Hydrocarbon Flow Rate Research Articles

Evaluation of the effectiveness of the method of studying water saturation for solving urgent decarbonization problems

At present, the impact of the decarbonization trend on the oil and gas industry is becoming more and more tangible. One of the promising approaches to carbon dioxide utilization is the technology of its injection into the productive formation for enhanced oil recovery. The projects realized in the world have shown the efficiency of liquefied carbon dioxide application as a solvent for wells, which leads to increase of hydrocarbon flow rate due to various mechanisms. CO2 injection has been proven to reduce the interfacial tension at the hydrocarbon-water interface and improve water wettability of the rock, converting it from a film state to a droplet state. However, when implementing this approach, it is worth paying attention to the study of formation parameters such as saturation and capillary forces. In this paper, the capillarometry principle is considered to calculate the water saturation parameter of a complex reservoir type with low filtration properties. The study is to evaluate an effective approach to study the estimated residual water saturation under complex pore space geometry and possible pore hydrophilicity disturbance. The practical interest of this work is to increase the study of reservoir properties at the pore level for prediction of its physical and chemical properties in the modeling of composite dynamic model for solving topical issues in reservoir development.

Development of Software for 3D Well Visualization Modeling Using Acoustic, Gamma, Neutron and Density Logging for Fossil Energy Sources Sustainable Production

Achieving the UN Sustainable Development Goals is impossible without sustainable oil and gas production, both in terms of ensuring equal access to cheap energy and preserving the environment, as well as caring for non-renewable fossil energy sources. This actualizes the need for the digital 3D modeling of wells, which allows one to assess their current condition and predict their future condition as well as determine the feasibility of investing in their reconstruction and the expansion of the well network. This is possible due to the fact that the visualization of a well, reflecting its physical and technical parameters, gives engineers, designers and ecologists the opportunity to recognize the defects of the well (cracks, cavities, behind casing and interlayer leaks, etc.) and predict their appearance and proliferation on which the service life, hydrocarbon flow rate, pollution, operating and capital costs directly depend. The software required for this must be versatile enough to cover different types of logging and fit different operating systems. The goal of the study is to develop a software for creating visual 3D models of wells based on acoustic and various types of radioactive logging data, capable of integrating drilling rig parameters and geophysical survey data with modern 3D modeling and programming methods. The developed software meets the requirements of various operating systems and the specifics of different types of logging, which is designed to help in increasing the productivity of oil and gas wells, save energy consumption and reduce groundwater pollution from chemicals used in hydrocarbon production. This is achievable by ensuring trouble-free execution and the operation of well systems, minimizing the risks of collapses and the destruction of well walls through accurate monitoring and forecasting their dynamic condition in real time using 3D models, which is not available for static 2D models.

A hybrid machine learning approach based study of production forecasting and factors influencing the multiphase flow through surface chokes

Surface chokes are widely utilized equipment installed on wellheads to control hydrocarbon flow rates. Several correlations have been suggested to model the multiphase flow of oil and gas via surface chokes. However, substantial errors have been reported in empirical fitting models and correlations to estimate hydrocarbon flow because of the reservoir's heterogeneity, anisotropism, variance in reservoir fluid characteristics at diverse subsurface depths, which introduces complexity in production data. Therefore, the estimation of daily oil and gas production rates is still challenging for the petroleum industry. Recently, hybrid data-driven techniques have been reported to be effective for estimation problems in various aspects of the petroleum domain. This paper investigates hybrid ensemble data-driven approaches to forecast multiphase flow rates through the surface choke (viz. stacked generalization and voting architectures), followed by an assessment of the impact of input production control variables. Otherwise, machine learning models are also trained and tested individually on the production data of hydrocarbon wells located in North Sea. Feature engineering has been properly applied to select the most suitable contributing control variables for daily production rate forecasting. This study provides a chronological explanation of the data analytics required for the interpretation of production data. The test results reveal the estimation performance of the stacked generalization architecture has outperformed other significant paradigms considered for production forecasting.

Harnessing dimethyl ether and methyl formate fuels for direct electrochemical energy conversion

In this work, the oxidation of a mixture of dimethyl ether (DME) and methyl formate (MF) was studied in both an aqueous electrochemical cell and a vapor-fed polymer electrolyte membrane fuel cell (PEMFC) utilizing a multi-metallic alloy catalyst, Pt3Pd3Sn2/C, discovered earlier by us. The current obtained during the bulk oxidation of a DME-saturated 1 M MF was higher than the summation of the currents provided by the two fuels separately, suggesting the cooperative effect of mixing these fuels. A significant increase in the anodic charge was realized during oxidative stripping of a pre-adsorbed DME + MF mixture as compared to DME or MF individually. This is ascribed to greater utilization of specific catalytic sites on account of the relatively lower adsorption energy of the dual- molecules than of the sum of the individual molecules as confirmed by the density functional theory (DFT) calculations. Fuel cell polarization was also conducted using a Pt3Pd3Sn2/C (anode) and Pt/C (cathode) catalysts-coated membrane (CCM). The enhanced surface coverage and active site utilization resulted in providing a higher peak power density by the DME + MF mixture-fed fuel cell (123 mW cm−2 at 0. 45 V) than with DME (84 mW cm−2 at 0.35 V) or MF (28 mW cm−2 at 0.2 V) at the same total anode hydrocarbon flow rate, temperature, and ambient pressure.

The effect of fracturing on permeability in carbonate reservoir rocks

Hydrocarbon flow rates from tight carbonate reservoirs often depend on the distribution and properties of fractures throughout the reservoir interval. Hence, quantification of fracture parameters can contribute to understanding of reservoir characteristics and reservoir potential. In this paper, natural fractures in tight carbonate reservoir rocks of the Upper Cretaceous Shiranish Formation in the Taq Taq field (Kurdistan Region of North Iraq) were examined primarily using core samples, XRMI micro-resistivity image logs and conventional wireline logs, with additional dynamic data from well tests and mud logs. The Shiranish Formation is composed of a variety of limestones and argillaceous limestones with arithmetic mean matrix porosity and geometric mean permeability values of 1.64 ± 0.37% and 0.0223 ± 0.59 mD, respectively. However, fracturing has enhanced the permeability by up to four orders of magnitude above the maximum matrix permeability (1.79 ± 0.59 mD). Hydrocarbons are produced entirely from the fracture network in these rock types in the Taq Taq reservoir. Observed open and partially-open fractures have NE-SW orientations; these are classified as macro-fractures with average aperture of 0.17 ± 0.18 mm, arithmetic mean height of 11.70 ± 45.40 mm and arithmetic mean length of 26.7 ± 32.32 cm, where the uncertainties are standard deviations. Fracture aperture size and fracture height control fracture permeability and fluid flow. However, while fracture frequency has no effect on permeability, fracture distance distribution influences flow rates and hydrocarbon production. The dominant NE-SW trending fractures are more likely to remain open within the NE-SW oriented present day stress field at Taq Taq. Furthermore, the effect of overburden stress on the permeability and production rate was examined in laboratory tests on core plugs by increasing the confining stress during permeability measurements using constant flow rates. It was found that the magnitude of fracture permeability was reduced by 70% by applying 4000 psi of confining stress. In the reservoir, this effect would be exacerbated by reduced reservoir fluid pressures as a function of production. However, fractures with apertures greater than 0.10 mm are preserved as productive fractures even at high confining pressures and implying that hydraulic fracturing could open existing fractures significantly, enhancing production. This last observation implies that the use of hydraulic fracturing in tight carbonate reservoirs with natural fracturing is likely to be commercially viable.

Natural fractures characterization by integration of FMI logs, well logs and core data: a case study from the Sarvak Formation (Iran)

Carbonate reservoirs in Iran are the most important and main sources of oil and gas production. Hydrocarbon flow rates from carbonate reservoirs heavily rely on the development of natural fractures. This study focuses on the role of natural fractures on reservoir quality considering the Sarvak carbonate reservoir (southwest Iran) as the second most important oil reservoir of Iran. To identify small-scale fractures around the borehole walls, cores description and image logs were utilized. Due to high cost of coring, lack of orientation and low core recovery in fractured zones indirect methods based on image logs and conventional well logs were exploited for fracture characterizations. For this purpose, a complete set of well data including image logs (FMI), well-log-derived porosity and permeability data together with petrophysical logs were employed. Interpretation of image logs allows different types of natural structures such as open, vuggy, partly-filled and filled fractures, bedding planes and stylolites to be identified. Comparisons between the petrophysical-log and image-log interpretations provide useful relationships with reservoir characteristics. Neutron and sonic logs show a direct relationship with fracture porosity, while the density log displays an inverse correlation with fracture porosity. Neutron-density and neutron-sonic cross-plots show that the dominant lithology of the studied well is limestone with minor fractions of dolomite and shale. Total porosity ranges from 2 to 30%, while the contribution of secondary porosity, on average, is below 3%. Relationships between fracture-frequency diagrams and reservoir permeability show that high permeability zones are well correlated with the high frequencies of open and vuggy fractures and zones that have flowed oil and associated gas in production tests. Natural fracture characterization based on systematic and integrated interpretations of image logs and petrophysical data can play an important role in optimizing field development, resource recovery and production from the Sarvak reservoir. Once calibrated, this method also offers potential as an exploration tool.

A Comparative Study of a:SiCN:H Thin Films Fabricated with Acetylene and Methane

In this paper we present a comparative study of the properties of amorphous hydrogenated silicon carbonitride (SiCN:H) thin films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD). The elemental composition, growth rate, density, and refractive index values of the SiCN:H thin films were analyzed as functions of flow rates of pure acetylene (C2H2) and methane (CH4) hydrocarbon precursors. The mechanical properties were studied with nanoindentation measurements to compare hardness and Young’s modulus of the SiCN:H thin films deposited with different carbon sources. Variable angle spectroscopic ellipsometry (VASE), elastic recoil detection (ERD), and Rutherford backscattering spectrometry (RBS) were used to determine thin film properties. Higher carbon content in the thin films was achieved by acetylene compared to methane at the same flow rate due to its lower ionization energy during the deposition. Infrared (IR) absorption spectra of the thin films deposited with acetylene precursor were analyzed to determine the correlation between the hydrocarbon flow rate and the intra-molecular bond intensities in the thin films. We found that the major contribution to the hardness comes from hydrogen (H) in the SiCN matrix which makes the films less dense. Carbon improves the hardness, however, H introduced by the hydrocarbon reduces the mechanical strength.

A Comparative Study of the Cubic-Plus-Association Equation of State and a Peng-Robinson Equation of State–Based Solid Model for Asphaltene Simulation in the Wellbore

Summary Asphaltene is one of the main flow-assurance concerns in oil production. Its precipitation and further deposition along the flow path (wellbore or reservoir) can cause reduced hydrocarbon flow rates and even a total blockage. These potential damages have caused a growing interest in computationally efficient methods to predict asphaltene precipitation, depending on flow conditions. This paper presents two different approaches: (i) a model from Li and Firoozabadi (2010), using a simplified version of the cubic-plus-association equation of state (CPA EOS), and (ii) a version of a solid model based on the Peng-Robinson (PR) EOS, with no association term. The two approaches are compared in isolated flash calculations and wellbore flow simulations with asphaltene deposition. The comparisons are made using the same fluid parameters for both approaches as much as possible. Results show that, if provided with adequate input data, the solid model can consistently match results from the more complex CPA model quite successfully for several fluid compositions. An attempt is made to explain the “success” of the solid model in reproducing CPA model results. The solid model cannot adjust to fluid-composition changes in a manner similar to that of CPA. Therefore, the solid model seems more suitable for wellbore than reservoir simulation, which tends to involve a higher level of fluid mixing. However, the efficiency of the solid model can reduce the computational time by a factor of 2 in comparison with CPA.

Simulating the Efficiency of Electromagnetic Pigging in Pipelines and Production Tubing Aided by Nanopaint

SummaryWax and hydrates deposition is a major concern for hydrocarbon transport in pipelines, production tubing, and other pipes in cold environments. Traditionally, chemical, mechanical, and thermal methods are used to mitigate the deposition at the expense of production interruption, complex maintenance, costs, and environmental hazards, and many of these methods are not feasible in deep water environments.This paper studies the potential of nanopaint-aided electromagnetic pigging. This process has potentially low production impact, simple maintenance, low energy cost, and no chemical expense or hazards. The electromagnetic pig contains an induction coil that emits an alternating magnetic field. The alternating magnetic field induces heat in the nanopaint coating (i.e., coating with embedded paramagnetic nanoparticles) on the pipeline’s inner wall and in the pipeline wall itself. The heat then melts and peels off the wax and hydrates adhering to the pipeline, allowing the hydrocarbon to carry them away. Without loss of generality, we focus on wax remediation in this paper.We analyze the heating effectiveness and efficiency of electromagnetic pigging. The heating effectiveness is measured by the maximum pigging speed that allows deposit removal. The heating efficiency is measured by the ratio of the heat received by the wax over the total emitted electromagnetic energy, which we define as the pig induction factor (PIF).An axisymmetric transient model is built to study the heat transfer without considering phase change. Based on our numerical model, we compare the PIF for different coil designs, different hydrocarbon flow rates, and different pig traveling speeds. We reevaluate the maximum pig speed defined by the static pig model from our previous work and found the electromagnetic pigging system is much more effective than previously estimated, while we confirm that a solenoid with larger radius allows higher pig speed. We find that faster pig speed generally improves the efficiency but decreases effectiveness and that shorter solenoids with larger radius have higher efficiency. The hydrocarbon flow rate does not impact the heating process if the wax is thicker than the threshold wax thickness. Based on the simulation results, the field application is discussed.

Assessment of the Effect of Hydrocarbon and Steam Mixture Flow Rate on the Main Parameters of High-Purity Hydrogen Production in a Membrane-Catalytic Device with a Fixed Membrane Area

Assessment of the Effect of Hydrocarbon and Steam Mixture Flow Rate on the Main Parameters of High-Purity Hydrogen Production in a Membrane-Catalytic Device with a Fixed Membrane Area

Primary standard for traceability in low liquid hydrocarbon fuel flow rates

We developed a primary standard for low liquid hydrocarbon flow rates that works on light oil (diesel), kerosene and industrial gasoline. To achieve a calibration accuracy of below 0.1% over a wide flow range from 0.02 L h−1 to 100 L h−1 as required by the industry, this primary standard adopts the gravimetric calibration method performing static weighing with flying-start-and-finish, incorporating a compactly designed conical rotating double-wing diverter for the upper flow range (1 L h−1 to 100 L h−1) and a pair of high-speed switching valves as a diverter for the lower flow range (0.02 L h−1 to 6 L h−1). The uncertainty of liquid mass measurement (in which the evaporation error is a dominant factor) as well as the uncertainty of liquid collection time (in which the diverter timing error is a major factor) are minimized to a level that curbs their dominance to the overall mass flow uncertainty. On the other hand, the uncertainty due to the estimation of liquid density at the flowmeter under test, which is a significant contributing factor to the overall uncertainty of volumetric flow, is being reduced by temperature control measures through a self-developed thermostatic chamber. Intra-facility and inter-facility comparisons within NMIJ were performed, all showing a good agreement, and hence providing supporting evidence for the calibration and measurement capability (CMC), which are 0.020%–0.044% for the mass flow rates and 0.044%–0.066% for the volumetric flow rates as claimed by the facility.

Microwave plasma-based high temperature dehydrogenation of hydrocarbons and alcohols as a single route to highly efficient gas phase synthesis of freestanding graphene

Understanding underlying processes behind the simple and easily scalable graphene synthesis methods enables their large-scale deployment in the emerging energy storage and printable device applications. Microwave plasma decomposition of organic precursors forms a high-temperature environment, above 3000 K, where the process of catalyst-free dehydrogenation and consequent formation of C2 molecules leads to nucleation and growth of high-quality few-layer graphene (FLG). In this work, we show experimental evidence that a high-temperature environment with a gas mixture of H2 and acetylene, C2H2, leads to a transition from amorphous to highly crystalline material proving the suggested dehydrogenation mechanism. The overall conversion efficiency of carbon to FLG reached up to 47%, three times as much as for methane or ethanol, and increased with increasing microwave power (i.e. with the size of the high-temperature zone) and hydrocarbon flow rate. The yield decreased with decreasing C:H ratio while the best quality FLG (low D/G–0.5 and high 2D/G–1.5 Raman band ratio) was achieved for C:H ratio of 1:3. The structures contained less than 1 at% of oxygen. No additional hydrogen was necessary for the synthesis of FLG from higher alcohols having the same stoichiometry, 1-propanol and isopropanol, but the yield was lower, 15%, and dependent on the atom arrangement of the precursor. The prepared FLG nanopowder was analyzed by scanning electron microscopy, Raman, x-ray photoelectron spectroscopy, and thermogravimetry. Microwave plasma was monitored by optical emission spectroscopy.

Optimization the Process of Chemically Modified Carbon Nanofiber Coated Monolith via Response Surface Methodology for CO2 Capture.

In the present study, a sequence of experiments was performed to assess the influence of the key process parameters on the formation of a carbon nanofiber-coated monolith (CNFCM), using a four-level factorial design in response surface methodology (RSM). The effect of reaction temperature, hydrocarbon flow rate, catalyst and catalyst promoter were examined using RSM to enhance the formation yield of CNFs on a monolith substrate. To calculate carbon yield, a quadratic polynomial model was modified through multiple regression analysis and the best possible reaction conditions were found as follows: a reaction temperature of 800 °C, furfuryl alcohol flow of 0.08525 mL/min, ferrocene catalyst concentration of 2.21 g. According to the characterization study, the synthesized CNFs showed a high graphitization which were uniformly distributed on a monolith substrate. Besides this, the feasibility of carbon dioxide (CO2) adsorption from the gaseous mixture (N2/CO2) under a range of experimental conditions was investigated at monolithic column. To get the most out of the CO2 capture, an as-prepared sample was post-modified using ammonia. Furthermore, a deactivation model (DM) was introduced for the purpose of studying the breakthrough curves. The CO2 adsorption onto CNFCM was experimentally examined under following operating conditions: a temperature of 30–50 °C, pressure of 1–2 bar, flow rate of 50–90 mL/min, and CO2 feed amount of 10–40 vol.%. A lower adsorption capacity and shorter breakthrough time were detected by escalating the temperature. On the other hand, the capacity for CO2 adsorption increased by raising the CO2 feed amount, feed flow rate, and operating pressure. The comparative evaluation of CO2 uptake over unmodified and modified CNFCM adsorbents confirmed that the introduced modification procedure caused a substantial improvement in CO2 adsorption.

A case study on 3D characterisation of pore structure in a tight sandstone gas reservoir: The Collyhurst Sandstone, East Irish Sea Basin, northern England

Pore systems of tight-gas reservoirs control important parameters such as flow capacity, producible pore volumes, hydrocarbon flow rates and storage which are complex to characterise and to quantify. Detailed understanding of 3D pore structure is vital in predicting tight-gas reservoir productivity. This study investigates the pore architecture of a sandstone sample from Collyhurst Sandstone Formation, northern England, a tight gas reservoir. X-ray Computed Tomography (XCT) was employed to quantify the pore system (pore size, shape, geometry, and connectivity). Three types of pores were identified: inter-grain pores which are at the boundary of detrital grains and/or authigenic minerals, intra-grains pores which are pores within the detrital mineral grains, and intra-cement pores which are pores within the cement phase (authigenic minerals). The first pore type is primary in origin, whereas the latter two are secondary pores. A centerline tree and a pore network model (PNM) algorithm were applied for pore network analysis and a porosity value was estimated. The image-based porosity value was validated with laboratory experimental measurement. 3D image estimates 3.1% volume porosity, while 4.6% was recorded from the laboratory experiment. Spatial quantification of pore types and analysis of pore connectivity of the studied sandstone improves understanding on gas flow behaviour and gas storage. Furthermore, the results are useful in predicting permeability and multi-flow phase properties in a tight gas reservoir.

Exploration of an unconventional petroleum resource through extensive core analysis and basin geology interpretation utilising play element methodology: the Lower Goldwyer Formation, onshore Canning Basin, Western Australia

Theia Energy Pty Ltd1 (Theia Energy) discovered a potential unconventional hydrocarbon resource in the Ordovician Lower Goldwyer (GIII) Formation shale located on the Broome Platform of the onshore Canning Basin. The collation, processing, analysis and interpretation of all available regional data culminated in a successful exploration well, Theia-1 (drilled in 2015), which, based upon petrophysical and core analyses, intersected a 70 m gross oil column at 1500–1570 m depth. Theia-1 recovered essential core and wireline log data required to analyse and assess the play elements and reservoir properties necessary for a viable shale oil and gas development. Utilisation of an ‘Unconventional Play Element’ methodology has proven the unconventional hydrocarbon potential of the GIII Formation, and preliminary modelling indicates that economic stimulated flow rates may be achieved. Further operations (a test well with multi-stage hydraulic fracture stimulation) are scheduled in the coming permit year to further quantify the presence of extractable organic matter in the GIII Formation, assess hydrocarbon flow rates, determine fluid composition and appraise commercial viability. This paper will discuss Theia Energy’s exploration campaign in the onshore Canning Basin starting with the regional evaluation, which encompassed all available geoscience data (offset wells, pre-existing seismic and potential analogue fields) and modern specialised shale analysis (sequence stratigraphy, paleogeography, geochemistry, unconventional petrophysics and petroleum systems modelling), to develop a robust regional geological model for the GIII Formation. Pre-drill analysis reduced exploration risk and successfully identified the key geological play elements essential for the successful Theia-1 exploration evaluation program.

Experimental Study on Hydrocarbon Liquids Migration in Double-Porosity Medium Using Digital Image Analysis

The development activity of the country has played a part in natural disasters and climate change such as earthquake, El-Nino, tsunamis and water pollution have caused negative impact on human health and geo-environment. More complicated problems arise when the subsurface has experienced earthquake vibration, which no doubt influences the migration of hydrocarbon liquid into the groundwater sources. These problems need to be addressed in ensuring sustainable groundwater utilization. This paper aims to study the characteristics of hydrocarbon liquid migration that are important for the remediation cleanup of contaminated groundwater. The danger of reproductive toxic hydrocarbon chemicals has made actual on-site study infeasible and has been more practically replaced by physical model simulations. For this purpose, a physical laboratory experimental study was conducted to investigate the pattern and characteristics of different quantity toluene hydrocarbon migration in double-porosity medium under the vibration effect by using digital image analysis. The results of the experiments show that lower quantity of toluene hydrocarbon will take longer time to migrate to the bottom compared to higher quantity of toluene hydrocarbon. During experiment, air bubbles were continuously observed at the soil surface of toluene reducing due to the wettability of the liquids in the soil sample and the air trapped between the fractured aggregate and intra-inter aggregate pores. This study indicate that the digital image analysis is capable to provide the hydrocarbon flow rate and useful information for researchers and professionals to comprehensively understand migration characteristic.

High-Performance Brine Viscosifiers for High Temperatures

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 183964, “High-Performance Brine Viscosifiers for High Temperatures,” by Peter J. Boul, Suhaib Abdulquddos, and Carl J. Thaemlitz, Saudi Aramco, prepared for the 2017 SPE Middle East Oil and Gas Show and Conference, Manama, Bahrain, 6–9 March. The paper has not been peer reviewed. Many viscosifiers currently used in high-density solids-free reservoir drilling fluids (RDFs) and completion fluids (CFs) are incompatible with high-density brines or require the use of prohibitively expensive brines to achieve target densities. There is substantial commercial benefit to developing a brine viscosifier with a higher temperature tolerance than is currently offered. A supramolecular viscosifier package has been developed that uses noncovalent associations between additives to enhance the thermal resilience of divalent brine fluids. Static aging-test data indicate that the supramolecular viscosifier outperforms high-performance, commercially available starch/xanthan brine viscosifier. Background The exploitation of oil and gas reservoirs found at increasing depths and the development of horizontal and slimhole drilling have increased the demand for high-density solids-free RDFs, CFs, and workover fluids (WFs). The use of divalent brine-based drilling fluids and CFs in well sections with temperatures exceeding 260°F is limited because of degradation of the polymers used to viscosify the fluid and suspend drill cuttings. Effective drilling fluids have numerous functions in well construction. They must have the physical properties required to carry cuttings from beneath the drill bit up the annulus of the well for separation at the surface. They must also provide cooling for the bit and be able to reduce-friction between the drillstring and the formation being drilled. This must be accomplished without damaging the formation. The inflow of fluids or solids from the drilling mud can cause formation damage, which can reduce the rate of penetration during drilling and can also decrease the rate of hydrocarbon production from a producing well. RDFs, CFs, and WFs must be density-adjusted to provide the hydrostatic head to preserve the integrity of the wellbore walls and to prevent blowouts. Although drilling through much of the well can be accomplished with oil- or water-based fluids weighted by solid particles of such minerals as barite, the reservoir sections offer a different challenge because of the concern that these solids could plug pores in the formation and reduce hydrocarbon-flow rates. It is for this reason that operators look to brines to provide density in RDFs. Recently, research in nanomaterials has revealed the potential of low-solids nanofluids for the prevention of formation damage.

Influence of CVD Growth Parameters on the Corrosion Resistance of the Resultant Graphene Coating

Graphene coatings have been reported to suppress corrosion of various metal substrates due to their chemical inertness. However, the extent of protection offered depends on the uniformity and defect density of the graphene layers developed on the metallic substrates. Among the various synthesis methods, chemical vapour deposition (CVD) is one of the most promising ones to produce graphene coating on a variety of metal substrates. However, achieving controlled CVD growth of large area, uniform and less defective graphene coating is still challenging. This study investigates the influence of various CVD growth parameters during the graphene synthesis, such as hydrogen flow, carbon precursor flow, growth temperature and cooling rate used on the uniformity of the resultant graphene coating and its corrosion resistance. The barrier properties of graphene-coated Cu substrates were evaluated using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) in 0.1 M NaCl for 1008 h. High graphene growth temperature (1060 ºC) and low hydrocarbon flow rate (1 sccm) in the absence of H2 flow were identified to synthesize a uniform graphene coating, which showed durable barrier performance. During the initial hours of immersion, the graphene coated copper (Cu) specimens showed about one and half order of magnitude improvement in corrosion resistance in 0.1 M NaCl and even after 1008 h, the corrosion resistance provided by the graphene coating was almost five times more than that of bare Cu. The optimized CVD graphene parameters reported here can provide a new direction to achieve long-term durable graphene coating.

Chemical vapor deposition parameters dependent length control of hexagonal graphene

This paper presents a process metamodel-based artificial neural network full factorial experimental design and analysis to study the yield of lengthy hexagonal graphene grown by chemical vapor deposition. All of the process variables of chemical vapor deposition such as temperature, pressure, and gas flow rate under the study played a role in influencing hexagonal graphene length; the current study investigated their main effects and interactions. The metamodel-based analysis demonstrates that the hydrocarbon flow rate and the pressure are the most statistically significant factors that influence the length of hexagonal graphene. In particular, minimum and maximum values of the chamber pressure are not significant in terms of the concentrating effect they may have on the flowing mixture of gases with very small flow rate, i.e. 50 sccm. At the highest flow rate of 400 sccm, the chamber pressure stepped up to 764 Torr, which can support the growth reaction to the extent that the resultant hexagonal graphene length of 900 µm can be achieved. However, the two level effect of the flow rate can optimize the length to 990 µm and ≈1390 µm at 700 Torr and 764 Torr, respectively. In addition, the response surface graph confirms the factors of significance and adds that higher flow with lower pressure will consistently yield tall hexagonal graphene. We found that gas flow rate is the most significant of the control variables and only the optimum value of the gas flow rate of 225 sccm can ensure the growth of tall hexagonal graphene. We also found that the interaction of flow rate with temperature of the gases in the chamber is extremely significant to the quality of output. Outcomes of this investigation are beneficial for moving close to producing hexagonal graphene on production scale for future applications.

Effect of shut-in time on gas flow rate in hydraulic fractured shale reservoirs

Some shale gas and oil wells undergo month-long shut-in times after multi-stage hydraulic fracturing well stimulation. Field data indicate that in some wells, such shut-in episodes surprisingly increase the gas and oil flow rate. In this paper, we report a numerical simulation study that supports such observations and provides a potentially viable underlying imbibition and drainage mechanism. In the simulation, the shale reservoir is represented by a triple-porosity fracture-matrix model, where the fracture forms a continuum of interconnected network created during the well stimulation while the organic and inorganic matrices are embedded in the fracture continuum. The effect of matrix wettability, capillary pressure, relative permeability, and osmotic pressure, that is, chemical potential characteristics are included in the model.The simulation results indicate that the early lower flow rates are the result of obstructed fracture network due to high water saturation. This means that the injected fracturing fluid fills such fractures and blocks early gas or oil flow. Allowing time for the gravity drainage and imbibition of injected fluid in the fracture-matrix network is the key to improving the hydrocarbon flow rate during the shut-in period.