Seismic data is increasingly utilized in Unconventional settings to high-grade Earth Models. Seismic inversions provide all manner of qualitative/quantitative input into the geologic interpretations; from fault/fracture swarm identification to reservoir richness, thickness, and brittleness calculations to geologic facies mapping, well path picking, etc. However, it is well-known that inversions are non-unique representations of the real-world and require calibration/interpretation to settle on reservoir properties for use in Earth Models. The greater the calibration constraints placed on the inversions, the less the requirement for non-unique interpretation of the inversion, or equivalently, the higher the inversion resolution.
Typically, seismic inversions are calibrated with vertical well data points with good sonic/density logs and then stratigraphically constrained by structural/stratigraphic picks from other available wells. However, the abundance of vertical wells with adequate sonic/density is generally very limited. Also, the seismic calibration is limited to the single seismic trace of the vertical well/seismic intersection. While horizontal data would be ideal for calibrating properties in addition to stratal boundaries, properties for horizontal control are limited by both the complications of anisotropy, inadequate QC of field logs (particularly shear), and the very rare presence of horizontal sonic/density logs. In most cases, properties in the inversions are calibrated with vertical wells only.
A typical horizontal well has approximately 20-40 times more samples in the target zone than a corresponding vertical well and with large lateral coverage. Quantico’s experience with a wide variety of geological settings and its vast library of well data – with more horizontal logging and drilling data than possessed by virtually any single oil and gas company – enables operators to significantly increase calibration and resolution in seismic inversions. Quantico has developed reliable horizontal log QC such that bad data is eliminated from use. Quantico has addressed anisotropy by calibrating vertical to horizontal wells in various basins. Quantico has developed its proprietary QLog product to provide shear, compressional and density data for horizontal wells without running open hole logging tools. All of these developments enable more timely, accurate, and cost-effective seismic inversions than ever before. Quantico can work closely with client personnel to provide fit-for-purpose expertise to assist customers using Quantico QLog products in the inversion process or provide an inversion service on request.
Deciding if a given area is worthy of development, deciding on a well path, or determining frac design are all big decisions – with potential impact in the millions to hundreds of millions of dollars. Providing an operational process with all the necessary expertise to dependably deliver a complete, timely, accurate seismic inversion to the customer ensures these key decisions are made optimally.