Compressional sonic, shear sonic, and density logs and core measurements provide the information necessary to model the seismic expression of a logged interval. In addition to modeling the logged interval "as-is", the logs can be stretched, squeezed, and editted to simulate other potential reservoir possibilities.
For example, at well #33, sonic and density logs were used to investigate the effect of rock quality on AVO signatures. The reservoir in the well #33 consists of two rock types: laminated shaly sand (found at the top and base of the reservoir) and a shalier, bioturbated sand (found in the centre of the reservoir). The purpose of the investigation was to understand the AVO signature associated with these rock types. A key observation from this work was that the shalier, bioturbated gas filled rock type comprising the centre of the reservoir does not provide enough acoustic impedance contrast to be imaged using seismic. Fortunately, the shalier rock type is encased in a sandier laminated shaly-sand rock, that exhibits a bright spot. The AVO synthetic and associated AVO signatures from the top and base of the reservoir indicate that a boundary between shale and gas filled laminated shaly sand will create a strong seismic reflection that increases in strength with offset. By substituting gas-filled bioturbated shaly sand for the cleaner laminated shaly sand allows the interpreter to examine the effect of rock type on the seismic reflection. In this manner, the interpreter can examine:
