Building 3D subsurface models conforming to seismic structural and stratigraphic features

Abstract

Subsurface modeling from seismic and borehole data is important for reservoir prediction, geophysical exploration, and production. A reasonable model should honor borehole rock properties and conform to seismic structural and stratigraphic features. Such a subsurface model can be difficult to build in cases complicated by faults and unconformities. Automatic and semiautomatic methods have been proposed to build subsurface models from seismic and borehole data; however, seismic structural and stratigraphic features and borehole measurements are not fully used in most methods. I have developed a workflow to fully use seismic and borehole data to build subsurface models that honor borehole measurements and conform to seismic horizons, faults, unconformities, and stratigraphic features such as channels. In this workflow, I first automatically remove the faulting and folding in seismic and borehole data and map them into an unfaulted and flattened space, in which seismic reflectors and borehole measurements corresponding to the same geologic layers are horizontally aligned. I then build a subsurface model in this unfaulted and flattened space by computing a sequence of 2D horizontal interpolations of borehole data. Each horizontal interpolation is guided by the stratigraphic features apparent in the corresponding horizontal seismic slice, so that the interpolant conforms to the seismic stratigraphic features. I finally map the interpolated model back into the input space and obtain a subsurface model that honors the seismic and borehole data. I demonstrate the proposed workflow using synthetic and real examples complicated by faults and unconformities.