Measurement of Annular Flow for Drilling Engineering by Electromagnetic Flowmeter Based on Double-Frequency Excitation

Abstract

Using downhole annular electromagnetic flow measurement to obtain annular flow in real-time is a foundation of microflow control drilling technology. The existing annular flow electromagnetic measurement method based on low-frequency rectangular excitation is affected by slurry interference and formation fluid invasion, which results in large noise generated on the electrode output signal. These noise causes the instability of the flow measurement system output and lower accuracy. Double-frequency rectangular wave excitation has the advantages of excellent zero-point stability attributed to low-frequency rectangular wave excitation and fast response speed with great ability to suppress slurry interference. First, the double-frequency rectangular wave excitation for annular flow electromagnetic measurement is researched, and its corresponding electromagnetic induction signal process is investigated. In order to verify the feasibility of downhole annular electromagnetic flow measurement, a flow verification platform for comparison of standard and detected parameters is established for simulation experiment, and the ability to suppress slurry interference and response speed of the technology in downhole slurry flow measurement are analyzed. The test results show that the downhole annular electromagnetic flow measurement based on double-frequency rectangular wave excitation can not only satisfy the requirements of regular electromagnetic flow measurement but also suppress the annular slurry interference effectively.

Research on New Drilling Downlink Communication Based on Anisotropic Magnetoresistive Technology

“…Equation (15) shows that the tangential component of magnetic field intensity is continuous. To facilitate the subsequent establishment and derivation of the magnetic field intensity model, the potential function is introduced.…”

“…However, the weak current-carrying information in electric current field information transmission has restricted its development to a certain extent. At present, the main application occasions of electric current field information transmission are generally in underwater, mine, subway emergency communication, and other fields [15]. Schiltz C. W pointed out that the technology of communication by conducting electric current field was feasible, and introduced a wireless transceiver device based on electric current field communication [16].…”

Electrodes Optimization of an Annular Flow Electromagnetic Measurement System for Drilling Engineering

“…Wi and they are all real numbers, the average of the vector weight function is W . The standard deviation of the vector weight function Wσ can be expressed by equation (20). This article has been accepted for publication in a future issue of this journal, but has not been fully edited.…”

“…However, under the special measurement environment (high temperature, high pressure and strong vibration environment) of underground annulus flow [19], if too many electrodes are used, it is not conducive to the tightness and reliability of the downhole measurement system. The electrode optimization can be realized by improving the electrode shape and excitation method [20]. In addition, many researches have been implemented based on virtual current density, but they all aimed at circular pipelines.…”

Study on a New Electromagnetic Flow Measurement Technology Based on Differential Correlation Detection

“…The inter-electrode interference of the EMF mainly includes differential interference, in-phase interference, power-line interference, electro-chemistry interference, and slurry fluid interference. The improvement of the EMF measurement accuracy also optimizes anti-interference technology [8][9][10].…”