Forward Stratigraphic Modeling of Kuwait Formation, Linking Facies Architecture to Hydrocarbon Occurrence

The objective of this study is to perform forward stratigraphic modeling on the Kuwait Formation (also known as Kuwait Group) exposed stratigraphic succession along the Jal Az-Zor escarpment to explain the enigmatic occurrence of an elongated NW-SE geobody mapped from subsurface data at northern Kuwait. Outcrop measurements such as; stratigraphic successions, facies distribution, critical facies trends, and paleocurrent analysis have been collected along the 60 km length of the Jal Az-Zor escarpment. Such measurements were combined with thin section lab analysis to reveal the various sedimentary processes such as wave activity, grain size distribution, sediment supply sources, accommodation space, and erosional rates. These measurements were combined with subsurface data such as seismic attributes to reconstruct the paleography of the area and run a forward stratigraphic model simulation. The vertical succession was also utilized to reconstruct the relative sea-level fluctuation through time to develop an accurate model. Forward stratigraphic modeling resulted in building a robust and reliable facies distribution 3D model for the Jal Az-Zor escarpment that demonstrates the complex facies architecture. The model shows the various stacking patterns of several depositional sequences that are observed in the field as well as the subsurface. The enigmatic geobody mapped from seismic as a channel system in previous publications turned out to be a paleoshoreline. This shoreline is composed of high-quality sands as a result of an elevated level of wave activity. Reworking of barrier island sands was also found to be responsible for the enhanced reservoir quality. Consequently, regardless of the subsurface structure, the main driver of successful hydrocarbon accumulation is directly linked to the NW-SE trending paleoshoreline. To the best of the authors’ knowledge, this is the first time forward-stratigraphic modeling is performed along the Jal Az-Zor escarpment in north Kuwait and using such an approach to unravel Kuwait Formation heavy hydrocarbon subsurface occurrences.

Use of seismic-based new rose diagram to determine the major sediment-supply direction of progradational systems

A conventional method for identifying sediment-supply directions is to characterize the seismic progradational reflection configuration, which is based mainly on qualitative observation of numerous seismic profiles. We have developed a more quantitative and practical way to determine the major sediment-supply direction (MSSD) using a new type of rose diagram based on seismic progradational sequence angles. In accordance with similar principles of the rose diagram used in structural geology, we have developed an analytical method and a workflow for a new rose diagram of seismic-based progradational sequence angles to determine MSSD. The Bozhong sag, a subbasin of the Bohai Bay Basin with two typical progradational sequences (I and II), provides a suitable example to analyze MSSD and test the new method. Our result indicates that the MSSD of the two progradational sequences (I and II) corresponds to azimuths of 10°–20° and 340°–350°, respectively, intuitively indicating two sequences derived from different provenance-transport systems. The new rose diagram of seismic progradational angles offers a powerful and quantitative method for seismic-based sedimentary provenance and paleocurrent analysis.