井中激发的瞬态、稳态响应与测井方法集成

研究井中激发的瞬态响应时需结合井内、外瞬态物理场的传播、扩散过程和探头的综合响应。发射探头能同时激发声、电、磁3种瞬态物理场, 采用多种探头同时接收可获得地层的多个物理参数, 实现测井方法集成。压电管和压电片激发瞬态振动瞬间同时激发同频谱的瞬变电磁场; 带磁芯的线圈在其电流导通、关断瞬间激发瞬变电磁场时, 磁芯磁致伸缩变形同时激发振动, 振动和瞬变电磁在井和地层中分别根据声和电磁的规律传播、扩散。在井中对瞬态电磁场和声场同时测量可实现电阻率和声波测井。利用圆柱形井壁对径向传播声波的无数次反射形成的固有频率, 采用共振响应的方式进行大功率激发, 使能量有效地穿过井壁进入地层, 可实现远距离探测。进一步加大激发功率, 瞬态强磁场激发砂岩孔隙流体的核磁共振, 强振动激发震电效应, 在井中用高灵敏度探头接收可实现核磁和震电测量。采用稳态大功率超声激发高通量中子可实现中子、密度测井, 再利用其导通和关断瞬间激发的瞬态响应进行声波和电阻率测井, 最后实现测井原理集成的终极目标——声电磁核组合, 这种集成方法可应用于裸眼井和套管井测井。

Borehole transient response should be investigated with consideration to the propagation and diffusion of transient physical fields inside and outside the borehole and the comprehensive responses of probes.A transmitter can actually excite three transient physical fields (acoustic, electric and magnetic) at the same time, and multiple probes can work simultaneously to obtain multiple physical parameters of formation, allowing for the integration of logging techniques.The piezoelectric tube and plate excite the transient vibration and electromagnetic field with the same spectrum.The coil with magnetic core produces the transient electromagnetic field when its current is turned on and off.At the same time, the magnetostrictive deformation of the magnetic core also excites the vibration, which propagates in the borehole according to the law of acoustics and diffuses according to the electromagnetic law.Resistivity and acoustic logging can be achieved by simultaneous measurement of transient electromagnetic and acoustic fields in borehole.The natural frequency and resonance response formed by continuous reflection of radial acoustic wave from cylindrical sidewall can be used to transmit at a high power, and the energy can effectively pass through the sidewall into the formation, so that the formation far away from the borehole can be detected.When the excitation power is further increased, the nuclear magnetic resonance of pore liquid in sandstone is excited by the transient strong magnetic field, and the seismoelectric effect is excited by the strong vibration.The nuclear magnetic and seismoelectric measurement can be realized by using highly sensitive probes in the borehole.Neutron and density logging can be achieved as the high-flux neutrons are produced by steady-state high-power ultrasonic excitation, and acoustic and resistivity logging can be obtained using transient responses produced as it turns on and off, which is the ultimate goal of principle integration.The integrated tool can be used in open hole and cased hole.