| With the oil and gas exploitation entering into the late period in the course of production, the water cut of many production wells is higher than before and the yield is reducing. The residual oil recovery is the important assurance of oilfield stable production and increase the ultimate recovery factor in this period. In order to exploit the residual oil, we must detect it first. The transient electromagnetic methods are introduced into the detection field of residual oil, and the transmitting system of borehole transient electromagnetic methods is established. The system with more sensitive to the low resistivity layers, large of detection has important significance and widespread applications in the residual oil recovery.Based on the theory of transient electromagnetic methods, the related problems of borehole transient electromagnetic transmitting technology were analyzed; the basic problems of borehole transient electromagnetic methods were discussed. The paper derives the theoretical formula for the borehole electromagnetic response of four-cylindrical-layer model about borehole, the casing, the cement sheath and the formation. The influencing Factors of transient electromagnetic response are studied by numerical simulation. According to the theoretical studies, the scheme to transmitting system of borehole transient electromagnetic methods is designed. By the Combination of single chip and timing control unit together, the related functional module can work orderly. The needed waveforms can be emitted by transmitter circuit, and the emission current can be turned off quickly. The descend edge of emission current and turn-off time can be measured precisely in this system. Finally the models of borehole transient electromagnetic transmitting technology are validated on the testing platform. The results show that this system has achieved the design requirements, and it also can provide certain reference for research on the borehole transient electromagnetic technology. |
PDF Full Text Request