The Development of a Gas–Liquid Two-Phase Flow Sensor Applicable to CBM Wellbore Annulus

2018

Journal of Sensors

Self Cite

Turbodrill is an important type of drilling tool. Rotating speed is a key parameter to measure and control the efficiency of a turbodrill. Therefore, it is necessary to measure the rotating speed when a turbodrill is working under a well. However, current speed measurement devices and sensors cannot meet the requirements of the on-site downhole conditions due to many factors, including inadequate sealing, signal interference, difficult installation, and theoretical limitations. To break the aforementioned bottleneck, a new speed sensor used for turbodrills is designed based on the centrifugal force theory. In more detail, the measurement of the speed is performed based on a functional relation between the rotating speed and the centrifugal force of the turbodrill. Besides, the sensor was tested both in-lab and on-site. The test results illustrate that the measurement error is within ±4%, which meets the practical on-site conditions.

Section: Measurement Indexesmentioning

confidence: 96%

Design of a Centrifugal Force-Based Speed Sensor for Downhole Turbodrills

Ding

2018

Journal of Sensors

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“…Causes of null drift include initial deformation of the strain gauge and the irreversible and permanent residue deformation of the strain gauge when it suffers a large hit. The AD8230 chip (Analog Devices, Norwood, MA, USA) was used for building the hardware circuit to solve the problem of null drift, as shown in Figure 3 [ 21 ].…”

Section: Design Of the Sensormentioning

confidence: 99%

The Development and Test of a Sensor for Measurement of the Working Level of Gas–Liquid Two-Phase Flow in a Coalbed Methane Wellbore Annulus

Ding

2018

Sensors

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Coalbed methane (CBM) is one kind of clean-burning gas and has been valued as a new form of energy that will be used widely in the near future. When producing CBM, the working level within a CBM wellbore annulus needs to be monitored to dynamically adjust the gas drainage and extraction processes. However, the existing method of measuring the working level does not meet the needs of accurate adjustment, so we designed a new sensor for this purpose. The principle of our sensor is a liquid pressure formula, i.e., the sensor monitors the two-phase flow patterns and obtains the mean density of the two-phase flow according to the pattern recognition result in the first step, and then combines the pressure data of the working level to calculate the working level using the liquid pressure formula. The sensor was tested in both the lab and on site, and the tests showed that the sensor’s error was ±8% and that the sensor could function well in practical conditions and remain stable in the long term.

“…2 Theoretical calculation model of gas output Gas-liquid two-phase flow exists in CBM extraction wells irrespective of gas-liquid-solid three-phase flow due to the existence of coal dust (Ma et al 2017). This means that parameters related to two-phase flow remains key to calculating CBM outputs (Wu et al 2016). This means that gas outputs from each coal seam can be calculated by establishing a model for these volumes from commingled CBM drainage and extraction wells.…”

Section: Introductionmentioning

confidence: 99%

A dynamic evaluation technique for assessing gas output from coal seams during commingling production within a coalbed methane well: a case study from the Qinshui Basin

Yuan

et al. 2020

Int J Coal Sci Technol

Self Cite

Gas drainage is carried out based on output from each coal bed throughout commingling production of coalbed methane (CBM). A reasonable drainage process should therefore initially guarantee main coal bed production and then enhance gas output from other beds. Permanent damage can result if this is not the case, especially with regard to fracture development in the main gas-producing coal bed and can greatly reduce single well output. Current theoretical models and measuring devices are inapplicable to commingled CBM drainage, however, and so large errors in predictive models cannot always be avoided. The most effective currently available method involves directly measuring gas output from each coal bed as well as determining the dominant gas-producing unit. A dynamic evaluation technique for gas output from each coal bed during commingling CBM production is therefore proposed in this study. This technique comprises a downhole measurement system combined with a theoretical calculation model. Gas output parameters (i.e., gas-phase flow rate, temperature, pressure) are measured in this approach via a downhole measurement system; substituting these parameters into a deduced theoretical calculation model then means that gas output from each seam can be calculated to determine the main gas-producing unit. Trends in gas output from a single well or each seam can therefore be predicted. The laboratory and field test results presented here demonstrate that calculation errors in CBM outputs can be controlled within a margin of 15% and therefore conform with field use requirements.