Quantification of Temperature-Dependent Sorption Kinetics in Shale Gas Reservoirs: Experiment and Theory

A critical component of natural gas in organic-rich shales is adsorbed gas within organic matter. Quantification of adsorbed gas is essential for reliable estimates of gas-in-place in shale reservoirs. However, conventional high-pressure adsorption measurements for coal on the volumetric method are prone to error when applied to characterize sorption kinetics in shale-gas systems due to limited adsorption capacity and finer pores of shale matrix. An innovated laboratory apparatus and measurement procedures have been developed for accurate determination of the relatively small amount of adsorbed gas in the Marcellus shale sample. The custom-built volumetric apparatus is a differential unit composed of two identical single-sided units (one blank and one adsorption side) connected with a differential pressure transducer. The scale of the differential pressure transducer is ± 50 psi, a hundred-fold smaller than the absolute pressure transducer measuring to 5000 psi, leading to a significant increase in the accuracy of adsorption measurement. Methane adsorption isotherms on Marcellus shale are measured at 303, 313, 323 and 333 K with pressure up to 3000 psi. A fugacity-based Dubinin-Astakhov (D-A) isotherm is implemented to correct for the non-ideality and predict the temperature-dependence of supercritical gas sorption. The Marcellus shale studied displays generally linear correlations between adsorption capacity and pressure over the range of temperature and pressure investigated, indicating the presence of a solute gas component. It is noted that the condensed phase gas storage exists as the adsorbed gas on shale surface and dissolved gas in kerogen, where the solute gas amount is proportional to the partial pressure of that gas above the solution. To our best understanding, it is the first time to observe the contribution of dissolved gas to total gas storage. With adsorption potential being modeled by a temperature dependence expression, the D-A isotherm can successfully describe supercritical gas sorption for shale at multiple temperatures. Adsorption capacity remarkably decreases with temperature attributed to the isosteric heat of adsorption. Lastly, the wide applicability of the proposed fugacity-based D-A model is also tested for literature adsorption data on Woodford, Barnett, and Devonian shale. Overall, the fugacity-based D-A isotherm provides precise representations of the temperature-dependent gas adsorption on shales investigated in this work. The application of the proposed adsorption model allows predicting adsorption data at multiple temperatures based on the adsorption data collected at a single temperature. This study lays the foundation for accurate evaluation of gas storage in shale.

PENGURANGAN INTENSITAS FLUKTUASI TEKANAN PADA PEMBESARAN MENDADAK ALIRAN UDARA – AIR SEARAH HORISONTAL DENGAN PENEMPATAN RING

This research aims to reduce the effect of pressure fluctuations intensity on the sudden expansion of two phase flow of air - water in the same direction with the horizontal placement of the ring. Measurements done by installing a differential pressure transducer device that is placed on pressure points before and after sudden expansion. Output voltage signal recorded by a digital storage osciloscope. Tests conducted on water discharge 0.000038 m 3 / s; 0.000078 m 3 / s; 0.000116 m 3 / s; 0.000154 m 3 / s; 0.000198 m 3 / s; 0.000244 m 3 / s; 0.000284 m 3 / s and air flow 0.000065 m 3 / s; 0.00013 m 3 / s; 0.000195 m 3 / s; 0.000255 m 3 / s; 0.00032 m 3 / s; 0.000385 m 3 / s; 0.00045 m 3 / s. Results showed that if the total mass flow rate increases the pressure drop increases. Installation of the ring can reduce the pressure fluctuations intensity, the most effective installation of the ring using the ring the same diameter. Flow path is generally slug and plug flow pattern.

Differential Pressure Transducer for Corrosion Monitoring of Iron

In this study, differential pressure transducer (DPT) has been applied as an alternate corrosion monitoring device for monitoring corrosion of iron in atmospheric environment by measuring very small changes in the amount of oxygen. The result of corrosion current obtained from DPT method has been compared with that obtained from AC impedance method. The difference in the value of corrosion current obtained from these two methods was attributed to the error in choosing the value of proportionality constant k of the Stern-Geary equation.DOI: http://dx.doi.org/10.3126/ijasbt.v2i1.10112Int J Appl Sci Biotechnol, Vol. 2(1): 109-111

Experimental Investigation of the Gas Velocities in Three Biomass Cookstoves

In this study, gas velocities in different sections of three biomass cookstoves are found. A system using a Kiel probe, an electronic differential pressure transducer, and a thermocouple was used to measure pressure and temperature in order to calculate gas velocities. A Kiel probe and a sensitive electronic pressure transducer help in achieving quantifiable gas velocities. A woodgas stove, a rocket stove, and an open fire (for the purposes of this publication, an open fire is considered to be a type of stove) were tested at similar positions with respect to a cooking pot. The rocket stove and open fire used wood fuel, while the woodgas stove used pellet fuel. The gas velocity results ranged as follows: woodgas stove, 0.6 m/s to 1.56 m/s; rocket stove, 0.87 m/s to 2.88 m/s; open fire, −0.1 m/s to 1.42 m/s. The standard deviations of the velocities were mostly under 30% of the average. The ability to measure pressure and temperature simultaneously while running the stove normally can help cookstove testing and research. The goal is to not only know what stoves perform well or perform poorly, but to understand why stoves perform the way they do.

Implementation, Characterization, and Evaluation of an Inexpensive Low-Power Low-Noise Infrasound Sensor Based on a Micromachined Differential Pressure Transducer and a Mechanical Filter

The implementation, characterization, and evaluation of a low-cost infrasound sensor developed at the Infrasound Laboratory at the New Mexico Institute of Mining and Technology (Infra-NMT) are described. This sensor is based on a commercial micromachined piezoresistive differential pressure transducer that uses a mechanical high-pass filter to reject low-frequency outband energy. The sensor features a low-noise, 2.02-mPa rms (0.5–2 Hz), 5.47-mPa rms (0.1–20 Hz), or 5.62-mPa rms (0.05–20 Hz), flat response between 0.01 and at least 40 Hz; inband sensitivity of 45.13 ± 0.23 μV Pa−1; and a nominal linear range from −124.5 to +124.5 Pa. Intended for outdoor applications, the influence of thermal changes in the sensor’s response has been minimized by using a thermal compensated pressure transducer powered by an ultralow drift (<5 ppm °C−1) and noise (<4μV from peak to peak) voltage reference. The sensor consumes a minimum of 24 mW and operates with voltages above 8 V while drawing 3 mA of current. The Infra-NMT specifications described above were independently verified using the infrasound test chamber at the Sandia National Laboratories’ (SNL’s) Facility for Acceptance, Calibration, and Testing (FACT), and the following procedures are for comparison calibration against traceable reference stands in voltage and pressure. Because of the intended broad frequency response of this sensor, the testing chamber was configured in a double-reference sensor scheme. A well-characterized microbarometer (with a flat-amplitude response between 0.01 and 8 Hz) and a microphone (with a flat-amplitude response above 8 Hz) were used simultaneously in this double-reference test configuration.

Intelligent Vacuum-Pumping Detection Device Base on STM32MCU

Large centrifugal water pumps are widely applied in various water-supply and drainage systems. The vacuum-pumping is pre-requisite for their start-up so that the intelligent vacuum-pumping detection device utilizing STM32F103 as the main controller was presented to realize the automatic control especially of unattended pumps. A differential pressure transducer was adopted to measure the vacuum degree in pump chamber. Afterwards, an electrical signal of corresponding value was output, and then entered the ADC of STM32F103 after conditioning. The threshold algorithm was introduced for the judgement whether vacuum-pumping had been accomplished. Actual applications indicated this detection device was feasible and reliable, and the judgement algorithm was simply implemented and performed well in practice.

Discharge Measurements Using the Classic Gibson Method With Instrumentation Installed Inside a Pipeline

The Gibson method (pressure-time method) is one of the basic methods of discharge (flow rate) measurement applied in hydropower plants. Flow rate is determined by integrating the recorded variation of pressure difference between two measuring (hydrometric) sections in a pipeline (penstock). The Gibson method in its classic version consists in direct measurement of pressure difference variation between two hydrometric sections of a pipeline. Particular difficulties, related to application of the method in its various versions, arise in conditions of no access to the hydrometric sections from the outside of a pipeline. In such cases, it is necessary to install dedicated measuring instrumentation inside the pipeline. Such instrumentation has been implemented for the purpose of efficiency tests of two Francis turbines (upgraded and not upgraded) fed from a common penstock of 10 m diameter. The hydrometric sections were furnished with pressure taps connected by means of small copper tubes (impulse tubes) and hermetic manifolds to the differential pressure transducer. The transducer was installed in a hermetic housing and its electric signal was sent from the inside of the penstock to a computer data acquisition system. Using this method, the efficiency characteristics of the tested hydraulic turbines were determined. According to the authors’ knowledge, the pressure-time method has not been used in such an application so far. The method under consideration requires transmitting pressure signals from both penstock sections to the differential pressure transducer by means of impulse tubes. This raises the question on the influence exerted by dynamic properties of the connecting pipes / transducer system on the discharge measurement results. The previously developed computational method incorporating dynamic models of the piping and the transducer has been applied in order to determine this influence. In result of calculations conducted, the piezometric tubes / transducer system has been found to exert a negligible influence on the discharge measurement results.