4D (Time Lapse) - Solutions
Challenge

Reservoir monitoring as fluids are drained out of the reservoir is an extremely important step in efficient drainage of the reservoir.  History matching is commonly used by reservoir engineers for monitoring. Changes in pore pressure and water saturation measured at some specified intervals in wells in the past are used to predict the future performance of the reservoir. The challenge is that reservoir heterogeneity between the wells may not be captured without additional information between the wells. There are several examples in current literature of by-passed oil even though history matching is accurate at well location.

RSI Solutions

By inverting time lapse seismic data we relate changes in acoustic and elastic attributes to changes in pore pressure and water saturation as the reservoir is drained. Therefore, starting from a static reservoir model we update the dynamic reservoir model through history matching (at well location) and through calibrated inversion (away from the well) giving the reservoir engineer a more accurate reservoir management tool. The steps in this process include:

  • iMOSS to develop rock physics models to calibrate rock properties at well control data points. For 4D, in addition to fluid substitution modeling to simulate hydrocarbon removal, this includes pressure depletion modeling to determine the effects of pore pressure changes on log measurements as well as repeat seismic surveys.
  • AVATAR pre-stack and post-stack seismic data conditioning to increase the fidelity, resolution, and accuracy of gathers and stacks, including angle stacks. This is performed on the initial seismic survey as well as all subsequent repeat surveys.
  • iMOSS to tie surface seismic data, pre-stack and post-stack, to well log acoustic impedance reflection coefficients and extract a convolutional matching filter (seismic wavelet).
  • Rock physics-driven pre-stack simultaneous seismic inversion, tightly integrated with well data to predict robust static reservoir attributes of porosity, lithology and pore fluids and geomechanical reservoir attributes such as Young’s modulus and Poisson’s ratio away from well control.
  • iMOSS to calibrate inverted acoustic and elastic attributes to well data.
  • Multi-attribute geological and rock property interpretation of the changes between subsequent seismic surveys. This includes a comparison of the theoretical changes as determined by rock physics modeling with the changes observed in the updated seismically-derived rock property volumes.
  • WISE: Advanced modelling of the effect of reservoir changes on seismic and CSEM data