Dang Ruirong

Research of sensor about detecting sand production in oil and gas wells

Theres no report on sand production detection sensor at home, and no application in heavy oil abroad. In order to meet the needs of heavy oil sand production detection, a PZT sensor is developed which used piezoelectric material. The performance test and a large number of indoor and field experiments show that the sensor can not only distinguish the strong noise and sand signal, but also have stable performance and meet the requirements of sand production of heavy oil.

Forward simulation of remaining oil exploration in cross-well by time domain electromagnetic method

Based on electromagnetic field theory, this paper derived the general expressions of time domain responses for cross-well electromagnetic logging. The emission waveform may be chosen as bipolar square wave by calculating the spectrums of three types of transmit signals. And the effects of thickness, magnetic permeability and electrical conductivity of the casing on time domain electromagnetic logging responses were analyzed. The computation results show that the casing change whether thinner or thicker has an obvious effect on the time domain logging responses. The simulation results also indicate the higher the casing electrical conductivity, the lower the response signal amplitude; and the lower the magnetic permeability, the more easy the electromagnetic signals through the casing. Furthermore, the sensitivity analysis of the time domain electromagnetic responses to the formation resistivity indicates that the electromagnetic responses are fairly sensitive to the formation resistivity. This result proved the feasibility and effectiveness of cross-well time domain electromagnetic logging technology applies to the field of oil and gas exploration.

Numerical analysis of eddy current effect for low frequency electromagnetic method in cross-well

In order to analyze the eddy current caused by the excitation signal and its influence on the secondary field response, the general analytical expressions of eddy current density for low frequency electromagnetic in cross-well is deduced. Based on the axially symmetric time harmonic electromagnetic theory, this expression is established by Helmholtz equation of electric field in radial non-uniform formation. Eddy current density distribution of infinite homogeneous conductive medium and layered media in cross-well show that the metal casing has a strong absorption to electromagnetic signal and the frequency of the emission signal has important influence on its capability of penetrating the casing. The character of EMF (electromotive force)-frequency curves for the non magnetic high resistance formation demonstrates that the low frequency electromagnetic signal can penetrate the casing perfectly, and it also shows that response signal has the highest resolution to the formation resistivity while excited by the frequency about 200Hz.