contamination of mud filtrate-bottom oil, particularly if the base oil is free of aromatics (different from crude oil), but rich in olefins (also different from crude oil) . In other embodiments, by changing the wavelength (or frequency) of the light reflected by the TOG when tuning the TOG, the present invention also performs Raman spectroscopy in combination with a single wavelength detector for light that is Raman diffused by sample.

A difficulty with the implementation of a downhole TOG spectrometer is temperature. Typically, manufacturers qualify optical tunable filters for temperatures of 80 ° C or less. The illustrative embodiment of the invention combines a TOG with a downhole absorption cooling system, when desired. The absorption cooling system cools the TOG spectrometer to help operate the TOG spectrometer at high ambient downhole temperatures. The components of the TOG and the spectrometer associated with the TOG can be placed in thermal contact with a water source (either as a liquid or as a hydrate). TOG is cooled as the water is evaporated from the liquid or released by the hydrate. The resulting water content that carries away the heat of the TOG and is absorbed by an absorbent, which heats up in the process. The absorbent transfers its excess heat to the fluid in the well bore with which it is in thermal contact. It can also be useful to determine the change in the TOG response with temperature, so that someone can correct for their temperature response if the TOG temperature has changed substantially during downhole work as it might occur if one has run out of cooling water. before the job is completed.

In an illustrative embodiment, a TOG is used to perform spectroscopic nanometric scans of the section of the hydrocarbon band that spans from approximately 1650 to 1850 nm. Other bands of wavelengths can also be scanned depending on which elements or measurements are desired when measuring transmissivity, reflectivity, and absorbance or light fluorescence response. From these TOG transmissivity, reflectivity, light fluorescence and spectral absorbance measurements, the present invention quantifies aromatics, olefins (unlikely in crude oil, but common in OBM filtrate, which therefore provides a way to estimate the percentage of filtrate contamination based on measurements of olefin), saturated, methane and possibly ethane, propane, and butane. With the TOG nanometer resolution spectroscopy, the illustrative modality determines or estimates the percentage of contamination of the well-oil-based mud filtrate (OBM) in a sample of forming fluid, particularly if the OBM contaminants are free of olefins, but rich in olefins. The illustrative modality can estimate the degree of cleaning or contamination removal from the formation fluid by monitoring an OBM property present in a fluid formation.

Furthermore, with nanometric resolution spectroscopy provided by a particular illustrative modality, the particular illustrative modality can determine or estimate subtle chemical composition differences between two fluid formations taken at different depths in a well bore. These differences can be used to estimate the compartmentalization of a reservoir, which means determining whether different sections of a reservoir are separate compartments (along which fluids do not flow) or whether they are connected to one another. Separate compartments have to be drained separately (separate wells) and may need different types of processing for your fluids.

Multibillion dollar decisions on how to develop a reservoir (well locations, types of production facilities, etc.) are based on whether a reservoir is compartmentalized or not. One way to estimate compartmentalization is based on phytane / pristane ratios of liquid crude oil or by using any other distinguishing features such as any unexpected subtle differences in the fluid spectrum that are capable of being resolved with the use of a TOG. Segregation by gravity will cause some expected spectral differences in fluids of different depths even when there is no compartmentalization. For example, the top of a column of crude oil is expected to be richer in gas than the bottom. For a path width of 2 mm, the optical absorption peaks of the dominant liquid hydrocarbon (C6 +) are close to 1725 nm, while the corresponding peak absorbent hydrocarbon gases such as methane, ethane, propane, butane, spin between 1677 nm and 1725 nm. Subtle differences in the spectrum outside the regions where these hydrocarbon gases absorb are unexpected and therefore provide evidence of compartmentalization.

In one aspect of the invention, MEMS or piezoelectric devices are arranged between a first and second mirrored members to operatively apply forces to vary a distance between the first and second mirrored members. MEMS and piezoelectric technology are well known to those skilled in the art. MEMS is a process by which micron-sized electromechanical devices are manufactured on silicon wafers using photolithography and engraving techniques. These mechanical devices are formed on integrated circuit chips so that devices that incorporate MEMS technology essentially become miniature electromechanical systems. MEMS devices are activated by analog voltages that create an electrical field that will cause MEMS devices to physically deflect since they are made of silicon and therefore respond to the electric field.

Consequently, in a particular modality a source

Processor-controlled DC is connected to MEMS or piezoelectric devices via conductors to MEMS devices preferably and by variations in the distance between the first and second mirrored members. In another particular embodiment, the distance between the first and second row of mirrored members does not vary, and individual members or elements of the mirrored member lines are switched off and on for optical multiplexing, which is discussed below. One of the advantages of using MEMS devices on a silicon integrated circuit chip is that MEMS devices are low-mass, low-energy, and low-voltage devices.

The low mass means that the MEMS device has little sensitivity to shock and vibration, which is important in wire rope applications and even more important in applications that record during drilling, where shock and vibration are even worse. The low voltage and low energy mean that one can use common printed circuit board designs and use battery power in conjunction with MEMS devices if desired. Preferably, voltages between approximately 0 and 10 volts are provided to control the desired deflection of MEMS or piezoelectric devices. These low voltages help to ensure low attenuation of cavity signals and low insertion losses. Voltages between approximately 0 and 10 volts applied also reduce polarization-dependent loss due to high signal attenuation. In addition, although the source has been described as a DC source, it will be recognized by those skilled in the art that the source may alternatively be an AC source with an appropriate rectifier circuit, or an AC source that applies power directly to MEMS devices where MEMS devices are configured to operate on AC power.

MEMS devices can be any type of micro-electromechanical actuator system operable to move uniformly and easily mirrored members of a tunable optical network. For example, swing arms, pivot points, spring-like or other resilient mechanisms, levers, moment arm, torque generating devices, and other devices that can apply the correct amount of force to mirrored members are configurable in devices Silicon MEMS and are within the scope of the present invention. In the illustrative embodiment, MEMS devices are implemented by a pair of pistons that are extensible to push evenly against the mirrored mirrors to separate the mirrored members. The MEMS device is physically connected to conductors to receive power from the power source.

The illustrative modality provides a well-bottomed instrument that can measure in real time, nanometric resolution, continuous optical spectrum of fluids, particularly over the hydrocarbon band region of the spectrum. The spectrum of nanometric resolution (ie resolution in the range of 1 to 2 nanometers) over a near-infrared hydrocarbon band (1650 to 1850 nm) contains detailed information about hydrocarbons. This information is of high commercial value for the oil industry. For example, from the hydrocarbon band region, information about the methyl (-CH₃) for methylene (-CH2) which is indicative of the average hydrocarbon chain size and information regarding concentrations of methane, ethane, propane, and so on.

This spectral region also contains information on the concentrations of aromatics, olefins, and paraffins, which can be used to quantify the percentage of oil-based mud filtrate (OBM) in a crude oil mixture. For example, for environmental benevolence, synthetic base oils for OBMs are designed to be aromatic-free, while raw oils always have some aromatics. Conversely, many synthetic sludges contain olefins or esters, which are not present in raw oils. These distinctions provide a means to quantify percentages of OBM filtrate in mixtures of filtrate with crude oil. Of course, for reliable information these subtle spectrum information are useful for having high spectral resolution (in both, wavelength and absorbance) as provided in an illustrative of a particular illustrative modality.

It is possible to estimate the size of the hydrocarbon chain from the methyl to methylene ratio by applying Fourier transform infrared spectroscopy to individual fluid inclusions greater than 15 microns in the rock using an A-590 Brucker microscope attached to a Bruker IFS 88 FTIR spectrometer (JM Dereppe, J. Pironom, C. Moreaux, American Mineralogist, v. 79, p. 712 to 718, 1994). An infrared beam, and an MCT detector, cooled with N2 liquid, allowed IR detection between 600 and 5000 cm-1 ((Barres et al., 1987). The spectrum, presented in number of absorbance units (cm-1) , were recorded in the transmission mode with a spectral resolution of 4 cm-1 after 400 accumulations. A chain size coefficient can be calculated by comparing the CH3-CH2 ratio of the sample to the same relationships measured in a standard series of n- alkane.

In an illustrative embodiment, the present invention provides a TOG to reflect a band of broadband wavelengths or white light. White light that interacted with a fluid sample is reflected from the TOG to an optical sensor. The optical sensor can include, but is not limited to, a single photodetector and amplifier which can feel reflected light from TOG. A continuous variable wavelength control is provided for TOG to allow the creation of a nanometer resolution spectrum to perform chemometric correlations to estimate the percentage of oil-based mud filtrate for the oil gas ratio and spectrally infrared synthetic chromatograms.

In an illustrative embodiment, white light is transmitted through a first window, however a formation fluid or downhole fluid, through a second window and to the TOG. TOG acts as a diffraction element. The light is detected as it is reflected by the TOG. The individual elements of the TOG can be grouped together in groups or sections. The electronic control system continuously adjusts the voltages applied to various sections of TOG elements within the selected wavelength range. In a particular illustrative modality, a photodetector is provided to detect the light that interacted with a downhole fluid and reflected by TOG. When desired, a transform, such as a Hadamard transform, can be used to recover a spectrum for reflected light. The application of the Hadamard transform is discussed below in connection with figure 9.

Spectral peaks can be identified in the reflected light collected from the optical spectra of the scanned wave size band. TOG can oscillate around a single wavelength matching a central wavelength for one or each of the spectral peaks for derivative spectroscopy. Derivative spectroscopy reduces the effects of displacement and reference artifacts. The reduction of displacements and artifacts facilitates the maintenance of robust chemometric predictions of fluid properties based on spectra for the fluid. The WMS can also be executed with the use of optical multiplexing or selective activation of the TOG or elements of the optical network to selectively reflect different sizes of light waves from the elements or sections of activated TOG elements, as discussed below with figure 9, by optically multiplexing two close by frequencies reflected by two adjacent elements or neighboring elements in the TOG that are alternately turned on and off to alternately reflect different nearby wavelengths of fluid light.

A particular illustrative modality provides a piezoelectric controlled TOG or MEMS that is suitable for downhole use in part because the TOG is small, light and temperature resistant. In a particular illustrative embodiment, TOG is resistant to rock bottom shock and vibration because it can be a low-mass device manufactured in an electronic semiconductor device or piezoelectric material. In another particular illustrative modality, TOG is also physically small so that it can be easily retrofitted into an existing downhole tool with minimal reengineering for floor space, energy, light or control. In another illustrative modality, TOG can potentially withstand temperatures up to 175 ° C or more, which makes it suitable to withstand high temperatures for downhole use. In another illustrative embodiment, absorption can be added to reinforce TOG's ability to withstand downhole temperatures.

In another illustrative modality, TOG also has no macroscopically moving parts. The wave size reflected by the TOG is controlled by the microscope movement that varies the distance between two mirrored members. Thus, in an illustrative modality, TOG is durable and robust, and thus suitable for the use of downhole.

In another particular illustrative embodiment, white light is alternatively directed through an unknown fluid sample and a reference chamber that contains a reference compound that has a known optical spectrum. White light can also be reflected by the unknown fluid sample to collect reflectance spectra for the fluid sample. Spectra are collected for the unknown fluid and the reference fluid. The spectrum of the reference fluid is compared and correlated with the spectrum of the unknown fluid sample. Thus, by comparing and correlating the spectrum of the unknown fluid with the spectrum of the reference fluid over wavelength regions where the spectrum matrix of the unknown fluid does not interfere with the spectrum of the reference compound, the concentration of the reference compound in the unknown fluid matrix can be estimated.

For example, if the reference fluid contains one hundred parts per million (PPM) of a particular component (for example, H₂S) and the unknown fluid has a spectrum that looks the same, but that has twice the absorbance at each wavelength without interference, so the unknown fluid can be estimated to contain two hundred PPM H₂S.

Now changing to figure 1, figure 1 is a schematic diagram of an illustrative embodiment of the tool arranged in a well hole 18 in a steel cable in an illustrative environment. As shown in Figure 1, a downhole tool 10 contains a downhole MEMS nanometer resolution spectrometer 410 is disposed in a well hole 14. Well hole 18 is formed in formation 16. Tool 10 is arranged through a steel cable 12. The tool data can be transmitted to the surface to a computer processor 20 with memory within an intelligent transaction system 30.

Figure 2 is a schematic diagram of another illustrative modality of the tool that has a nanometer resolution spectrometer

MEMS arranged in a drill column 15 in an environment that monitors while drilling. Figure 3 is a schematic diagram of another illustrative modality that has a MEMS nanometer resolution spectrometer arranged in a flexible pipe 13 in a rock bottom environment. Sampling and analysis by the nanometer resolution spectrometer

MEMS 410 can be run at varying depths if arranged from a steel cable 12, drill string 15, or flexible tubing 13.

Figure 4 is a schematic diagram of an illustrative embodiment of the present invention as arranged in a borehole 18 in a steel cable in a borehole environment showing a cross section of a steel cable forming test tool. 10. As shown in figure 4, tool 10 is arranged in a well hole 14 filled with well hole fluid 434. Tool 10 is positioned in well hole 18 by support arms with reserve 416. A snorkel tube 418 with conditioner contacts the hole wall of well 432 to extract formation fluid from formation 414. In an illustrative embodiment, tool 10 contains a well-bottom MEMS nanometer resolution spectrometer 410 that contains the TOG arranged inside or next to flow line 426. Electronic control and acquisition (350 as shown in figure 5) that includes a processor, memory and databases shown in figure 6 are housed in tool 10. The pump 412 pumps the forming fluid from the formation 414 into the flow line 426. In the illustrative embodiment the fluid moves through the flow line 426 and into the valve 420 which directs the forming fluid to the line 422 to save the fluid in a sample tank or to line 428 where the forming fluid exits to the well bore.

Now changing to figure 5, another illustrative modality of the tool is illustrated. As shown in figure 5, a light source 201 provides light 202 to collimate lenses 203. Collimated white light 204 is transmitted through a first window 303, through a forming fluid or downhole fluid 341, through a second window 302 and for TOG 250. The tunable network acts as a diffraction element.

The reflected light 233 is detected by the optical detector 230 as it is reflected by the TOG 250. The electronic mirror spacing control 350 sweeps and wavelength of the TOG 250 over a selected band of frequencies and wavelengths. A photodetector 230 and an ordered blocking filter 232 are used to detect the light reflected by the TOG 250. A transform, for example, a Hadamard-type transform can be used to recover a spectrum or spectra for the fluid from the detected light. The electrical energy is provided by the 351 energy source, which can be a battery.

To collect a spectrum more quickly, the entire tunable optical MEMS network, which consists of a multiplicity of mirrored members, can be subdivided into a hundred or more regions or sets of mirrored members, each of which is then operated as if it were a network. separate dedicated to a single wave size. Then, each set of separate network elements can either project or not project its dedicated light wave size onto the spectrometer's photodetector. Each separate network can then be considered as an alloy filter for its dedicated wavelength.

This configuration acts as an optical multiplexer that allows projection of more than one wave size (for example, 50 wave sizes) or more than one wave size band, simultaneously for a single optical sensor, such as a photodetector and then rotates sequentially through several predetermined patterns of projected wavelengths. A mathematical transform (Hadamard) can then be used to process the photosensor response data for each pattern to determine the amount of light it may have detected at each individual wavelength. This approach also allows you to mimic the absorption spectrum of a reference sample (for example, H₂S) projecting all wavelengths except those wavelengths in which the sample can absorb light.

In another particular embodiment, a set of light diverters, for example, mirrors 343, 344, 345, and 347, can be used to redirect light 204 through reference sample 342. Diverter 347 can be rotated so that at position shown, mirror 347 reflects light 204 from light diverter 345 and intercepts light from sample 341. Light 204 reflected from mirror 343 to mirror 344 through reference sample 342 to mirror 345 where it is reflected from mirror 347 within light path 204 to impact the TOG 250.

The rear side 346 of mirror 347 intercepts light that passes through the sample 341, when in the position shown in figure 5 and reflects the light that passes through the reference sample. When mirror 347 is rotated from the position shown to the position shown by the drawn line 15 348, the light from sample 341 is not intercepted and passes to reach TOG 250 and the light from reference sample 342 is not reflected to TOG 250

The rotation of the mirror 347 is controlled positively by a motor controlled by electronics 350. Thus, the illustrative mode allows the comparison of the spectra for the reference sample 342 with the spectra for the reference sample 341. The spectra for the reference sample 342 can be obtained on the surface and compared to the spectra for the reference sample obtained at the bottom of the well to recalibrate the TOG spectrometer for measurements at the bottom temperature.

Now changing to figure 6, in another particular illustrative embodiment, TOG 250 comprises a multiplicity of mirrored members or elements aligned along lines 254 and 256, which can include a line or set of lower network elements or mirrors 254 and a line or set of lower network elements or 256 mirrors on a MEMS 258 semiconductor chip. The two lines or sets of elements or mirrored elements 254, 256 can each be divided into smaller sets or regions. The smallest subset of a line of elements can be an individual element or a member of a line. Each minor element, subset or region can be controlled independently to reflect or not reflect light. A piezoelectric device can be incorporated within the MEMS chip. A feedback loop 266 can be provided between optical detector 230 and electronic control of spacing and mirror region 350.

The electronic mirror spacing control 350 may include a processor 630, memory 632 and database 634 to store a computer program for execution by the processor. The computer program can contain instructions for finding peaks within a hydrocarbon band and performing derivative spectroscopy around a central wave size for each of the peaks. The spacing 255 or distance between the upper mirrored members 256 and the lower 254 determines the wavelength of the light reflected by the TOG 250 to the optical detector 230 through the ordered blocking filter 232.

Changing now to figure 7, a flowchart 700 is shown in which, in an illustrative embodiment of a method and apparatus, spectra are collected for an unknown downhole fluid in block 702. The spectra are then collected for a sample of fluid from downhole reference in block 704. The collected reference fluid spectra and unknown fluid spectra are collected and compared in block 706. The composition for the unknown fluid is estimated at block 708 and the process ends.

Now changing to figure 8, a flow chart 800 is shown in which in another illustrative embodiment a wavelength range is continuously (which is outside an interruption in the spectral coverage) swept over a hydrocarbon band in block 802 for an unknown fluid . In one embodiment, the process finds spectral peaks and subpeaks (on the shoulders of larger peaks) in the hydrocarbon band in block 804. The wavelength modulation spectroscopy is performed for each peak and subpeak and the derivative spectra estimated in block 806. The composition of the unknown fluid is estimated from the spectrum in block 808 and the process ends.

Spectral peaks can be identified in the hydrocarbon band of the scanned wave sizes by mirrored limb spacing control and 350 electronic data acquisition. Derivative spectrometry can be performed centered around a single wave size matching a wave size single center for one or each of the spectral peaks. Derivative spectroscopy reduces the effects of displacement and reference artifacts. The reduction of displacements and artifacts facilitates the maintenance of robust chemometric predictions of fluid properties based on the spectra for the fluid.

Now changing to figure 9, in a particular illustrative modality, a network such as TOG 250 comprises a multiplicity of members or mirrored elements aligned along an upper line 256 and lower line 254. In another particular illustrative mode the network is not tunable, but has selectable elements to reflect and not reflect light from the members spread from the upper line. Thus, the network can be used for optical multiplexing, however, the distance between the upper element line and the lower element line for the network is not adjustable (that is, tunable), so the optical network is referred to as an optical network. selectable (SOG) instead of as a TOG. Mirrored TOG members that may include, but are not limited to, a lower set or row of elements or members such as network mirrors 254 and an upper set of network mirrors 256 on a MEMS 258 semiconductor chip. Each member or element mirrored 251, 253, 257, 259, 261 and 263 of the set or upper row of mirrored members 256 can each be switched on and off independently. Each mirrored member reflects incident light that strikes the mirrored member when the mirrored member is turned on and does not reflect incident light when the mirrored member is turned off. In another illustrative embodiment, each element independent of the lower and upper row of mirror members 254, 256 can be individually turned on or off. The selectable on and off state for each mirrored member or member of the SOG or TOG is controlled by the electronic member control 350. A piezoelectric device can be incorporated within the MEMS 258 semiconductor chip. A feedback loop 266 can be provided between optical detector 230 and electronic control of spacing and mirror members 350. The electronic limb control 350 may include a 630 processor, memory 632 and database 634 to store a computer program for execution by the processor. The computer program can contain instructions for finding peaks within a hydrocarbon band and performing derivative spectroscopy around a central wave size for each of the peaks. Each of the mirrored members or elements can be turned on or off to determine the wavelength or frequency band or wavelengths of light reflected by the TOG 250 for the optical detector 230. Elements can also be separated into groups for control at the group level to reflect not reflect as a selectable element group. In another particular illustrative embodiment, the reflected light from the TOG passes through the ordered blocking filter 232.

In another particular illustrative embodiment, a white light source provides white light 202 that passes through the sample 341. The light that passes through the sample is directed to a fixed network 206 that divides the light 204 that has passed through the sample into multiple frequencies or frequency bands (or wavelength bands) fi af_n 281, 283, 285 and 287. The fixed network directs a different frequency or different frequency band of light to each of the members or elements in mirrored lines 254 and 256. Similarly, the light that was reflected by the sample can be divided into multiple frequencies or multiple frequency bands (or wavelength bands) fi af_n 281, 283, 285 and 287.

Then a single frequency or single frequency band can be selected for incident light reflection by striking a particular mirrored member or element by tuning in the mirrored member at which the only incident light frequency collides. In a particular embodiment, the incident light angle 204 on the two lines of members or mirrored elements is such that the light is reflected only from the upper line 256 and not from the lower line 254. Then each of the members mirrored in line 256 can be individually linked in a frequency or frequency band reflected by each of the members or elements mirrored in line 256 one at a time to oil light from the reflected from the only element that is switched on. Then, by directing a single frequency or frequency band to individual mirrored members and connecting the mirrored members one at a time, the light from the sample can be optically multiplexed in this way to perform a Hadamard spectroscopy to find spectral peaks to perform analysis of the sample 202.

In another illustrative embodiment, the spacing 255 or distance between the upper mirrored members 256 and the lower 254 can be controlled by the electronic limb control that changes the frequency of the light reflected by the upper line 256 and the lower line 254 of mirrored members.

Now changing to figure 10, a flowchart 1000 is shown in which in another illustrative embodiment a fluid is exposed to light at the bottom of the well in block 1002. Different sizes of light waves that interacted with a fluid a fluid light are directed in towards a first optical network in block 1004. Light measured at different wavelengths is reflected from a first optical network in block 1006. The fluid's property is estimated from the light measured in block 1008. The light is selected from a group consisting of light that reflects from the fluid and light that passes through the fluid in block 1010. A part of the plurality of elements is activated in the first optical network to select a range of light wave sizes reflected by the activated part in block 1012. Different wavelengths that interact with the fluid are reflected for each of the elements of the first optical network 1012. In another illustrative embodiment a secondary fluid is exposed to light in block 1014. The property of the secondary fluid is estimated in block 1016. The property of the fluid is compared to the property of the second fluid in block 1018. It is determined whether the fluid is derived from it formation compartment than the secondary fluid in block 1020. In another illustrative embodiment a plurality of elements includes an upper line of element alignment above a lower line of elements in block 1022. A lower row of elements does not reflect light from the first optical network in block 1024. In another illustrative embodiment a Hadamard spectroscopy is performed on the light measured from the activated part of the first optical network in block 1026. The reflected light from each element of the first optical network is optically multiplexed in block 1028. The first optical network includes tunable optical filter and elements that include mirrored members in block 1030. The reflected light from the filtered TOG before the reflected light be measured in block 1032.

Since the foregoing disclosure is directed to illustrative embodiments of the invention, various modifications will become apparent to those skilled in the art. It is understood that all variations within the scope of the appended claims are understood by the foregoing disclosure. The examples of the most important features of the invention have been summarized preferably in general lines so that its detailed description which follows can be better understood, and so that the contributions to the technique can be appreciated.