The development of Middle Cretaceous carbonate platforms, Persian Gulf, Iran: constraints from seismic stratigraphy, well and biostratigraphy

Abstract

In the Iranian Persian Gulf several fields have been producing oil from Middle Cretaceous carbonates. Geological studies of these fields (limited to industry reports) describe the subsurface using lithostratigraphic principles. Lithological boundaries are obvious and are the focus for the correlation of the interwell areas. Most of the structural highs, which were easily found, have been drilled. The lack of a sufficiently detailed seismic sequence stratigraphic analysis has precluded the definition of reliable models at both regional and field scales.The development of many oil and gas fields requires seismic sequence stratigraphy as a predictive technique, particularly in areas between drilled structures. This study aims to re-evaluate the field-scale stratigraphy in an oil field in the southern Persian Gulf using these techniques. The high quality seismic and well data from this field form one of the first datasets of this kind presented in the literature. High-resolution seismic data reveal the internal complexity of carbonates. The Cenomanian carbonate systems of the southeastern Persian Gulf reveal internal architecture and subsurface variability that neither seismic nor well data alone can provide. This paper analyses the seismic character of the Cenomanian Khatiyah and Mishrif formations and discusses how, even after more than 25 years of production, application of sequence stratigraphic principles can improve the understanding of an oil field. For this oil field, the combination of seismic, wireline logs and biostratigraphy has allowed a better understanding of the internal heterogeneity of the Mishrif reservoir. Understanding the successive stages of drowning and back-stepping of a carbonate platform within this reservoir unit has important implications for well planning and further reservoir development.Important new information on the depositional geometries has also been obtained from within the Khatiyah Formation (the regional source rock) which leads to exploration targets in the interwell area. This information gives new insights as to the stratigraphic distribution and internal variability of the carbonate platforms and isolated build-up geometries. The insights gained are important to the estimation of reservoir volume, connectivity and variability.

Significance of angular unconformities between Cretaceous and Tertiary strata in the northwestern segment of the Zagros fold–thrust belt, Kurdistan Region, NE Iraq

“…In general, the sedimentary record shows that the Late Cretaceous represents a period of major change in the area of the present-day Zagros foreland basin (Loutfi, Baslaib & Abu Hamd, 1987; Burchette, 1993; Droste & Steenwinkel, 2004; Farzadi, 2005, 2006 a ). Rapid thickness variations and facies changes in Albian and Cenomanian sedimentary rocks, which have been documented both from seismic data and in the field, have been related to the reactivation of deep-seated pre-existing N–S-trending normal and strike-slip faults (Koop & Stoneley, 1982; Sepehr & Cosgrove, 2004; Sherkati & Letouzey, 2004).…”

Integrated bio- and carbon isotope stratigraphy of the Campanian–Danian sedimentary succession in Lurestan (Zagros Basin, Iran): Implications for syntectonic facies distribution and basin evolution

“…This Campanian age of the thrusting and coeval olistostrome deposition, however represents the youngest age of the frontal emplacement of the thrust system related to the Neo-Tethys oceanic obduction and therefore its onset should be older. Widespread karstification of the upper part of Sarvak and Mishrift formations has been interpreted as major doming of the Arabian margin as the consequence of the obduction during the Cenomanian-Turonian boundary at about 90 Ma (e.g., James and Wynd, 1965;Burchette, 1993;Alavi, 2004;Farzadi, 2006;Sharp et al, 2010), coeval with HP blueschist exhumation (Agard et al, 2011). The age of the massive Tethys intra-oceanic obduction above the Arabian margin, from Oman to Turkey, is also constrained by the radiometric ages of the ophiolitic suites of Kermanshah and Neyriz varying between 98 to 86 Ma (as compiled in Shafaii and Stern, 2015).…”

“…1A). Most papers indicate that the ZTB marks the position of the suture between the Iranian micro-continent and the Arabian Plate along which the subduction and the continental collision occurred (e.g., Takin, 1972;Berberian et al, 1982;Agard et al, 2005 and2006;Paul et al, 2006 and2010). This is supported by the presence of obducted ophiolite fragments (e.g., Ricou, 1971;Ricou et al, 1977) (Fig.…”

The Cogollo Group and the oceanic anoxic events 1a and 1b, Maracaibo basin, Venezuela

“…These ideas have also been explored in the Persian Gulf, at the platforms of the Middle Cretaceous carbonates (Khatiyah and Mishrif formations), where it is estimated that a high organic matter content in mudstone and wackestone facies of the inner shelf act as the source rock and adjacent porosity level act as reservoir facies (Farzadi 2006). Therefore, the generation and storage of hydrocarbons occurred in adjacent facies.…”