Covalent organic frameworks as tracers for fluorescent upstream imaging

Abstract

The present disclosure relates to methods of characterizing and analyzing drilling cuttings, such as drilling cuttings labeled with a fluorescent covalent organic framework tracer.

Description

Priority claim

[0001] This application claims priority to U.S. patent application No. 17 / 949,481, filed on September 21, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This document relates to fluorescent covalent organic frameworks. Fluorescent covalent organic frameworks are environmentally friendly and can be used in oil and gas applications, including as tracers for oilfield applications or as tags for drill cutting marking. Background Art

[0003] Oilfield tracers are used in a single well or across multiple wells to determine the production or oil saturation of a formation, to check well connectivity, to determine the quality of isolation from completions, cementing, or packer installations, and for other oilfield surveys. Most tracers used in oilfield operations require labor-intensive and time-consuming sampling and detection protocols that prolong and complicate the time to obtain and interpret results from the tracers. Due to these issues, an efficient system for simple and rapid detection and monitoring of tracers in the field is highly desirable.

[0004] A large number of fluorophores have been used for oil well tracing. One of the main drawbacks in terms of classical fluorescent dye tracing is the low level of detection sensitivity, which requires extraction of labels and, in some cases, their pre-concentration, followed by instrumental (fluorometer) analysis. Many other fluorophores (e.g., fluorescent quantum dots and fluorescent organic complexes) also have the same problem of lacking the required intensity. Recently, the use of persistent luminescent nanoagents has been proposed as a step towards automated CCD camera-assisted tracer detection. Chuang et al., Sci. Rep. (2016) 6:27993. However, the complex synthesis of these nanoagents and the presence of toxic lanthanides in their cores have become limiting factors for their widespread use. Therefore, it is desirable to have brightly luminescent, stable, eco-friendly fluorescent tracers that can be easily detected on site. Summary of the invention

[0005] The present disclosure provides a method for logging a well. In some embodiments, the method includes adding a fluorescent covalent organic framework (COF) tracer to a well while drilling; injecting the fluorescent COF tracer into drill cuttings generated while drilling the well, thereby marking the drill cuttings with the fluorescent COF tracer; pumping the marked drill cuttings upward in the well toward the annulus of the well; collecting the marked drill cuttings; and identifying the fluorescent COF tracer in the drill cuttings.

[0006] In some embodiments of the methods, the fluorescent COF tracer comprises a fluorescent building block, a covalently attached fluorescent moiety, a fluorophore loaded into the channels and pores of the COF, or a combination thereof.

[0007] In some embodiments of the method, the fluorescent COF tracer is added to the well via the drill string of the well. In some embodiments, the fluorescent COF tracer is injected into the produced drill cuttings by breaking a capsule containing the fluorescent COF tracer.

[0008] In some embodiments of the methods, where more than one fluorescent COF tracer is added to the well, each fluorescent COF tracer has a different fluorescence emission wavelength and fluorescence emission spectrum.

[0009] In some embodiments of the method, the marked drill cuttings are included in the drilling mud.In some embodiments, the drilling mud is pumped upward by a water circulation.

[0010] In some embodiments, the method further comprises separating the tagged drill cuttings from the drilling mud after collecting the tagged drill cuttings.In some embodiments, the tagged drill cuttings are collected at a shale shaker.

[0011] In some embodiments of the method, the fluorescent COF tracer in the drill cuttings is identified by ultraviolet (UV) light and a camera.

[0012] In some embodiments, the method further includes determining a depth associated with the marked drill cuttings based on identification of the fluorescent COF tracer.

[0013] In some embodiments of the methods, the well is an oil well.

[0014] The present disclosure also provides a method for determining the depth of drill cuttings in a well. In some embodiments, the method includes obtaining drill cuttings from the well, wherein the drill cuttings are labeled with a fluorescent covalent organic framework (COF) tracer; and identifying the fluorescent COF tracer in the drill cuttings by ultraviolet (UV) light and a camera, wherein the fluorescent COF tracer has a fluorescence emission wavelength and a fluorescence emission spectrum that allows the depth associated with the labeled drill cuttings to be determined. In some embodiments, the identification is performed at the well site.

[0015] In some embodiments of the methods, where more than one fluorescent COF tracer is added to the well, each fluorescent COF tracer has a different fluorescence emission wavelength and fluorescence emission spectrum.

[0016] In some embodiments of the method, the drill cuttings are labeled with the fluorescent COF tracer downhole while drilling. In some embodiments, the fluorescent COF tracer is injected into the drill cuttings by destroying a capsule containing the fluorescent COF tracer.

[0017] The present disclosure also provides a composition comprising drill cuttings obtained from drilling and one or more fluorescent covalent organic framework (COF) tracers attached to the drill cuttings. In some embodiments, the fluorescent COF tracer comprises a fluorescent building block, a covalently attached fluorescent moiety, a fluorophore loaded into the channels and pores of the COF, or a combination thereof. In some embodiments, the fluorescent COF tracer is detectable by ultraviolet (UV) spectroscopy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1A-1B shows the use of a two-dimensional COF ( Figure 1A ) and 3D COF ( Figure 1B )’s basic topology diagram.

[0019] Figure 2 Post-synthetic modification of a non-fluorescent COF with a fluorescent moiety is shown.

[0020] Figure 3 Depicted are COF pores loaded with fluorescent dye.

[0021] Figure 4 An exemplary synthetic procedure for fluorescent COFs is shown.

[0022] Figure 5 The application of fluorescent COF tracer in drill cuttings depth identification is shown. DETAILED DESCRIPTION

[0023] The present disclosure provides fluorescent covalent organic frameworks (COFs) for oil and gas applications. These environmentally friendly fluorescent COF materials can be used, for example, as tracers for waterfront mapping in high permeability zones of reservoirs. These tracers can also be used, for example, as tags for cuttings marking to allow real-time accurate cuttings depth assignment. Tracers can also be used for well logging (or borehole logging) to determine depth, subsurface formations, and events encountered while drilling.

[0024] In some embodiments, the use of fluorescent COF tracers allows for real-time detection of tracers at the oil field. In some embodiments, detection is performed using a UV camera and an AI recognition system. In some embodiments, the system is installed at the shale shaker. The method of the present disclosure is a simple, fast, and automated method for tagging and field detection.

[0025] The COF tracers disclosed herein are extended structures that can greatly increase the strength of the tracer and extend the fluorescence lifetime of the tracer due to conjugation. The high stability of COF materials is built-in through covalent bonds. In addition, the fluorescent COF tracers disclosed herein can be considered green and environmentally friendly due to the chemical properties of the skeleton (which is stable and does not contain toxic metal ions as building blocks).

[0026] In some embodiments of the methods of the present disclosure, fluorescent COFs aggregate, resulting in enhanced fluorescence detectable to the naked eye. In some embodiments, macroscopically sized aggregates of fluorescent tags are used for drill cuttings fluorescent labeling, where the possibility of inserting a large number of small fluorescent nanotags into the macroscopic structure causes an enhancement in the fluorescent response. In some embodiments, macroscopic labeling of drill cuttings with high-intensity fluorescence allows the construction of a simple and rapid, almost near-real-time tracer detection system.

[0027] definition

[0028] Unless otherwise defined, all technical and scientific terms used in this document have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. Methods and materials used in this application are described in this document; other suitable methods and materials known in the art may also be used. The materials, methods and examples are illustrative only and are not intended to be limiting. All publications, patent applications, patents, sequences, database entries and other references mentioned in this document are incorporated by reference in their entirety. In the event of a conflict, the present specification (including definitions) shall prevail.

[0029] As used in this disclosure, the terms "a", "an", and "the" are used to include one or more, unless the context clearly dictates otherwise. The term "or" is used to refer to a non-exclusive "or", unless otherwise specified. The statement "at least one of A and B" has the same meaning as "A, B, or A and B". In addition, it should be understood that the words or terms used in this disclosure and not otherwise defined are for descriptive purposes only and not for limiting purposes. The use of any section headings is intended to aid in reading the document and should not be construed as limiting; information related to the section heading may appear within or outside that particular section.

[0030] In the methods described in this disclosure, except when a time or order of operations is explicitly stated, the actions may be performed in any order. In addition, specified actions may be performed simultaneously unless explicit claim language states that they are performed separately. For example, a required action of performing X and a required action of performing Y may be performed simultaneously in a single operation, and the resulting process will fall within the literal scope of the required process.

[0031] As used in this disclosure, the term "downhole" may refer to a location below the Earth's surface, such as within a wellbore or a location fluidly connected to a wellbore.

[0032] Fluorescent covalent organic frameworks

[0033] Covalent organic framework (COF) is a class of 2D and 3D materials consisting of rigid organic building blocks, which are connected by reactions between organic precursors, resulting in the formation of strong covalent bonds and providing porous, stable and crystalline structures. COF is a class of polymers with unique conformations and morphologies that can be pre-designed completely. This is achieved by topologically guided polymer growth combined with geometric matching between monomers. This molecular design principle is different from linear polymers, hyperbranched polymers, cross-linked polymers and biopolymers, and improves the ability to pre-design first-order and higher-order structures. In some embodiments of the method disclosed herein, fluorescent COFs aggregate, resulting in enhanced fluorescence detectable by the naked eye. In some embodiments, fluorescent COFs are environmentally friendly.

[0034] The COF of the present disclosure is a fluorescent COF composed of covalently bonded organic building blocks. The organic porous material has an ordered structure, and has a high specific surface area, high porosity, regular pore size, easy regulation, flexible structure, easy functionalization, and excellent thermal stability and chemical stability. In some embodiments, the building blocks of COF have a π-skeleton and a rigid conformation. Examples of building blocks (monomers) include benzene, simple aromatic hydrocarbons, heterocycles, and macrocycles. In some embodiments, one or more of the monomers are fluorescent moieties. In some embodiments, the building blocks are designed to have different C2, C3, C4, C6, and T d In some embodiments, the monomer has one or more functional groups including, but not limited to, aldehyde, amine, boronic acid, catechol, squaric acid, quinone, methyl, anhydride, silanol, hydrazine, benzonitrile, cyano, tetrafluoro, and combinations thereof.

[0035] In some embodiments, the monomer has an aldehyde functional group. In some embodiments, the monomer is a C2 monomer having an aldehyde functional group. Examples of such monomers include, but are not limited to:

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043] .

[0044] In some embodiments, the monomer is a C3 monomer having an aldehyde functional group. Examples of such monomers include, but are not limited to:

[0045]

[0046]

[0047]

[0048]

[0049] .

[0050] In some embodiments, the monomer is a C4 monomer having an aldehyde functional group. Examples of such monomers include, but are not limited to:

[0051] .

[0052] In some embodiments, the monomer is a C6 monomer having an aldehyde functional group. Examples of such monomers include, but are not limited to:

[0053] .

[0054] In some embodiments, the monomer is T having an aldehyde functional group. d Monomers. Examples of such monomers include, but are not limited to:

[0055] .

[0056] In some embodiments, the monomer has an amine functional group. In some embodiments, the monomer is a C2 monomer having an amine functional group. Examples of such monomers include, but are not limited to:

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] .

[0063] In some embodiments, the monomer is a C3 monomer having an amine functional group. Examples of such monomers include, but are not limited to:

[0064]

[0065]

[0066]

[0067] .

[0068] In some embodiments, the monomer is a C4 monomer having an amine functional group. Examples of such monomers include, but are not limited to:

[0069] .

[0070] In some embodiments, the monomer is a C6 monomer having an amine functional group. Examples of such monomers include, but are not limited to:

[0071] .

[0072] In some embodiments, the monomer is a T having an amine functional group. d Monomers. Examples of such monomers include, but are not limited to:

[0073] .

[0074] In some embodiments, the monomer has one or more functional groups, including but not limited to boric acid, catechol, squaric acid, quinone, methyl, anhydride, silanol, hydrazine, benzonitrile, cyano, tetrafluoro, and combinations thereof. Examples of such monomers include but are not limited to:

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] .

[0092] In some embodiments, the COF is a two-dimensional COF. Examples of two-dimensional COFs include, but are not limited to, tetragonal COFs, rhombic COFs, kagome-type COFs, triangular COFs, and heteropore COFs. Topological diagrams for designing two-dimensional COFs are provided in Figure 1A Shown in.

[0093] In some embodiments, the COF is a three-dimensional COF. In some embodiments, the three-dimensional COF has at least one building block with Td or orthogonal geometry. In some embodiments, the three-dimensional COF has a network selected from ctn, bor, dia, srs, rra, and pts. The topology used to design the three-dimensional COF is Figure 1B Shown in.

[0094] COF of the present disclosure is a fluorescent COF. In some embodiments, COF has fluorescence as an intrinsic property of the porous chemical nature of the skeleton. In some embodiments, COF has fluorescence attributed to the inclusion of fluorescent agents in macromolecular voids. In some embodiments, COF materials are designed according to isoreticular chemical principles to provide a large number of pre-designed structures with adjustable physicochemical properties. The extended structure of the covalent organic skeleton connected via covalent bonding allows the formation of highly stable macromolecules with a complete conjugated chemical bond system.

[0095] In some embodiments, the fully conjugated structure of the COF acts as a conductor and enhances fluorescence by light-induced energy transfer. In some embodiments, the COF is tunable, allowing the design of various skeletons with specific fluorescence emission wavelengths. In addition, in some embodiments, the porous nature of the skeleton is used as a matrix for the insertion of fluorescent molecules and a matrix for post-synthetic modification with fluorophores. Therefore, the fluorescent COF of the present disclosure can be obtained, for example, due to the intrinsic fluorescence of the skeleton (attributable to the fluorescence of the building blocks), obtained from post-synthetic modification of the pores of the COF using covalent attachment of fluorescent agents, and obtained by the fluorescence of the skeleton caused by the insertion of fluorophores.

[0096] In some embodiments, the rigidity of the core and fixed pore geometry of the COF prevents aggregation-induced fluorescence quenching and thus provides advantages in fluorescence intensity over common fluorescently labeled polymers.

[0097] COF composed of fluorescent building blocks

[0098] In some embodiments, the COF used in the method of the present disclosure is composed of one or more fluorescent building blocks (fluorophores). For example, the fluorescence of the covalent organic framework may be due to the emission characteristics of the precursor building blocks that are connected together to form the framework structure. The rigid and fixed positioning of the connector in the framework will prevent the aggregation of the fluorescent part. The conjugation of the chemical bonds between the luminescent monomers can enhance the energy transfer between the different parts of the macromolecule and induce the strong emission involving the excitation of multiple fluorophores.

[0099] Examples of suitable fluorophore building blocks include, but are not limited to, carbazole, pyrene, tetraphenylene, triphenylbenzene, triazine, perylene, tetraphenylthiophene, triphenylene, and tetrazine. In some embodiments, the fluorophore monomer is selected from:

[0100]

[0101]

[0102] .

[0103] In some embodiments, the fluorescent COF contains a fluorophore combined with one or more rigid building blocks or heterocyclic units, such as described in the present disclosure. In some embodiments, the fluorescent COF contains a rigid building block selected from:

[0104] .

[0105] In some embodiments, the fluorescent COF contains a heterocyclic unit building block selected from:

[0106] .

[0107] In some embodiments, the fluorescent COF is composed of the following scaffold:

[0108] .

[0109] In some embodiments, the COF composed of fluorescent building blocks includes any of the COFs disclosed in Geng et al. Chem. Rev. (2020) 120(16):8814–8933, which is incorporated herein by reference in its entirety.

[0110] Post-synthetic modification

[0111] In some embodiments, the COF used in the method of the present disclosure is fluorescent due to post-synthesis modification of non-fluorescent COF with fluorescent moieties. In some embodiments, the fluorescent moieties are covalently attached to the pores and / or channels of the COF. In some embodiments, post-synthesis modification of the channels and voids of the covalent organic framework leads to the formation of fluorescent materials, wherein the luminescent fragments are covalently and regularly attached to the core of the framework. Due to the regular arrangement of the modified fragments in the COF core for 2D or 3D expansion, the spacing of the covalently attached fluorophores will prevent them from aggregating.

[0112] Examples of suitable fluorescent moieties that can be used for post-synthetic modification of COFs include, but are not limited to, derivatives of the rhodamine dye family, derivatives of the BODIPY dye family, derivatives of the DABCO dye family, cyanines and cyanine derivatives, xanthenes and xanthene derivatives, fluorescein, fluorescein derivatives, fluorescein isothiocyanate, acridine, acridine derivatives, coumarin derivatives, pyrene derivatives, anthracene derivatives, 4',6-diamidino-2-phenylindole dihydrochloride and other phenylindole derivatives, squaric acid derivatives, naphthalene derivatives, oxadiazole derivatives, anthracene derivatives, oxazine derivatives, arylmethine derivatives, tetrapyrrole derivatives, and 8-hydroxyquinoline derivatives. In some embodiments, the fluorescent moiety is fluorescein or a fluorescein derivative. In some embodiments, the fluorescein or fluorescein derivative is fluorescein isothiocyanate (FITC). In some embodiments, post-synthetic modification of a non-fluorescent COF with a fluorescent moiety involves modifying the COF with FITC, such as Figure 2 shown.

[0113] In some embodiments, moieties that can be used for COF insertion and post-synthesis modification include salts, ions, and oxides of rare earth elements that interact with the core of the framework to form fluorescent materials. Examples of such moieties include, but are not limited to, derivatives of yttrium (Y), samarium (Sm), europium (Eu), cerium (Ce), lanthanum (La), and terbium (Tb), erbium (Er), ytterbium (Yb), and neodymium (Nd).

[0114] In some embodiments, the moieties that can be used for post-synthesis modification of COFs include lanthanide complexes formed between organic chelating building blocks of COFs, such as salen-type ligands and lanthanide salts. Examples of such moieties include, but are not limited to, lanthanides such as Eu(III), Sm(III), Tb(III), La(III), and Dy(III), and other moieties such as Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. In some embodiments, when the pH of the solution is reduced from six to two, the emission of the lanthanide luminescent probe increases by about six times. In some embodiments, this property is used to detect acidic gases in drilled formations.

[0115] In some embodiments, the moieties that can be used to induce fluorescence in the framework material are ions and gases that react with the framework to turn on fluorescence. Examples of such moieties include, but are not limited to, protons, metal ions, iodine, fluorine, nitrogen oxides, carbon dioxide, hydrogen sulfide, chlorine, and chloride ions.

[0116] Insertion of fluorophores within COF pores

[0117] In some embodiments, the COF used in the methods of the present disclosure is fluorescent due to the insertion of fluorophores as guest molecules in the non-fluorescent COF matrix. In some embodiments, the specific pore geometry and size in the COF can be adjusted and allow only appropriate fluorophore molecules to be captured and stored in separate cages to exclude the possibility of aggregation-induced fluorescence quenching. Therefore, in some embodiments, fluorophores are loaded into the channels and pores of the COF. Figure 3 An example of such a COF is shown in .

[0118] In some embodiments, fluorescent molecules and materials that match the size of the pores of the covalent organic framework are used for insertion. Examples of such molecules and materials include, but are not limited to, rare earth metal ions and oxides, fluorescent dyes, fluorescent quantum dots, fluorescent lanthanide complexes, fluorescent nanoparticles, and the like.

[0119] In some embodiments, fluorescent backbone materials are incorporated into composite materials and / or protected with glass, ceramic or polymer matrices to isolate the fluorescent material from leakage and / or destructive effects of the downhole environment, as well as to enhance the connectivity of the material or increase adsorption into the formation.

[0120] method

[0121] Any fluorescent COF can be used in the methods of the present disclosure, such as the fluorescent COFs described in the present disclosure or the fluorescent COFs obtained by the techniques described in the present disclosure. For example, the fluorescent COF tracer can contain fluorescent building blocks, covalently attached fluorescent moieties, fluorophores loaded into the channels and pores of the COF, or combinations thereof. In some embodiments, the fluorescent COF tracer contains fluorescent building blocks. In some embodiments, the fluorescent COF tracer contains covalently attached fluorescent moieties, such as fluorescent moieties covalently attached by post-synthesis modification of non-fluorescent COFs. In some embodiments, the fluorescent COF tracer contains fluorophores loaded into the channels and pores of COFs such as non-fluorescent COFs. In some embodiments, the fluorescent COF is environmentally friendly.

[0122] Fluorescent COFs can be used as tracers or tags in oil and gas applications. In some embodiments, fluorescent COFs are used to tag drill cuttings, map water lines in high permeability zones of reservoirs, or both. In some embodiments, tags are mixed with drilling mud and attached to fragments of the formation at the drill bit face to identify the depth of the drill cuttings. In some embodiments, the marked drill cuttings are separated on a shale shaker after the drill cuttings are returned with the circulation of the drilling mud. In some embodiments, the shale shaker is located at the well site, allowing real-time identification and analysis.

[0123] The fluorescent COF tracers disclosed herein can be used for drill cuttings marking and logging, for example, based on the depth of the drill cuttings. The fluorescent COF tracer can be delivered into the well via a drill string and can be facing the formation at the drill bit location. After drilling, drill cuttings are formed and can be marked by injecting a fluorescent tracer into the formed drill cuttings, for example, by breaking a capsule with an encapsulated tag or tag solution. In some embodiments, water circulation of the drilling mud pumps the resulting drill cuttings with the fluorescent COF tag (tracer) upward toward the annulus. In some embodiments, the drill cuttings with the fluorescent COF tracer travel upward to the mud shaker. At the shaker site, the drill cuttings with the fluorescent tag can be separated from the mud, and the fluorescent COF tracer ( Figure 5 ).

[0124] Preliminary detection and identification of fluorescent COF tracers can be performed in the field (well site). In some embodiments, detection and identification are based on the fluorescent response of the tracer. For example, detection of fluorescent COF tracers can be performed at a shale shaker using a camera equipped with ultraviolet (UV) light and a camera recognition system based on artificial intelligence (AI). Compared with known fluorescent tracers that do not contain COF structures, the enhanced fluorescence efficiency of fluorescent COF tracers can additionally facilitate AI-based camera recognition technology. In some embodiments of the methods of the present disclosure, fluorescent COFs aggregate, resulting in enhanced fluorescence that is detectable to the naked eye.

[0125] In some embodiments, the fluorescent COF tracer can be further identified, for example, in a laboratory. For example, the identification of the fluorescent COF tracer can be further performed using extraction and using analytical methods, including but not limited to fluorescence, Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), X-ray fluorescence (XRF), nuclear magnetic resonance (NMR) spectroscopy, gas chromatography (GC) or liquid chromatography (LC) and mass spectrometry (MS). For example, FTIR can be used to detect the presence of specific functional groups in the COF skeleton; PXRD and XRF can be used to detect specific patterns of crystal structures; NMR can be used to detect the unique chemical structure of the organic skeleton; MS or a combination of GC or LC and MS can provide data on the molecular weight of the building blocks and / or guest molecules of the COF; and specific fluorescence emission wavelengths can be recorded and estimated via fluorescence determination. Therefore, in some embodiments of the methods of the present disclosure, the fluorescent COF tracer is detected not only by the unique fluorescence emission wavelength and fluorescence emission spectrum of the tracer, but also by a secondary analytical method.

[0126] In some embodiments of the methods of the present disclosure, a camera equipped with UV light is used for rapid, on-site preliminary detection of fluorescent COFs. In some embodiments, the camera is placed on top of a shale shaker, such as an on-site shale shaker. The enhanced fluorescence efficiency of the fluorescent COFs of the present disclosure allows for AI-based identification of camera tags.

[0127] In some embodiments, the various fluorescence wavelengths of the fluorescent COF tracers that can be used in the methods of the present disclosure allow for barcoding of a parameter (depth of origin of drill cuttings). For example, the unique properties of the fluorescent COF tracers can be used to program the sequential release of the tracers and, therefore, barcode the labeling parameter (depth of drill cuttings). In some embodiments, the injection of the fluorescent COF tracers is programmed according to the order of the colors of the fluorescent response, or the order of the colors of the fluorescent response of the tracers / the PXRD patterns of the materials, or the order of the colors of the fluorescent response / PXRD patterns / molecular weight of the building blocks and the combination of particle size and shape, for unique barcoding of the labeling parameters. In some embodiments, the programmed barcoding injection and identification of the fluorescent COF tracers is based on three parameters: the color of the fluorescent response, the molecular weight of the porous material monomer, and the powder X-ray diffraction pattern of the unit cell of the label material. In some embodiments, programmed barcoded injection and identification of fluorescent COF tracers are based on four parameters: the color of the fluorescent response, the molecular weight of the porous material forming monomers, the powder X-ray diffraction pattern of the unit cell of the tag material, and the particle size and shape of the injected tracer. In this way, a 3D matrix of barcoded labels can be used for fluorescent COF tracers. In some embodiments, drilled wells are labeled at specific depth intervals with injections of tags having one or more of a unique structure, fluorescence emission wavelength, or color. In this way, drill cuttings labeled with tags having a unique structure, fluorescence emission wavelength, and / or color generated from each depth interval can be identified. In some embodiments, identification of the tags allows the depth of origin of the drill cuttings to be assigned. In some embodiments, the depth interval for labeling is about 50 meters.

[0128] In some embodiments, the fluorescent barcoded COF tracer is capable of changing the fluorescent response or structure or composition of the contained guest molecule when exposed to a reservoir (well) environment, and thus indicating specific parameters of the downhole environment, such as the presence of acid gas, detection of hydrocarbons, or signs of specific minerals. Therefore, the present disclosure also provides methods for detecting the presence of acid gas, hydrocarbons, and / or detecting and identifying specific minerals within a well.

[0129] Therefore, the present disclosure provides a method of logging a well. In some embodiments, the method includes adding a fluorescent covalent organic framework (COF) tracer to a well while drilling; injecting the fluorescent COF tracer into drill cuttings produced while drilling the well, thereby marking the drill cuttings with the fluorescent COF tracer; pumping the marked drill cuttings upward in the well toward the annulus of the well; collecting the marked drill cuttings; and identifying the fluorescent COF tracer in the drill cuttings. In some embodiments of the method, the fluorescent COF tracer is added to the well via the drill string of the well. In some embodiments, the well is an oil well.

[0130] In some embodiments, the fluorescent COF tracer is a fluorescent COF tracer as described in the present disclosure. In some embodiments, the fluorescent COF tracer contains fluorescent building blocks, covalently attached fluorescent moieties, fluorophores loaded into the channels and pores of the COF, or combinations thereof. In some embodiments, the fluorescent COF tracer contains fluorescent building blocks. In some embodiments, the fluorescent COF tracer contains covalently attached fluorescent moieties, such as fluorescent moieties covalently attached by post-synthesis modification of non-fluorescent COFs. In some embodiments, the fluorescent COF tracer contains fluorophores loaded into the channels and pores of COFs such as non-fluorescent COFs.

[0131] In some embodiments, the fluorescent COF tracer is injected into the produced drill cuttings by destroying the capsule containing the fluorescent COF tracer, thereby marking the drill cuttings with the fluorescent COF tracer. In some embodiments, the capsule contains the fluorescent COF tracer in solution.

[0132] In some embodiments of the method, one or more than one fluorescent COF tracer is added to the well. In some embodiments, when more than one fluorescent COF tracer is added to the well, each fluorescent COF tracer has a different fluorescence emission wavelength and fluorescence emission spectrum. In some embodiments, various fluorescent COF tracers are added to the well simultaneously (at the same time). In some embodiments, various fluorescent COF tracers are added to the well individually.

[0133] In some embodiments, the marked drill cuttings are contained in the drilling mud that is pumped upward by the water circulation. In some embodiments, the method further comprises separating the marked drill cuttings from the drilling mud after collecting the marked drill cuttings. In some embodiments, the marked drill cuttings are collected at a shale shaker. In some embodiments, the shale shaker is located on-site.

[0134] In some embodiments of the method, the fluorescent COF tracer in the drill cuttings is identified by ultraviolet (UV) light and a camera. In some embodiments, the method includes determining a depth associated with the marked drill cuttings based on the identification of the fluorescent COF tracer.

[0135] The present disclosure also provides a method for determining the depth of drill cuttings in a well. In some embodiments, the method includes obtaining drill cuttings from a well, wherein the drill cuttings are marked with a fluorescent COF tracer. The method also includes identifying the fluorescent COF tracer in the drill cuttings by ultraviolet (UV) light and a camera. In some embodiments, the fluorescent COF tracer has a fluorescence emission wavelength and a fluorescence emission spectrum that allows the depth associated with the marked drill cuttings to be determined. In some embodiments, the identification of the fluorescent COF tracer is performed after collecting the drill cuttings. In some embodiments, the drill cuttings are collected by a shale shaker. In some embodiments, the shale shaker is at the well site.

[0136] In some embodiments of the method, more than one fluorescent COF tracer is added to the well, wherein each fluorescent COF tracer has a different fluorescence emission wavelength and fluorescence emission spectrum. In some embodiments, while drilling the well, drill cuttings are marked with the fluorescent COF tracer downhole. In some embodiments, the fluorescent COF tracer is injected into the drill cuttings by destroying a capsule containing the fluorescent COF tracer.

[0137] The present disclosure also provides a method for detecting drill cuttings using fluorescence. In some embodiments, the drill cuttings are marked with a fluorescent COF tracer. In some embodiments, the detection is performed at a well site. In some embodiments of the method, the fluorescent COF tracer in the drill cuttings is detected and identified by ultraviolet (UV) light and a camera. In some embodiments, the method includes determining a depth associated with the marked drill cuttings based on the identification of the fluorescent COF tracer.

[0138] The present disclosure also provides a composition comprising drill cuttings obtained from drilling and one or more fluorescent COF tracers attached to the drill cuttings. In some embodiments, the fluorescent COF tracer is a fluorescent COF tracer as described in the present disclosure. In some embodiments, the fluorescent COF tracer contains a fluorescent building block, a covalently attached fluorescent moiety, a fluorophore loaded into the channels and pores of the COF, or a combination thereof. In some embodiments, the fluorescent COF tracer contains a fluorescent building block. In some embodiments, the fluorescent COF tracer contains a covalently attached fluorescent moiety, such as a fluorescent moiety covalently attached by post-synthesis modification of a non-fluorescent COF. In some embodiments, the fluorescent COF tracer contains a fluorophore loaded into the channels and pores of a COF such as a non-fluorescent COF. In some embodiments, the fluorescent COF tracer can be detected by ultraviolet (UV) spectroscopy.

[0139] Example

[0140] Example 1 - Synthesis of fluorescent COF

[0141] An exemplary fluorescent COF (TPE-Ph COF) can be prepared according to the method described in Dalapati et al. J. Am. Chem. Soc. (2016) 138:5797-5800 and in Figure 4 The procedure shown in was used to synthesize the 2-hydroxy-1-(2-phenylethylene) ...

[0142] Example 2 – Detection and high-precision identification of fluorescent COF tags

[0143] Initial detection and identification of fluorescent COF tags can be performed in the field and is based on the fluorescent response of the tag. Detection can be performed at the shale shaker using a camera equipped with UV light and an AI-based camera recognition system.

[0144] Extraction and further analytical methods (including fluorescence determination, FTIR, PXRD, XRF, NMR, GC or LCMS and mass spectrometry) can be used to further carry out accurate laboratory identification of fluorescent COF tags. FTIR can be used to detect the presence of specific functional groups in the COF skeleton. PXRD and XRF can be used to detect the specific pattern of the crystal structure. NMR can be used to detect the unique chemical structure of the organic skeleton. The combination of mass spectrum or chromatography and mass spectrum will provide data on the molecular weight of the building blocks and / or guest molecules of the relevant skeleton. Specific fluorescence emission wavelengths can be recorded and estimated via fluorescence determination.

[0145] These analytical methods will provide data that is unique to each of the selected COF tracers, with each type of tracer being characterized by a unique fluorescence emission wavelength and fluorescence emission spectrum.

[0146] In addition to the fluorescent response, the crystal structure of the fluorescent COF tag material can be used as a second unique parameter for identifying the tag. Powder X-ray diffraction analysis can be used for this purpose. The PXRD pattern of the tag will be unique for each crystal structure of each type of tracer. In addition, mass spectrometry will provide the mass spectrum of the building blocks that make up each type of COF tag. The mass spectrum of the building blocks will provide another unique and targeted parameter for these tracers.

[0147] Example 3 - Drill Cuttings Marking

[0148] Fluorescent COF tracers can be used for cuttings tagging and logging as a function of depth. The fluorescent tracer is delivered into the well via the drill string and faces the formation at the drill bit location. The fluorescent tracer is injected into the resulting drill cuttings by breaking a capsule with an encapsulated tag or tag solution while drilling. Water circulation of the drilling mud pumps the resulting fluorescently tagged cuttings upward toward the annulus. The fluorescently traced cuttings travel upward to the shale shaker. At the shaker location, the fluorescently tagged cuttings are then separated from the mud and the color of the tracer is detected in UV light using a camera, such as Figure 5 shown.

[0149] Example 4 - Programmable Barcoding

[0150] The unique properties of the fluorescent COF tags can be used to program the sequential release of the tracer and thus barcode the labeling parameters (depth of drill cuttings). The injection of the fluorescent tags can be programmed according to the order of the colors of the fluorescent response of the tags, or the order of the colors / PXRD patterns of the fluorescent response of the materials, or the order of the colors / PXRD patterns / molecular weight of the fluorescent response of the building blocks and the combination of particle size and shape, for unique barcoding of the labeling parameters. Thus, a 3D matrix of barcoded tags can be used to label materials.

[0151] For example, every 50 meters of drilled wells would be tagged with an injection of a batch of tags having a unique structure, fluorescence emission wavelength, and color for a programmed sequential release of fluorescent COF tags at each depth interval. Thus, drill cuttings produced from 100 m to 150 m depth would be tagged with tags of a single color, e.g., blue tags; drill cuttings produced at 151 m to 200 m depth would be tagged with tags of a second color, e.g., red tags, and so on. For each depth interval, with the unique color and structure of the programmed tags, knowing their injection sequence, one can assign the depth of origin of the drill cuttings based on the color of the tags on the drill cuttings as they return to the shale shaker. If uncertainty arises in determining the color of the tags or a detailed evaluation of the tags is required, the tags can be further analyzed in the laboratory using PXRD, FTIR, GC / LC-MS, or any other analysis to provide a unique chemical composition of the tags for each depth interval.

[0152] Other Implementations

[0153] It should be understood that although the present invention has been described in conjunction with its detailed description, the foregoing description is intended to illustrate rather than limit the scope of the present invention, which is defined by the scope of the appended claims. Other aspects, advantages and modifications are within the scope of the appended claims.

Claims

1. A method for well logging, the method comprising: adding a fluorescent covalent organic framework (COF) tracer into the well while drilling the well; injecting the fluorescent COF tracer into drill cuttings produced when drilling the well, thereby marking the drill cuttings with the fluorescent COF tracer; pumping the marked drill cuttings upward in the well toward an annulus of the well; collecting the marked drill cuttings; as well as The fluorescent COF tracer is identified in the drill cuttings. 2 . The method of claim 1 , wherein the fluorescent COF tracer comprises fluorescent building blocks, covalently attached fluorescent moieties, fluorophores loaded into channels and pores of the COF, or combinations thereof.

3. The method of claim 1, wherein the fluorescent COF tracer is added to the well via a drill string of the well.

4. The method of claim 1, wherein the fluorescent COF tracer is injected into produced drill cuttings by destroying a capsule containing the fluorescent COF tracer.

5. The method of claim 1, wherein more than one fluorescent COF tracer is added to the well, and wherein each fluorescent COF tracer has a different fluorescence emission wavelength and fluorescence emission spectrum.

6. The method of claim 1, wherein the marked drill cuttings are contained in a drilling mud.

7. The method of claim 6, wherein the drilling mud is pumped upwards by water circulation.

8. The method of claim 6, further comprising separating the marked drill cuttings from the drilling mud after collecting the marked drill cuttings.

9. The method of claim 1, wherein the tagged drill cuttings are collected at a shale shaker.

10. The method of claim 1, wherein the fluorescent COF tracer in the drill cuttings is identified by ultraviolet (UV) light and a camera.

11. The method of claim 1 further comprising determining a depth associated with the marked drill cuttings based on identification of the fluorescent COF tracer.

12. The method of claim 1, wherein the well is an oil well.

13. A method of determining the depth of drill cuttings in a well, the method comprising: obtaining drill cuttings from the well, wherein the drill cuttings are labeled with a fluorescent covalent organic framework (COF) tracer; as well as The fluorescent COF tracer in the drill cuttings is identified by ultraviolet (UV) light and a camera, wherein the fluorescent COF tracer has a fluorescence emission wavelength and a fluorescence emission spectrum that allows for determination of a depth associated with the marked drill cuttings.

14. The method of claim 13, wherein more than one fluorescent COF tracer is added to the well, and wherein each fluorescent COF tracer has a different fluorescence emission wavelength and fluorescence emission spectrum.

15. The method of claim 13, wherein the drill cuttings are labeled with the fluorescent COF tracer downhole while drilling the well.

16. The method of claim 15, wherein the fluorescent COF tracer is injected into the drill cuttings by destroying a capsule containing the fluorescent COF tracer.

17. The method of claim 13, wherein the identifying is performed on-site at the well.

18. A composition comprising drill cuttings obtained from drilling a well and one or more fluorescent covalent organic framework (COF) tracers attached to the drill cuttings.

19. The composition of claim 18, wherein the fluorescent COF tracer comprises fluorescent building blocks, covalently attached fluorescent moieties, fluorophores loaded into channels and pores of the COF, or combinations thereof.

20. The composition of claim 18, wherein the fluorescent COF tracer is detectable by ultraviolet (UV) spectroscopy.

Images