Outcrop-to-subsurface correlation and sequence stratigraphy of a mixed carbonate–siliciclastic ramp using element geochemistry and well logging; Upper Cretaceous Kometan Formation, Zagros Foreland, NE Iraq

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989592%3A15310%2F24%3A73622282" target="_blank" >RIV/61989592:15310/24:73622282 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0037073823002191" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0037073823002191</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.sedgeo.2023.106547" target="_blank" >10.1016/j.sedgeo.2023.106547</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Outcrop-to-subsurface correlation and sequence stratigraphy of a mixed carbonate–siliciclastic ramp using element geochemistry and well logging; Upper Cretaceous Kometan Formation, Zagros Foreland, NE Iraq

Popis výsledku v původním jazyce

Surface analogues are suitable tools to link reservoir models to real facies but they require a robust outcrop-tosubsurface stratigraphic correlation. In this study, we correlate gamma-ray (GR), and porosity logs from nine wells drilled in the Cretaceous Kometan Formation, a prolific carbonate reservoir of northern Iraq, with geochemical logs from three sections representing surface analogues. The sections were sampled for microfacies, X-ray diffraction mineralogy, and element geochemistry using X-ray fluorescence spectrometry calibrated by ICP-MS data. Six microfacies composed of mudstones to packstones with planktonic, and benthic foraminifers were identified in outcrop, and interpreted as middle ramp, outer ramp, and basin deposits. The microfacies show increasing Al and K, and decreasing Ca concentration trends from the middle ramp to the basin settings. Their subsurface analogues are carbonates, marls and shales with benthic foraminifers, deposited in proximal, inner to middle ramp parts of the Kometan mixed carbonate–siliciclastic ramp system. The K + Al logs are correlated for 33 km, and the subsurface GR logs for over 100 km distance, but both reflect detrital admixture in biogenic carbonate. However, the outcrop- and subsurface log patterns show opposite vertical trends. The subsurface, inner ramp GR maxima in the middle Kometan, correlate with the outcrop K + Al minima jointly reflecting landwards and seawards shifts of the middle ramp carbonate factory during transgressions and regressions, respectively. The maxima and minima are interpreted as maximum regression (mrs) and maximum flooding surfaces (mfs) in the T–R sequence-stratigraphic model. Neutron-density and sonic logs indicate that the best reservoir quality is achieved in fractured pure carbonates, which are controlled by these T–R cycles. The results highlight the importance of elemental geochemistry in stratigraphic correlation of lithologically uniform sequences, and suggest that outcrop geochemistry can be correlated with well logs.

Název v anglickém jazyce

Outcrop-to-subsurface correlation and sequence stratigraphy of a mixed carbonate–siliciclastic ramp using element geochemistry and well logging; Upper Cretaceous Kometan Formation, Zagros Foreland, NE Iraq

Popis výsledku anglicky

Surface analogues are suitable tools to link reservoir models to real facies but they require a robust outcrop-tosubsurface stratigraphic correlation. In this study, we correlate gamma-ray (GR), and porosity logs from nine wells drilled in the Cretaceous Kometan Formation, a prolific carbonate reservoir of northern Iraq, with geochemical logs from three sections representing surface analogues. The sections were sampled for microfacies, X-ray diffraction mineralogy, and element geochemistry using X-ray fluorescence spectrometry calibrated by ICP-MS data. Six microfacies composed of mudstones to packstones with planktonic, and benthic foraminifers were identified in outcrop, and interpreted as middle ramp, outer ramp, and basin deposits. The microfacies show increasing Al and K, and decreasing Ca concentration trends from the middle ramp to the basin settings. Their subsurface analogues are carbonates, marls and shales with benthic foraminifers, deposited in proximal, inner to middle ramp parts of the Kometan mixed carbonate–siliciclastic ramp system. The K + Al logs are correlated for 33 km, and the subsurface GR logs for over 100 km distance, but both reflect detrital admixture in biogenic carbonate. However, the outcrop- and subsurface log patterns show opposite vertical trends. The subsurface, inner ramp GR maxima in the middle Kometan, correlate with the outcrop K + Al minima jointly reflecting landwards and seawards shifts of the middle ramp carbonate factory during transgressions and regressions, respectively. The maxima and minima are interpreted as maximum regression (mrs) and maximum flooding surfaces (mfs) in the T–R sequence-stratigraphic model. Neutron-density and sonic logs indicate that the best reservoir quality is achieved in fractured pure carbonates, which are controlled by these T–R cycles. The results highlight the importance of elemental geochemistry in stratigraphic correlation of lithologically uniform sequences, and suggest that outcrop geochemistry can be correlated with well logs.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GA22-15405S" target="_blank" >GA22-15405S: Raně diagenetická mobilita geochemických indikátorů redoxních podmínek a paleoklimatologický význam kontinentálních červených vrstev</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2024

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

SEDIMENTARY GEOLOGY

ISSN

0037-0738

e-ISSN

1879-0968

Svazek periodika

459

Číslo periodika v rámci svazku

JAN

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

15

Strana od-do

"106547-1"-"106547-15"

Kód UT WoS článku

001166843400001

EID výsledku v databázi Scopus

2-s2.0-85178335518