Polymer tracers loaded with fluorescent dyes for drilling depth determination

Abstract

A method of performing surface logging of a well includes adding each of a plurality of polymeric tracers to a circulating drilling fluid in a certain order of addition while drilling the well. Each polymeric tracer includes a polymer and a corresponding fluorescent dye having an emission wavelength or an excitation wavelength that is different from an emission wavelength or an excitation wavelength of each other fluorescent dye. The method includes collecting a sample of drill cuttings carried by the drilling fluid while drilling the well, where the sample of drill cuttings includes polymeric tracers adhered to the drill cuttings. The method includes extracting the dyes in the sample of drill cuttings into an extraction solution; determining an indication of a type and a concentration of each of the dyes in the extraction solution; and determining a depth associated with the sample of drill cuttings based on the indication of the concentration of each of the dyes and the order of addition.

Description

[0001] Priority Statement

[0002] This application claims priority to U.S. Patent Application No. 17 / 001,467, filed August 24, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0003] Surface logging (also known as mud logging) creates a detailed record (logging profile) of the borehole by examining the cuttings carried to the surface by the circulating drilling fluid (most commonly drilling mud). Surface logging provides owners and producers with valuable information about the lithology and fluid content of the borehole at the time of drilling. In some cases, foam or compressed air is used instead of mud as the circulating drilling fluid. Summary of the Invention

[0004] In one aspect, a method for surface logging of a well includes adding each of a plurality of polymeric tracers in a predetermined order to a circulating drilling fluid during drilling of the well. Each polymeric tracer comprises a polymer and a corresponding fluorescent dye, and each fluorescent dye has an emission wavelength, an excitation wavelength, or both, different from the emission wavelength of each of the other fluorescent dyes. The method includes collecting drill cuttings samples carried by the drilling fluid during drilling in the presence of the drilling fluid, wherein the drill cuttings samples include polymeric tracers attached to the drill cuttings. The method includes extracting the dyes from the drill cuttings samples into an extraction solution; determining an indication of the type and concentration of each of the dyes in the extraction solution; and determining the depth associated with the drill cuttings sample based on the indication of the concentration of each of the dyes and the order of addition.

[0005] An embodiment may include one or any combination of two or more of the following features.

[0006] Each polymer tracer includes polymer nanoparticles.

[0007] The method includes determining an indication of the type and concentration of each of these fluorescent dyes in the extraction solution based on the excitation spectrum of the extraction solution, the emission spectrum of the extraction solution, or both.

[0008] Indications for determining the type and concentration of each of these fluorescent dyes include analysis of the extract solution using a fluorometer or ultraviolet spectrometer.

[0009] Indications for determining the type and concentration of each of these fluorescent dyes include: irradiating the extraction solution; and collecting the emission spectrum of the extraction solution in response to the irradiation. The method includes determining the intensity of the emission spectrum of each of these fluorescent dyes at the emission wavelength; and, based on the corresponding intensity, determining an indication of the concentration of each of these fluorescent dyes.

[0010] The method includes using mass spectrometry to determine an indication of the type and concentration of each of these fluorescent dyes in the extraction solution.

[0011] The method includes using mass spectrometry to determine an indication of the concentration of the polymer tracer in the extraction solution.

[0012] Extracting these fluorescent dyes involves dissolving the polymer tracer in a solvent.

[0013] One or more of these polymer tracers contain a styrene-based polymer.

[0014] One or more of these polymer tracers contain a polysaccharide-based polymer.

[0015] One or more of these polymer tracers contain polymers based on acrylates, polyesters, polyamides, or polycarbonates.

[0016] One or more of these polymer tracers include polymer nanoparticles, wherein the corresponding fluorescent dye is attached to the polymer of these nanoparticles.

[0017] One or more of these polymer tracers include polymer nanoparticles, wherein the corresponding fluorescent dye is encapsulated inside these nanoparticles.

[0018] One or more of these polymer tracers comprise a polymer, wherein the corresponding fluorescent dye is attached to the polymer.

[0019] At least some of these polymer tracers adhere to the drill cuttings during the cuttings generation process.

[0020] This method involves using pyrolysis-gas chromatography-mass spectrometry to analyze the properties of these drill cuttings.

[0021] This method includes performing core-based porosity or mineralogical analysis on these drill cuttings.

[0022] In one aspect, the composition includes drill cuttings obtained from drilling; and one or more polymeric tracers attached to these drill cuttings. Each polymeric tracer comprises a polymer and a corresponding fluorescent dye, and each fluorescent dye has an emission wavelength different from the emission wavelength of each other fluorescent dye, an excitation wavelength different from the excitation wavelength of each other fluorescent dye, or both.

[0023] An embodiment may include one or any combination of two or more of the following features.

[0024] One or more of these polymer tracers contain a styrene-based polymer.

[0025] One or more of these polymer tracers contain a polysaccharide-based polymer.

[0026] One or more of these polymer tracers contain polymers based on acrylates, polyesters, polyamides, or polycarbonates.

[0027] One or more of these polymer tracers include polymer nanoparticles, wherein the corresponding fluorescent dye is attached to the polymer of these nanoparticles.

[0028] One or more of these polymer tracers include polymer nanoparticles, wherein the corresponding fluorescent dye is encapsulated inside these nanoparticles.

[0029] One or more of these polymer tracers comprise a polymer, wherein the corresponding fluorescent dye is attached to the polymer.

[0030] At least some of these polymer tracers adhere to the surface of these drill cuttings.

[0031] At least some of these polymer tracers permeate into these drill cuttings.

[0032] These polymer nanoparticles and fluorescent dyes are soluble in common organic solvents.

[0033] Details of one or more embodiments are set forth in the following drawings and description. Other features and advantages will become apparent from the description and drawings, as well as from the claims. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of surface logging operations.

[0035] Figure 2 This is a schematic diagram of a nanoparticle tracer loaded with fluorescent dye.

[0036] Figure 3 It's a flowchart.

[0037] Figure 4 This is a schematic diagram of the tracer injection sequence.

[0038] Figure 5 This is a schematic diagram of the process used for depth measurement.

[0039] Figure 6 This is a schematic diagram of the process used for depth measurement.

[0040] Figure 7 This is a scheme for synthesizing nanoparticle tracers loaded with fluorescent dyes.

[0041] Figure 8 These are photographs of the intermediates and products used in the synthesis of nanoparticle tracers loaded with fluorescent dyes.

[0042] Figure 9 It is the Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectrum of polymer nanoparticle tracers loaded with Rhodamine B fluorescent dye.

[0043] Figure 10 The pyrolysis-GCMS (gas chromatography-mass spectrometry) chromatogram and mass spectra of the polymer nanoparticle tracer loaded with Rhodamine B fluorescent dye are shown.

[0044] Figure 11A This is a scheme for synthesizing polymer tracers loaded with fluorescent dyes.

[0045] Figure 11B Fluorescent dyes are shown.

[0046] Figure 12A This is a scheme for synthesizing polymer tracers loaded with fluorescent dyes.

[0047] Figure 12B Fluorescent dyes are shown.

[0048] Figure 13 This is a scheme for synthesizing polymer tracers loaded with fluorescent dyes. Detailed Implementation

[0049] This document describes surface logging methods used for formation analysis during drilling. In these methods, various types of polymeric tracers loaded with fluorescent dyes, such as polymeric nanoparticle tracers, are injected into circulating drilling fluid in a specific sequence. When drill cuttings are generated by downhole drill bit operations, the fluorescent dye-loaded polymeric tracers adhere to the cuttings. When the cuttings return to the surface, they are analyzed to identify which type of fluorescent dye-loaded polymeric tracer adhered to them. For example, excitation spectroscopy, emission spectroscopy, or both can be used to identify the type of fluorescent dye-loaded polymeric tracer present in a given cuttings sample. Based on the injection sequence of the fluorescent dye-loaded polymeric tracers and the relative concentration of each type of tracer adhered to a given cuttings sample, the origin depth of the cuttings can be determined. In this specification, the phrase "polymeric tracer" is sometimes used to encompass polymeric tracers such as polymeric nanoparticle tracers.

[0050] Attaching fluorescent dye-loaded polymer tracers, such as polymer nanoparticle tracers, to drill cuttings enables accurate depth measurements both in real-time (e.g., at the drilling site) and subsequently, even if the drill cuttings are moved or disturbed during transport or storage, or if they settle. Furthermore, by loading the polymer tracer with fluorescent dye, the dye incorporated into or affixed to the polymer (such as nanoparticles) can be easily separated from dirty drilling mud, facilitating dye analysis and producing more accurate results. For example, organic solvents can be used to extract fluorescent dye-loaded polymer tracers from drilling fluid.

[0051] Figure 1 A drilling system 100 and an associated surface logging apparatus 102 are shown. The drilling system 100 includes a derrick 110 that supports the weight of a drill string 112 and allows selective positioning of the drill string via a blowout preventer 114 at the wellhead of a wellbore 116. The drill string 112 has a downhole end connected to a drill bit 118, which is operable to drill the wellbore 116 in the formation 120. To facilitate drilling and removal of drill cuttings 122, a circulation pump 124 circulates drilling fluid 126 through the wellbore 116. The inlet of the circulation pump 124 is connected to a drilling fluid reservoir via a first conduit 127. In the system shown, the reservoir is a mud pit 128. In some systems, the reservoir may be, for example, one or more tanks. The outlet of the circulation pump 124 is connected to the top of the drill string 112 via a second conduit 130. The blowout preventer 114 is connected to a rocking platform 132 via a third conduit 134. The mud pit 128 is connected to the rocking table 132 and receives drilling fluid 126 from the rocking table 132.

[0052] In the case of real-time field logging of cuttings, the suction line 136 or other continuous transfer line connects the surface logging unit 102 to the rocking stage 132. The surface logging unit 102 includes analytical equipment operable to identify the polymeric tracer 138 loaded with fluorescent dyes, such as polymeric nanoparticle tracers, associated with the drill cuttings 122, and to perform rock physical analysis on the drill cuttings 122. For example, the surface logging unit 102 includes a mass spectrometer (e.g., pyrolysis-GCMS), a densitometer, an X-ray diffractometer, a fluorescence spectrometer, an ultraviolet (UV) spectrometer, other mineralogical analysis instruments, and sample cleaning equipment. Identification of the polymeric tracer loaded with fluorescent dyes is used to determine the depth of the drill cuttings origin.

[0053] The surface logging unit 102 is located in the field and directly connected to the drilling fluid circulation system. This configuration facilitates near real-time depth information. For example, a field surface logging unit directly connected to the drilling fluid circulation system can provide depth-related quantities of drill cuttings within minutes of delivery of the cuttings sample. In some instances, sample analysis is performed remotely from the drilling site.

[0054] During drilling, drilling fluid 126 is pumped from mud pit 128 and flows through first conduit 127 into the suction head of circulation pump 124. Circulation pump 124 then pumps drilling fluid 126 from pump outlet to the top of drill string 112 through second conduit 130. A polymer tracer 138 loaded with fluorescent dye is introduced in a specific sequence into the drilling fluid 126 between circulation pump 124 and blowout preventer 114 or between mud pit 128 and circulation pump 124.

[0055] Drilling fluid 126 carrying a polymer tracer 138 loaded with fluorescent dye flows downhole through the wellhead and blowout preventer 114 in the drill string 112 and enters the wellbore 116 through the drill bit 118. As the drilling fluid 126 exits the drill bit 118, the polymer tracer 138 loaded with fluorescent dye adheres to the drill cuttings 122 generated by the drill bit 118. The drilling fluid 126 flows through the wellbore annulus to the wellhead, carrying the drill cuttings 122 and the attached polymer tracer 138 loaded with fluorescent dye. The drilling fluid 126 flows through the blowout preventer 114 and through a third conduit 134 to the rocking platform 132. Before the drilling fluid 126 flows to the mud pit 128, the rocking platform 132 removes the drill cuttings 122 and the attached polymer tracer 138 loaded with fluorescent dye from the drilling fluid 126. At least a portion of drill cuttings 122 and the attached polymer tracer 138 loaded with fluorescent dye is transferred to a surface logging device 102 for analysis to confirm the source depth and rock physical properties of the drill cuttings 122.

[0056] When the embodiments shown depict vertical wellbores, the principles of this disclosure can also be applied to inclined or horizontal wellbores or drilling systems using coiled tubing.

[0057] Reference Figure 2 In this example, the polymeric tracers loaded with fluorescent dyes include various types of polymeric nanoparticle tracers 200a and 200b loaded with fluorescent dyes. Each type of polymeric nanoparticle tracer 200a and 200b includes polymeric nanoparticles 202a and 202b (collectively referred to as nanoparticles 202) containing fluorescent dyes 204a and 204b. Each fluorescent dye 204a and 204b (collectively referred to as fluorescent dye 204) has an excitation spectrum (e.g., peak excitation wavelength) and an emission spectrum (e.g., peak emission wavelength) that differ from the excitation spectrum of each other fluorescent dye 204. Figure 2 In some examples, fluorescent dye 204 is encapsulated within the corresponding nanoparticle 202. In others, fluorescent dye 204 is attached to the polymer of the corresponding nanoparticle 202. The nanoparticle 202 is formed of a polymer, such as a styrene-based polymer, an acrylate-based polymer, a polyester, a polyamide, a polycarbonate, or other types of polymer. The composition of nanoparticle 202 and fluorescent dye 204 is further discussed below.

[0058] Figure 3 An exemplary method is demonstrated for identifying the source depth and rock physical properties of drill cuttings using a polymeric tracer loaded with a fluorescent dye. This method is relative to... Figure 1 The drilling system 100 and surface logging device 102 are described in this manner. Typically, multiple types of polymer tracers loaded with fluorescent dyes, such as polymer nanoparticle tracers, are injected into circulating drilling fluid in a predetermined sequence. The fluorescent dye-loaded polymer tracers adhere to the drill cuttings, and the drill cuttings are then analyzed to identify which type(s) of fluorescent dye-loaded polymer tracers have been adhered to them. Based on the injection sequence and the identified one or more types of fluorescent dye-loaded polymer tracers, the origin depth of the drill cuttings can be determined.

[0059] While the drilling system 100 is used to form the wellbore 116, the surface logging device 102 performs surface logging. During drilling, multiple types of polymeric tracers 138 loaded with fluorescent dyes are added to the circulating drilling fluid 126 (300) in a specific sequence. For example, each type of fluorescent dye-loaded nanoparticle tracer comprises polymeric nanoparticles, the corresponding type of fluorescent dye being encapsulated within or attached to the polymer of the nanoparticles. Each type of polymeric tracer has an excitation spectrum, an emission spectrum, or both that differ from the excitation spectrum of the fluorescent dye of each other type of polymeric tracer. The fluorescent dye 138 loaded with fluorescent dyes is added to the drilling fluid 126 between the circulating pump 124 and the blowout preventer 114. The order in which the various types of fluorescent dye-loaded polymeric tracers are added to the drilling fluid 126 can be a repeating sequence, wherein the sequence restarts after the last tracer type in the sequence is added to the drilling fluid.

[0060] Addition may include injecting the polymer tracer of the first type of fluorescent dye-loaded polymer tracer for a first time period, such as between 30 and 180 seconds, before switching to the second type of polymer tracer loaded with a fluorescent dye. In some instances, switching includes waiting for a period of time, such as between 60 and 240 seconds, after stopping the injection of the first type of polymer tracer loaded with a fluorescent dye and before starting the injection of the next type of polymer tracer loaded with a fluorescent dye. Further description of the tracer injection is provided in US 2020 / 0116019, the entire contents of which are incorporated herein by reference.

[0061] Some polymeric tracers loaded with fluorescent dyes adhere to drill cuttings 122 during drill cuttings generation, such as by adhering to the cuttings, penetrating into the cuttings, or both. Samples (302) of drill cuttings 122 are collected when circulating drilling fluid 126 returns to the surface. For example, samples are collected after the drilling fluid returns to the surface and before it returns to the mud pit or other storage tank. In some instances, sample collection includes bagging the cuttings at intervals between 5 and 8 meters upstream of the wellbore. In some instances, sample collection includes collecting samples of circulating drilling fluid 126 containing drill cuttings.

[0062] Each sample comprises drill cuttings with an attached polymer tracer loaded with a fluorescent dye. The fluorescent dye in the tracer is extracted by exposing the sample to a solvent in which both the polymer of the tracer (e.g., polymer nanoparticles) and the fluorescent dye are soluble (304). Exposure to the solvent dissolves the polymer (e.g., polymer nanoparticles) and the dye.

[0063] For each sample, now including dissolved fluorescent dyes, analysis is performed to determine the type of each dye in the sample and to measure the concentration of each type of dye (306). Analysis can be performed by fluorescence assays, gas chromatography-mass spectrometry (GC-MS), ultraviolet (UV) spectroscopy, digital photography recording the transport of nanoparticles upon UV excitation, or other analytical methods. For example, for fluorescence assays or UV spectroscopy, the emission or excitation spectrum of the sample is measured, and the type of fluorescent dye present in the sample is identified based on the wavelength of the peaks in the emission or excitation spectrum. The concentration of each dye, either absolutely or relative to each other dye, can then be determined based on the intensity of the peaks in the spectrum. A tracer is definitively identified as present when the concentration of a fluorescent dye from a given tracer is significantly (e.g., more than three times) greater than any background “noise” signal from natural geological species or from cross-contamination of tracers from reused drilling mud.

[0064] The depth associated with the drill cuttings in the sample is confirmed (308) based at least in part on the measured concentration of each type of fluorescent dye and the injection sequence, as discussed in further detail below. For example, the downstroke time and upstroke time of the circulating drilling fluid and each type of polymeric tracer loaded with fluorescent dye can be calculated, such that the polymeric tracer of the individual type of fluorescent dye loaded in the sequence is associated with a specific depth. Because the polymeric tracer loaded with fluorescent dye adheres to the drill cuttings, the source depth of the drill cuttings can be determined even if the drill cuttings are moved or disturbed during transport or storage, thus allowing for depth determination with high accuracy.

[0065] When drilling system 100 uses drilling mud as drilling fluid, it can be used Figure 3 The method is illustrated in the diagram. This method can also be used when drilling system 100 uses foam as drilling fluid. Using polymers loaded with fluorescent dyes, such as polymer nanoparticles, as tracers enables surface logging for drilling using lightweight underbalanced foam because some polymers have densities similar to water. For example, polystyrene has a density of approximately 1.04 g / cm³, and polymethacrylate has a density of approximately 1.18 g / cc. In contrast, tracers with higher densities (such as silica or metal oxides with densities equal to or greater than twice that of water) cannot be used with lightweight underbalanced foam.

[0066] Figure 5An exemplary workflow for depth determination using polymer nanoparticle tracers loaded with fluorescent dyes is shown. A similar workflow can be followed for non-nanoparticle polymer tracers. Multiple types of fluorescent dye-loaded nanoparticle tracers 550, each loaded with a corresponding type of fluorescent dye, are dispersed in water to form multiple colloidal suspensions 551. Each type of fluorescent dye has an emission spectrum, an excitation spectrum, or both that differ from the emission spectrum of each other type of fluorescent dye. Examples of fluorescent dyes that can be combined with polymer nanoparticles as tracers are given in Table 1:

[0067]

[0068] Table 1. Fluorescent dyes used as tracers for depth measurement when combined with polymer nanoparticles.

[0069] Arrange the colloidal suspensions in sequence (e.g., by...) Figure 4 The sequence described herein (discussed below) is injected into circulating drilling fluid, such as water-based drilling mud (502). For example, a colloidal dispersion of each type of fluorescent dye-loaded nanoparticle tracer is formed at a concentration between 500 and 1500 ppm and injected into the drilling fluid at a rate between 1 and 10 liters per minute. After the injection of the fluorescent dye-loaded nanoparticle tracer, the drilling fluid 552 (such as drilling mud) includes fluorescent dye-loaded nanoparticle tracer 550. In some instances, a variety of cans are provided, each containing a colloidal dispersion of a corresponding type of fluorescent dye-loaded nanoparticle tracer. These cans are automatically and regularly switched to the injection pump, enabling rapid switching between tracers according to a predetermined sequence.

[0070] Figure 4 A specific example is shown of introducing ten different polymer tracers loaded with fluorescent dyes in a sequence 150 into drilling fluid. In this sequence 150, the tracers (T1...T10) are introduced in a pulsed manner, with each tracer added over one minute, followed by a two-minute pause before the addition of the next tracer. Other sequences may have different numbers of tracers or different delivery timings. The amount of tracer in this sequence, its delivery timing, and delivery concentration are determined based on factors such as, for example, drilling rate, feasible tracer injection rate into the mud pipe, fluid circulation rate, drill string / tubing inner diameter (ID), and tracer detection sensitivity limits.

[0071] Refer again Figure 5A sample 554 (504) of drill cuttings is obtained, for example from circulating drilling fluid or from drilling fluid returned to the surface. Sample 554 includes nanoparticle tracers 550 loaded with fluorescent dyes that adhere to drill cuttings 556 and are dispersed in drilling fluid (such as drilling mud). In some instances, less than all of the nanoparticle tracers loaded with fluorescent dyes adhere to drill cuttings 556.

[0072] A clean sample (506) of drill cuttings is removed, for example by dynamic washing, to remove the mud, leaving a clean sample 558 on the clean drill cuttings 556. This sample contains nanoparticle tracers 550 loaded with a fluorescent dye. A solvent is added to the clean sample (508), and the polymer nanoparticles are dissolved in the solvent, thereby releasing the fluorescent dye into the solution. The result is a solution 560 of the fluorescent dye, in which the drill cuttings 556 are suspended. The solvent is one in which both the fluorescent dye and the polymer nanoparticles are soluble. For example, the solvent can be an organic solvent, such as tetrahydrofuran, chloroform, dichloromethane, toluene, xylene, benzene, dimethylformamide, or other solvents.

[0073] For example, the drill cuttings (510) can be removed from the solution by filtration or centrifugation, leaving a solution 560 containing the fluorescent dye but free of drill cuttings. For example, centrifugation pushes the powder and fine particles to the bottom of the centrifuge vial. The solution 560 can then be removed from the top of the vial using a pipette and transferred to another location, leaving the powder.

[0074] Solution 560 was analyzed (512) to determine the type of each fluorescent dye in solution 560 and to measure the concentration of each type of fluorescent dye. The measured concentrations, along with the order of injection of nanoparticles, were used to determine the depth associated with sample 554. Figure 5 In this example, the analysis is performed using a portable UV spectrometer 562 that produces emission spectra 564 as output. The intensity of each emission peak indicates the concentration of a fluorescent dye having an emission wavelength corresponding to that peak wavelength. The portable spectrometer 562 can be positioned at the drilling site, such as on the drill rig, to provide substantially real-time information about the drilling depth. Other types of analysis that can be performed, in addition to or instead of UV spectroscopy, include fluorescence assays, GC-MS, digital imaging, or other analytical techniques. The analysis can be performed at the drilling site or in a field laboratory.

[0075] Reference Figure 6In a specific example, multiple types of fluorescent dye-loaded nanoparticle tracers, 600a-600d, are injected into borehole 602. The first type, 600a, is injected first, followed by the second type, 600b, the third type, 600c, and finally the fourth type, 600d, in a specific injection sequence. Therefore, the first type, 600a, fluorescent dye-loaded nanoparticle tracer has the shallowest penetration, while the fourth type, 600d, penetrates to the deepest point of the borehole.

[0076] The drill cuttings returned to the surface are labeled with fluorescent dye-loaded nanoparticle tracers, such as those adhering to the surface of the cuttings or penetrating into them. The cuttings are cleaned, and the cleaned dust 606 is collected, for example, from a mud shaker. After solvent extraction, the fluorescent dye-loaded nanoparticle tracers are removed from the cuttings, leaving unlabeled cuttings 608 and the fluorescent dye extracted from solution 610.

[0077] Solution 610 was analyzed using one or more analytical techniques. Figure 6 In this example, the analysis is performed using UV spectroscopy analysis with a UV spectrometer 612, which outputs an emission or excitation spectrum 614 of solution 610. Each peak or group of peaks in the spectrum corresponds to one of the fluorescent dyes. The relative intensity of the peaks in the spectrum indicates the concentration of each dye in solution 610, which in turn can be used in combination with the injection sequence to determine the depth at which drill cuttings 604 originate in the borehole 602.

[0078] In some instances, fluorescence assays or UV spectroscopy are used to identify fluorescent dyes, and other analytical techniques, such as pyrolysis-GCMS, are used to analyze the properties of drill cuttings. This allows the origin depth of the drill cuttings to be correlated with the properties of the cuttings from that depth. In some instances, core-based porosity or mineralogical analyses are performed on the drill cuttings. Compared to elemental tracers, tracers composed of polymer nanoparticles loaded with fluorescent dyes typically do not interfere with analyses such as routine X-ray refraction or other core-based porosity or mineralogical analyses performed on reservoir cores and drill cuttings.

[0079] Fluorescent dye-loaded nanoparticle tracers can be formed by emulsion polymerization of monomers (such as styrene monomers or acrylic monomers) with fluorescent dyes incorporated into emulsion micelles, or can be polyesters, polyamides, polycarbonates, or other types of polymers. Further description of emulsion polymerization is provided in US 2020 / 0116019, the entire contents of which are incorporated herein by reference. Fluorescent dye-loaded nanoparticle tracers can be formed using an aqueous solution containing a polymer with a fluorescent dye. Fluorescent dye-loaded nanoparticle tracers can be formed by swelling a dye (such as a hydrophobic dye) within polymer nanoparticles. Fluorescent dye-loaded nanoparticles can be formed via emulsification-solvent evaporation. In some examples, fluorescent dyes such as fluorescein isothiocyanate (FITC) can be covalently attached to amine-modified styrene or acrylate nanoparticles via a reaction between isothiocyanate and amine.

[0080] Styrene monomers may include, for example, 4-acetoxystyrene, 4-diphenylmethylstyrene, 4-benzyloxy-3-methoxystyrene, 4-tert-butoxystyrene, 4-bromostyrene, 4-chlorostyrene, 2,6-dichlorostyrene, 2,6-difluorostyrene, 3,4-dimethoxystyrene, 2,4-dimethylstyrene, 4-ethoxystyrene, 4-fluorostyrene, 4-methylstyrene, α-methylstyrene, pentafluorophenyl 4-vinylbenzoate, 2,3,4,5,6-pentafluorostyrene, 4-(trifluoromethyl)styrene, 2,4,6-trimethylstyrene, 4-methoxystyrene, 4-vinylbenzocyclobutene, 4-chloromethylstyrene, 4-vinylbiphenyl, 4-vinylbenzoic acid, 1,1-diphenylethylene, 3,5-bis(trifluoromethyl)styrene, 4-vinylphenyl acetate, and trimethoxy(4-vinylphenyl)silane. Aminostyrene monomers include, but are not limited to, (1S)-1-(3-vinylphenyl)-1,2-ethylenediamine and 4-vinylphenol.

[0081] Acrylic acid monomers can be methacrylic acid monomers, such as 1-naphthyl methacrylate, pentabromophenyl methacrylate, phenyl methacrylate, propyl methacrylate, stearyl methacrylate, potassium salt of 3-sulfopropyl methacrylate, tetrahydrofurfuryl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2-[(1′,1′, 1′-Trifluoro-2′-(trifluoromethyl)-2′-hydroxy)propyl]-3-norbornyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 3,3,4,4,5,5,6,6,7,7,8,8,8-tetrafluorooctyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, and 1,1,1,3,3,3-hexafluoroisopropyl methacrylate.

[0082] In some instances, nanoparticle tracers are formed by reacting amine-containing styrene monomers (such as 4-vinylaniline) with epoxide monomers, such as 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyoctane, 1,2-epoxydodecane, 1,2-epoxytetradecane, 1,2-epoxyhexadecane, 2-hexadecylepoxyethylene, allyl glycidyl ether, butyl glycidyl ether, tert-butyl glycidyl ether, 3,4-epoxy-1-butene, 1,2-epoxy-5-hexene, and 1,2-epoxy-9-decyl Alkenes, 4-chlorophenyl glycidyl ether, 1,2-epoxy-3-phenoxypropane, (2,3-epoxypropyl)benzene, 2-ethylhexyl glycidyl ether, furfuryl glycidyl ether, hexadecyl glycidyl ether, isopropyl glycidyl ether, 4-methoxyphenyl glycidyl ether, 2-methylphenyl glycidyl ether, 2,2,3,3,4,4,5,5-octafluoropentyl glycidyl ether, 2,3-epoxy-1-(1-ethoxyethoxy)propane, 1,2-epoxydecane, 1,2-epoxyoctadecane, 1,2-epoxyeicosane, 2,2,3,3,4,4,5,5-epoxy 5,5-Nonafluoropentylethylene oxide, 2,2,3,3,4,4,5,5,6,6,7,7,7-Tetrafluoroheptylethylene oxide, 1,2-Epoxy-1H,1H,2H,3H,3H-Heptafluoroundecane, Methyl glycidyl ether, Ethyl glycidyl ether, Epichlorohydrin, Propyl glycidyl ether, Lauryl glycidyl ether, Tert-butyldimethylsilyl(S)-glycidyl ether, 3-Glycidyloxypropyltrimethoxysilane, 3-Glycidyloxypropyl(dimethoxy)methylsilane, [8-(Glycidyloxy)-n-octyl] Trimethoxysilane, triethoxy(3-glycidoxypropyl)silane, diethoxy(3-glycidoxypropyl)methylsilane, 1,1,1,3,5,5,5-heptamethyl-3-(3-glycidoxypropyl)trisiloxane, 3-[2-(perfluorohexyl)ethoxy]-1,2-epoxypropane, benzyl glycidyl ether, 4-tert-butylphenyl glycidyl ether, 2,4-dibromophenyl glycidyl ether, (S)-glycidyltriphenylmethyl ether, (S)-N-glycidylphthalimide, and 4-glycidoxycarbazole.

[0083] Libraries of nanoparticle tracers loaded with fluorescent dyes can be generated from various combinations of monomers (for nanoparticle formation, e.g., via emulsion polymerization) and fluorescent dyes. Examples of combinations of monomers and fluorescent dyes are given in Table 2. Other combinations may also be used, and monomers, dyes, or both may be used in addition to those listed in Table 2.

[0084]

[0085]

[0086] Table 2. Combinations of monomers and fluorescent dyes used as tracers for polymer nanoparticles.

[0087] In some instances, fluorescent dye-loaded nanoparticle tracers are provided with selective surface functional groups. For example, fluorescent dye-loaded polymer nanoparticles can be surface-functionalized with glycidylated polyethyleneimine to impart colloidal stability in brine. Polymer nanoparticles can be surface-functionalized to reduce retention in reservoir rocks and keep the nanoparticles stable / suspended in a thermosalinous environment, allowing them to be transported to deeper reservoirs with injected water. Similarly, the wettability of nanoparticle tracers can be tuned through surface functionalization to achieve optimal cuttings penetration in oil-based or water-based mud systems. For example, a positively charged polyethyleneimine coating will have an affinity for drill cuttings from siliceous debris reservoirs. Surface functionalization can also be designed to tailor the affinity for drill cuttings from carbonate reservoirs (e.g., coatings with functional groups such as chelates and carboxylates). The surface of polymer nanoparticles can also be selectively hydrophobicated to be compatible with oil-based muds and impregnated into cuttings with mixed wettability.

[0088] In some instances, polymer nanoparticles possess upper temperature limits that do not interfere with the pyrolysis profile of source rock decomposition, such as those between 400°C and 800°C. For example, styrene nanoparticles may have upper temperature limits between 600°C and 800°C, and methylpropionic acid nanoparticles may have upper temperature limits between 400°C and 800°C. Polymer nanoparticle tracers with these upper temperature limits allow for both source depth confirmation and pyrolysis-GCMS analysis to determine the composition and properties of drill cuttings.

[0089] Example

[0090] The following description is based on Figure 7 The present paper illustrates an example of an emulsion polymerization process for synthesizing polystyrene nanoparticle tracers loaded with rhodamine B fluorescent dye. Two types of nanoparticle tracers, “A” and “B”, containing different amounts of rhodamine B, were synthesized. The amounts of starting materials for types A and B are shown in Tables 3 and 4, respectively.

[0091]

[0092] Table 3. Raw materials used in the synthesis of type A nanoparticle tracers.

[0093]

[0094] Table 4. Raw materials used in the synthesis of type B nanoparticle tracers.

[0095] Reference Figure 8 Rhodamine B and SDS were dissolved in 55 mL of deionized (DI) water to produce red solution 800. Red solution 800 was bubbled under nitrogen (N2) for 15 minutes, then heated to 90°C in an oil bath. Acrylamide dissolved in 1–2 mL of DI water was injected into the Rhodamine / SDS solution, followed by dropwise injection of vinylbenzene chloride. After mixing at 90°C for 2 hours, type A and type B dispersions 802 and 804 were formed, representing red poly(vinylbenzyl chloride) nanoparticles loaded with Rhodamine B in the red dye solution. Dynamic light scattering (DLS) measurements of dispersion 802 showed that the particle sizes of the unprocessed nanoparticles A and B were 173.13 ± 1.83 nm and 51.54 ± 1.15 nm, respectively.

[0096] The nanoparticles were precipitated from the dispersion by adding an equal volume of methanol, resulting in red solid nanoparticles 806, which were then separated from the liquid using centrifugation. The red solid nanoparticles 806 were transferred to a 15 mL centrifugal filter equipped with a 3k membrane. The red solid nanoparticles 806 were washed three times with DI water and centrifuged at 9000 rpm for 10 minutes. The solid was then freeze-dried under vacuum.

[0097] Using an ATR module, an ATR iD7 / iTX GE crystal, and a DTGS (deuterated triglycine sulfate) potassium bromide (KBr) detector, at Nicolet TM FTIR-ATR (Fourier Transform Infrared-Attenuated Total Reflectance) data were collected using an iS50 FTIR spectrometer (Thermo Scientific). Data were collected in the range of 600-4000 cm⁻¹. -1 Use 4 wavenumbers (cm) within the range -1 The FTIR-ATR spectra of type A nanoparticles were collected by averaging 100 scans at a resolution of [resolution value missing]. Figure 9 As shown in the image.

[0098] Pyrolysis-GCMS was performed using a Frontier pyrolyzer (Frontier Labs) connected to a GC-MS system (Agilent Technologies), as in Escape Gas Analysis (EGA). For these measurements, the nanoparticles were rapidly pyrolyzed at 550 °C for 0.2 min. The column used for separation was an Agilent HP-5ms ultrainert (UI) column with the following specifications: 30 m length, 0.25 mm inner diameter (ID), and 0.25 μm membrane. The post-inlet set temperature was 280 °C, with a split ratio of 25:1 and a split flow rate of 25 mL / min. In constant flow mode, the carrier gas helium flow rate through the column was 1.1 mL / min. The oven temperature was started at 75 °C and increased to 150 °C at 10 °C / min, and then increased to 325 °C at 50 °C / min. Pyrolysis-GCMS chromatogram and mass spectrometry of nanoparticle type A Figure 10 As shown in the figure, the m / z of vinylbenzyl chloride and its derivatives are visible in mass spectra.

[0099] Other methods for attaching fluorescent dyes to polymers can also be used to form polymer tracers loaded with fluorescent dyes.

[0100] In some instances, polymeric tracers loaded with fluorescent dyes are formed by reacting polysaccharides with fluorescent dyes. Figure 11A In a specific example, phenol red-substituted dextran was formed. Dextran is a water-soluble polymer with hydroxyl groups, where the hydroxyl groups react with epichlorohydrin to form a chlorinated derivative. Chlorinated dextran reacts with a phenol red solution in water at pH 11 to form phenol red-substituted dextran. In these reactions, other polysaccharides, such as xanthan gum, cellulose, or starch, can be used instead of dextran. Fluorescent dyes other than phenol red can also be used. Examples of suitable fluorescent dyes are... Figure 11B The following are shown and include m-cresol purple, alizarin red, alizarin red S, alizarin yellow GG, cresol red, purple, thymol blue, and bromophenol blue.

[0101] In some instances, polymeric tracers loaded with fluorescent dyes are formed by attaching the fluorescent dye to polysaccharides using a condensation reaction (such as via ester bond formation). Figure 12A In a specific example, Rhodamine B attaches to the dextran via ester bonds between the hydroxyl groups on the dextran and the acid groups on the Rhodamine B. In such condensation reactions, fluorescent dyes containing acid or ester groups can be used, such as… Figure 12B Those shown in the text replace Rhodamine B.

[0102] In some instances, polymeric tracers loaded with fluorescent dyes are formed by attaching the fluorescent dye to a polysaccharide via a transesterification reaction, in which the dye is linked to the polysaccharide through ester bonds formed between ester groups on the dye and hydroxyl groups on the polysaccharide. Figure 13 In a specific example, dextran is reacted with lumogen yellow 083. Other dyes containing ester groups, such as rhodamine 6G, can also be used in such transesterification reactions.

[0103] Specific embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions described in the claims can be performed in a different order and still achieve the desired result. For instance, the processes depicted in the drawings do not necessarily require the specific order or sequence shown to achieve the desired result.

Claims

1. A method for surface logging of a well, the method comprising: During drilling the well, each of a variety of polymer tracers is added to the circulating drilling fluid in a certain order, wherein each polymer tracer comprises a polymer and a corresponding fluorescent dye, wherein each fluorescent dye has an emission wavelength different from the emission wavelength of each other fluorescent dye, an excitation wavelength different from the excitation wavelength of each other fluorescent dye, or both. Collect drill cuttings samples carried by the drilling fluid during drilling in the presence of drilling fluid, wherein the drill cuttings samples include polymer tracers attached to these drill cuttings; These dyes were extracted from the drill cuttings sample into an extraction solution; Indicators to determine the type and concentration of each of these dyes in the extraction solution; as well as Based on the concentration indication of each of these dyes and the order of addition, the depth associated with the drill cuttings sample is determined. Extracting these fluorescent dyes involves dissolving the polymer tracer in a solvent.

2. The method as described in claim 1, wherein, Each polymer tracer includes polymer nanoparticles.

3. The method of claim 1, further comprising determining an indication of the type and concentration of each of the fluorescent dyes in the extraction solution based on the excitation spectrum of the extraction solution, the emission spectrum of the extraction solution, or both.

4. The method of claim 1, wherein, Indications for determining the type and concentration of each of these fluorescent dyes include analysis of the extract solution using a fluorometer or ultraviolet spectrometer.

5. The method of claim 1, wherein, Indications for determining the type and concentration of each of these fluorescent dyes include: irradiating the extraction solution; and collecting the emission spectrum of the extraction solution in response to the irradiation.

6. The method of claim 5, further comprising: Determine the intensity of the emission spectrum of each of these fluorescent dyes at that emission wavelength; And an indication of the concentration of each of these fluorescent dyes based on their respective intensities.

7. The method of claim 1, further comprising using mass spectrometry to determine an indication of the type and concentration of each of the fluorescent dyes in the extraction solution.

8. The method of claim 1, further comprising using mass spectrometry to determine an indication of the concentration of the polymer tracer in the extraction solution.

9. The method of claim 1, wherein, One or more of these polymer tracers contain a styrene-based polymer.

10. The method of claim 1, wherein, One or more of these polymer tracers contain a polysaccharide-based polymer.

11. The method of claim 1, wherein, One or more of these polymer tracers contain polymers based on acrylates, polyesters, polyamides, or polycarbonates.

12. The method of claim 1, wherein, One or more of these polymer tracers include polymer nanoparticles, wherein the corresponding fluorescent dye is attached to the polymer of these nanoparticles.

13. The method of claim 1, wherein, One or more of these polymer tracers include polymer nanoparticles, wherein the corresponding fluorescent dye is encapsulated inside these nanoparticles.

14. The method of claim 1, wherein, At least some of these polymer tracers adhere to the drill cuttings during their formation.

15. The method of claim 1, further comprising using pyrolysis-gas chromatography-mass spectrometry to analyze the properties of the drill cuttings.

16. The method of claim 1, further comprising performing core-based porosity or mineralogical analysis on the drill cuttings.

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