A novel experimental setup for axial-torsional coupled vibration impact-assisted PDC drill bit drilling.

The geological conditions of hot dry rock (HDR) reservoirs are complex. The geothermal mining of HDR faces major challenges in the drilling and construction of wells, fracturing to create storage, and flowing to extract heat. Vibration impacts help improve the rock-breaking efficiency, where the axial-torsional coupled vibration impact technology can increase the bit penetration depth and reduce the stick-slip effect. To study the feasibility and efficiency of the axial-torsional-coupled vibration impact-assisted Polycrystalline Diamond Compact (PDC) bit to break high-temperature and high-pressure rocks, a new experimental setup was designed. The system includes a drilling fluid circulation system, an axial-torsional coupled impact drilling system, a formation simulation system, and a data acquisition and control system. This setup can produce a rock-breaking torque of 2000 N·m, a drilling speed of 200 rpm, a weight on bit of 100 kN, an axial vibration frequency of 100 Hz, and a torsional vibration frequency of 50 Hz. It can simulate the formation pressure of 70 MPa and the rock temperature of 400 °C. A series of rock-breaking drilling experiments were successfully conducted using this setup. The results show that the axial-torsional coupled vibration-impact assisted PDC bit has a good performance in breaking high-temperature and hard rocks, which can accelerate the application of this new technology in deep formation drilling.

Multifunctional Viologen-Derived Supramolecular Network with Photo/Vapochromic and Proton Conduction Properties.

A supramolecular network [H4bdcbpy(NO3)2·H2O] (H4bdcbpy = 1,1'-Bis(3,5-dicarboxybenzyl)-4,4'-bipyridinium) (1) was prepared by a zwitterionic viologen carboxylate ligand in hydrothermal synthesis conditions. The as-synthesized (1) has been well characterized by means of single-crystal/powder X-ray diffraction, elemental analysis, thermogravimetric analysis and infrared and UV-vis spectroscopy. This compound possesses a three-dimensional supramolecular structure, formed by the hydrogen bond and π-π interaction between the organic ligands. This compound shows photochromic properties under UV light, as well as vapochromic behavior upon exposure to volatile amines and ammonia, in which the electron transfer from electron-rich parts to the electron-deficient viologen unit gives rise to colored radicals. Moreover, the intensive intermolecular H-bonding networks in 1 endows it with a proton conductivity of 1.06 × 10-3 S cm-1 in water at 90 °C.

Rock-breaking performances of innovative triangular-shaped polycrystalline diamond compact cutter.

Due to high hardness and high abrasion, conventional planar polycrystalline diamond compact (PDC) cutters can easily get broken and dull when drilling in (ultra-)deep formations. To enhance the drilling performance, an innovative kind of non-planar PDC cutter, namely, a triangular-shaped PDC cutter, has been developed by altering the 2D planar cutting face into a 3D cutting structure of a triangular trustum of a pyramid. According to the numerical simulation results, the triangular-shaped PDC cutter can easily break hard rocks by a smaller cutting force than the conventional planar PDC cutter. Furthermore, it requires less mechanical specific energy for breaking the same volume of rock than the planar PDC cutter. The triangular-shaped PDC cutter shows great potential in improving the drilling performances of the PDC bit in hard and abrasive formations.

A novel experimental apparatus for single polycrystalline diamond compact cutter tests.

Polycrystalline diamond compact (PDC) bits are increasingly favored in the drilling field due to their high efficiency in rock breaking together with their longevity. To investigate the rock failure mechanism and further improve the performance of PDC bits, innovative experimental equipment is proposed in this paper. With its assistance, we can study the characteristics of rock-breaking using a PDC cutter under different conditions, e.g., high pressure and high temperature (HPHT), confining pressure, and jet impingement. The setup can be grouped into three parts: a rock cutting system, high-pressure jet generation system, and controlling system. A series of experiments was conducted to demonstrate the reliability of the setup. The results demonstrate the improvement in performance of PDC bits in the exploration of HPHT formations.

The effect of guest cations on proton conduction of LTA zeolite.

Zeolites as important crystalline microporous materials have been widely used as catalysts, sorbents and ion-exchangers. In such materials, the guest ions in the pores can not only balance the charge of the framework but also make a difference to the pore environment and the resulting performance. In this work, we focus on the proton conduction properties of zeolites, and have comprehensively studied for the first time the effect of guest ions on proton conduction. To this end, aluminosilicate NaA zeolite (LTA) and ion-exchanged NaA zeolites by different guest ions (i.e. Li+, K+, Mg2+, Ca2+ and Sr2+) have been successfully synthesized. The study indicates that the guest ions could affect the proton conduction properties through the synergistic effect between the pore features (e.g. pore size, pore polarity, etc.) and guest ions, the ionic concentrations, and the interference between different ions. Among various guest ions, the existence of Na+ ions can greatly promote the proton conduction properties. The proton conductivity of NaA can reach 1.98 × 10-3 S cm-1 (100% RH) at room temperature and 9.12 × 10-3 S cm-1 (80 °C) under the condition of 100% RH. In addition, guest monovalent ions (Li+, Na+ and K+) exhibit better proton conductivity than divalent ions (Mg2+, Ca2+ and Sr2+). The distinct effect of these guest ions enables zeolites with tunable proton conductivity, which will provide more opportunities to design zeolitic proton conducting materials.

An innovative experimental apparatus for the analysis of natural gas hydrate erosion process using cavitating jet.

Natural Gas Hydrate (NGH) develops and exists in pores of soil sediments under deep seabed and permafrost regions. A cavitation jet is an efficient method of rock breaking, especially for soft hydrate sediment erosion. This paper presents an experimental apparatus that was developed to synthesize NGH and hydrate-bearing sediments and analyze the drilling efficiency of the cavitation jet. The visualization study of fluid flow and breaking mechanism can be conducted over a temperature range varying from -20 °C to 100 °C and up to a maximum confining pressure of 20 MPa. This apparatus is mainly composed of the pressure control and injection system, the cooling system, the cavitation system, and the reaction vessels into which the lab-fabricated temperature/pressure/resistivity sensor probe is inserted. The basic principles of this apparatus are discussed, and a series of experiments were performed to verify that the cavitating jet can be practically applied in the exploitation of NGH reservoirs.

A zwitterionic ligand-based water-stable metal-organic framework showing photochromic and Cr(vi) removal properties.

As one of the highly crystalline porous materials, metal-organic frameworks (MOFs) have drawn immense attention due to their diverse structures and a wide variety of applications. In this study, [In3(ipbp)2(µ2-OH)(µ2-O)3] (1) that has a three-dimensional framework, including two types of cages with cuboctahedra and trigonal antiprism configurations, has been successfully synthesized based on the zwitterionic ligand 1-(3,5-dicarboxyphenyl)-4,4'-bipyridinium bromide (H2(ipbp)Br). Strikingly, a relatively rare trapeziform metal layer consisting of In3+, µ2-OH, µ2-O, carboxyl, and nitrogen from the ligand appears in the structure of 1. Benefitting from the formation of the ipbp radicals under UV light irradiation, compound 1 exhibits photochromic property that can transform the color from yellow to green. Moreover, it possesses commendable Cr(vi) removal capacity with the maximum adsorption amount of 74.4 mg·g-1 due to the surface electrostatic interaction between the crystal surface and Cr(vi) in the aqueous system. This work will promote the design of functional MOFs that show potential applications in UV light detection and removal of oxyanions.

Red Room-Temperature Phosphorescence of CDs@Zeolite Composites Triggered by Heteroatoms in Zeolite Frameworks.

Carbon dots (CDs) with red-emitting room-temperature phosphorescence (RTP) are rarely reported because of the increasing nonradiative decay of the excited states and the decreasing energy gap between the excited states and ground states. Herein, we demonstrate a facile strategy for modulating the RTP properties of CDs in terms of donor-acceptor energy transfer (EnT) in the CDs-in-zeolite system. Upon tuning of the heteroatoms (Zn2+, Mn2+) doped in the aluminophosphate zeolite frameworks, CDs@zeolite composites with green and red phosphorescence have been prepared via in situ hydrothermal synthesis. In such composites, the zeolite matrix provides an efficient confinement role in stabilizing the triplet states of CDs. Significantly, the Mn-doped zeolite could act as an energy acceptor allowing EnT from excitons of CDs to the dopant in the host matrix, generating the intriguing red RTP behavior. This work provides an effective strategy for developing CD-based composite materials with special RTP emissions as well as new fields for applications.

Design of experimental setup for liquid nitrogen assisted polycrystalline diamond compact bit drilling.

A liquid nitrogen assisted polycrystalline diamond compact (PDC) bit drilling method is expected to be suitable for hot dry rock (HDR) drilling because the huge thermal stress induced in the drilling process can help to break the rock and the low temperature liquid nitrogen can efficiently cool the drilling tools. However, there is no experimental research on liquid nitrogen assisted PDC bits breaking high temperature granite, and the rock breaking efficiency of this new drilling method is still unclear. To investigate the feasibility and efficiency of liquid nitrogen assisted PDC bit breaking HDR, a novel experimental setup was designed. This setup is composed of four units: the drilling fluid circulation system, drilling system, formation simulation system, and data acquisition and control system. It can also be used to research the effects of drilling parameters such as weight on bit, rotary speed, drilling fluid jet pressure, and feed speed on drilling efficiency. A series of drilling experiments using liquid nitrogen and water have been successfully carried out with this setup. The results indicate that liquid nitrogen assisted PDC bit drilling has excellent performance in breaking HDR, which can accelerate the application of this new technique in geothermal drilling.

Note: A novel experimental setup for high-pressure abrasive liquid nitrogen jet.

A high-pressure abrasive liquid nitrogen (L-N2) jet is considered as an efficient rock-breaking technology due to its unique low-temperature characteristic. In order to experimentally investigate the impact of an abrasive L-N2 jet on rock breakage, a new setup, which considers the low temperature and high expansibility of L-N2, is put forward in this note. The setup is composed of four units: the power system, nitrogen-gas pressurization system, particle mixing system, and impingement system. Both a pre-mixed abrasive L-N2 jet and a post-mixed abrasive L-N2 jet can be achieved by this equipment. Moreover, it can also be used to investigate the influences of injection parameters and particle parameters on rock breakage. A series of experiments have been carried out based on the setup. The results further promote the application of an abrasive L-N2 jet.

A Zwitterionic Ligand-Based Cationic Metal-Organic Framework for Rapidly Selective Dye Capture and Highly Efficient Cr2 O72- Removal.

A cationic metal-organic framework (MOF), [Cu2 L(H2 O)2 ]⋅(NO3 )2 ⋅5.5 H2 O (1) has been successfully synthesized from a zwitterionic ligand 1,1'-bis(3,5-dicarboxyphenyl)-4,4'-bipyridinium chlorine ([H4 L]Cl2 ). The framework of compound 1 contains classical {Cu2 (O2 C)4 } paddlewheels, and possesses typical nbo-type topology and two types of channels with sizes of 5.0 and 15.54 Å. Benefitting from the 3D cationic framework and high pore volume, compound 1 shows interesting selective adsorption ability for anionic dyes. Such material can be successfully employed in a chromatographic column to efficiently separate mixed dyes of Fluorescein Sodium and Methylene Blue. In addition, compound 1 exhibits excellent Cr2 O72- removal capacity with maximum adsorption amount of 222.5 mg g-1 , which ranks among the higher Cr2 O72- adsorption amounts of MOF materials ever reported, based on ion-exchange. The strategy to construct cationic MOFs based on zwitterionic ligands will promote the development of functional porous materials for the capture and removal of anionic pollutant species from contaminated liquid.

Design of experimental setup for supercritical CO2 jet under high ambient pressure conditions.

With the commercial extraction of hydrocarbons in shale and tight reservoirs, efficient methods are needed to accelerate developing process. Supercritical CO2 (SC-CO2) jet has been considered as a potential way due to its unique fluid properties. In this article, a new setup is designed for laboratory experiment to research the SC-CO2 jet's characteristics in different jet temperatures, pressures, standoff distances, ambient pressures, etc. The setup is composed of five modules, including SC-CO2 generation system, pure SC-CO2 jet system, abrasive SC-CO2 jet system, CO2 recovery system, and data acquisition system. Now, a series of rock perforating (or case cutting) experiments have been successfully conducted using the setup about pure and abrasive SC-CO2 jet, and the results have proven the great perforating efficiency of SC-CO2 jet and the applications of this setup.

3D porous metal-organic framework as an efficient electrocatalyst for nonenzymatic sensing application.

Novel electroactive materials with high surface area and stability have great potential for electrochemical sensor. Herein, we demonstrate the exploitation of a porous Cu-based metal-organic framework (Cu-MOF) with large pore size as nonenzymatic sensors for the electrochemical determination of hydrogen peroxide (H2O2) and glucose. The Cu-MOF shows high stability even in NaOH solution. The as-prepared Cu-MOF modified carbon paste electrode (CPE) presents a well-behaved redox event from electroactive metal centers in the MOF at the physiological pH which can be utilized to catalyze the electroreduction of H2O2. It also exhibited excellent electrocatalytic activity towards the oxidation of glucose in alkaline solution. The results showed that the nonenzymatic sensors based on the Cu-MOF display excellent analytical performances, which make it a promising candidate in electrochemical sensor.

Study and application of a high-pressure water jet multi-functional flow test system.

As the exploration and development of oil and gas focus more and more on deeper formation, hydraulic issues such as high-pressure water jet rock breaking, wellbore multiphase flow law, cuttings carrying efficiency, and hydraulic fracturing technique during the drilling and completion process have become the key points. To accomplish related researches, a high-pressure water jet multi-functional flow test system was designed. The following novel researches are carried out: study of high-pressure water jet characteristics under confining pressure, wellbore multiphase flow regime, hydraulic pressure properties of down hole tools during jet fracturing and pulsed cavitation jet drilling, and deflector's friction in radial jet drilling. The validity and feasibility of the experimental results provided by the system with various test modules have proved its importance in the research of the high-pressure water jet and well completion technology.