Active seismic monitoring of underground formation under production, for use in hydrocarbon industry, involves allowing separation of induced microseismic signals from seismic signals emitted during surveillance

摘要

The microseismic signals of induction separate with the monitoring signal recorded compared with a benchmark spectrum model and consider spectral contribution from each source (Si) of the basic frequency issuing and in their respective harmonic wave, recombinate microseismic signals in the time domain by being inverted. There is earthquake record circulation Transmitted station to enter composition, and one or more focus (5) are connect with it and are simultaneously emitted by orthogonal signalling relative to each other in this case to form a compound vibration signal. It is received by the return of the signal of composition and is recorded by least one geophone (2), tracer signal processing is with point anaseismic respective contribution to received signal and rebuilds to be equivalent to and will pass through the seismogram for respectively operating those of focus acquisition. The spectral contribution for receiving the microseismic signals of signal, which passes through, reduces amplitude and phase value acquisition associated with benchmark spectrum model against the amplitude and phase value recorded. Spectral comparison model is a running model, is made of the spectral contribution of record circulation before using a pervious spectral model and considering. The spectrum model of operation is or average by one of the frequency spectrum of the extrapolation or insertion of the frequency spectrum from adjacent spectral values or median is formed by determining from the pervious and/or subsequent recording obtained from the identical source in identical frequency. The respective contribution (Cp, i, n) in different sources is calculated for each record n of a record cycle p using N focus (Si). Then the ratio (Ep, n) of the contribution of the spectral model (Mp, n) of an operation is calculated, there is running model, formed by updating a pervious spectral model (Mp, n-1) from the frequency issued during preceding record (n-1) and their harmonic wave. Partially (aircraft, n) for can it is related with active seismic monitoring circulation p record n then by inference therefore be to passive microseismic activity only it is related circulation p record n part (pp, n) by inference. Seismogram for active seismic monitoring makes respective spectral contribution (Cp, i, n) to be inverted formation in the time domain after the measurement circulation of completion one by each focus (Si) for basic frequency and their harmonic wave. Following microseismic signals are found by the inversion in the time domain of the corresponding portion of signal (pp, n). Spectral contribution (Cp, i, n) is obtained by increasing a transmission function (Tp, i, n, r) between the wavelet character source associated with a receiver (r) and a wavelet character of a seismogram by source. Transmission function is continually updated during the current cycle from estimation, r) (Tp, i, n-1 are manufactured during previous cycle and are manufactured during through the current cycle of relationship Tp, i, n, r=(1-h) Tp, i, n-1, r+hT0p, i, n, r with an initial estimate (T0p, i, n, r)