Method for quantitatively assessing connectivity for well pairs at varying frequencies

摘要

Method for quantitatively assessing connectivity for well pairs at varying frequencies. A time series of measurements (12) is chosen for each of the two wells such that the particular measurements will be sensitive to subsurface connectivity if it exists (11). The two time series may then be pre-processed by resampling to time intervals commensurate with response time between the two wells (13), detrending the measurements (14), and detecting and eliminating spiking noises (15). Then the time series are transformed to the frequency domain where coherence and phase between the two series are compared for varying frequencies (16). This comparison is used to make a determination of connectivity.

主权项

1. A method for quantitatively assessing connectivity between two wells in a subsurface region for the purpose of planning or managing production of hydrocarbons from the subsurface region, comprising:
obtaining for each of at least two wells a time series of measurements characterizing a physical or operating condition of the well as a function of discrete time from a downhole monitoring gauge disposed within the well; resampling each of the time series of measurements at a different time interval; comparing, in a computer system, spectral content of a first time series of measurements from a first well of at least two wells to spectral content of a second time series of measurements from a second well of at least two wells, wherein said comparison between wells of spectral content of time series of measurements comprises:
(a) obtaining for each of the wells the time series of measurements characterizing the physical or operating condition of the well, said physical or operating condition being selected to show coherence between the two wells only if the wells are hydraulically connected through the subsurface region;(b) estimating either cross-spectral coherence or both cross-spectral coherence and phase of the two time series, wherein coherence or phase is estimated by a mathematical computation of cross-spectral coherence or phase, yielding numerical values of coherence or phase at varying frequencies; and(c) quantitatively assessing connectivity between the two wells using the estimated coherence or the estimated coherence and phase; and based on the comparison, determining connectivity between the at least two wells; and based on the connectivity determination, managing production of hydrocarbons from the subsurface region using the well connectivity assessment.